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1952 Jaguar C Type
The Jaguar C-Type (officially called the Jaguar XK120-C) is a racing sports car built by Jaguar and sold from 1951 to 1953. The "C" stands for "competition".
The car combined the running gear of the contemporary, road-proven XK120, with a lightweight tubular frame designed by Jaguar Chief Engineer William Heynes, and an aerodynamic aluminium body, jointly developed by William Heynes, R J (Bob) Knight and later Malcolm Sayer. A total of 53 C-Types were built, 43 of which were sold to private owners, mainly in the US.
The road-going XK120’s 3.4-litre twin-cam, straight-6 engine produced between 160 and 180 bhp (134 kW). The C-Type version was originally tuned to around 205 bhp (153 kW). The early C-Types were fitted with SU carburettors and drum brakes. Later C-Types, produced from mid 1953, were more powerful, using triple twin-choke Weber carburettors and high-lift camshafts. They were also lighter, and braking performance was improved by using disc brakes on all four wheels. The lightweight, multi-tubular, triangulated frame was designed by Heynes. Heynes, Knight and Sayer together developed the aerodynamic body. Made of aluminium in the barchetta style, it was devoid of road-going items such as carpets, weather equipment and exterior door handles. According to the Jaguar Heritage Registry, the cars were produced between May 1952, starting with XKC001, and ending in August 1953 with XK054. The original alloy body was marked with the prefix K (e.g. K1037).
The C-Type was successful in racing, most notably at the Le Mans 24 hours race, which it won twice.
In 1951, the car won at its first attempt. The factory entered three, whose driver pairings were Stirling Moss and Jack Fairman, Leslie Johnson and triple Mille Miglia winner Clemente Biondetti, and the eventual winners, Peter Walker and Peter Whitehead. The Walker-Whitehead car was the only factory entry to finish, the other two retiring with lack of oil pressure. A privately entered XK120, owned by Robert Lawrie, co-driven by Ivan Waller, also completed the race, finishing 11th.
In 1952, Jaguar, worried by a report about the speed of the Mercedes-Benz 300SLs that would run at Le Mans, modified the C-Type’s aerodynamics to increase the top speed. However, the consequent rearrangement of the cooling system made the cars vulnerable to overheating, and all three retired from the race. The Peter Whitehead-Ian Stewart and Tony Rolt/Duncan Hamilton cars blew head gaskets, and the Stirling Moss-Peter Walker car, the only one not overheating having had a full-sized radiator hurriedly fitted, lost oil pressure after a mechanical breakage.[3] Testing by Norman Dewis at MIRA after the race proved that the overheating was caused more by the revisions to the cooling system than by the altered aerodynamics: the water pump pulley was undersized, so it was spinning too fast and causing cavitation; also the header tank was in front of the passenger-side bulkhead, far from the radiator, and the tubing diameter was too small at 7/8 inch. With the pump pulley enlarged, and the tubing increased to 1 1/4 inch, the problem was eliminated. The main drawback of the new body shape was that it reduced downforce on the tail to the extent that it caused lift and directional instability at speeds over 120 mph (193 km/h) on the Mulsanne Straight. These cars had chassis numbers XKC 001, 002 and 011. The first two were dismantled at the factory, and the third survives in normal C-type form.
In 1953, C-Types won again, and also placed second and fourth.[4] This time the body was in thinner, lighter aluminium and the original twin H8 sand cast SU carburettors were replaced by three DCO3 40mm Webers, which helped boost power to 220 bhp (164 kW). Philip Porter mentions additional changes:
Further weight was saved by using a rubber bag fuel tank ... lighter electrical equipment and thinner gauge steel for some of the chassis tubes ... [T]he most significant change to the cars were the triple Weber carburetors and [switch to] disc brakes.
Duncan Hamilton and Tony Rolt won the race at 105.85 mph (170.35 km/h) – the first time Le Mans had been won at an average of over 100 miles per hour (161 km/h).
Disc brakes were novel in 1953, and Jaguar's win, partly due to their superiority, set off a scramble to include discs in production cars.
1954, the C-Type's final year at Le Mans, saw a fourth place by the Ecurie Francorchamps entry driven by Roger Laurent and Jacques Swaters.
20x30 in 77x51 cm
None of my work is Ai assisted and is copyright Rg Sanders aka Ronald George Sanders.
1952 Jaguar C Type
The Jaguar C-Type (officially called the Jaguar XK120-C) is a racing sports car built by Jaguar and sold from 1951 to 1953. The "C" stands for "competition".
The car combined the running gear of the contemporary, road-proven XK120, with a lightweight tubular frame designed by Jaguar Chief Engineer William Heynes, and an aerodynamic aluminium body, jointly developed by William Heynes, R J (Bob) Knight and later Malcolm Sayer. A total of 53 C-Types were built, 43 of which were sold to private owners, mainly in the US.
The road-going XK120’s 3.4-litre twin-cam, straight-6 engine produced between 160 and 180 bhp (134 kW). The C-Type version was originally tuned to around 205 bhp (153 kW). The early C-Types were fitted with SU carburettors and drum brakes. Later C-Types, produced from mid 1953, were more powerful, using triple twin-choke Weber carburettors and high-lift camshafts. They were also lighter, and braking performance was improved by using disc brakes on all four wheels. The lightweight, multi-tubular, triangulated frame was designed by Heynes. Heynes, Knight and Sayer together developed the aerodynamic body. Made of aluminium in the barchetta style, it was devoid of road-going items such as carpets, weather equipment and exterior door handles. According to the Jaguar Heritage Registry, the cars were produced between May 1952, starting with XKC001, and ending in August 1953 with XK054. The original alloy body was marked with the prefix K (e.g. K1037).
The C-Type was successful in racing, most notably at the Le Mans 24 hours race, which it won twice.
In 1951, the car won at its first attempt. The factory entered three, whose driver pairings were Stirling Moss and Jack Fairman, Leslie Johnson and triple Mille Miglia winner Clemente Biondetti, and the eventual winners, Peter Walker and Peter Whitehead. The Walker-Whitehead car was the only factory entry to finish, the other two retiring with lack of oil pressure. A privately entered XK120, owned by Robert Lawrie, co-driven by Ivan Waller, also completed the race, finishing 11th.
In 1952, Jaguar, worried by a report about the speed of the Mercedes-Benz 300SLs that would run at Le Mans, modified the C-Type’s aerodynamics to increase the top speed. However, the consequent rearrangement of the cooling system made the cars vulnerable to overheating, and all three retired from the race. The Peter Whitehead-Ian Stewart and Tony Rolt/Duncan Hamilton cars blew head gaskets, and the Stirling Moss-Peter Walker car, the only one not overheating having had a full-sized radiator hurriedly fitted, lost oil pressure after a mechanical breakage.[3] Testing by Norman Dewis at MIRA after the race proved that the overheating was caused more by the revisions to the cooling system than by the altered aerodynamics: the water pump pulley was undersized, so it was spinning too fast and causing cavitation; also the header tank was in front of the passenger-side bulkhead, far from the radiator, and the tubing diameter was too small at 7/8 inch. With the pump pulley enlarged, and the tubing increased to 1 1/4 inch, the problem was eliminated. The main drawback of the new body shape was that it reduced downforce on the tail to the extent that it caused lift and directional instability at speeds over 120 mph (193 km/h) on the Mulsanne Straight. These cars had chassis numbers XKC 001, 002 and 011. The first two were dismantled at the factory, and the third survives in normal C-type form.
In 1953, C-Types won again, and also placed second and fourth.[4] This time the body was in thinner, lighter aluminium and the original twin H8 sand cast SU carburettors were replaced by three DCO3 40mm Webers, which helped boost power to 220 bhp (164 kW). Philip Porter mentions additional changes:
Further weight was saved by using a rubber bag fuel tank ... lighter electrical equipment and thinner gauge steel for some of the chassis tubes ... [T]he most significant change to the cars were the triple Weber carburetors and [switch to] disc brakes.
Duncan Hamilton and Tony Rolt won the race at 105.85 mph (170.35 km/h) – the first time Le Mans had been won at an average of over 100 miles per hour (161 km/h).
Disc brakes were novel in 1953, and Jaguar's win, partly due to their superiority, set off a scramble to include discs in production cars.
1954, the C-Type's final year at Le Mans, saw a fourth place by the Ecurie Francorchamps entry driven by Roger Laurent and Jacques Swaters.
When I look at the amazing objects in the cosmos, I can’t seem to stop my imagination from racing at times. This galaxy particular is a prime example as it certainly has a lot going on. I have to admit, this certainly took a long time to arrive with a rendition that I felt was the best I could do at this time. It almost appears on fire with smoke rising above. Like a massive intergalactic craft approaching for landing. In my mind, I can see two search-lights below, and above the disk, the cavitation of gases producing a smoke-like appearance. Perhaps I should slow down on the coffees :).
NGC 3521 is classified as a flocculent galaxy. They have a patchy or fluffy look about them. About 30 percent of spiral galaxies are flocculent, and about 10 percent are grand design. The remaining are referred to as multi-armed.
NGC 3521 is only 26 million light-years away in the constellation of Leo. It has a trace of a bar structure and a weak inner ring. Its centre contains an HII region, classifying it as HII LINER.
Gigantic bubble like shells are present around the galaxy. They are likely to be the result of tidal debris, streams of stars that have been ripped away from satellite galaxies in the distant past.
Instruments Used:
10 Inch RCOS fl 9.1
Astro Physics AP-900 Mount
SBIG STL 11000m
FLI Filter Wheel
Astrodon Lum, Red, Green, Blue Filters
Baader Planetarium H-alpha 7nm Narrowband-Filter
Lum 92 X 900 seconds
Ha 38 X 900 seconds
Blue 38 X 450 seconds
Green 16 X 450 seconds
Red 30 X 450 seconds
Total time 43 Hours
Thanks for looking
Angiopteris fokiensis Leaf and Spores. This picture combines two aspects of my photography that I have been trying to improve - more extreme macro and backlighting.
Angiopteris is unique among ferns in having explosively dispersed spores, thought to be caused by the cavitation of an airspace between spore layers (Hovenkamp, Peter, June 2009, "Spore movement driven by the spore wall in an eusporangiate fern". Grana. 48 (2): 122–127.
#Angiopterisfokiensis #Angiopteris #fokiensis #spores #sori #sorus #fern #botany #botanic #flora #macro #macrophotography #botanicphotography
A brown pelican divebombs a school of minnows in the shallow waters of Pensacola Bay, Florida. I really wish that I had been able to capture the pelicans head underwater…but the minnow’s reaction and cavitation beneath the wave tells the story.
From the archives and taken 28 March, 2022.
Black Watch Variant 3: "Depth Charge"
Featuring: Anchor chain, harpoon guns, sonic cavitation cannon.
Equipped for aquatic mobility.
- Playing around a big water tank by throwing things into it. Here, the heavy solid ball is moving fast enough to create cavities in the water. It looks like a jet.
The NZR K class of 1877 was the first example of American-built locomotives to be used on New Zealand's railways. Their success coloured locomotive development in New Zealand until the end of steam.
K88 "Washington"
The NZR bought eight of these locomotives in the 1870's. They were built by Rogers, of Patterson New Jersey and gave excellent service, finally being written off in the 1920's. This one was buried in a riverbank for about fifty years, before being dug up and restored to steam. They are a 2-4-2 tender locomotive. This wheel arrangement was later named "Columbia" after a loco which appeared at the Columbia exhibition, but Rogers called it a Hudson Double Ender. These locos were very successful and greatly influenced the type of locomotives used in New Zealand for the rest of the steam era. The first two bore names when they arrived, "Washington" and "Lincoln", but there was enough fuss made about buying engines from the rebel colonies and so the names did not last long. Neither did the bells, but in restoration both the name and the bell have returned. The crosshead feedpump has not been restored, perhaps wisely in view of the poor reliability of such pumps. The problem was that they were controlled by throttling the suction side, which causes cavitation and so is very hard on the pump. Curiously the Americans persisted in controlling pumps in this way for about 50 years, from the 1830's until injectors started to take over.
No private group or multiple group invites please!
Ningún grupo privado o grupo múltiple invita por favor
Aucun groupe privé ou groupe multiple ne vous invite
Geen privégroep of meerdere groepsuitnodigingen alstublieft
Keine private Gruppe oder mehrere Gruppen laden bitte ein
Nenhum grupo privado ou grupo múltiplo convida por favor
=============================================
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Paraffin birds this time lolololol
Look in large and see the shadow of the blades on the plane and also look at the propeller blades and see where they going round and left a trail under the wing
blur
- Windowed Borderless Gaming (~48 MP, resized with lanczos 2)
- In-Game Photo Mode (pause, freecam, Motion Blur/DOF, FOV)
- Jim2point0's CT (uncap FOV/cam distance, HUD toggle)
- ReShade
Baltimore National Aquarium - 21 Nov 2015
Peacock Preying Mantis Shrimp
World's Deadliest: Shrimp Packs a Punch. The Peacock Mantis Shrimp looks like the praying mantis’s outlandish underwater cousin, with its loud rainbow shell and big, googly eyes. But this extremely aggressive predator doesn’t play around, smashing its way through crabs, mollusks and even the skulls of small fish. They push their prey up against a rock and start beating on it until their shells crack open, so swift that the club packs a second punch from a phenomenon called cavitation. The water gets squeezed out of the way and literally boils. In a millisecond or so, the bubbles collapse, forming a shock wave that helps to fracture and destroy the target.”
To view more of my images, license this image or obtain prints, please visit my website gallery by clicking on the link below:
babybluesproductions.smugmug.com/Nature-Photography/Anima...
5d Mark III, 1/200sec, f/2.8, ISO 12800, 200mm (EF 70-200mm f/2.8L IS II USM), extension tubes 12&20mm, LR5 processed with NIK Color Efex Pro 2.
- The watch seems to be distorted and stretched out, is it entering warp in that bubble formed by its movement?
I'm going to call this "The Oyster Shell Paddle"
I Oiled this Paddle because I loved the paddle grain so much it will enable me to give it a quick rub down and re-oil anytime in the future. Easy servicing!
The Main shaft and paddle blade are all one piece from a Green Ash Slab, it's been drying in my garage for around fifteen years. Due to a knot half way down the main shaft I decided to laminate the shaft back and front with 1/4" strips and shaped the shaft once it was all bonded and cured.
I have sanded out the paddle blade overlaps to give minimal cavitation once in the water.
The Blade shape was derived from the grain of the plank and what was left when the live edge was stripped back.
Nearly separating from the hustling and bustling atmosphere of the urban life, Hon Chong Promontory is seen as the convergence of mountains and sea. This is also one of the most beautiful city's showpieces of Nha Trang city attracting numerous tourists.
Hon Chong complex has included large rocks stacking each other for centuries. This is a large square rock block lying on a flat and huge rock. The side overlooking the sea houses vast hand-shaped indentations. The promontory has long become a tourist spot attracting tourists to Nha Trang city. Here, tourists can feel Hon Chong Promontory as the intersection of the mountain and sea. Just a few steps, tourists can touch the sea or the foot of the hill. In particular, going to Hon Chong, tourists also have a chance to hear many interesting stories about the promontory among charming natural scenery. Hon Chong Promontory is becoming one of the new enchanting tourist attractions in Nha Trang.
Hon Chong is located in the inner city of Nha Trang. Located in La San Hill, Phuoc Vinh ward, Hon Chong is a floating rock on the sea. According to the interpretation of scientists, it is the remains of the cavitation between the sea water and foothill. Hon Chong owns the romantic scenery. The mountain, sea and shore are side by side. Unlike other beaches along Tran Phu Street in downtown, beach at Hon Chong area is fairly tranquil. Going to Hon Chong, tourists can comfortably sit on the rocky promontory to fish out or move a few meters of the shore to bathe in smooth sands and gentle blue waters. In particular, multi-sized islands offshore surrounding whole area reduce the wind speed and impact of the typhoon. Beach on Nha Trang Bay and Hon Chong Promontory is thus considered one of the beautiful and safe bays, which are must-see tourist spots of Nha Trang travel.
As one of the unique Nha Trang attractions, Hon Chong is home to swim, climb and admire the wonderful beach. There are also numerous interesting folktales around Hon Chong Promontory. Most specially, there is a giant hand deeply embedded in the rock with the palm and five fingers on the large rock located on the top edge of Hon Chong. It seems that there was a giant hand having clung and left the trace right from the formation of these rocks. There is also another legend relating with the existence of an ancient giant having gone fishing here. A huge fish took the bait and pulled away. He had to pull back with a hand holding a fishing rod meanwhile a hand tightly clinging to the rocks, which had left the remains as shown today. These unique legends always leave a special impression to tourists in minds when participating in Nha Trang tour.
Beach in Hon Chong Promontory has been recently explored for tourism development. In the past, tourists who would like to come here had to overcome steep hills and walk around. Tran Phu Street is now extended into La San Hill. Running along the coast towards the northeast from the city center, tourists will set foot on Hon Chong. Path to Hon Chong now is credibly dreamy thanks to a side of waters with golden sands endlessly stretching, and other side of the beautiful architectural works which is always busy passersby. Many tour operators have organized team games tied to rocks, hills and beaches here to create excitement for tourists. Hon Chong Promontory is also rendezvous for nature lovers to admire the beautiful natural landscapes.
Looking back the city, Hon Chong Promontory - La San Hill is one of the most beautiful coastal city' showpieces with flexible curve of beaches along Tran Phu street and towering coconut ranges reaching out to catch the waves. Standing on Hon Chong, tourists can contemplate Hon Yen from afar, Cau Da Port on the right, Hon Tre Island and Nha Trang coast up to 6 km in sight. Hidding Lasan Hills is Nha Trang estuary and Cu Lao fishing landings. Viewing from Hon Chong is Co Tien Mountain in the other side. From Hon Chong Promontory, tourists will have a chance to clearly contemplate Hon Do (Red) (where houses a pagoda). It is unique features that bring Hon Chong to become the indispensable highlight in Nha Trang tours.
In addition, on the way to Hon Chong, tourists will visit Nha Trang Bay Assembly Hall, which showcases a great number of pictures of Hon Chong and sights in Nha Trang. Setting foot on scenic Hon Chong complex - Nha Trang, tourists have an opportunity to witness marvels of the nature, unleash their own imagination for the soul soaring and emotional sublimation among the immense blue of heaven and earth together with sea breeze. They are actually enjoyable experiences. Hon Chong Promontory thus becomes one of tourist attractions rich in humanity of Nha Trang tourism.
Read more: www.alotrip.com/guide-vietnam-attractions/hon-chong-promo...
Hah!
One the second try I got exactly what I wanted (along with the usual surprises).
The firecracker is inside a plastic test tube mounted into the bottom of the bottle. the tube is painted black to absorb most of the light.
A wonderful explosion cavity in the water and a shock wave induced cavitation towards the top of the bottle.
Wonderful.
Even the background colors are good.
Cheers.
Rhododendron maximum is a species of Rhododendron native to the Appalachians of eastern North America, from Alabama north to coastal Nova Scotia. Its common names include great laurel, great rhododendron, rosebay rhododendron, American rhododendron and big rhododendron.
Description
Rhododendron maximum is an evergreen shrub growing to 4 m (13 ft), rarely 10 m (33 ft), tall. The leaves are 9–19 cm (3.5–7.5 in) long and 2–4 cm (0.79–1.57 in) broad. The flowers are 2.5–3 cm (0.98–1.18 in) diameter, white, pink or pale purple, often with small greenish-yellow spots. The fruit is a dry capsule 15–20 mm (0.59–0.79 in) long, containing numerous small seeds. The leaves can be poisonous. Leaves are sclerophyllous, simple, alternate, and oblong (10 to 30 cm long, 5 to 8 cm wide). It retains its waxy, deep-green leaves for up to 8 years, but once shed are slow to decompose. It produces large, showy, white to purple flowers each June and July.
Distribution and habitat
Rosebay rhododendron is the most frequently occurring and dominant species of Rhododendron in the southern Appalachian region, and occurs occasionally on mesic hill-slopes throughout the upper Piedmont Crescent of the Southeastern United States.
Ecology
Approximately 12,000 square miles in the southern Appalachians are occupied by this species[5] where it dominates the understory. This species has historically been confined to riparian areas and other mesic sites but takes advantage of disturbed areas where it is present to advance onto sub-mesic sites. It prefers deep well-drained acid soils high in organic matter where it produces a thick, peat-like humus. It prefers low to medium light conditions for optimum carbon gain, and has a tremendous capacity for avoiding cavitation during freeze-thaw cycles. Where extensive overstory mortality has eliminated most of the overstory, this species forms a thick and continuous subcanopy known locally as 'laurel slicks' or 'laurel hells'. Rosebay rhododendron is an important structural and functional component of southern Appalachian forest ecosystems. What is not clear is whether or not we are in a period of advancement or retreat for this species. For example, on poorly drained sites on ridge or upper slope positions, large areas of rosebay rhododendron, particularly at the high elevations, have recently died out presumably due to the Phytophthora fungus, or due to recent prolonged periods of below-average precipitation. Yet, rosebay rhododendron now occupies sites that historically were free of evergreen understory. There are still important questions to be answered regarding this species to completely understand its role in forest understories.
In North Carolina, US, Pestalotiopsis which is a genus of ascomycete fungi causes grey-brown spots on the living leaves.
Reproduction
Rosebay rhododendron is clonal. It is capable, however, of reproducing both vegetatively and sexually. It reproduces vegetatively through a process called 'layering' where it produces roots from above ground woody parts when in contact with the forest floor. The fruit is produced from showy flowers from March to August. The fruit is an oblong capsule that ripens in the fall, and splits along the sides soon after ripening to release large numbers of minute seed (c. 400 per capsule). Microsite requirements for seed germination are relatively specific (e.g., high in organic matter such as rotting logs); hence, the majority of reproduction is vegetative resulting in a clonal distribution.
Cultivation
Seeds from rosebay rhododendron are minute and it is estimated that approximately 11 million are contained in 1 kg. Commercial seed production is generally from cultivated hybrids. Seeds from wild sources are not commonly sold commercially. Rosebay rhododendron is a slow-growing shrub and has a very high sprout potential. If mechanical removal is attempted in the case of forest management, extremely high densities are attained by this species in a matter of a few years. Prescribed fire has also been used to control this species but with limited success.
Uses
Rosebay rhododendron is a striking and aesthetically pleasing feature of mesic southern Appalachian forests. It is one of the largest and hardiest rhododendrons grown commercially. Several cultivars with white to purple flowers have been selected for the horticultural trade. Where it occurs naturally, it produces a showy, white, pink, or light purple flower primarily in June, but occurs from March into August. Rosebay rhododendron maintains deep-green foliage year round. This species affords protection to steep watersheds and shelter for wildlife. The wood is very hard and is occasionally used for specialty wood products.
Detrimental effects
For all its prized qualities as a naturally occurring component of the landscape or as plantings in residential and commercial landscaping, rosebay rhododendron can have an inhibitory effect on regeneration of other plant species. There is some evidence to suggest that due to fire suppression and the absence of other cultural activities (i.e., mountain-land grazing), this species has advanced beyond the mesic forest sites into sub-mesic understories. The significance of this movement onto previously unoccupied sites centers around the impacts of rosebay rhododendron on plant succession and resource availability. Rosebay rhododendron is associated with reduced woody and herbaceous seedling abundance throughout its range, and hence poses a serious impediment to the production of wood products. The mechanism(s) by which rosebay rhododendron reduces seedling survival has been the subject of much debate. Possible sources of inhibition include allelopathy, competition for resources including light, physical and chemical attributes of the forest floor and soil, and interactions between some or all sources.
Alternate common names
R. maximum has also been called:
Great rhododendron
Late rhododendron
Summer rhododendron
Great laurel
Bigleaf laurel
Deertongue laurel
Rose tree
Rose bay
Bayis
Symbolism
Rhododendron maximum is the state flower of the U.S. state of West Virginia.
A painting of the rescue by A. Cumming of Lenzie, Scotland. As someone who was there I am amazed at how accurately the artist (who was not there) portrayed the scene. The following is the story of this scene:
PART 1:
My mind drifted for a moment, drawn to the glass of ice cold water sat on my desk. The water tilted within the glass and then shuddered as the ship around it rolled on the wave and vibrated to the cavitation of the propeller. I glanced towards the black porthole. I had tightened the dogs on it earlier when the roll of the ship coincided with a high wave and momentarily our cabin view looked underwater, down into the ocean. I was a little weary. With the warm air and physical nature of our work I knew I should get some sleep before my duty watch started on the ship’s navigation bridge at midnight.
But I had to finish my Correspondence course. As only a second trip deck cadet, training as a Navigation Officer, I was almost the lowest of the low, and it was important my study at sea was completed on time. Our ship, “Wellpark”, was only three days from arrival in Kaohsiung in Taiwan and my work would have to be posted back to Nautical College in Glasgow on the other side of the world for marking. As luck would have it, we had speeded up a few days earlier from our normal cruising speed to our maximum of 15 knots, so that the ship could meet its dry-dock slot in Korea and still connect into a lucrative string of cargo charters thereafter. Dammit: I had even less time to finish my studies!
I could have excused myself. As I had just written in a letter to my mother it had already been a very eventful trip, a real experience for a young man keen to see the world. The journey itself from my home in the extreme north of Scotland to the south of Argentina had involved no less than seven separate flights over three days. And the weeks at sea crossing the lower latitudes of the South Atlantic, watching the albatross glide for days, before we moved into the warmer Indian Ocean and relaxed in its sunshine, had made it seem more like a cruise. After the mountainous waves we endured around South Africa we had time for fun after work, playing games on deck and organising our Crossing the Line Ceremony. Later we had passed through the Sunda Straits, passing tropical islands on both sides. Here we watched brightly coloured sailing boats dart between the islands, flying fish, and plumes of smoke erupt from a huge volcano. We were a happy ship and we were on a journey that had now taken us into the South China Sea.
It was 7.53 pm on Sunday 1st October when I had just focussed my mind back on my Correspondence course that suddenly the ship’s emergency alarms rang, and my life changed forever.
Immediately the tannoy blared, “This is not a drill!”. Still wearing my jeans and T-shirt, I scooped up my helmet and lifejacket and headed from my cabin, out through the water-tight door on to the main deck and up the two steel staircases to my emergency station on the poop deck next to the port lifeboat. All over the ship, cadets and men rose from what they were doing. Some were in the shower, some in the laundry, some eating, some relaxing and some fast asleep. All rose as one and ran to take up their posts at the three main emergency stations: by the port and starboard lifeboats and on the ship’s bridge.
As we gathered at our post, of course we were intrigued. What was happening? It was pitch dark outside and we could see nothing. Were we in danger of sinking and in trouble ourselves? Was there a fire on board? We relaxed as word filtered round it was a fishing boat that had fired off a distress flare, and we had time to laugh at the first-trip cadet who arrived at the emergency station in slippers and pyjamas.
And then we saw it…well, our keen eyes saw a flame, just a brief glimpse, distant in the black of the night out on the starboard (right) side of the ship. A roll was called and the senior cadets were selected to climb up into the port lifeboat with three officers, as we attended to removing the covers off the launching equipment and unshackling the boat for lowering.
40 minutes had elapsed from the sighting of the flare and the call to emergency stations, when we were ordered to lower the lifeboat to the water. Wellpark had closed in on the boat in distress but from where we were we could no longer see it. At 171 metres long, and a laden weight of over 40,000 tonnes, Wellpark had slowed but was still pushing into the waves at around 7 knots. In the wake of tropical storm ‘Lola’ the sea’s swell was high, there being roughly 15 feet (4.5 metres) between the peaks and troughs of the waves. Quickly the lifeboat was lowered until the tops of the passing waves ran below its hull. On a given signal the fore and aft quick release buckles were pressed to drop the boat onto the top of a wave. But disaster! The release buckle holding the front of the boat did not release, and the falling wave threatened to leave the rescue craft hanging vertically, and hurl its crew into the dark waters.
Desperately they hung on, until the waters rose once more under the boat. Then it thrust the rear of the boat upwards, slamming a cadet’s head against 100 kilos of lifeboat pulley blocks dangling from the ship. Only his helmet saved him from serious injury. In an instant the Second Officer grabbed an axe and swung at the jammed release catch. The steel rings parted and the boat dropped onto the wave. Quickly the Lister engine was put into gear and the Training Officer swung the tiller, accelerating the boat away from the ship, out onto the waves and into the surrounding darkness.
Up above, there had been excited activity since the Chief Officer spotted the red flare, four points on the port bow. Immediately Captain,Hector Connell, had been called to the ship’s command point on the bridge and all other staff had been called to Emergency Stations by alarm and tannoy. The Wellpark swung her bows towards the point of light in the darkness as the Radio Officer began to relay the distress signal. Hearing the distress call, “Manhattan Viscount”, 40 miles to the south advised she would come to assist. But the Russian cargo ship, “Zoia Kosmodiemanskaia”, and the British gas tanker, “Norman Lady” were much closer and they were going to arrive on the emergency scene much sooner.
Out on the sea, the lifeboat battled its way towards the boat in distress. Although accustomed to a life at sea, many of its crew began to suffer from sea-sickness as the small boat rose and fell on the large waves. Swallowed amongst them they often lost sight of the boat they had been sent to investigate, but the powerful beam of the Aldis signalling light shone from the Wellpark’s bridge wing to guide them. With radio instructions too, it helped show them the way. It was 20 minutes before they got close, and then out of the darkness they saw what appeared to be a grossly overcrowded wooden craft. The lifeboat manoeuvred in close, but had to hold off slightly to prevent being thrown against the larger craft by the waves. Although the crew reached out, the desperate people on the boat held back from jumping into the lifeboat, fearful that their rescuers could not be trusted. There were shouts and cries in the confusion, but amongst it someone demanded of the lifeboat crew what nation they were from. When the reply was given that they were British, Scottish at that, the word rapidly spread and without hesitation the first man jumped across the dark waters to the lifeboat. Quickly, in two more passes, about 15 men leapt from all angles for the boat, many landing heavily on the hard thwarts of the lifeboat as it bucked on the waves. Now the boat in distress was heeling over with the shift of humanity wanting to escape the deathtrap their boat had become. But with shouts of, “We’ll come back” the lifeboat withdrew and headed back to Wellpark. Huddled low in the center of the lifeboat one man told his saviours that there were over 300 refugees from South Vietnam crammed on the distress craft.
Looking down from the poop deck to the returning lifeboat I saw a large number of men and one boy. Having not yet seen the distress craft, I thought, what sort of small fishing boat carried such a number? We had rigged a rope pilot ladder down the vertical side of the ship. The lifeboat nosed in under the ship’s side, which had now been turned to provide some shelter. But still the lifeboat rose and fell on the ship’s swell so that when one man started up the ladder the lifeboat lifted suddenly on the next wave and chased him up the ladder. A man started to climb but only got half way before fear or exhaustion took over. Grimly he hung on before eventually carrying on to the top. We watched, helpless to do more, as one at a time they struggled up towards the ship, terrified one would drop down to the lifeboat or disappear into the blackness of the waves. Exhausted they collapsed to the deck where we sat them against the hatch coaming. The ship's cook and his staff dashed to the ship’s stores to gather blankets and to provide drinks for the rescued. Empty of its cargo, the lifeboat twisted and tossed on the waves and we saw many cadets heaving with sea-sickness. But sick as they were, none requested to leave his post.
Again the lifeboat left the ship’s side and headed off into to the dark. I crossed to the starboard side of the vessel and was on the maindeck as Wellpark tried to move closer to protect the refugee boat. Now the refugee boat moved in to the arc of light provided by the ship’s lights mounted high on her deck cranes. For the first time I saw the boat close up. And my eyes failed to comprehend what I was seeing. Here was this wooden boat 60 –70 feet (20 metres) long, packed from stem to stern with people stood shoulder to shoulder on its deck. Here they were riding out the aftermath of a tropical storm some 148 miles from the nearest land. There was a strong, farmyard type smell and I could hear the roaring of the boats engine. The craft was pointing towards the side of Wellpark, and I could tell its commander was frantically trying to get it to reverse away. Suddenly the boat crested a huge swell and was swept towards Wellpark. It’s pointed bow rose high above the Wellpark’s railings immediately above me. I was entranced, fixed to the spot, knowing I was in the wrong place at the wrong time. There was no escape and any second that boat would crash down on the very spot I occupied. But at the exact moment I thought death would come to me, somehow, the giant mouth of the sea sucked the refugee boat back over the Wellpark’s rails and back into the ocean. With relief I saw the boat pass down the side of the ship and back into the dark behind Wellpark. It was 9.00pm
As Wellpark was turned and moved to offer shelter for the rescue operation, the Russian ship “Zoia Kosmodiemanskaia” moved in perilously close. Her lights were so close, to us it seemed like she was trying to interfere, putting her bow between Wellpark and the refugee boat. Now we were beginning to understand what was happening and who we were trying to help. A Russian ship, from a Communist state might try to‘steal’ the refugees and take them back to Vietnam. If it had seemed like just one more interesting high point on our voyage, now we realized it really was a matter of life and death. Wellpark’s Captain ordered the Russian ship to keep her distance.
Tiny against the ocean, Wellpark’s 25 foot long lifeboat closed on the distress craft once more. This time about 20 men, women and children leapt into the boat. Some clasped the hands of its crew thanking them for what they were doing, kissing their hands in gratitude. This time the ship was closer and we found the lifeboat back on the port side at the bottom of the ladder after barely ten minutes. But now we realized we had to help these people reach the deck. We lowered ropes. Some had the strength to pull themselves up the vertical ladder some of the way; others we had to lift completely as they simply were too weak to climb. Focused on the job in hand I barely noticed the small crowd that was forming on the steel deck behind us. As the last was brought on deck we lowered more fuel to the lifeboat. Some cadets looked up at their colleagues on deck. They were physically weak from sea-sickness, but again they set off once more in to the night.
Up on the bridge the ships engine was stopped, started, slowed and speeded up on over 120 separate occasions as her Captain sought to provide shelter to the refugee boat. Constantly turning, and working to adjust to the erratic manoeuvres of the distress craft, and the ‘assisting’ ships, Hector Connell would later be praised for his masterly seamanship.
Now he commanded the lifeboat to follow the Wellpark. As the clock passed 10pm, on the deck we were ordered to get all available ropes from the rope store. This included the large floating polypropylene mooring ropes as well as smaller throwing ropes. We tied the bigger ropes together and passed them down to the lifeboat which took them in tow. It struggled to drag them over the waves and made slow progress to the distress vessel. They signalled that the refugees should tie the ropes to their boat, but the British crew could not make themselves understood. Part by luck and part intentionally, the lifeboat was steered so that the ropes fouled the distress craft’s propeller. Quickly we spun the ropes onto the winches and pulled the boat towards the Wellpark’s side. Passing down ropes we wanted the refugees to fix our ropes to the bitts on their boats deck. But the boat was relatively small compared to Wellpark and as it lifted and fell on the waves the ropes kept breaking or pulling off the fixings on the vessel. In all, working hard as a group of cadets, it took us an hour to get the distress craft tied securely to Wellpark so that the rest of the deck crew could start to haul the huge numbers of men, women and children up from the boat below.
Now I could see the mass of humanity covering every part of the simple wooden boat. So disciplined and trained were we that we acted naturally even though none of us had ever experienced, or trained for, such an event. As we organized ourselves into lifting teams to get the Vietnamese on deck I was tasked with searching everyone as they came on board. Of course I had no training for this. We told the poor people we had to search them, but the refugees did not seem to understand our English, and we resorted to comical sign language in a poor version of charades to eventually convey what we meant. But I was shocked at the reaction I got. The women and children in front of me put their hands in the air, in the way I had only seen soldiers in war films surrender. I was embarrassed and horrified to realize these people were frightened of me. Frantically I urged them to put their arms down, and cautiously they did so.
I was lost to time. But on we went, working under the ship’s floodlights, pulling on the ropes, hauling babies in baskets, children on ropes and helping the adults up the scrambling nets and ladders. I was unaware of what everyone else was doing, we were all doing our bit hidden within the crowd at the ship’s railings as the ship’s catering staff led the Vietnamese down towards the ship’s accommodation. Many just collapsed on to the steel deck where they were, just too weak to go on. Realising how dehydrated and starved these people were, the ships cooks and stewards quickly set about making gallons of soup and coffee and handed out all the bedding material they could. But this was a ship equipped and stored for 50 crew, not a population of 400. So starved and thirsty were the refugees that civilities like handing out portions of food gave way to handing out whole packets of cereals and any other foods that came immediately to hand.
It was ten minutes past midnight when the last refugee was pulled from the decrepit craft below. Now Wellpark slowly made way forwards. A large mooring rope was passed down to the lifeboat who landed two crew onto the craft. Unable to find a suitably strong fixing point they moved down in to its stinking hull and found a large beam to secure the tow rope to. As the lifeboat returned to the Wellpark’s port quarter, we cut the refugee craft free of the ropes binding it to the side of Wellpark so it would drift astern and take up its position on tow. But now the lifeboat struggled against the swell to pick up the falls so it could be lifted on board. Time and again the lifeboat approached but could not safely reach the ship for fear of being lifted by a wave to crash against the dangling pulleys. The sea seemed to have become rougher and it took until almost 2.00 a.m to hook up the lifeboat. Up it came, with its tired crew, but one of the davits jammed leaving the boat slewed on its mountings. We secured it there, allowing the crew to dismount awkwardly. There was a sober quietness, everyone was so exhausted. As Wellpark started to get back on course and up to speed. we started to gather our ropes and equipment back up. All around us the Vietnamese were quiet, lying on the ships deck in darkness, now the ship’s deck lights had been switched off for navigation.
I got changed into my uniform and climbed up to the ship’s bridge to start my watch at 4.00am. I took up position as lookout on the starboard bridge wing, looking down on the sleeping refugees curled up on top of No.5 hatch. Although our games nets enclosed the area, there was no protection from the elements, but the night was warm and humid. Some large waves started to come on board, rolling down the deck on the port side, as the ship rolled. The Captain ordered the ship to slow a little to protect the exposed people. From my high view point, I looked down and marvelled at the numbers of people, so quiet and peaceful. Were they dreaming sweetly, enjoying the luxury and safety of Wellpark’s steel decks? Or were they unconscious, utterly drained by their experience? I was tired too and I had to keep active to stay awake. Occasionally I looked back into the darkness behind the ship where the refugee boat snaked from side to side across Wellpark’s wake.
Suddenly there was a loud cracking noise, and I saw the black bulk of the refugee boat suddenly fall apart and disappear in to the dark. Just the stem post and a few beams remained attached to the rope, and they danced on the waters churned white by Wellpark’s propellor. The refugee boat had been lost at sea forever.
Other chapters of this story are here:
PART A www.flickr.com/photos/pentlandpirate/1438584566/in/set-72...
PART B www.flickr.com/photos/pentlandpirate/1438558408/in/set-72...
PART 2 www.flickr.com/photos/pentlandpirate/1437528215/in/set-72...
PART 3 www.flickr.com/photos/pentlandpirate/1461744696/in/set-72...
PART 4 www.flickr.com/photos/pentlandpirate/1460893557/in/set-72...
PART 5 www.flickr.com/photos/pentlandpirate/1437563459/in/set-72...
PART 6 www.flickr.com/photos/pentlandpirate/1438381480/in/set-72...
You can also join the Wellpark Reunion site here : wellparkreunion.ning.com/main/authorization/signIn?target...
Read more at www.shipsnostalgia.com/guides/MV_Wellpark
“Top of 31-foot-long diffusers fit around Saturn S-IV engine nozzle bells in static test stand at the Douglas Aircraft Company’s Sacramento installation. Prior to ignition of engines, air is evacuated from diffusers, simulating the near-vacuum conditions in which S-IV engines will be ignited in outer space. Douglas Missile & Space Systems technician is working on one of six RL-10A3 engines suspended from battleship tank. First static firing will occur shortly.”
If, like me, you’ve tossed & turned many-a-night wondering how in/on the world (literally) do you realistically test fire a rocket engine that’s designed to operate exclusively in a near vacuum/vacuum, and the above merely whets your appetite, we’re in luck thanks to the following:
Douglas Missile & Space Systems Division’s “ALTITUDE SIMULATION IN SATURN SIV STAGE TESTING/Douglas Paper 3172”, at:
libarchstor2.uah.edu/digitalcollections/files/original/20...
Credit: UAH Archives and Special Collections/Digital Collections website
We have:
“ABSTRACT
Altitude Simulation in Saturn SIV Stage Testing
The Douglas Aircraft Company has been involved in testing the Saturn SIV stage at the Sacramento Test Center for the past two years. The propulsion system for the SIV stage consists of six (6) Pratt & Whitney Aircraft Company rocket engines which are designed specifically for high altitude start and operation. During static firing tests of this engine at sea level, a steam jet ejector in combination with a diffuser, are used to simulate altitude conditions. The intent of this paper is to examine the performance of this altitude simulation system, and to discuss problems encountered in making it operational.
--------------------
The Douglas Aircraft Company has been involved in testing the Saturn SIV stage at the Sacramento Test Center for the past two years. The SIV is an upper stage of the National Aeronautics and Space Administration's Saturn Space Vehicle. A later version of the Saturn Space Vehicle is programmed to launch an Apollo to the moon. The propulsion system for the SIV stage consists of six (6) Pratt & Whitney Aircraft Company RLIOA-3 rocket engines capable of generating a total of 90,000 pounds thrust at altitude. These engines were designed specifically for high altitude start and operation and, therefore, require an altitude simulation system to permit sea level static testing. The normal starting altitude of the Pratt & Whitney RLlOA-3 engine, when used as part of the SIV stage, is approximately 240,000 feet, where the expected absolute pressure is 0.17 psia.
It is not required that this low a pressure be obtained for sea level testing, however. The engine requires sufficient pressure drop between the liquid oxygen pump inlet and the combustion chamber to attain a pre-start flow of liquid oxygen. This flow must be sufficient to cool the pump so that stall free acceleration and mainstage operation can be achieved. The time interval required, as well as the quality and quantity of liquid oxygen required, had to be established during static testing. Even more basic, however, is the requirement that the high expansion ratio (40:1) thrust chamber bell be operated without flow separation. If the engine were operated at sea level back pressures, separation would occur, with attendant structural and performance degradation. The engine bell construction was intended for altitude operation and thus not designed to withstand the high loads which would be encountered in sea level operation.
The total altitude simulation system utilized in the SIV stage static testing is comprised of four elements: (1) the diffusers, (2) the eiectors, (3) the accumulators, and (4) the steam boilers and feed water system.
The diffusers are attached to each of the six engines with a flexible seal, and are closed at the opposite end by blow-off doors. In this configuration they serve as a vacuum chamber to provide low ambient pressures (less than 0.9 psia) in the forty-five (45) second period up to and including engine ignition. By controlling the engine exhaust gas flow through internal geometry, the diffusers also sustain the required absolute pressure at the engine bell exit after the engine start transient. The diffusers are approximately thirty-five (35) feet long, and are of double wall construction to provide for water cooling. The walls are fabricated from low carbon steel and are spaced one-fourth inch apart to accommodate a cooling water flow rate of approximately 3100 gallons per minute per diffuser.
Each diffuser is connected to a two stage steam jet ejector system with a thirty (30) inch vacuum line. A pneumatically operated butterfly valve is installed in this vacuum line to permit isolation of the eiectors from the diffusers. The initial purpose of this isolation was twofold: (1) to prevent hot gases from the diffuser being sucked through the eiectors just after engine ignition, and (2) to prevent aspiration of air through the ejector and into the lower end of the diffuser during normal engine operation, where after-burning would cause high temperatures and resultant damage to the diffusers. These butterfly valves were also found to be of value in the sequencing of ejector operation with respect to the diffuser during the initiation of vacuum pumping.
Each stage of the two stage ejector is thirty (30) feet long, and they are assembled together in a vertical array on the front of the test stand.
history.nasa.gov/MHR-5/Images/fig150.jpg
The first stage suction chamber is at the level of the diffuser vacuum line. Steam reaches the second stage ejector without intervening valves between them and the constant pressure steam regulators. The first stage steam lines were provided with intervening three-inch valves to permit delaying the entrance of steam into the first stage ejectors until the second stage had established a partial vacuum throughout the system. It was learned early in testing of the altitude system, however, that this delay was not necessary inasmuch as no significant change in vacuum pull-down characteristics were encountered with simultaneous admission of steam to both ejector stages. Manifolding for delivery of steam to both stages of the ejectors is supplied through an eighteen (18) inch steam line from the constant pressure regulators in the accumulator area.
Two thirty thousand (30,000) gallon capacity steam accumulators serve as storage vessels for the steam energy used to power the ejectors. These vessels are half-filled with water, and when charged, hold heat in this water at 406°. The upper half of each accumulator contains steam at 406° and 250 psia pressure. To insure optimum performance of the eiectors, motive steam is supplied from the accumulators at a constant pressure. This is accomplished by the use of constant pressure regulators (one for each accumulator), which maintain 135 psia at the ejector nozzles. The regulators are of the twelve (12) inch, 90' angle valve type, and are commanded open and closed by the automatic SIV stage firing sequence. The actual opening travel of the regulating valve is controlled by high pressure water from the accumulators. This controlling water is regulated as a function of the pressure in the eighteen (18) inch steam line. The opening travel of the poppet in the constant pressure regulators then increases as the accumulator pressure falls off during a test run.
A boiler of 250 BHP capacity is used to produce 8625 pounds per hour of dry and saturated steam at 250 psig for charging the steam accumulators. The process of charging the accumulators requires approximately twelve (12) hours. The "package” boiler is oil fired, and is automatically actuated with boiler steam pressure. The normal supporting systems for operation of a steam boiler are part of this complex area, which includes the feedwater system, deaerator, blow down tank, and oil storage tank.
The design specifications for the steam supply system and ejectors of the altitude simulation system were established as a function of the Pratt & Whitney RL10A-3 engine chilldown flow rates during the period prior to engine ignition. The internal convergent-divergent geometry of the diffusers was established using the parameters of engine combustion products flow during firing operation to assure a sustained pressure of 3.0 psia or less at the engine bell exit.
The Pratt & Whitney RL10A-3 engine utilizes liquid oxygen and liquid hydrogen as propellants. Since both of these propellants have very low boiling temperatures (-297° and -423°F, respectively), each pump must be chilled to essentially its respective liquid boiling point to assure that at engine ignition liquid will be present at the pump inlet and not gas, since gas would cause pump cavitation. To accomplish adequate chilldown of the liquid hydrogen pump at sea level requires forty-five seconds of time, during which gaseous hydrogen is dumped into a stand vent system, and carried off to a burn stack. During the last ten (10) seconds of this forty-five (45) second period, the liquid oxygen pump is simultaneously being chilled down, and dumping approximately 2.0 pounds per second of first gaseous and then as chilldown proceeds, liquid oxygen into each diffuser. These gases must be carried out of each diffuser while continuously maintaining a pressure of 0.9 psia or less. The low pressure in the diffusers during chilldown is required to provide the proper pressure drop between the engine pump inlet and the engine combustion chamber or diffuser to assure the chilldown propellant flow rates.
Operation of the altitude simulation system in conjunction with the Pratt & Whitney engine starting sequence was of such critical nature that control of the system was integrated into an automatic engine firing logic. The base for the timing of logic events was established with time T=0 occurring at engine start command. At T-60 seconds or fifteen (15) seconds prior to initiation of the firing logic, the manually switched sequence of starting three (3) electric motor-driven water pumps and opening of the deflector plate water: valve is started. This timing assures full water flow through the cooling water jacket of the diffusers, as well as full water flow for deflector plate cooling by engine start command. The automatic engine firing logic is initiated at the beginning of LH₂ chilldown which is forty-five (45) seconds prior to engine ignition, or T-45 seconds. Simultaneous with LH₂ chilldown initiation, both the constant pressure regulators and the first stage ejector steam valves are opened to begin the vacuum pumping action with the diffuser butterfly valves closed. Ten (10) seconds later, at T-35 seconds, the diffuser butterfly valves are opened, and the diffusers are evacuated to approximately 0.5 psia by pumping action from the operating ejectors. To provide feedback information to the automatic engine firing logic that the altitude simulation system is functioning properly, specifically that the diffuser pressure is at or below 2.5 psia, pressure switches set to pick up at 2.5 psia are installed on each diffuser. The picked-up talkback is required from all six of the diffuser pressure switches by T-10 seconds to enable the logic signal commanding the start of the liquid oxygen pump chilldown. If these talkbacks are not all received, a hold is automatically imposed in the logic. The difficulty must then be isolated and corrected before a recycle of the sequence can be performed. At T-0 seconds the logic signal for engine ignition is given, and the first stage ejector steam valves are closed. After successful engine start is achieved at approximately T+2.4 seconds, as indicated by proper signals from each of the engines, the altitude simulation system is automatically shut down by simultaneously closing the constant pressure regulators, and the diffuser butterfly valves. With the steam jet ejector system no longer operating, a pressure of less than 1.0 psia (3.0 psia maximum allowable) is sustained at the engine bell exit until engine cutoff, by the pressure physics of engine exhaust gas flow controlled by internal diffuser geometry.”
Based on the above documentation and following footage, specifically during the 1:41 - 2:16 mark, I think these are also the engines used on SA-5. Interestingly (to me) the closeup footage of the engines firing, at the end of the segment cited, appears to be from nearly the same perspective:
www.youtube.com/watch?v=HqQ8t9qfNrc
Credit: The Space Archive/YouTube
Along with, from which I've inserted a pertinent image into the document extract:
Lake Mead is a reservoir formed by the Hoover Dam on the Colorado River in the Southwestern United States. It is located in the states of Nevada and Arizona, 24 mi (39 km) east of Las Vegas. It is the largest reservoir in the US in terms of water capacity. Lake Mead provides water to the states of Arizona, California, and Nevada as well as some of Mexico, providing sustenance to nearly 20 million people and large areas of farmland.
At maximum capacity, Lake Mead is 112 miles (180 km) long, 532 feet (162 m) at its greatest depth, has a surface elevation of 1,229 feet (375 m) above sea level, has a surface area of 247 square miles (640 km2), and contains 28.23 million acre-feet (34.82 km3) of water.
The lake has remained below full capacity since 1983 owing to drought and increased water demand. As of May 31, 2022, Lake Mead held 26.63% of full capacity at 7.517 million acre-feet (9,272,000 megaliters), having dropped below the reservoir's previous all-time low of 9.328 million acre-feet (11,506,000 megaliters) recorded in July 2016 by June 2021 and never returning to that level. In a draft 2022 Colorado River annual operating plan, released by the U.S. Bureau of Reclamation, a "Shortage Condition" is expected to be declared for 2022, due to the lake level falling below 1,075 feet (327.7 m), which will result in a projected 4.44% curtailment in downstream water delivery.
The lake was named after Elwood Mead, who was the commissioner of the U.S. Bureau of Reclamation from 1924 to 1936, during the planning and construction of the Boulder Canyon Project that created the dam and lake. Lloyd Joseph Hudlow, an engineer with the Bureau of Reclamation, came to Boulder City in March 1933 to assist in the survey, and ended up as the project manager.
Lake Mead was established as the Boulder Dam Recreation Area in 1936, administered by the National Park Service. The name was changed to the Lake Mead National Recreation Area in 1947, and Lake Mohave and the Shivwits Plateau were later added to its jurisdiction. Both lakes and the surrounding area offer year-round recreation options.
The accumulated water from Hoover Dam forced the evacuation of several communities, most notably St. Thomas, Nevada, the last resident of which left the town in 1938. The ruins of St. Thomas are currently visible (as of May 23, 2022) via dirt road and hiking trail, due to Lake Mead's low water level.[11] Lake Mead also covered the sites of the Colorado River landings of Callville and Rioville, Nevada, and the river crossing of Bonelli's Ferry, between Arizona and Nevada.
At lower water levels, a high-water mark, or "bathtub ring", is visible in photos that show the shoreline of Lake Mead. The bathtub ring is white because of the deposition of minerals on previously submerged surfaces.
Nine main access points to the lake are available. On the west are three roads from the Las Vegas metropolitan area. Access from the north-west from Interstate 15 is through the Valley of Fire State Park and the Moapa River Indian Reservation to the Overton Arm of the lake.
The lake is divided into several bodies. The large body closest to the Hoover Dam is Boulder Basin. The narrow channel, which was once known as Boulder Canyon and is now known as The Narrows, connects Boulder Basin to Virgin Basin to the east. The Virgin River and Muddy River empty into the Overton Arm, which is connected to the northern part of the Virgin Basin. The next basin to the east is Temple Basin, and following that is Gregg Basin, which is connected to the Temple Basin by the Virgin Canyon.
When the lake levels are high enough, a section of the lake farther upstream from the Gregg Basin is flooded, which includes Grand Wash Bay, the Pearce Ferry Bay and launch ramp, and about 55 miles (89 km) of the Colorado River within the lower Grand Canyon, extending to the foot of 240 Mile Rapids (north of Peach Springs, Arizona). In addition, two small basins, the Muddy River Inlet and the Virgin River Basin, are flooded when the lake is high enough where these two rivers flow into the lake. As of February 2015, these basins remain dry.
Jagged mountain ranges surround the lake, offering a scenic backdrop, especially at sunset. Two mountain ranges are within view of the Boulder Basin, the River Mountains, oriented northwest to southeast and the Muddy Mountains, oriented west to northeast. Bonelli Peak lies to the east of the Virgin Basin.
Las Vegas Bay is the terminus for the Las Vegas Wash which is the sole outflow from the Las Vegas Valley.
Lake Mead receives the majority of its water from snow melt in the Colorado, Wyoming, and Utah Rocky Mountains. Inflows to the lake are largely moderated by the upstream Glen Canyon Dam, which is required to release 8.23 million acre-feet (10,150,000 megaliters) of water each year to Lake Mead. Hoover Dam is required to release 9 million acre-feet (11,000,000 megaliters) of water each year, with the difference made up by tributaries that join the Colorado below Glen Canyon or flow into Lake Mead.
Outflow, which includes evaporation and delivery to Arizona, California, Nevada, and Mexico from Lake Mead is generally in the range of 9.5 to 9.7 million acre-feet (11,700,000 to 12,000,000 megaliters), resulting in a net annual deficit of about 1.2 million acre-feet (1,500,000 megaliters).
Before the filling of Lake Powell (a reservoir of similar size to Lake Mead) behind Glen Canyon Dam, the Colorado River flowed largely unregulated into Lake Mead, making Mead more vulnerable to drought. From 1953 to 1956, the water level fell from 1,200 to 1,085 feet (366 to 331 m). During the filling of Lake Powell from 1963 to 1965, the water level fell from 1,205 to 1,090 feet (367 to 332 m). Many wet years from the 1970s to the 1990s filled both lakes to capacity, reaching a record high of 1,225 feet (373 m) in the summer of 1983.
In these decades prior to 2000, Glen Canyon Dam frequently released more than the required 8.23 million acre-feet (10,150,000 megaliters) to Lake Mead each year. That allowed Lake Mead to maintain a high water level despite releasing significantly more water than it is contracted for. Since 2000, the Colorado River has experienced the southwestern North American megadrought, with average or above-average conditions occurring in only five years (2005, 2008–2009, 2011 and 2014) in the first 16 years of the 21st century. Of any 16-year period in the last 60 years, 2000-2015 had the lowest water availability.
Although Glen Canyon was able to meet its required minimum release until 2014, the water level in Lake Mead has steadily declined. The decreasing water level is due to the loss of the surplus water that once made up for the annual overdraft.
In June 2010, the lake was at 39% of its capacity, and on November 30, 2010, it reached 1,081.94 ft (329.78 m), setting a new record monthly low. From mid-May 2011 to January 22, 2012, Lake Mead's water elevation increased from 1,095.5 to 1,134.52 feet (333.91 to 345.80 m) after a heavy snowmelt in the Rocky Mountains prompted the release of an extra 3.3 million acre-feet (4,100,000 ML) from Glen Canyon into Lake Mead.
In 2012 and 2013, the Colorado River basin experienced its worst consecutive water years on record, prompting a low Glen Canyon release in 2014 – the lowest since 1963, during the initial filling of Lake Powell – in the interest of recovering the level of the upstream reservoir, which had fallen to less than 40% capacity as a result of the drought. Consequently, Lake Mead's level fell significantly, reaching a new record low in 2014, 2015 and 2016. In 2014, its record low was 1,081.82 feet (329.74 m) on July 10, 2014.
On June 26, 2015, Lake Mead reached another new record low when it fell to 1,074.71 feet (327.57 m), the first official "drought trigger" elevation, for the first time since the lake was filled. If the lake is below this elevation at the beginning of the water year, an official shortage declaration by the Bureau of Reclamation will enforce water rationing in Arizona and Nevada. The water year begins October 1 to coincide with seasonal Rocky Mountain snowfall, which produces most of the Colorado River's flow.
Lake Mead's water level rebounded a few feet by October 2015 and avoided triggering the drought restrictions. The water level started falling in Spring 2016 and fell below the drought trigger level of 1,075 feet again in May 2016. It fell to a new record low of 1,071.60 feet (326.62 m) on July 1, 2016, before beginning to rebound slowly. Drought restrictions were narrowly avoided again when the lake level rose above 1,075 feet on September 28, 2016, three days before the deadline, and the Bureau of Land Reclamation did not issue a shortage declaration.
A reprieve from the steady annual decline occurred in 2017, when lake levels rose throughout the year due to heavier than normal snowfall in the Rocky Mountains. As a result of the large snowmelt, the lake regained the water levels it had in 2015 with a seasonal high of 1,089.77 feet (332.16 m). The seasonal low of 1,078.96 feet (328.87 m) in 2017 was close to that experienced in 2014, safely above the drought trigger. That level was still 36 feet (11 m) below the seasonal low experienced in 2012, and the lake was projected to begin falling again in 2018.
Despite those and other predictions of an impending shortage determination by 2020, snowpack of 140% of average in the Upper Colorado River basin as of April 2019 resulted in 128% above average inflow into Lake Powell, resulting in 1,090.20-foot (332.29 m) water level on Lake Mead. In December 2019, Lake Mead water level reached 1,090.47 feet (332.38 m), about ten feet (three meters) above projections. As of April, 2020, the water level stood at 1,096.39 feet (334.18 m), again benefiting from above average mountain snowpack (107% of average).
Since 2018, Lake Mead water levels have remained well above the 1,075-foot (328 m) level that would trigger a shortage determination. In May 2020, the Bureau of Reclamation expected that the continued Colorado River basin drought would yield a Lake Mead level of 1,084.39 feet (330.52 m) by 2022[needs update]. On July 28, 2022, the level was 1,040.58 feet (317.17 m), the lowest level since 1937 when the reservoir was initially filled.
As a result of the decreasing water level, marinas and boat launch ramps have either had to be relocated to another area of the lake or have closed down permanently. The Las Vegas Bay Marina was relocated in 2002 and the Lake Mead Marina was relocated in 2008 to Hemenway Harbor. Overton Marina and Echo Bay Marina have been closed due to low levels in the northern part of the Overton Arm. Government Wash, Las Vegas Bay, and Pearce Ferry boat launch ramps have been closed. Las Vegas Boat Harbor and Lake Mead Marina in Hemenway Harbor/Horsepower Cove remain open, along with Callville Bay Marina, Temple Bar Marina, Boulder Launch Area (former location of the Lake Mead Marina) and the South Cove launch ramp.
Changing rainfall patterns, climate variability, high levels of evaporation, reduced snow melt runoff, and current water use patterns are putting pressure on water management resources at Lake Mead as the population relying on it for water, and the Hoover Dam for electricity, continues to increase. To lower the minimum lake level necessary to generate electricity from 1,050 feet (320 m) to 950 feet (290 m), Hoover Dam was retrofitted with wide-head turbines, designed to work efficiently with less flow in 2015 and 2016.
If water levels continue to drop, Hoover Dam would cease generating electricity when the water level falls below 950 feet (290 m) and the lake would stabilize at a level of 895 feet (273 m) when the water reaches the lowest water outlet of the dam. In order to ensure that the city of Las Vegas will continue to be able to draw its drinking water from Lake Mead, nearly $1.5 billion was spent on building a new water intake tunnel in the middle of the lake at the elevation of 860 feet (260 m). The 3-mile (4.8 km) tunnel took seven years to build under the lake and was put into operation in late 2015.
According to a 2016 estimate, about 6% of Lake Mead's water evaporates annually. Covering 6 percent of Lake Mead with floating photovoltaics has a potential generating capacity of 3,400 megawatts, which is comparable to the capacity of Hoover Dam, and would reduce water lost to evaporation in the covered area by as much as 90%.
A 2021 estimate stated that covering 10% of the lake's surface with foam-backed floating photovoltaics could result in "enough water conserved and electricity generated to service Las Vegas and Reno combined."
In December 2021, Arizona, California, Nevada, and the U.S. Department of the Interior signed an agreement to spend $200 million for 2022 and 2023 to subsidize water users who voluntarily reduce their usage or undertake capital projects to improve efficiency. Along with a variety of state and local regulations, this aims to retain the "500+ Plan" aims to retain 500,000 acre-feet (620,000,000 m3) in the reservoir, which equates to 35% of capacity. At the same time an agreement was reached with the Gila River Indian Community and the Colorado River Indian Tribes which is expected to save an estimated 11 vertical feet of reservoir water.
Hoover Dam is a concrete arch-gravity dam in the Black Canyon of the Colorado River, on the border between the U.S. states of Nevada and Arizona. It was constructed between 1931 and 1936 during the Great Depression and was dedicated on September 30, 1935, by President Franklin D. Roosevelt. Its construction was the result of a massive effort involving thousands of workers, and cost over one hundred lives. It was referred to as Hoover Dam after President Herbert Hoover in bills passed by Congress during its construction, but was named Boulder Dam by the Roosevelt administration. The Hoover Dam name was restored by Congress in 1947.
Since about 1900, the Black Canyon and nearby Boulder Canyon had been investigated for their potential to support a dam that would control floods, provide irrigation water and produce hydroelectric power. In 1928, Congress authorized the project. The winning bid to build the dam was submitted by a consortium named Six Companies, Inc., which began construction of the dam in early 1931. Such a large concrete structure had never been built before, and some of the techniques were unproven. The torrid summer weather and lack of facilities near the site also presented difficulties. Nevertheless, Six Companies turned the dam over to the federal government on March 1, 1936, more than two years ahead of schedule.
Hoover Dam impounds Lake Mead, the largest reservoir in the United States by volume when full. The dam is located near Boulder City, Nevada, a municipality originally constructed for workers on the construction project, about 30 mi (48 km) southeast of Las Vegas, Nevada. The dam's generators provide power for public and private utilities in Nevada, Arizona, and California. Hoover Dam is a major tourist attraction; nearly a million people tour the dam each year. The heavily traveled U.S. Route 93 (US 93) ran along the dam's crest until October 2010, when the Hoover Dam Bypass opened.
As the United States developed the Southwest, the Colorado River was seen as a potential source of irrigation water. An initial attempt at diverting the river for irrigation purposes occurred in the late 1890s, when land speculator William Beatty built the Alamo Canal just north of the Mexican border; the canal dipped into Mexico before running to a desolate area Beatty named the Imperial Valley. Though water from the Imperial Canal allowed for the widespread settlement of the valley, the canal proved expensive to operate. After a catastrophic breach that caused the Colorado River to fill the Salton Sea, the Southern Pacific Railroad spent $3 million in 1906–07 to stabilize the waterway, an amount it hoped in vain would be reimbursed by the federal government. Even after the waterway was stabilized, it proved unsatisfactory because of constant disputes with landowners on the Mexican side of the border.
As the technology of electric power transmission improved, the Lower Colorado was considered for its hydroelectric-power potential. In 1902, the Edison Electric Company of Los Angeles surveyed the river in the hope of building a 40-foot (12 m) rock dam which could generate 10,000 horsepower (7,500 kW). However, at the time, the limit of transmission of electric power was 80 miles (130 km), and there were few customers (mostly mines) within that limit. Edison allowed land options it held on the river to lapse—including an option for what became the site of Hoover Dam.
In the following years, the Bureau of Reclamation (BOR), known as the Reclamation Service at the time, also considered the Lower Colorado as the site for a dam. Service chief Arthur Powell Davis proposed using dynamite to collapse the walls of Boulder Canyon, 20 miles (32 km) north of the eventual dam site, into the river. The river would carry off the smaller pieces of debris, and a dam would be built incorporating the remaining rubble. In 1922, after considering it for several years, the Reclamation Service finally rejected the proposal, citing doubts about the unproven technique and questions as to whether it would, in fact, save money.
Soon after the dam was authorized, increasing numbers of unemployed people converged on southern Nevada. Las Vegas, then a small city of some 5,000, saw between 10,000 and 20,000 unemployed descend on it. A government camp was established for surveyors and other personnel near the dam site; this soon became surrounded by a squatters' camp. Known as McKeeversville, the camp was home to men hoping for work on the project, together with their families. Another camp, on the flats along the Colorado River, was officially called Williamsville, but was known to its inhabitants as "Ragtown". When construction began, Six Companies hired large numbers of workers, with more than 3,000 on the payroll by 1932 and with employment peaking at 5,251 in July 1934. "Mongolian" (Chinese) labor was prevented by the construction contract, while the number of black people employed by Six Companies never exceeded thirty, mostly lowest-pay-scale laborers in a segregated crew, who were issued separate water buckets.
As part of the contract, Six Companies, Inc. was to build Boulder City to house the workers. The original timetable called for Boulder City to be built before the dam project began, but President Hoover ordered work on the dam to begin in March 1931 rather than in October. The company built bunkhouses, attached to the canyon wall, to house 480 single men at what became known as River Camp. Workers with families were left to provide their own accommodations until Boulder City could be completed, and many lived in Ragtown. The site of Hoover Dam endures extremely hot weather, and the summer of 1931 was especially torrid, with the daytime high averaging 119.9 °F (48.8 °C). Sixteen workers and other riverbank residents died of heat prostration between June 25 and July 26, 1931.
The Industrial Workers of the World (IWW or "Wobblies"), though much-reduced from their heyday as militant labor organizers in the early years of the century, hoped to unionize the Six Companies workers by capitalizing on their discontent. They sent eleven organizers, several of whom were arrested by Las Vegas police. On August 7, 1931, the company cut wages for all tunnel workers. Although the workers sent the organizers away, not wanting to be associated with the "Wobblies", they formed a committee to represent them with the company. The committee drew up a list of demands that evening and presented them to Crowe the following morning. He was noncommittal. The workers hoped that Crowe, the general superintendent of the job, would be sympathetic; instead, he gave a scathing interview to a newspaper, describing the workers as "malcontents".
On the morning of the 9th, Crowe met with the committee and told them that management refused their demands, was stopping all work, and was laying off the entire work force, except for a few office workers and carpenters. The workers were given until 5 p.m. to vacate the premises. Concerned that a violent confrontation was imminent, most workers took their paychecks and left for Las Vegas to await developments. Two days later, the remainder were talked into leaving by law enforcement. On August 13, the company began hiring workers again, and two days later, the strike was called off. While the workers received none of their demands, the company guaranteed there would be no further reductions in wages. Living conditions began to improve as the first residents moved into Boulder City in late 1931.
A second labor action took place in July 1935, as construction on the dam wound down. When a Six Companies manager altered working times to force workers to take lunch on their own time, workers responded with a strike. Emboldened by Crowe's reversal of the lunch decree, workers raised their demands to include a $1-per-day raise. The company agreed to ask the Federal government to supplement the pay, but no money was forthcoming from Washington. The strike ended.
Before the dam could be built, the Colorado River needed to be diverted away from the construction site. To accomplish this, four diversion tunnels were driven through the canyon walls, two on the Nevada side and two on the Arizona side. These tunnels were 56 ft (17 m) in diameter. Their combined length was nearly 16,000 ft, or more than 3 miles (5 km). The contract required these tunnels to be completed by October 1, 1933, with a $3,000-per-day fine to be assessed for any delay. To meet the deadline, Six Companies had to complete work by early 1933, since only in late fall and winter was the water level in the river low enough to safely divert.
Tunneling began at the lower portals of the Nevada tunnels in May 1931. Shortly afterward, work began on two similar tunnels in the Arizona canyon wall. In March 1932, work began on lining the tunnels with concrete. First the base, or invert, was poured. Gantry cranes, running on rails through the entire length of each tunnel were used to place the concrete. The sidewalls were poured next. Movable sections of steel forms were used for the sidewalls. Finally, using pneumatic guns, the overheads were filled in. The concrete lining is 3 feet (1 m) thick, reducing the finished tunnel diameter to 50 ft (15 m). The river was diverted into the two Arizona tunnels on November 13, 1932; the Nevada tunnels were kept in reserve for high water. This was done by exploding a temporary cofferdam protecting the Arizona tunnels while at the same time dumping rubble into the river until its natural course was blocked.
Following the completion of the dam, the entrances to the two outer diversion tunnels were sealed at the opening and halfway through the tunnels with large concrete plugs. The downstream halves of the tunnels following the inner plugs are now the main bodies of the spillway tunnels. The inner diversion tunnels were plugged at approximately one-third of their length, beyond which they now carry steel pipes connecting the intake towers to the power plant and outlet works. The inner tunnels' outlets are equipped with gates that can be closed to drain the tunnels for maintenance.
To protect the construction site from the Colorado River and to facilitate the river's diversion, two cofferdams were constructed. Work on the upper cofferdam began in September 1932, even though the river had not yet been diverted. The cofferdams were designed to protect against the possibility of the river's flooding a site at which two thousand men might be at work, and their specifications were covered in the bid documents in nearly as much detail as the dam itself. The upper cofferdam was 96 ft (29 m) high, and 750 feet (230 m) thick at its base, thicker than the dam itself. It contained 650,000 cubic yards (500,000 m3) of material.
When the cofferdams were in place and the construction site was drained of water, excavation for the dam foundation began. For the dam to rest on solid rock, it was necessary to remove accumulated erosion soils and other loose materials in the riverbed until sound bedrock was reached. Work on the foundation excavations was completed in June 1933. During this excavation, approximately 1,500,000 cu yd (1,100,000 m3) of material was removed. Since the dam was an arch-gravity type, the side-walls of the canyon would bear the force of the impounded lake. Therefore, the side-walls were also excavated to reach virgin rock, as weathered rock might provide pathways for water seepage. Shovels for the excavation came from the Marion Power Shovel Company.
The men who removed this rock were called "high scalers". While suspended from the top of the canyon with ropes, the high-scalers climbed down the canyon walls and removed the loose rock with jackhammers and dynamite. Falling objects were the most common cause of death on the dam site; the high scalers' work thus helped ensure worker safety. One high scaler was able to save a life in a more direct manner: when a government inspector lost his grip on a safety line and began tumbling down a slope towards almost certain death, a high scaler was able to intercept him and pull him into the air. The construction site had become a magnet for tourists. The high scalers were prime attractions and showed off for the watchers. The high scalers received considerable media attention, with one worker dubbed the "Human Pendulum" for swinging co-workers (and, at other times, cases of dynamite) across the canyon. To protect themselves against falling objects, some high scalers dipped cloth hats in tar and allowed them to harden. When workers wearing such headgear were struck hard enough to inflict broken jaws, they sustained no skull damage. Six Companies ordered thousands of what initially were called "hard boiled hats" (later "hard hats") and strongly encouraged their use.
The cleared, underlying rock foundation of the dam site was reinforced with grout, forming a grout curtain. Holes were driven into the walls and base of the canyon, as deep as 150 feet (46 m) into the rock, and any cavities encountered were to be filled with grout. This was done to stabilize the rock, to prevent water from seeping past the dam through the canyon rock, and to limit "uplift"—upward pressure from water seeping under the dam. The workers were under severe time constraints due to the beginning of the concrete pour. When they encountered hot springs or cavities too large to readily fill, they moved on without resolving the problem. A total of 58 of the 393 holes were incompletely filled. After the dam was completed and the lake began to fill, large numbers of significant leaks caused the Bureau of Reclamation to examine the situation. It found that the work had been incompletely done, and was based on less than a full understanding of the canyon's geology. New holes were drilled from inspection galleries inside the dam into the surrounding bedrock. It took nine years (1938–47) under relative secrecy to complete the supplemental grout curtain.
The first concrete was poured into the dam on June 6, 1933, 18 months ahead of schedule. Since concrete heats and contracts as it cures, the potential for uneven cooling and contraction of the concrete posed a serious problem. Bureau of Reclamation engineers calculated that if the dam were to be built in a single continuous pour, the concrete would take 125 years to cool, and the resulting stresses would cause the dam to crack and crumble. Instead, the ground where the dam would rise was marked with rectangles, and concrete blocks in columns were poured, some as large as 50 ft square (15 m) and 5 feet (1.5 m) high. Each five-foot form contained a set of 1-inch (25 mm) steel pipes; cool river water would be poured through the pipes, followed by ice-cold water from a refrigeration plant. When an individual block had cured and had stopped contracting, the pipes were filled with grout. Grout was also used to fill the hairline spaces between columns, which were grooved to increase the strength of the joints.
The concrete was delivered in huge steel buckets 7 feet high (2.1 m) and almost 7 feet in diameter; Crowe was awarded two patents for their design. These buckets, which weighed 20 short tons (18.1 t; 17.9 long tons) when full, were filled at two massive concrete plants on the Nevada side, and were delivered to the site in special railcars. The buckets were then suspended from aerial cableways which were used to deliver the bucket to a specific column. As the required grade of aggregate in the concrete differed depending on placement in the dam (from pea-sized gravel to 9 inches [230 mm] stones), it was vital that the bucket be maneuvered to the proper column. When the bottom of the bucket opened up, disgorging 8 cu yd (6.1 m3) of concrete, a team of men worked it throughout the form. Although there are myths that men were caught in the pour and are entombed in the dam to this day, each bucket deepened the concrete in a form by only 1 inch (25 mm), and Six Companies engineers would not have permitted a flaw caused by the presence of a human body.
A total of 3,250,000 cubic yards (2,480,000 cubic meters) of concrete was used in the dam before concrete pouring ceased on May 29, 1935. In addition, 1,110,000 cu yd (850,000 m3) were used in the power plant and other works. More than 582 miles (937 km) of cooling pipes were placed within the concrete. Overall, there is enough concrete in the dam to pave a two-lane highway from San Francisco to New York. Concrete cores were removed from the dam for testing in 1995; they showed that "Hoover Dam's concrete has continued to slowly gain strength" and the dam is composed of a "durable concrete having a compressive strength exceeding the range typically found in normal mass concrete". Hoover Dam concrete is not subject to alkali–silica reaction (ASR), as the Hoover Dam builders happened to use nonreactive aggregate, unlike that at downstream Parker Dam, where ASR has caused measurable deterioration.
With most work finished on the dam itself (the powerhouse remained uncompleted), a formal dedication ceremony was arranged for September 30, 1935, to coincide with a western tour being made by President Franklin D. Roosevelt. The morning of the dedication, it was moved forward three hours from 2 p.m. Pacific time to 11 a.m.; this was done because Secretary of the Interior Harold L. Ickes had reserved a radio slot for the President for 2 p.m. but officials did not realize until the day of the ceremony that the slot was for 2 p.m. Eastern Time. Despite the change in the ceremony time, and temperatures of 102 °F (39 °C), 10,000 people were present for the President's speech, in which he avoided mentioning the name of former President Hoover, who was not invited to the ceremony. To mark the occasion, a three-cent stamp was issued by the United States Post Office Department—bearing the name "Boulder Dam", the official name of the dam between 1933 and 1947. After the ceremony, Roosevelt made the first visit by any American president to Las Vegas.
Most work had been completed by the dedication, and Six Companies negotiated with the government through late 1935 and early 1936 to settle all claims and arrange for the formal transfer of the dam to the Federal Government. The parties came to an agreement and on March 1, 1936, Secretary Ickes formally accepted the dam on behalf of the government. Six Companies was not required to complete work on one item, a concrete plug for one of the bypass tunnels, as the tunnel had to be used to take in irrigation water until the powerhouse went into operation.
There were 112 deaths reported as associated with the construction of the dam. The first was Bureau of Reclamation employee Harold Connelly who died on May 15, 1921, after falling from a barge while surveying the Colorado River for an ideal spot for the dam. Surveyor John Gregory ("J.G.") Tierney, who drowned on December 20, 1922, in a flash flood while looking for an ideal spot for the dam was the second person. The official list's final death occurred on December 20, 1935, when Patrick Tierney, electrician's helper and the son of J.G. Tierney, fell from one of the two Arizona-side intake towers. Included in the fatality list are three workers who took their own lives on site, one in 1932 and two in 1933. Of the 112 fatalities, 91 were Six Companies employees, three were Bureau of Reclamation employees, and one was a visitor to the site; the remainder were employees of various contractors not part of Six Companies.
Ninety-six of the deaths occurred during construction at the site. Not included in the official number of fatalities were deaths that were recorded as pneumonia. Workers alleged that this diagnosis was a cover for death from carbon monoxide poisoning (brought on by the use of gasoline-fueled vehicles in the diversion tunnels), and a classification used by Six Companies to avoid paying compensation claims. The site's diversion tunnels frequently reached 140 °F (60 °C), enveloped in thick plumes of vehicle exhaust gases. A total of 42 workers were recorded as having died from pneumonia and were not included in the above total; none were listed as having died from carbon monoxide poisoning. No deaths of non-workers from pneumonia were recorded in Boulder City during the construction period.
The initial plans for the facade of the dam, the power plant, the outlet tunnels and ornaments clashed with the modern look of an arch dam. The Bureau of Reclamation, more concerned with the dam's functionality, adorned it with a Gothic-inspired balustrade and eagle statues. This initial design was criticized by many as being too plain and unremarkable for a project of such immense scale, so Los Angeles-based architect Gordon B. Kaufmann, then the supervising architect to the Bureau of Reclamation, was brought in to redesign the exteriors. Kaufmann greatly streamlined the design and applied an elegant Art Deco style to the entire project. He designed sculpted turrets rising seamlessly from the dam face and clock faces on the intake towers set for the time in Nevada and Arizona—both states are in different time zones, but since Arizona does not observe daylight saving time, the clocks display the same time for more than half the year.
At Kaufmann's request, Denver artist Allen Tupper True was hired to handle the design and decoration of the walls and floors of the new dam. True's design scheme incorporated motifs of the Navajo and Pueblo tribes of the region. Although some were initially opposed to these designs, True was given the go-ahead and was officially appointed consulting artist. With the assistance of the National Laboratory of Anthropology, True researched authentic decorative motifs from Indian sand paintings, textiles, baskets and ceramics. The images and colors are based on Native American visions of rain, lightning, water, clouds, and local animals—lizards, serpents, birds—and on the Southwestern landscape of stepped mesas. In these works, which are integrated into the walkways and interior halls of the dam, True also reflected on the machinery of the operation, making the symbolic patterns appear both ancient and modern.
With the agreement of Kaufmann and the engineers, True also devised for the pipes and machinery an innovative color-coding which was implemented throughout all BOR projects. True's consulting artist job lasted through 1942; it was extended so he could complete design work for the Parker, Shasta and Grand Coulee dams and power plants. True's work on the Hoover Dam was humorously referred to in a poem published in The New Yorker, part of which read, "lose the spark, and justify the dream; but also worthy of remark will be the color scheme".
Complementing Kaufmann and True's work, sculptor Oskar J. W. Hansen designed many of the sculptures on and around the dam. His works include the monument of dedication plaza, a plaque to memorialize the workers killed and the bas-reliefs on the elevator towers. In his words, Hansen wanted his work to express "the immutable calm of intellectual resolution, and the enormous power of trained physical strength, equally enthroned in placid triumph of scientific accomplishment", because "the building of Hoover Dam belongs to the sagas of the daring." Hansen's dedication plaza, on the Nevada abutment, contains a sculpture of two winged figures flanking a flagpole.
Surrounding the base of the monument is a terrazzo floor embedded with a "star map". The map depicts the Northern Hemisphere sky at the moment of President Roosevelt's dedication of the dam. This is intended to help future astronomers, if necessary, calculate the exact date of dedication. The 30-foot-high (9.1 m) bronze figures, dubbed "Winged Figures of the Republic", were both formed in a continuous pour. To put such large bronzes into place without marring the highly polished bronze surface, they were placed on ice and guided into position as the ice melted. Hansen's bas-relief on the Nevada elevator tower depicts the benefits of the dam: flood control, navigation, irrigation, water storage, and power. The bas-relief on the Arizona elevator depicts, in his words, "the visages of those Indian tribes who have inhabited mountains and plains from ages distant."
Excavation for the powerhouse was carried out simultaneously with the excavation for the dam foundation and abutments. The excavation of this U-shaped structure located at the downstream toe of the dam was completed in late 1933 with the first concrete placed in November 1933. Filling of Lake Mead began February 1, 1935, even before the last of the concrete was poured that May. The powerhouse was one of the projects uncompleted at the time of the formal dedication on September 30, 1935; a crew of 500 men remained to finish it and other structures. To make the powerhouse roof bombproof, it was constructed of layers of concrete, rock, and steel with a total thickness of about 3.5 feet (1.1 m), topped with layers of sand and tar.
In the latter half of 1936, water levels in Lake Mead were high enough to permit power generation, and the first three Allis Chalmers built Francis turbine-generators, all on the Nevada side, began operating. In March 1937, one more Nevada generator went online and the first Arizona generator by August. By September 1939, four more generators were operating, and the dam's power plant became the largest hydroelectricity facility in the world. The final generator was not placed in service until 1961, bringing the maximum generating capacity to 1,345 megawatts at the time. Original plans called for 16 large generators, eight on each side of the river, but two smaller generators were installed instead of one large one on the Arizona side for a total of 17. The smaller generators were used to serve smaller communities at a time when the output of each generator was dedicated to a single municipality, before the dam's total power output was placed on the grid and made arbitrarily distributable.
Before water from Lake Mead reaches the turbines, it enters the intake towers and then four gradually narrowing penstocks which funnel the water down towards the powerhouse. The intakes provide a maximum hydraulic head (water pressure) of 590 ft (180 m) as the water reaches a speed of about 85 mph (140 km/h). The entire flow of the Colorado River usually passes through the turbines. The spillways and outlet works (jet-flow gates) are rarely used. The jet-flow gates, located in concrete structures 180 feet (55 m) above the river and also at the outlets of the inner diversion tunnels at river level, may be used to divert water around the dam in emergency or flood conditions, but have never done so, and in practice are used only to drain water from the penstocks for maintenance. Following an uprating project from 1986 to 1993, the total gross power rating for the plant, including two 2.4 megawatt Pelton turbine-generators that power Hoover Dam's own operations is a maximum capacity of 2080 megawatts. The annual generation of Hoover Dam varies. The maximum net generation was 10.348 TWh in 1984, and the minimum since 1940 was 2.648 TWh in 1956. The average power generated was 4.2 TWh/year for 1947–2008. In 2015, the dam generated 3.6 TWh.
The amount of electricity generated by Hoover Dam has been decreasing along with the falling water level in Lake Mead due to the prolonged drought since year 2000 and high demand for the Colorado River's water. By 2014 its generating capacity was downrated by 23% to 1592 MW and was providing power only during periods of peak demand. Lake Mead fell to a new record low elevation of 1,071.61 feet (326.63 m) on July 1, 2016, before beginning to rebound slowly. Under its original design, the dam would no longer be able to generate power once the water level fell below 1,050 feet (320 m), which might have occurred in 2017 had water restrictions not been enforced. To lower the minimum power pool elevation from 1,050 to 950 feet (320 to 290 m), five wide-head turbines, designed to work efficiently with less flow, were installed.[102] Water levels were maintained at over 1,075 feet (328 m) in 2018 and 2019, but fell to a new record low of 1,071.55 feet (326.61 m) on June 10, 2021[104] and were projected to fall below 1,066 feet (325 m) by the end of 2021.
Control of water was the primary concern in the building of the dam. Power generation has allowed the dam project to be self-sustaining: proceeds from the sale of power repaid the 50-year construction loan, and those revenues also finance the multimillion-dollar yearly maintenance budget. Power is generated in step with and only with the release of water in response to downstream water demands.
Lake Mead and downstream releases from the dam also provide water for both municipal and irrigation uses. Water released from the Hoover Dam eventually reaches several canals. The Colorado River Aqueduct and Central Arizona Project branch off Lake Havasu while the All-American Canal is supplied by the Imperial Dam. In total, water from Lake Mead serves 18 million people in Arizona, Nevada, and California and supplies the irrigation of over 1,000,000 acres (400,000 ha) of land.
In 2018, the Los Angeles Department of Water and Power (LADWP) proposed a $3 billion pumped-storage hydroelectricity project—a "battery" of sorts—that would use wind and solar power to recirculate water back up to Lake Mead from a pumping station 20 miles (32 km) downriver.
Electricity from the dam's powerhouse was originally sold pursuant to a fifty-year contract, authorized by Congress in 1934, which ran from 1937 to 1987. In 1984, Congress passed a new statute which set power allocations to southern California, Arizona, and Nevada from the dam from 1987 to 2017. The powerhouse was run under the original authorization by the Los Angeles Department of Water and Power and Southern California Edison; in 1987, the Bureau of Reclamation assumed control. In 2011, Congress enacted legislation extending the current contracts until 2067, after setting aside 5% of Hoover Dam's power for sale to Native American tribes, electric cooperatives, and other entities. The new arrangement began on October 1, 2017.
The dam is protected against over-topping by two spillways. The spillway entrances are located behind each dam abutment, running roughly parallel to the canyon walls. The spillway entrance arrangement forms a classic side-flow weir with each spillway containing four 100-foot-long (30 m) and 16-foot-wide (4.9 m) steel-drum gates. Each gate weighs 5,000,000 pounds (2,300 metric tons) and can be operated manually or automatically. Gates are raised and lowered depending on water levels in the reservoir and flood conditions. The gates cannot entirely prevent water from entering the spillways but can maintain an extra 16 ft (4.9 m) of lake level.
Water flowing over the spillways falls dramatically into 600-foot-long (180 m), 50-foot-wide (15 m) spillway tunnels before connecting to the outer diversion tunnels and reentering the main river channel below the dam. This complex spillway entrance arrangement combined with the approximate 700-foot (210 m) elevation drop from the top of the reservoir to the river below was a difficult engineering problem and posed numerous design challenges. Each spillway's capacity of 200,000 cu ft/s (5,700 m3/s) was empirically verified in post-construction tests in 1941.
The large spillway tunnels have only been used twice, for testing in 1941 and because of flooding in 1983. Both times, when inspecting the tunnels after the spillways were used, engineers found major damage to the concrete linings and underlying rock. The 1941 damage was attributed to a slight misalignment of the tunnel invert (or base), which caused cavitation, a phenomenon in fast-flowing liquids in which vapor bubbles collapse with explosive force. In response to this finding, the tunnels were patched with special heavy-duty concrete and the surface of the concrete was polished mirror-smooth. The spillways were modified in 1947 by adding flip buckets, which both slow the water and decrease the spillway's effective capacity, in an attempt to eliminate conditions thought to have contributed to the 1941 damage. The 1983 damage, also due to cavitation, led to the installation of aerators in the spillways. Tests at Grand Coulee Dam showed that the technique worked, in principle.
There are two lanes for automobile traffic across the top of the dam, which formerly served as the Colorado River crossing for U.S. Route 93. In the wake of the September 11 terrorist attacks, authorities expressed security concerns and the Hoover Dam Bypass project was expedited. Pending the completion of the bypass, restricted traffic was permitted over Hoover Dam. Some types of vehicles were inspected prior to crossing the dam while semi-trailer trucks, buses carrying luggage, and enclosed-box trucks over 40 ft (12 m) long were not allowed on the dam at all, and were diverted to U.S. Route 95 or Nevada State Routes 163/68. The four-lane Hoover Dam Bypass opened on October 19, 2010. It includes a composite steel and concrete arch bridge, the Mike O'Callaghan–Pat Tillman Memorial Bridge, 1,500 ft (460 m) downstream from the dam. With the opening of the bypass, through traffic is no longer allowed across Hoover Dam; dam visitors are allowed to use the existing roadway to approach from the Nevada side and cross to parking lots and other facilities on the Arizona side.
Hoover Dam opened for tours in 1937 after its completion but following Japan's attack on Pearl Harbor on December 7, 1941, it was closed to the public when the United States entered World War II, during which only authorized traffic, in convoys, was permitted. After the war, it reopened September 2, 1945, and by 1953, annual attendance had risen to 448,081. The dam closed on November 25, 1963, and March 31, 1969, days of mourning in remembrance of Presidents Kennedy and Eisenhower. In 1995, a new visitors' center was built, and the following year, visits exceeded one million for the first time. The dam closed again to the public on September 11, 2001; modified tours were resumed in December and a new "Discovery Tour" was added the following year. Today, nearly a million people per year take the tours of the dam offered by the Bureau of Reclamation. Increased security concerns by the government have led to most of the interior structure's being inaccessible to tourists. As a result, few of True's decorations can now be seen by visitors. Visitors can only purchase tickets on-site and have the options of a guided tour of the whole facility or only the power plant area. The only self-guided tour option is for the visitor center itself, where visitors can view various exhibits and enjoy a 360-degree view of the dam.
The changes in water flow and use caused by Hoover Dam's construction and operation have had a large impact on the Colorado River Delta. The construction of the dam has been implicated in causing the decline of this estuarine ecosystem. For six years after the construction of the dam, while Lake Mead filled, virtually no water reached the mouth of the river. The delta's estuary, which once had a freshwater-saltwater mixing zone stretching 40 miles (64 km) south of the river's mouth, was turned into an inverse estuary where the level of salinity was higher close to the river's mouth.
The Colorado River had experienced natural flooding before the construction of the Hoover Dam. The dam eliminated the natural flooding, threatening many species adapted to the flooding, including both plants and animals. The construction of the dam devastated the populations of native fish in the river downstream from the dam. Four species of fish native to the Colorado River, the Bonytail chub, Colorado pikeminnow, Humpback chub, and Razorback sucker, are listed as endangered.
During the years of lobbying leading up to the passage of legislation authorizing the dam in 1928, the press generally referred to the dam as "Boulder Dam" or as "Boulder Canyon Dam", even though the proposed site had shifted to Black Canyon. The Boulder Canyon Project Act of 1928 (BCPA) never mentioned a proposed name or title for the dam. The BCPA merely allows the government to "construct, operate, and maintain a dam and incidental works in the main stream of the Colorado River at Black Canyon or Boulder Canyon".
When Secretary of the Interior Ray Wilbur spoke at the ceremony starting the building of the railway between Las Vegas and the dam site on September 17, 1930, he named the dam "Hoover Dam", citing a tradition of naming dams after Presidents, though none had been so honored during their terms of office. Wilbur justified his choice on the ground that Hoover was "the great engineer whose vision and persistence ... has done so much to make [the dam] possible". One writer complained in response that "the Great Engineer had quickly drained, ditched, and dammed the country."
After Hoover's election defeat in 1932 and the accession of the Roosevelt administration, Secretary Ickes ordered on May 13, 1933, that the dam be referred to as Boulder Dam. Ickes stated that Wilbur had been imprudent in naming the dam after a sitting president, that Congress had never ratified his choice, and that it had long been referred to as Boulder Dam. Unknown to the general public, Attorney General Homer Cummings informed Ickes that Congress had indeed used the name "Hoover Dam" in five different bills appropriating money for construction of the dam. The official status this conferred to the name "Hoover Dam" had been noted on the floor of the House of Representatives by Congressman Edward T. Taylor of Colorado on December 12, 1930, but was likewise ignored by Ickes.
When Ickes spoke at the dedication ceremony on September 30, 1935, he was determined, as he recorded in his diary, "to try to nail down for good and all the name Boulder Dam." At one point in the speech, he spoke the words "Boulder Dam" five times within thirty seconds. Further, he suggested that if the dam were to be named after any one person, it should be for California Senator Hiram Johnson, a lead sponsor of the authorizing legislation. Roosevelt also referred to the dam as Boulder Dam, and the Republican-leaning Los Angeles Times, which at the time of Ickes' name change had run an editorial cartoon showing Ickes ineffectively chipping away at an enormous sign "HOOVER DAM", reran it showing Roosevelt reinforcing Ickes, but having no greater success.
In the following years, the name "Boulder Dam" failed to fully take hold, with many Americans using both names interchangeably and mapmakers divided as to which name should be printed. Memories of the Great Depression faded, and Hoover to some extent rehabilitated himself through good works during and after World War II. In 1947, a bill passed both Houses of Congress unanimously restoring the name "Hoover Dam." Ickes, who was by then a private citizen, opposed the change, stating, "I didn't know Hoover was that small a man to take credit for something he had nothing to do with."
Hoover Dam was recognized as a National Historic Civil Engineering Landmark in 1984. It was listed on the National Register of Historic Places in 1981 and was designated a National Historic Landmark in 1985, cited for its engineering innovations.
I wanted a steel bearing hits water picture so here it is.
Two things of note. the arc of bubbles (cavitation) is related to the shock wave in the water.
Second, the optical bowing of the orange/blue interface. I can only figure that it is due to the plastic container blowing out and forming a lens. Any comments?
Cheers.
Reptilian sea creatures that prowl the waters around Okoto, particularly the islands of the Region of Water. Tarakava hunt their prey using lightning-fast strikes from their powerful arms, which swing fast enough to generate cavitation bubbles. The shock waves that result are fully capable of killing a target, and if it survives the Tarakava will go in for the kill with its powerful jaws and teeth. Underwater, Tarakava can move their streamlined bodies quickly with their muscular tails. They have also been occasionally seen resting on land, where they can aid terrestrial movement with their arms, albeit sluggishly.
The head was reverse-engineered from this head by Kingmarshy, which inspired the MOC. I tried to interpret the Tarakava as a much more organic creature, with its strange tread becoming its tail, and its punching ability being like that of the Mantis shrimp.
Unfortunately, the photos make the teal appear a lot bluer than in person, but it certainly is indeed teal.
© 2017 Skip Plitt Photography, All Rights Reserved.
This photo may not be used in any form without permission from the photographer. None of my images are in the Creative Commons. If you wish to use one of my images please contact me at: skipplittphotography@gmail.com
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One of the most remarkable of the Wunderwaffen (wonder weapons) produced by the Nazi Germany during World War II, the Messerschmitt Me 163 Komet holds the distinction of being the first and only tailless rocket-powered interceptor to see operational service. Like the other advanced weapons fielded by Germany during the final year of World War II, the Me 163 had little actual effect on the outcome of the war. Considering the conditions under which it was developed and deployed, however, the Me 163 can be rightly considered a significant technological accomplishment.
The concept for the Komet originated during the late thirties, when rocket propulsion for aircraft became increasingly attractive to a number of air planners in Nazi Germany. Although rockets potentially offered astounding performance advantages for an interceptor, their high fuel consumption posed seemingly insurmountable design difficulties. In spite of this, the Reichsluftfahrtministerium or RLM (Reich Air Ministry) supported the work of rocket engine designer Hellmuth Walter, issuing a contract in 1936 for the development of an 882 lb. thrust motor designated the R I-203. The engine was to be fueled by a mixture of T-Stoff (80 percent hydrogen peroxide with oxyquinoline or phosphate as a stabilizer and 20 percent water) and Z-Stoff (an aqueous solution of calcium permanganate) and intended to power the Heinkel He 176 aircraft then under development. Because the He 176, which had been designed solely as a high-speed aircraft with no military potential, the RLM ordered the Deutsches Forschungsinsitut für Segelflug (German Research Institute for Gliding Flight or DFS) to produce a second prototype of the DFS 39, a tailless aircraft designed by Dr. Alexander Lippisch. It was also to be a rocket-powered design under a top-secret program designated Project X. DFS was to build the aircraft's wings while Heinkel, which was already working on the He 176, was to manufacture the rest of the airframe. It soon became apparent to Lippisch, however, that the DFS 39's wingtip-mounted rudders would likely cause unacceptable flutter and that a central fin and rudder would offer better control. It was replaced by a new design, designated the DFS 194, with a single large vertical stabilizer mounted on the fuselage. Like the DFS 39, it was initially intended only to be a conventionally powered flying test bed for later rocket-powered designs.
Difficulties arising from the division of work between DFS and Heinkel and the secrecy surrounding the project led Lippisch to request that he be allowed to leave DFS and join Messerschmitt AG. The RLM granted his request on January 2, 1939, and shortly after Lippisch, his design team, and the partially completed DFS 194 arrived at the Messerschmitt works in Augsburg, it was decided to adopt rocket power for the aircraft. The airframe was completed at the Messerschmitt works in Augsburg and shipped to Pennemünde West early in 1940 for installation of a Walter R I-203. Flight-testing revealed that despite the unreliability its motor, the aircraft had excellent performance characteristics, reaching a speed of 342 mph in level flight during one test.
The move to Messerschmitt brought a change in the program's designation to Me 163. The success of the DFS 194 spurred development of the first prototype Me 163, designated the Me 163 V1, which was completed during early 1941. Flight testing commenced in the spring of 1941, comprising a series of unpowered flights before the Me 163 V1 was shipped to Peenemünde West for installation of a 1,653 lb. thrust Walter RII-203 rocket motor and its first powered flights. Despite a series of accidents and explosions involving the unreliable motor, on October 2, 1941, the Me 163 V1 set a new world speed record of 1,004.5 kph (623.8 mph). Impressed by the aircraft's performance, the RLM instructed Lippisch was to design an improved version of the Me 163 around a more powerful rocket motor under development by Walter. The new design, designated Me 163 B, was to be an operational interceptor and represented an almost complete redesign of the aircraft. Its landing gear remained similar to the earlier design, employing a wheeled trolley that was jettisoned after takeoff and an extendable skid for landing. Additional prototypes based on the Me 163 V1 configuration were designated Me 163 A.
The first Me 163 B prototype, the Me 163 V3, was completed in April 1942, but it was not until early fall that the first Walter 109-509A motors were ready for installation. The new motor used a more volatile fuel mixture of T-Stoff (80 percent hydrogen peroxide and 20 percent water) and C-Stoff (hydrazine hydrate, methyl alcohol, and water), which provided a maximum thrust of 1,500 kg (3,300 lb.). Unlike the earlier cold principle motor which directed all of the oxygen and water vapor produced by the decomposition of the hydrogen peroxide out of the engine's nozzle, the new motor employed a hot system in which the oxygen was ignited for additional thrust and better fuel efficiency. Flight testing of the first series of Me 163 B-0 preproduction aircraft proceeded through 1942 and demonstrated the dangers of the Me 163's unproven propulsion system. As fuel passed through the Walter motor's pumps, areas of vacuum sometimes formed in the liquid. This cavitation often caused a catastrophic explosion when the motor was started. Once in the air, the aircraft's climb rate proved remarkable, but compressibility problems limited its safe speed in a dive to below Mach 0.82. The Komet's landing gear also proved troublesome, with numerous pilots suffering back injuries as a result of the skid failing to extend properly or failing upon touchdown. Even when the skid operated properly, landings were always without power and at high speed, requiring the utmost care on the part of the pilot to prevent the aircraft from overturning on soft ground. Such mishaps often led to an explosion or the pilot being severely burned by leaking fuel.
Despite the problems encountered during testing, plans proceeded during 1943 to equip the first operational units with the operational version of the Komet, designated the Me 163 B-1a. Production began at dispersed facilities by the Klemm concern, but was later transferred to Junkers as the result of quality control problems. An operational training unit, Erprobungskommando 16 or EK 16 was formed during July 1943 at Pennemünde West, but moved to Bad Zwischenahn before the first group of pilot trainees arrived as the result of allied bombing of Pennemünde. The unit finally received its first group of 30 pilot trainees in the fall of 1943. By May 1944, organization of Jagdgeschwader 400 or JG 400, the first operational Me 163 wing, began in earnest with the formation of the unit's first group (I./JG 400) under the command of Hauptmann Wolfgang Späte. Späte planned to deploy Me 163s from a string of bases, each close enough that the short range of the Me 163 overlapped. The plan was never realized, owing in part to the special facilities needed for the aircraft. Instead, I./JG 400 was to provide protection for the synthetic oil refineries at Leuna, some 90 km (55 miles) from its base at Brandis. Two additional Me 163 groups, II. And III./JG 400 were formed before the end of the war, but saw limited combat.
The unit made its first interception of Allied bombers on August 16, 1944 without success. Early combat experiences demonstrated a number of problems that prevented the Me 163 from ever becoming an effective weapon. Although the aircraft's two MK 108 30mm cannons were capable of downing a four-engine bomber with only three or four hits, the Komet's high speed, coupled with the cannons' slow rate of fire and short range made effective gunnery nearly impossible against the slow moving bombers. As a result, Me 163 pilots recorded a total of only nine kills. Although capable of reaching its service ceiling of 12,100 m (39,690 ft) in just under three-and-a-half minutes, the Me 163 carried only enough fuel for eight minutes of powered flight. After one or two firing passes, the pilot had to glide back to base with no means of escaping Allied escort fighters. In response to pilots' combat reports, alternative weapons, including vertically firing 50mm cannons triggered by a photocell as the Me 163 passed through a bomber's shadow were tested but not produced in quantity. An improved variant of the aircraft with a greater endurance and a tricycle landing gear, designated the Me 163 C, was also produced in small numbers before the war's end, but was not flown operationally.
The operational history of the National Air and Space Museum's Me 163 B-1a, Werk-Nummer (serial number) 191301, remains obscure. One of five Me 163s brought to the United States after the war, it arrived at Freeman Field, Indiana, during the summer of 1945. There it received the foreign equipment code FE-500. On April 12, 1946, it was flown aboard a cargo aircraft to the U.S. Army Air Forces facility at Muroc dry lake in California for flight testing. Testing began there on May 3, 1946 in the presence of Dr. Alexander Lippisch and involved towing the unfueled Komet behind a B-29 to an altitude of 9,000 to 10,500 m (30,000 to 35,000 ft) before it was released for a glide back to earth under the control of test pilot Major Gus Lundquist. Powered tests were planned, but not carried out after delamination of the aircraft's wooden wings was discovered. It was then stored at Norton AFB, California until 1954, when it was transferred to the Smithsonian Institution. The aircraft remained on display in an unrestored condition at the museum's Paul E. Garber Restoration and Storage Facility in Suitland, Maryland, until 1996, when it was lent to the Mighty Eighth Air Force Heritage Museum in Savannah, Georgia. It is currently displayed at the Museum's Steven F. Udvar-Hazy Center in Chantilly, VA.
airandspace.si.edu/collection-objects/messerschmitt-me-16...
PNNL researchers saw for the first time a phenomenon that was theorized more than 20 years ago. Shown here is a PNNL illustration of the phenomenon, “solvent cavitation under solvo-phobic confinement,” which PNNL researchers saw occur with carbon-rich nanorods they mistakenly created. PNNL’s viewing of the phenomenon involved liquid spontaneously evaporating after being confined within tiny spaces in between touching nanorods. Image from S. Nune et al, Nature Nanotechnology, 2016.
Terms of Use: Our images are freely and publicly available for use with the credit line, "Courtesy of Pacific Northwest National Laboratory." Please use provided caption information for use in appropriate context.
There is a common dental procedure that nearly every dentist will tell you is completely safe, despite the fact that scientists have been warning of its dangers for more than 100 years.
What is this dental procedure?
The root canal.
Root-canaled teeth are essentially “dead” teeth that can become silent incubators for highly toxic anaerobic bacteria that can, under certain conditions, make their way into your bloodstream to cause a number of serious medical conditions—many not appearing until decades later.
Most of these toxic teeth feel and look fine for many years, which make their role in systemic disease even harder to trace back.
Sadly, the vast majority of dentists are oblivious to the serious potential health risks they are exposing their patients to, risks that persist for the rest of their patients’ lives.
The American Dental Association claims root canals have been proven safe, but they have NO published data or actual research to substantiate this claim.
Dr. Weston Price, regarded by many as the greatest dentist of all time, who, more than a century ago, made the connection between root-canaled teeth and disease.
Dr. Price was a dentist and researcher who traveled the world to study the teeth, bones, and diets of native populations living without the “benefit” of modern food. Around the year 1900, Price had been treating persistent root canal infections and became suspicious that root-canaled teeth always remained infected, in spite of treatments. Then one day, he recommended to a woman, wheelchair bound for six years, to have her root canal tooth extracted, even though it appeared to be fine.
She agreed, so he extracted her tooth and then implanted it under the skin of a rabbit. The rabbit amazingly developed the same crippling arthritis as the woman and died from the infection 10 days later. But the woman, now free of the toxic tooth, immediately recovered from her arthritis and could now walk without even the assistance of a cane.
Price discovered that it’s mechanically impossible to sterilize a root-canaled (e.g. root-filled) tooth. He then went on to show that many chronic degenerative diseases originate from root-filled teeth—the most frequent being heart and circulatory diseases. He actually found 16 different causative bacterial agents for these conditions. But there were also strong correlations between root-filled teeth and diseases of the joints, brain and nervous system. Dr. Price went on to write two groundbreaking books in 1922 detailing his research into the link between dental pathology and chronic illness. Unfortunately, his work was deliberately buried for 70 years, until finally one endodontist named George Meinig recognized the importance of Price’s work and sought to explain the truth.
Dr. Meinig, a native of Chicago, was a captain in the U.S. Army during World War II before moving to Hollywood to become a dentist for the stars. He eventually became one of the founding members of the American Association of Endodontists (root canal specialists).
In the 1990s, he spent 18 months immersed in Dr. Price’s research. In June of 1993, Dr. Meinig published the book Root Canal Cover-Up, which continues to be the most comprehensive reference on this topic today.
Your teeth are made of the hardest substances in your body.
In the middle of each tooth is the pulp chamber, a soft living inner structure that houses blood vessels and nerves. Surrounding the pulp chamber is the dentin, which is made of living cells that secrete a hard mineral substance. The outermost and hardest layer of your tooth is the white enamel, which encases the dentin.
The roots of each tooth descend into your jawbone and are held in place by the periodontal ligament. In dental school, dentists are taught that each tooth has one to four major canals. However, there are accessory canals that are never mentioned. Literally miles of them!
Just as your body has large blood vessels that branch down into very small capillaries, each of your teeth has a maze of very tiny tubules that, if stretched out, would extend for three miles. Weston Price identified as many as 75 separate accessory canals in a single central incisor (front tooth). Microscopic organisms regularly move in and around these tubules, like gophers in underground tunnels.
When a dentist performs a root canal, he or she hollows out the tooth, then fills the hollow chamber with a substance (called guttapercha), which cuts off the tooth from its blood supply, so fluid can no longer circulate through the tooth. But the maze of tiny tubules remains. And bacteria, cut off from their food supply, hide out in these tunnels where they are remarkably safe from antibiotics and your own body’s immune defenses.
Under the stresses of oxygen and nutrient deprivation, these formerly friendly organisms morph into stronger, more virulent anaerobes that produce a variety of potent toxins. What were once ordinary, friendly oral bacteria mutate into highly toxic pathogens lurking in the tubules of the dead tooth, just awaiting an opportunity to spread.
No amount of sterilization has been found effective in reaching these tubules—and just about every single root-canaled tooth has been found colonized by these bacteria, especially around the apex and in the periodontal ligament. Oftentimes, the infection extends down into the jawbone where it creates cavitations—areas of necrotic tissue in the jawbone itself.
Cavitations are areas of unhealed bone, often accompanied by pockets of infected tissue and gangrene. Sometimes they form after a tooth extraction (such as a wisdom tooth extraction), but they can also follow a root canal. According to Weston Price Foundation, in the records of 5,000 surgical cavitation cleanings, only two were found healed.
And all of this occurs with few, if any, accompanying symptoms. So you may have an abscessed dead tooth and not know it. This focal infection in the immediate area of the root-canaled tooth is bad enough, but the damage doesn’t stop there.
As long as your immune system remains strong, any bacteria that stray away from the infected tooth are captured and destroyed. But once your immune system is weakened by something like an accident or illness or other trauma, your immune system may be unable to keep the infection in check.
These bacteria can migrate out into surrounding tissues by hitching a ride into your blood stream, where they are transported to new locations to set up camp. The new location can be any organ or gland or tissue.
Dr. Price was able to transfer diseases harbored by humans to rabbits, by implanting fragments of root-canaled teeth, as mentioned above. He found that root canal fragments from a person who had suffered a heart attack, when implanted into a rabbit, would cause a heart attack in the rabbit within a few weeks.
He discovered he could transfer heart disease to the rabbit 100 percent of the time! Other diseases were more than 80 percent transferable by this method. Nearly every chronic degenerative disease has been linked with root canals, including:
Heart disease
Kidney disease
Arthritis, joint, and rheumatic diseases
Neurological diseases (including ALS and MS)
Autoimmune diseases (Lupus and more)
There may also be a cancer connection. Dr. Robert Jones, a researcher of the relationship between root canals and breast cancer, found an extremely high correlation between root canals and breast cancer. He claims to have found the following correlations in a five-year study of 300 breast cancer cases:
93 percent of women with breast cancer had root canals
7 percent had other oral pathology
Tumors, in the majority of cases, occurred on the same side of the body as the root canal(s) or other oral pathology.
Dr. Jones claims that toxins from the bacteria in an infected tooth or jawbone are able to inhibit the proteins that suppress tumor development. A German physician reported similar findings. Dr. Josef Issels reported that, in his 40 years of treating “terminal” cancer patients, 97 percent of his cancer patients had root canals. If these physicians are correct, the cure for cancer may be as simple as having a tooth pulled, then rebuilding your immune system.
One of three propellers on three shafts, which drove the world record breaking steam turbine driven boat Turbinia. Designed by Charles Parsons and built in 1894 on the Tyne, Turbinia famously showed a clean pair of heels to all comers at a Royal Navy review at Spithead. Famously, turbines would become would become the power plant of choice in vessels, civil and military, and their low maintenance and fantastic power output made most reciprocating engines redundant.
www.flickr.com/photos/bolckow/15267143762/in/photolist-pg...
The fairly in-efficient original design of propeller led to the introduction of research into cavitation. Turbinia is preserved in the Discovery Museum, Newcastle.
Hoover Dam is a concrete arch-gravity dam in the Black Canyon of the Colorado River, on the border between the U.S. states of Nevada and Arizona. It was constructed between 1931 and 1936 during the Great Depression and was dedicated on September 30, 1935, by President Franklin D. Roosevelt. Its construction was the result of a massive effort involving thousands of workers, and cost over one hundred lives. It was referred to as Hoover Dam after President Herbert Hoover in bills passed by Congress during its construction, but was named Boulder Dam by the Roosevelt administration. The Hoover Dam name was restored by Congress in 1947.
Since about 1900, the Black Canyon and nearby Boulder Canyon had been investigated for their potential to support a dam that would control floods, provide irrigation water and produce hydroelectric power. In 1928, Congress authorized the project. The winning bid to build the dam was submitted by a consortium named Six Companies, Inc., which began construction of the dam in early 1931. Such a large concrete structure had never been built before, and some of the techniques were unproven. The torrid summer weather and lack of facilities near the site also presented difficulties. Nevertheless, Six Companies turned the dam over to the federal government on March 1, 1936, more than two years ahead of schedule.
Hoover Dam impounds Lake Mead, the largest reservoir in the United States by volume when full. The dam is located near Boulder City, Nevada, a municipality originally constructed for workers on the construction project, about 30 mi (48 km) southeast of Las Vegas, Nevada. The dam's generators provide power for public and private utilities in Nevada, Arizona, and California. Hoover Dam is a major tourist attraction; nearly a million people tour the dam each year. The heavily traveled U.S. Route 93 (US 93) ran along the dam's crest until October 2010, when the Hoover Dam Bypass opened.
As the United States developed the Southwest, the Colorado River was seen as a potential source of irrigation water. An initial attempt at diverting the river for irrigation purposes occurred in the late 1890s, when land speculator William Beatty built the Alamo Canal just north of the Mexican border; the canal dipped into Mexico before running to a desolate area Beatty named the Imperial Valley. Though water from the Imperial Canal allowed for the widespread settlement of the valley, the canal proved expensive to operate. After a catastrophic breach that caused the Colorado River to fill the Salton Sea, the Southern Pacific Railroad spent $3 million in 1906–07 to stabilize the waterway, an amount it hoped in vain would be reimbursed by the federal government. Even after the waterway was stabilized, it proved unsatisfactory because of constant disputes with landowners on the Mexican side of the border.
As the technology of electric power transmission improved, the Lower Colorado was considered for its hydroelectric-power potential. In 1902, the Edison Electric Company of Los Angeles surveyed the river in the hope of building a 40-foot (12 m) rock dam which could generate 10,000 horsepower (7,500 kW). However, at the time, the limit of transmission of electric power was 80 miles (130 km), and there were few customers (mostly mines) within that limit. Edison allowed land options it held on the river to lapse—including an option for what became the site of Hoover Dam.
In the following years, the Bureau of Reclamation (BOR), known as the Reclamation Service at the time, also considered the Lower Colorado as the site for a dam. Service chief Arthur Powell Davis proposed using dynamite to collapse the walls of Boulder Canyon, 20 miles (32 km) north of the eventual dam site, into the river. The river would carry off the smaller pieces of debris, and a dam would be built incorporating the remaining rubble. In 1922, after considering it for several years, the Reclamation Service finally rejected the proposal, citing doubts about the unproven technique and questions as to whether it would, in fact, save money.
Soon after the dam was authorized, increasing numbers of unemployed people converged on southern Nevada. Las Vegas, then a small city of some 5,000, saw between 10,000 and 20,000 unemployed descend on it. A government camp was established for surveyors and other personnel near the dam site; this soon became surrounded by a squatters' camp. Known as McKeeversville, the camp was home to men hoping for work on the project, together with their families. Another camp, on the flats along the Colorado River, was officially called Williamsville, but was known to its inhabitants as "Ragtown". When construction began, Six Companies hired large numbers of workers, with more than 3,000 on the payroll by 1932 and with employment peaking at 5,251 in July 1934. "Mongolian" (Chinese) labor was prevented by the construction contract, while the number of black people employed by Six Companies never exceeded thirty, mostly lowest-pay-scale laborers in a segregated crew, who were issued separate water buckets.
As part of the contract, Six Companies, Inc. was to build Boulder City to house the workers. The original timetable called for Boulder City to be built before the dam project began, but President Hoover ordered work on the dam to begin in March 1931 rather than in October. The company built bunkhouses, attached to the canyon wall, to house 480 single men at what became known as River Camp. Workers with families were left to provide their own accommodations until Boulder City could be completed, and many lived in Ragtown. The site of Hoover Dam endures extremely hot weather, and the summer of 1931 was especially torrid, with the daytime high averaging 119.9 °F (48.8 °C). Sixteen workers and other riverbank residents died of heat prostration between June 25 and July 26, 1931.
The Industrial Workers of the World (IWW or "Wobblies"), though much-reduced from their heyday as militant labor organizers in the early years of the century, hoped to unionize the Six Companies workers by capitalizing on their discontent. They sent eleven organizers, several of whom were arrested by Las Vegas police. On August 7, 1931, the company cut wages for all tunnel workers. Although the workers sent the organizers away, not wanting to be associated with the "Wobblies", they formed a committee to represent them with the company. The committee drew up a list of demands that evening and presented them to Crowe the following morning. He was noncommittal. The workers hoped that Crowe, the general superintendent of the job, would be sympathetic; instead, he gave a scathing interview to a newspaper, describing the workers as "malcontents".
On the morning of the 9th, Crowe met with the committee and told them that management refused their demands, was stopping all work, and was laying off the entire work force, except for a few office workers and carpenters. The workers were given until 5 p.m. to vacate the premises. Concerned that a violent confrontation was imminent, most workers took their paychecks and left for Las Vegas to await developments. Two days later, the remainder were talked into leaving by law enforcement. On August 13, the company began hiring workers again, and two days later, the strike was called off. While the workers received none of their demands, the company guaranteed there would be no further reductions in wages. Living conditions began to improve as the first residents moved into Boulder City in late 1931.
A second labor action took place in July 1935, as construction on the dam wound down. When a Six Companies manager altered working times to force workers to take lunch on their own time, workers responded with a strike. Emboldened by Crowe's reversal of the lunch decree, workers raised their demands to include a $1-per-day raise. The company agreed to ask the Federal government to supplement the pay, but no money was forthcoming from Washington. The strike ended.
Before the dam could be built, the Colorado River needed to be diverted away from the construction site. To accomplish this, four diversion tunnels were driven through the canyon walls, two on the Nevada side and two on the Arizona side. These tunnels were 56 ft (17 m) in diameter. Their combined length was nearly 16,000 ft, or more than 3 miles (5 km). The contract required these tunnels to be completed by October 1, 1933, with a $3,000-per-day fine to be assessed for any delay. To meet the deadline, Six Companies had to complete work by early 1933, since only in late fall and winter was the water level in the river low enough to safely divert.
Tunneling began at the lower portals of the Nevada tunnels in May 1931. Shortly afterward, work began on two similar tunnels in the Arizona canyon wall. In March 1932, work began on lining the tunnels with concrete. First the base, or invert, was poured. Gantry cranes, running on rails through the entire length of each tunnel were used to place the concrete. The sidewalls were poured next. Movable sections of steel forms were used for the sidewalls. Finally, using pneumatic guns, the overheads were filled in. The concrete lining is 3 feet (1 m) thick, reducing the finished tunnel diameter to 50 ft (15 m). The river was diverted into the two Arizona tunnels on November 13, 1932; the Nevada tunnels were kept in reserve for high water. This was done by exploding a temporary cofferdam protecting the Arizona tunnels while at the same time dumping rubble into the river until its natural course was blocked.
Following the completion of the dam, the entrances to the two outer diversion tunnels were sealed at the opening and halfway through the tunnels with large concrete plugs. The downstream halves of the tunnels following the inner plugs are now the main bodies of the spillway tunnels. The inner diversion tunnels were plugged at approximately one-third of their length, beyond which they now carry steel pipes connecting the intake towers to the power plant and outlet works. The inner tunnels' outlets are equipped with gates that can be closed to drain the tunnels for maintenance.
To protect the construction site from the Colorado River and to facilitate the river's diversion, two cofferdams were constructed. Work on the upper cofferdam began in September 1932, even though the river had not yet been diverted. The cofferdams were designed to protect against the possibility of the river's flooding a site at which two thousand men might be at work, and their specifications were covered in the bid documents in nearly as much detail as the dam itself. The upper cofferdam was 96 ft (29 m) high, and 750 feet (230 m) thick at its base, thicker than the dam itself. It contained 650,000 cubic yards (500,000 m3) of material.
When the cofferdams were in place and the construction site was drained of water, excavation for the dam foundation began. For the dam to rest on solid rock, it was necessary to remove accumulated erosion soils and other loose materials in the riverbed until sound bedrock was reached. Work on the foundation excavations was completed in June 1933. During this excavation, approximately 1,500,000 cu yd (1,100,000 m3) of material was removed. Since the dam was an arch-gravity type, the side-walls of the canyon would bear the force of the impounded lake. Therefore, the side-walls were also excavated to reach virgin rock, as weathered rock might provide pathways for water seepage. Shovels for the excavation came from the Marion Power Shovel Company.
The men who removed this rock were called "high scalers". While suspended from the top of the canyon with ropes, the high-scalers climbed down the canyon walls and removed the loose rock with jackhammers and dynamite. Falling objects were the most common cause of death on the dam site; the high scalers' work thus helped ensure worker safety. One high scaler was able to save a life in a more direct manner: when a government inspector lost his grip on a safety line and began tumbling down a slope towards almost certain death, a high scaler was able to intercept him and pull him into the air. The construction site had become a magnet for tourists. The high scalers were prime attractions and showed off for the watchers. The high scalers received considerable media attention, with one worker dubbed the "Human Pendulum" for swinging co-workers (and, at other times, cases of dynamite) across the canyon. To protect themselves against falling objects, some high scalers dipped cloth hats in tar and allowed them to harden. When workers wearing such headgear were struck hard enough to inflict broken jaws, they sustained no skull damage. Six Companies ordered thousands of what initially were called "hard boiled hats" (later "hard hats") and strongly encouraged their use.
The cleared, underlying rock foundation of the dam site was reinforced with grout, forming a grout curtain. Holes were driven into the walls and base of the canyon, as deep as 150 feet (46 m) into the rock, and any cavities encountered were to be filled with grout. This was done to stabilize the rock, to prevent water from seeping past the dam through the canyon rock, and to limit "uplift"—upward pressure from water seeping under the dam. The workers were under severe time constraints due to the beginning of the concrete pour. When they encountered hot springs or cavities too large to readily fill, they moved on without resolving the problem. A total of 58 of the 393 holes were incompletely filled. After the dam was completed and the lake began to fill, large numbers of significant leaks caused the Bureau of Reclamation to examine the situation. It found that the work had been incompletely done, and was based on less than a full understanding of the canyon's geology. New holes were drilled from inspection galleries inside the dam into the surrounding bedrock. It took nine years (1938–47) under relative secrecy to complete the supplemental grout curtain.
The first concrete was poured into the dam on June 6, 1933, 18 months ahead of schedule. Since concrete heats and contracts as it cures, the potential for uneven cooling and contraction of the concrete posed a serious problem. Bureau of Reclamation engineers calculated that if the dam were to be built in a single continuous pour, the concrete would take 125 years to cool, and the resulting stresses would cause the dam to crack and crumble. Instead, the ground where the dam would rise was marked with rectangles, and concrete blocks in columns were poured, some as large as 50 ft square (15 m) and 5 feet (1.5 m) high. Each five-foot form contained a set of 1-inch (25 mm) steel pipes; cool river water would be poured through the pipes, followed by ice-cold water from a refrigeration plant. When an individual block had cured and had stopped contracting, the pipes were filled with grout. Grout was also used to fill the hairline spaces between columns, which were grooved to increase the strength of the joints.
The concrete was delivered in huge steel buckets 7 feet high (2.1 m) and almost 7 feet in diameter; Crowe was awarded two patents for their design. These buckets, which weighed 20 short tons (18.1 t; 17.9 long tons) when full, were filled at two massive concrete plants on the Nevada side, and were delivered to the site in special railcars. The buckets were then suspended from aerial cableways which were used to deliver the bucket to a specific column. As the required grade of aggregate in the concrete differed depending on placement in the dam (from pea-sized gravel to 9 inches [230 mm] stones), it was vital that the bucket be maneuvered to the proper column. When the bottom of the bucket opened up, disgorging 8 cu yd (6.1 m3) of concrete, a team of men worked it throughout the form. Although there are myths that men were caught in the pour and are entombed in the dam to this day, each bucket deepened the concrete in a form by only 1 inch (25 mm), and Six Companies engineers would not have permitted a flaw caused by the presence of a human body.
A total of 3,250,000 cubic yards (2,480,000 cubic meters) of concrete was used in the dam before concrete pouring ceased on May 29, 1935. In addition, 1,110,000 cu yd (850,000 m3) were used in the power plant and other works. More than 582 miles (937 km) of cooling pipes were placed within the concrete. Overall, there is enough concrete in the dam to pave a two-lane highway from San Francisco to New York. Concrete cores were removed from the dam for testing in 1995; they showed that "Hoover Dam's concrete has continued to slowly gain strength" and the dam is composed of a "durable concrete having a compressive strength exceeding the range typically found in normal mass concrete". Hoover Dam concrete is not subject to alkali–silica reaction (ASR), as the Hoover Dam builders happened to use nonreactive aggregate, unlike that at downstream Parker Dam, where ASR has caused measurable deterioration.
With most work finished on the dam itself (the powerhouse remained uncompleted), a formal dedication ceremony was arranged for September 30, 1935, to coincide with a western tour being made by President Franklin D. Roosevelt. The morning of the dedication, it was moved forward three hours from 2 p.m. Pacific time to 11 a.m.; this was done because Secretary of the Interior Harold L. Ickes had reserved a radio slot for the President for 2 p.m. but officials did not realize until the day of the ceremony that the slot was for 2 p.m. Eastern Time. Despite the change in the ceremony time, and temperatures of 102 °F (39 °C), 10,000 people were present for the President's speech, in which he avoided mentioning the name of former President Hoover, who was not invited to the ceremony. To mark the occasion, a three-cent stamp was issued by the United States Post Office Department—bearing the name "Boulder Dam", the official name of the dam between 1933 and 1947. After the ceremony, Roosevelt made the first visit by any American president to Las Vegas.
Most work had been completed by the dedication, and Six Companies negotiated with the government through late 1935 and early 1936 to settle all claims and arrange for the formal transfer of the dam to the Federal Government. The parties came to an agreement and on March 1, 1936, Secretary Ickes formally accepted the dam on behalf of the government. Six Companies was not required to complete work on one item, a concrete plug for one of the bypass tunnels, as the tunnel had to be used to take in irrigation water until the powerhouse went into operation.
There were 112 deaths reported as associated with the construction of the dam. The first was Bureau of Reclamation employee Harold Connelly who died on May 15, 1921, after falling from a barge while surveying the Colorado River for an ideal spot for the dam. Surveyor John Gregory ("J.G.") Tierney, who drowned on December 20, 1922, in a flash flood while looking for an ideal spot for the dam was the second person. The official list's final death occurred on December 20, 1935, when Patrick Tierney, electrician's helper and the son of J.G. Tierney, fell from one of the two Arizona-side intake towers. Included in the fatality list are three workers who took their own lives on site, one in 1932 and two in 1933. Of the 112 fatalities, 91 were Six Companies employees, three were Bureau of Reclamation employees, and one was a visitor to the site; the remainder were employees of various contractors not part of Six Companies.
Ninety-six of the deaths occurred during construction at the site. Not included in the official number of fatalities were deaths that were recorded as pneumonia. Workers alleged that this diagnosis was a cover for death from carbon monoxide poisoning (brought on by the use of gasoline-fueled vehicles in the diversion tunnels), and a classification used by Six Companies to avoid paying compensation claims. The site's diversion tunnels frequently reached 140 °F (60 °C), enveloped in thick plumes of vehicle exhaust gases. A total of 42 workers were recorded as having died from pneumonia and were not included in the above total; none were listed as having died from carbon monoxide poisoning. No deaths of non-workers from pneumonia were recorded in Boulder City during the construction period.
The initial plans for the facade of the dam, the power plant, the outlet tunnels and ornaments clashed with the modern look of an arch dam. The Bureau of Reclamation, more concerned with the dam's functionality, adorned it with a Gothic-inspired balustrade and eagle statues. This initial design was criticized by many as being too plain and unremarkable for a project of such immense scale, so Los Angeles-based architect Gordon B. Kaufmann, then the supervising architect to the Bureau of Reclamation, was brought in to redesign the exteriors. Kaufmann greatly streamlined the design and applied an elegant Art Deco style to the entire project. He designed sculpted turrets rising seamlessly from the dam face and clock faces on the intake towers set for the time in Nevada and Arizona—both states are in different time zones, but since Arizona does not observe daylight saving time, the clocks display the same time for more than half the year.
At Kaufmann's request, Denver artist Allen Tupper True was hired to handle the design and decoration of the walls and floors of the new dam. True's design scheme incorporated motifs of the Navajo and Pueblo tribes of the region. Although some were initially opposed to these designs, True was given the go-ahead and was officially appointed consulting artist. With the assistance of the National Laboratory of Anthropology, True researched authentic decorative motifs from Indian sand paintings, textiles, baskets and ceramics. The images and colors are based on Native American visions of rain, lightning, water, clouds, and local animals—lizards, serpents, birds—and on the Southwestern landscape of stepped mesas. In these works, which are integrated into the walkways and interior halls of the dam, True also reflected on the machinery of the operation, making the symbolic patterns appear both ancient and modern.
With the agreement of Kaufmann and the engineers, True also devised for the pipes and machinery an innovative color-coding which was implemented throughout all BOR projects. True's consulting artist job lasted through 1942; it was extended so he could complete design work for the Parker, Shasta and Grand Coulee dams and power plants. True's work on the Hoover Dam was humorously referred to in a poem published in The New Yorker, part of which read, "lose the spark, and justify the dream; but also worthy of remark will be the color scheme".
Complementing Kaufmann and True's work, sculptor Oskar J. W. Hansen designed many of the sculptures on and around the dam. His works include the monument of dedication plaza, a plaque to memorialize the workers killed and the bas-reliefs on the elevator towers. In his words, Hansen wanted his work to express "the immutable calm of intellectual resolution, and the enormous power of trained physical strength, equally enthroned in placid triumph of scientific accomplishment", because "the building of Hoover Dam belongs to the sagas of the daring." Hansen's dedication plaza, on the Nevada abutment, contains a sculpture of two winged figures flanking a flagpole.
Surrounding the base of the monument is a terrazzo floor embedded with a "star map". The map depicts the Northern Hemisphere sky at the moment of President Roosevelt's dedication of the dam. This is intended to help future astronomers, if necessary, calculate the exact date of dedication. The 30-foot-high (9.1 m) bronze figures, dubbed "Winged Figures of the Republic", were both formed in a continuous pour. To put such large bronzes into place without marring the highly polished bronze surface, they were placed on ice and guided into position as the ice melted. Hansen's bas-relief on the Nevada elevator tower depicts the benefits of the dam: flood control, navigation, irrigation, water storage, and power. The bas-relief on the Arizona elevator depicts, in his words, "the visages of those Indian tribes who have inhabited mountains and plains from ages distant."
Excavation for the powerhouse was carried out simultaneously with the excavation for the dam foundation and abutments. The excavation of this U-shaped structure located at the downstream toe of the dam was completed in late 1933 with the first concrete placed in November 1933. Filling of Lake Mead began February 1, 1935, even before the last of the concrete was poured that May. The powerhouse was one of the projects uncompleted at the time of the formal dedication on September 30, 1935; a crew of 500 men remained to finish it and other structures. To make the powerhouse roof bombproof, it was constructed of layers of concrete, rock, and steel with a total thickness of about 3.5 feet (1.1 m), topped with layers of sand and tar.
In the latter half of 1936, water levels in Lake Mead were high enough to permit power generation, and the first three Allis Chalmers built Francis turbine-generators, all on the Nevada side, began operating. In March 1937, one more Nevada generator went online and the first Arizona generator by August. By September 1939, four more generators were operating, and the dam's power plant became the largest hydroelectricity facility in the world. The final generator was not placed in service until 1961, bringing the maximum generating capacity to 1,345 megawatts at the time. Original plans called for 16 large generators, eight on each side of the river, but two smaller generators were installed instead of one large one on the Arizona side for a total of 17. The smaller generators were used to serve smaller communities at a time when the output of each generator was dedicated to a single municipality, before the dam's total power output was placed on the grid and made arbitrarily distributable.
Before water from Lake Mead reaches the turbines, it enters the intake towers and then four gradually narrowing penstocks which funnel the water down towards the powerhouse. The intakes provide a maximum hydraulic head (water pressure) of 590 ft (180 m) as the water reaches a speed of about 85 mph (140 km/h). The entire flow of the Colorado River usually passes through the turbines. The spillways and outlet works (jet-flow gates) are rarely used. The jet-flow gates, located in concrete structures 180 feet (55 m) above the river and also at the outlets of the inner diversion tunnels at river level, may be used to divert water around the dam in emergency or flood conditions, but have never done so, and in practice are used only to drain water from the penstocks for maintenance. Following an uprating project from 1986 to 1993, the total gross power rating for the plant, including two 2.4 megawatt Pelton turbine-generators that power Hoover Dam's own operations is a maximum capacity of 2080 megawatts. The annual generation of Hoover Dam varies. The maximum net generation was 10.348 TWh in 1984, and the minimum since 1940 was 2.648 TWh in 1956. The average power generated was 4.2 TWh/year for 1947–2008. In 2015, the dam generated 3.6 TWh.
The amount of electricity generated by Hoover Dam has been decreasing along with the falling water level in Lake Mead due to the prolonged drought since year 2000 and high demand for the Colorado River's water. By 2014 its generating capacity was downrated by 23% to 1592 MW and was providing power only during periods of peak demand. Lake Mead fell to a new record low elevation of 1,071.61 feet (326.63 m) on July 1, 2016, before beginning to rebound slowly. Under its original design, the dam would no longer be able to generate power once the water level fell below 1,050 feet (320 m), which might have occurred in 2017 had water restrictions not been enforced. To lower the minimum power pool elevation from 1,050 to 950 feet (320 to 290 m), five wide-head turbines, designed to work efficiently with less flow, were installed.[102] Water levels were maintained at over 1,075 feet (328 m) in 2018 and 2019, but fell to a new record low of 1,071.55 feet (326.61 m) on June 10, 2021[104] and were projected to fall below 1,066 feet (325 m) by the end of 2021.
Control of water was the primary concern in the building of the dam. Power generation has allowed the dam project to be self-sustaining: proceeds from the sale of power repaid the 50-year construction loan, and those revenues also finance the multimillion-dollar yearly maintenance budget. Power is generated in step with and only with the release of water in response to downstream water demands.
Lake Mead and downstream releases from the dam also provide water for both municipal and irrigation uses. Water released from the Hoover Dam eventually reaches several canals. The Colorado River Aqueduct and Central Arizona Project branch off Lake Havasu while the All-American Canal is supplied by the Imperial Dam. In total, water from Lake Mead serves 18 million people in Arizona, Nevada, and California and supplies the irrigation of over 1,000,000 acres (400,000 ha) of land.
In 2018, the Los Angeles Department of Water and Power (LADWP) proposed a $3 billion pumped-storage hydroelectricity project—a "battery" of sorts—that would use wind and solar power to recirculate water back up to Lake Mead from a pumping station 20 miles (32 km) downriver.
Electricity from the dam's powerhouse was originally sold pursuant to a fifty-year contract, authorized by Congress in 1934, which ran from 1937 to 1987. In 1984, Congress passed a new statute which set power allocations to southern California, Arizona, and Nevada from the dam from 1987 to 2017. The powerhouse was run under the original authorization by the Los Angeles Department of Water and Power and Southern California Edison; in 1987, the Bureau of Reclamation assumed control. In 2011, Congress enacted legislation extending the current contracts until 2067, after setting aside 5% of Hoover Dam's power for sale to Native American tribes, electric cooperatives, and other entities. The new arrangement began on October 1, 2017.
The dam is protected against over-topping by two spillways. The spillway entrances are located behind each dam abutment, running roughly parallel to the canyon walls. The spillway entrance arrangement forms a classic side-flow weir with each spillway containing four 100-foot-long (30 m) and 16-foot-wide (4.9 m) steel-drum gates. Each gate weighs 5,000,000 pounds (2,300 metric tons) and can be operated manually or automatically. Gates are raised and lowered depending on water levels in the reservoir and flood conditions. The gates cannot entirely prevent water from entering the spillways but can maintain an extra 16 ft (4.9 m) of lake level.
Water flowing over the spillways falls dramatically into 600-foot-long (180 m), 50-foot-wide (15 m) spillway tunnels before connecting to the outer diversion tunnels and reentering the main river channel below the dam. This complex spillway entrance arrangement combined with the approximate 700-foot (210 m) elevation drop from the top of the reservoir to the river below was a difficult engineering problem and posed numerous design challenges. Each spillway's capacity of 200,000 cu ft/s (5,700 m3/s) was empirically verified in post-construction tests in 1941.
The large spillway tunnels have only been used twice, for testing in 1941 and because of flooding in 1983. Both times, when inspecting the tunnels after the spillways were used, engineers found major damage to the concrete linings and underlying rock. The 1941 damage was attributed to a slight misalignment of the tunnel invert (or base), which caused cavitation, a phenomenon in fast-flowing liquids in which vapor bubbles collapse with explosive force. In response to this finding, the tunnels were patched with special heavy-duty concrete and the surface of the concrete was polished mirror-smooth. The spillways were modified in 1947 by adding flip buckets, which both slow the water and decrease the spillway's effective capacity, in an attempt to eliminate conditions thought to have contributed to the 1941 damage. The 1983 damage, also due to cavitation, led to the installation of aerators in the spillways. Tests at Grand Coulee Dam showed that the technique worked, in principle.
There are two lanes for automobile traffic across the top of the dam, which formerly served as the Colorado River crossing for U.S. Route 93. In the wake of the September 11 terrorist attacks, authorities expressed security concerns and the Hoover Dam Bypass project was expedited. Pending the completion of the bypass, restricted traffic was permitted over Hoover Dam. Some types of vehicles were inspected prior to crossing the dam while semi-trailer trucks, buses carrying luggage, and enclosed-box trucks over 40 ft (12 m) long were not allowed on the dam at all, and were diverted to U.S. Route 95 or Nevada State Routes 163/68. The four-lane Hoover Dam Bypass opened on October 19, 2010. It includes a composite steel and concrete arch bridge, the Mike O'Callaghan–Pat Tillman Memorial Bridge, 1,500 ft (460 m) downstream from the dam. With the opening of the bypass, through traffic is no longer allowed across Hoover Dam; dam visitors are allowed to use the existing roadway to approach from the Nevada side and cross to parking lots and other facilities on the Arizona side.
Hoover Dam opened for tours in 1937 after its completion but following Japan's attack on Pearl Harbor on December 7, 1941, it was closed to the public when the United States entered World War II, during which only authorized traffic, in convoys, was permitted. After the war, it reopened September 2, 1945, and by 1953, annual attendance had risen to 448,081. The dam closed on November 25, 1963, and March 31, 1969, days of mourning in remembrance of Presidents Kennedy and Eisenhower. In 1995, a new visitors' center was built, and the following year, visits exceeded one million for the first time. The dam closed again to the public on September 11, 2001; modified tours were resumed in December and a new "Discovery Tour" was added the following year. Today, nearly a million people per year take the tours of the dam offered by the Bureau of Reclamation. Increased security concerns by the government have led to most of the interior structure's being inaccessible to tourists. As a result, few of True's decorations can now be seen by visitors. Visitors can only purchase tickets on-site and have the options of a guided tour of the whole facility or only the power plant area. The only self-guided tour option is for the visitor center itself, where visitors can view various exhibits and enjoy a 360-degree view of the dam.
The changes in water flow and use caused by Hoover Dam's construction and operation have had a large impact on the Colorado River Delta. The construction of the dam has been implicated in causing the decline of this estuarine ecosystem. For six years after the construction of the dam, while Lake Mead filled, virtually no water reached the mouth of the river. The delta's estuary, which once had a freshwater-saltwater mixing zone stretching 40 miles (64 km) south of the river's mouth, was turned into an inverse estuary where the level of salinity was higher close to the river's mouth.
The Colorado River had experienced natural flooding before the construction of the Hoover Dam. The dam eliminated the natural flooding, threatening many species adapted to the flooding, including both plants and animals. The construction of the dam devastated the populations of native fish in the river downstream from the dam. Four species of fish native to the Colorado River, the Bonytail chub, Colorado pikeminnow, Humpback chub, and Razorback sucker, are listed as endangered.
During the years of lobbying leading up to the passage of legislation authorizing the dam in 1928, the press generally referred to the dam as "Boulder Dam" or as "Boulder Canyon Dam", even though the proposed site had shifted to Black Canyon. The Boulder Canyon Project Act of 1928 (BCPA) never mentioned a proposed name or title for the dam. The BCPA merely allows the government to "construct, operate, and maintain a dam and incidental works in the main stream of the Colorado River at Black Canyon or Boulder Canyon".
When Secretary of the Interior Ray Wilbur spoke at the ceremony starting the building of the railway between Las Vegas and the dam site on September 17, 1930, he named the dam "Hoover Dam", citing a tradition of naming dams after Presidents, though none had been so honored during their terms of office. Wilbur justified his choice on the ground that Hoover was "the great engineer whose vision and persistence ... has done so much to make [the dam] possible". One writer complained in response that "the Great Engineer had quickly drained, ditched, and dammed the country."
After Hoover's election defeat in 1932 and the accession of the Roosevelt administration, Secretary Ickes ordered on May 13, 1933, that the dam be referred to as Boulder Dam. Ickes stated that Wilbur had been imprudent in naming the dam after a sitting president, that Congress had never ratified his choice, and that it had long been referred to as Boulder Dam. Unknown to the general public, Attorney General Homer Cummings informed Ickes that Congress had indeed used the name "Hoover Dam" in five different bills appropriating money for construction of the dam. The official status this conferred to the name "Hoover Dam" had been noted on the floor of the House of Representatives by Congressman Edward T. Taylor of Colorado on December 12, 1930, but was likewise ignored by Ickes.
When Ickes spoke at the dedication ceremony on September 30, 1935, he was determined, as he recorded in his diary, "to try to nail down for good and all the name Boulder Dam." At one point in the speech, he spoke the words "Boulder Dam" five times within thirty seconds. Further, he suggested that if the dam were to be named after any one person, it should be for California Senator Hiram Johnson, a lead sponsor of the authorizing legislation. Roosevelt also referred to the dam as Boulder Dam, and the Republican-leaning Los Angeles Times, which at the time of Ickes' name change had run an editorial cartoon showing Ickes ineffectively chipping away at an enormous sign "HOOVER DAM", reran it showing Roosevelt reinforcing Ickes, but having no greater success.
In the following years, the name "Boulder Dam" failed to fully take hold, with many Americans using both names interchangeably and mapmakers divided as to which name should be printed. Memories of the Great Depression faded, and Hoover to some extent rehabilitated himself through good works during and after World War II. In 1947, a bill passed both Houses of Congress unanimously restoring the name "Hoover Dam." Ickes, who was by then a private citizen, opposed the change, stating, "I didn't know Hoover was that small a man to take credit for something he had nothing to do with."
Hoover Dam was recognized as a National Historic Civil Engineering Landmark in 1984. It was listed on the National Register of Historic Places in 1981 and was designated a National Historic Landmark in 1985, cited for its engineering innovations.
The Mike O'Callaghan–Pat Tillman Memorial Bridge is an arch bridge in the United States that spans the Colorado River between the states of Arizona and Nevada. The bridge is located within the Lake Mead National Recreation Area approximately 30 miles (48 km) southeast of Las Vegas, and carries Interstate 11 and U.S. Route 93 over the Colorado River. Opened in 2010, it was the key component of the Hoover Dam Bypass project, which rerouted US 93 from its previous routing along the top of Hoover Dam and removed several hairpin turns and blind curves from the route. It is jointly named for Mike O'Callaghan, Governor of Nevada from 1971 to 1979, and Pat Tillman, an American football player who left his career with the Arizona Cardinals to enlist in the United States Army and was killed in Afghanistan in 2004 by friendly fire.
As early as the 1960s, officials identified the US 93 route over Hoover Dam to be dangerous and inadequate for projected traffic volumes. From 1998 to 2001, officials from Arizona, Nevada, and several federal government agencies collaborated to determine the best routing for an alternative river crossing. In March 2001, the Federal Highway Administration selected the route, which crosses the Colorado River approximately 1,500 feet (460 m) downstream of Hoover Dam. Construction of the bridge approaches began in 2003, and construction of the bridge itself began in February 2005. The bridge was completed in 2010 and the entire bypass route opened to vehicle traffic on October 19, 2010. The Hoover Dam Bypass project was completed within budget at a cost of $240 million; the bridge portion cost $114 million.
The bridge was the first concrete-steel composite deck arch bridge built in the United States, and incorporates the widest concrete arch in the Western Hemisphere. At 890 feet (270 m) above the Colorado River, it is the second highest bridge in the United States after the Royal Gorge Bridge near Cañon City, Colorado, and is the world's highest concrete arch bridge.
In 1935, the American Association of State Highway Officials (AASHO, later AASHTO) authorized a southward extension of U.S. Route 93 from its previous southern terminus in Glendale, Nevada to Kingman, Arizona via Las Vegas, Boulder City, and a crossing of the Colorado River on the newly-constructed Hoover Dam (then known as Boulder Dam). Clark County was sparsely populated at the time, with a population of less than 9,000 at the 1930 U.S. Census (compared to an estimated 2 million in 2013). Development in and around Las Vegas in the latter half of the 20th century made Las Vegas and its surrounding area a tourist attraction, and US 93 became an important transportation corridor for passenger and commercial traffic between Las Vegas and Phoenix. In 1995, the portion of US 93 over Hoover Dam was included as part of the CANAMEX Corridor, a high-priority transportation corridor established under the North American Free Trade Agreement (NAFTA). This bridge is a key component of the proposed Interstate 11 project.
Through traffic on US 93 combined with pedestrian and tourist traffic at Hoover Dam itself led to major traffic congestion on the dam and on the approaches to the dam. The approaches featured hairpin turns on both the Nevada and Arizona sides of the dam, and the terrain caused limited sight distances around curves. In addition to traffic safety considerations, officials were also concerned about the safety and security of Hoover Dam, specifically the impact a vehicle accident could have on the dam's operation and the waters of Lake Mead. Officials first discussed the need for a new Colorado River crossing that would bypass the dam in the 1960s. The U.S. Bureau of Reclamation, which operates the dam, began work on the "Colorado River Bridge Project" in 1989, but the project was put on hold in 1995. In 1997 the Federal Highway Administration took over the project and released a draft environmental impact statement in 1998. From 1998 to 2001 state officials from Arizona and Nevada as well as several federal government agencies studied the feasibility of several alternative routes and river crossings, as well as the feasibility of modifying the roadway over the dam, restricting traffic over the dam, or doing nothing.
In March 2001, the Federal Highway Administration issued a Record of Decision indicating its selection of the "Sugarloaf Mountain Alternative" routing. The project called for approximately 2.2 miles (3.5 km) of highway in Nevada, 1.1 miles (1.8 km) of highway in Arizona, and a bridge length of 1,900 feet (580 m) that would cross the river 1,500 feet (460 m) downstream (south) of Hoover Dam. Design work began in July 2001.
Security measures implemented following the September 11 attacks prohibited commercial truck traffic from driving across Hoover Dam. Prior to the completion of the bridge, commercial vehicles were required to follow a detour between Boulder City and Kingman via US 95, Nevada State Route 163, the Colorado River crossing between Laughlin, Nevada and Bullhead City, Arizona, and Arizona State Route 68. The detour was 104 miles (167 km) long, but only added 23 miles (37 km) to the normal journey on US 93.
Project design was by the Hoover Support team, led by HDR, Inc. and including T.Y. Lin International, Sverdrup Civil, Inc., and other specialist contributors.
The bridge has a length of 1,900 feet (579 m) and a 1,060 ft (320 m) span. The roadway is 900 ft (270 m)[1] above the Colorado River and four lanes wide. This is the first concrete-and-steel composite arch bridge built in the United States. It includes the widest concrete arch in the Western Hemisphere and is also the second highest bridge in the nation, with the arch 840 ft (260 m) above the river. The twin arch ribs are connected by steel struts.
The composite design, using concrete for the arch and columns with steel construction for the roadway deck, was selected for schedule and cost control while being aesthetically compatible with the Hoover Dam. Sean Holstege in The Arizona Republic has called the bridge "an American triumph". USA Today called it "America's Newest Wonder" on October 18, 2010.
Pedestrian access is provided over the bridge to tourists who wish to take in a different view of the nearby dam and river below, but the dam is not visible for those driving across it. A parking area is provided near the bridge on the Nevada side at what was a staging area during construction. A set of stairs and disabled access ramps lead to the sidewalk across the bridge.
Work began in 2003 on the approaches in both states and the construction contract for the arch bridge was awarded in October 2004. The largest obstacle to the project was the river crossing. The bridge and the bypass were constructed by a consortium of different government agencies and contractors, among them the Federal Highway Administration, the Arizona Department of Transportation, and Nevada Department of Transportation, with RE Monks Construction and Vastco, Inc, constructing the Arizona Approach, Edward Kraemer & Sons, Inc, the Nevada Approach and Las Vegas Paving Corporation undertaking the roadway surfacing on both approaches. The bridge itself was built by Obayashi Corporation and PSM Construction USA, Inc., while Frehner Construction Company, Inc. was responsible for completing the final roadway installations. A permit problem between Clark County and the subcontractor Casino Ready Mix arose in May 2006 over the operation of a concrete-batch plant for the project, and this caused a four-month delay.
Construction required hoisting workers and up to 50 short tons (45 t) of materials 890 feet (270 m) above the Colorado River using 2,300 ft (700 m)-long steel cables held aloft by a "high-line" crane system. High winds caused a cableway failure in September 2006, resulting in a further two-year delay. The approach spans, consisting of seven pairs of concrete columns—five on the Nevada side and two on the Arizona side—were completed in March 2008. In November 2008, construction worker Sherman Jones died in an accident.
The arches are made of 106 pieces—53 per arch—mostly 24 ft (7.3 m) cast in place sections. The arch was constructed from both sides of the bridge concurrently, supported by diagonal cable stays strung from temporary towers. The twin arch spans were completed with the casting of the center segments in August 2009. That same month, the two halves of the arch were completed, and were 3⁄8 inch (9.5 mm) apart; the gap was filled with a block of reinforced concrete. The temporary cable stays were removed, leaving the arch self-supporting. By December, all eight of the vertical piers on the arch had been set and capped, and at the end of the month the first two of thirty-six 50-short-ton (45 t) steel girders had been set into place.
By mid-April 2010, all of the girders were set in place, and for the first time construction crews could walk across the structure from Arizona to Nevada. Shortly thereafter, the pouring of the bridge deck began. The bridge deck was fully paved in July, and the high-line cranes were removed from the site as the overall project neared completion.[citation needed] The bridge was completed with a dedication ceremony on October 14, 2010. and a grand opening party on October 16. It was opened to bicycle and pedestrian traffic on October 18 and to vehicular traffic on October 19, a few weeks earlier than estimated. The building of the bridge was featured in episode 5x02 of the TV series Extreme Engineering. The filming of this episode took place before the start of work on the arch.
When the bridge opened to traffic, the roadway over Hoover Dam was closed to through traffic, and all visitor access to the dam was routed to the Nevada side; vehicles are still allowed to drive across the dam to the Arizona side following a security inspection, but must return to the Nevada side to return to US 93. The former US 93 route between the dam and its junction with the present US 93 route has been re-designated as Nevada State Route 172. The highway using the bridge was given the added designation of Interstate 11 in 2018, after the completion of the Boulder City freeway bypass.
Hoover Dam is a concrete arch-gravity dam in the Black Canyon of the Colorado River, on the border between the U.S. states of Nevada and Arizona. It was constructed between 1931 and 1936 during the Great Depression and was dedicated on September 30, 1935, by President Franklin D. Roosevelt. Its construction was the result of a massive effort involving thousands of workers, and cost over one hundred lives. It was referred to as Hoover Dam after President Herbert Hoover in bills passed by Congress during its construction, but was named Boulder Dam by the Roosevelt administration. The Hoover Dam name was restored by Congress in 1947.
Since about 1900, the Black Canyon and nearby Boulder Canyon had been investigated for their potential to support a dam that would control floods, provide irrigation water and produce hydroelectric power. In 1928, Congress authorized the project. The winning bid to build the dam was submitted by a consortium named Six Companies, Inc., which began construction of the dam in early 1931. Such a large concrete structure had never been built before, and some of the techniques were unproven. The torrid summer weather and lack of facilities near the site also presented difficulties. Nevertheless, Six Companies turned the dam over to the federal government on March 1, 1936, more than two years ahead of schedule.
Hoover Dam impounds Lake Mead, the largest reservoir in the United States by volume when full. The dam is located near Boulder City, Nevada, a municipality originally constructed for workers on the construction project, about 30 mi (48 km) southeast of Las Vegas, Nevada. The dam's generators provide power for public and private utilities in Nevada, Arizona, and California. Hoover Dam is a major tourist attraction; nearly a million people tour the dam each year. The heavily traveled U.S. Route 93 (US 93) ran along the dam's crest until October 2010, when the Hoover Dam Bypass opened.
As the United States developed the Southwest, the Colorado River was seen as a potential source of irrigation water. An initial attempt at diverting the river for irrigation purposes occurred in the late 1890s, when land speculator William Beatty built the Alamo Canal just north of the Mexican border; the canal dipped into Mexico before running to a desolate area Beatty named the Imperial Valley. Though water from the Imperial Canal allowed for the widespread settlement of the valley, the canal proved expensive to operate. After a catastrophic breach that caused the Colorado River to fill the Salton Sea, the Southern Pacific Railroad spent $3 million in 1906–07 to stabilize the waterway, an amount it hoped in vain would be reimbursed by the federal government. Even after the waterway was stabilized, it proved unsatisfactory because of constant disputes with landowners on the Mexican side of the border.
As the technology of electric power transmission improved, the Lower Colorado was considered for its hydroelectric-power potential. In 1902, the Edison Electric Company of Los Angeles surveyed the river in the hope of building a 40-foot (12 m) rock dam which could generate 10,000 horsepower (7,500 kW). However, at the time, the limit of transmission of electric power was 80 miles (130 km), and there were few customers (mostly mines) within that limit. Edison allowed land options it held on the river to lapse—including an option for what became the site of Hoover Dam.
In the following years, the Bureau of Reclamation (BOR), known as the Reclamation Service at the time, also considered the Lower Colorado as the site for a dam. Service chief Arthur Powell Davis proposed using dynamite to collapse the walls of Boulder Canyon, 20 miles (32 km) north of the eventual dam site, into the river. The river would carry off the smaller pieces of debris, and a dam would be built incorporating the remaining rubble. In 1922, after considering it for several years, the Reclamation Service finally rejected the proposal, citing doubts about the unproven technique and questions as to whether it would, in fact, save money.
Soon after the dam was authorized, increasing numbers of unemployed people converged on southern Nevada. Las Vegas, then a small city of some 5,000, saw between 10,000 and 20,000 unemployed descend on it. A government camp was established for surveyors and other personnel near the dam site; this soon became surrounded by a squatters' camp. Known as McKeeversville, the camp was home to men hoping for work on the project, together with their families. Another camp, on the flats along the Colorado River, was officially called Williamsville, but was known to its inhabitants as "Ragtown". When construction began, Six Companies hired large numbers of workers, with more than 3,000 on the payroll by 1932 and with employment peaking at 5,251 in July 1934. "Mongolian" (Chinese) labor was prevented by the construction contract, while the number of black people employed by Six Companies never exceeded thirty, mostly lowest-pay-scale laborers in a segregated crew, who were issued separate water buckets.
As part of the contract, Six Companies, Inc. was to build Boulder City to house the workers. The original timetable called for Boulder City to be built before the dam project began, but President Hoover ordered work on the dam to begin in March 1931 rather than in October. The company built bunkhouses, attached to the canyon wall, to house 480 single men at what became known as River Camp. Workers with families were left to provide their own accommodations until Boulder City could be completed, and many lived in Ragtown. The site of Hoover Dam endures extremely hot weather, and the summer of 1931 was especially torrid, with the daytime high averaging 119.9 °F (48.8 °C). Sixteen workers and other riverbank residents died of heat prostration between June 25 and July 26, 1931.
The Industrial Workers of the World (IWW or "Wobblies"), though much-reduced from their heyday as militant labor organizers in the early years of the century, hoped to unionize the Six Companies workers by capitalizing on their discontent. They sent eleven organizers, several of whom were arrested by Las Vegas police. On August 7, 1931, the company cut wages for all tunnel workers. Although the workers sent the organizers away, not wanting to be associated with the "Wobblies", they formed a committee to represent them with the company. The committee drew up a list of demands that evening and presented them to Crowe the following morning. He was noncommittal. The workers hoped that Crowe, the general superintendent of the job, would be sympathetic; instead, he gave a scathing interview to a newspaper, describing the workers as "malcontents".
On the morning of the 9th, Crowe met with the committee and told them that management refused their demands, was stopping all work, and was laying off the entire work force, except for a few office workers and carpenters. The workers were given until 5 p.m. to vacate the premises. Concerned that a violent confrontation was imminent, most workers took their paychecks and left for Las Vegas to await developments. Two days later, the remainder were talked into leaving by law enforcement. On August 13, the company began hiring workers again, and two days later, the strike was called off. While the workers received none of their demands, the company guaranteed there would be no further reductions in wages. Living conditions began to improve as the first residents moved into Boulder City in late 1931.
A second labor action took place in July 1935, as construction on the dam wound down. When a Six Companies manager altered working times to force workers to take lunch on their own time, workers responded with a strike. Emboldened by Crowe's reversal of the lunch decree, workers raised their demands to include a $1-per-day raise. The company agreed to ask the Federal government to supplement the pay, but no money was forthcoming from Washington. The strike ended.
Before the dam could be built, the Colorado River needed to be diverted away from the construction site. To accomplish this, four diversion tunnels were driven through the canyon walls, two on the Nevada side and two on the Arizona side. These tunnels were 56 ft (17 m) in diameter. Their combined length was nearly 16,000 ft, or more than 3 miles (5 km). The contract required these tunnels to be completed by October 1, 1933, with a $3,000-per-day fine to be assessed for any delay. To meet the deadline, Six Companies had to complete work by early 1933, since only in late fall and winter was the water level in the river low enough to safely divert.
Tunneling began at the lower portals of the Nevada tunnels in May 1931. Shortly afterward, work began on two similar tunnels in the Arizona canyon wall. In March 1932, work began on lining the tunnels with concrete. First the base, or invert, was poured. Gantry cranes, running on rails through the entire length of each tunnel were used to place the concrete. The sidewalls were poured next. Movable sections of steel forms were used for the sidewalls. Finally, using pneumatic guns, the overheads were filled in. The concrete lining is 3 feet (1 m) thick, reducing the finished tunnel diameter to 50 ft (15 m). The river was diverted into the two Arizona tunnels on November 13, 1932; the Nevada tunnels were kept in reserve for high water. This was done by exploding a temporary cofferdam protecting the Arizona tunnels while at the same time dumping rubble into the river until its natural course was blocked.
Following the completion of the dam, the entrances to the two outer diversion tunnels were sealed at the opening and halfway through the tunnels with large concrete plugs. The downstream halves of the tunnels following the inner plugs are now the main bodies of the spillway tunnels. The inner diversion tunnels were plugged at approximately one-third of their length, beyond which they now carry steel pipes connecting the intake towers to the power plant and outlet works. The inner tunnels' outlets are equipped with gates that can be closed to drain the tunnels for maintenance.
To protect the construction site from the Colorado River and to facilitate the river's diversion, two cofferdams were constructed. Work on the upper cofferdam began in September 1932, even though the river had not yet been diverted. The cofferdams were designed to protect against the possibility of the river's flooding a site at which two thousand men might be at work, and their specifications were covered in the bid documents in nearly as much detail as the dam itself. The upper cofferdam was 96 ft (29 m) high, and 750 feet (230 m) thick at its base, thicker than the dam itself. It contained 650,000 cubic yards (500,000 m3) of material.
When the cofferdams were in place and the construction site was drained of water, excavation for the dam foundation began. For the dam to rest on solid rock, it was necessary to remove accumulated erosion soils and other loose materials in the riverbed until sound bedrock was reached. Work on the foundation excavations was completed in June 1933. During this excavation, approximately 1,500,000 cu yd (1,100,000 m3) of material was removed. Since the dam was an arch-gravity type, the side-walls of the canyon would bear the force of the impounded lake. Therefore, the side-walls were also excavated to reach virgin rock, as weathered rock might provide pathways for water seepage. Shovels for the excavation came from the Marion Power Shovel Company.
The men who removed this rock were called "high scalers". While suspended from the top of the canyon with ropes, the high-scalers climbed down the canyon walls and removed the loose rock with jackhammers and dynamite. Falling objects were the most common cause of death on the dam site; the high scalers' work thus helped ensure worker safety. One high scaler was able to save a life in a more direct manner: when a government inspector lost his grip on a safety line and began tumbling down a slope towards almost certain death, a high scaler was able to intercept him and pull him into the air. The construction site had become a magnet for tourists. The high scalers were prime attractions and showed off for the watchers. The high scalers received considerable media attention, with one worker dubbed the "Human Pendulum" for swinging co-workers (and, at other times, cases of dynamite) across the canyon. To protect themselves against falling objects, some high scalers dipped cloth hats in tar and allowed them to harden. When workers wearing such headgear were struck hard enough to inflict broken jaws, they sustained no skull damage. Six Companies ordered thousands of what initially were called "hard boiled hats" (later "hard hats") and strongly encouraged their use.
The cleared, underlying rock foundation of the dam site was reinforced with grout, forming a grout curtain. Holes were driven into the walls and base of the canyon, as deep as 150 feet (46 m) into the rock, and any cavities encountered were to be filled with grout. This was done to stabilize the rock, to prevent water from seeping past the dam through the canyon rock, and to limit "uplift"—upward pressure from water seeping under the dam. The workers were under severe time constraints due to the beginning of the concrete pour. When they encountered hot springs or cavities too large to readily fill, they moved on without resolving the problem. A total of 58 of the 393 holes were incompletely filled. After the dam was completed and the lake began to fill, large numbers of significant leaks caused the Bureau of Reclamation to examine the situation. It found that the work had been incompletely done, and was based on less than a full understanding of the canyon's geology. New holes were drilled from inspection galleries inside the dam into the surrounding bedrock. It took nine years (1938–47) under relative secrecy to complete the supplemental grout curtain.
The first concrete was poured into the dam on June 6, 1933, 18 months ahead of schedule. Since concrete heats and contracts as it cures, the potential for uneven cooling and contraction of the concrete posed a serious problem. Bureau of Reclamation engineers calculated that if the dam were to be built in a single continuous pour, the concrete would take 125 years to cool, and the resulting stresses would cause the dam to crack and crumble. Instead, the ground where the dam would rise was marked with rectangles, and concrete blocks in columns were poured, some as large as 50 ft square (15 m) and 5 feet (1.5 m) high. Each five-foot form contained a set of 1-inch (25 mm) steel pipes; cool river water would be poured through the pipes, followed by ice-cold water from a refrigeration plant. When an individual block had cured and had stopped contracting, the pipes were filled with grout. Grout was also used to fill the hairline spaces between columns, which were grooved to increase the strength of the joints.
The concrete was delivered in huge steel buckets 7 feet high (2.1 m) and almost 7 feet in diameter; Crowe was awarded two patents for their design. These buckets, which weighed 20 short tons (18.1 t; 17.9 long tons) when full, were filled at two massive concrete plants on the Nevada side, and were delivered to the site in special railcars. The buckets were then suspended from aerial cableways which were used to deliver the bucket to a specific column. As the required grade of aggregate in the concrete differed depending on placement in the dam (from pea-sized gravel to 9 inches [230 mm] stones), it was vital that the bucket be maneuvered to the proper column. When the bottom of the bucket opened up, disgorging 8 cu yd (6.1 m3) of concrete, a team of men worked it throughout the form. Although there are myths that men were caught in the pour and are entombed in the dam to this day, each bucket deepened the concrete in a form by only 1 inch (25 mm), and Six Companies engineers would not have permitted a flaw caused by the presence of a human body.
A total of 3,250,000 cubic yards (2,480,000 cubic meters) of concrete was used in the dam before concrete pouring ceased on May 29, 1935. In addition, 1,110,000 cu yd (850,000 m3) were used in the power plant and other works. More than 582 miles (937 km) of cooling pipes were placed within the concrete. Overall, there is enough concrete in the dam to pave a two-lane highway from San Francisco to New York. Concrete cores were removed from the dam for testing in 1995; they showed that "Hoover Dam's concrete has continued to slowly gain strength" and the dam is composed of a "durable concrete having a compressive strength exceeding the range typically found in normal mass concrete". Hoover Dam concrete is not subject to alkali–silica reaction (ASR), as the Hoover Dam builders happened to use nonreactive aggregate, unlike that at downstream Parker Dam, where ASR has caused measurable deterioration.
With most work finished on the dam itself (the powerhouse remained uncompleted), a formal dedication ceremony was arranged for September 30, 1935, to coincide with a western tour being made by President Franklin D. Roosevelt. The morning of the dedication, it was moved forward three hours from 2 p.m. Pacific time to 11 a.m.; this was done because Secretary of the Interior Harold L. Ickes had reserved a radio slot for the President for 2 p.m. but officials did not realize until the day of the ceremony that the slot was for 2 p.m. Eastern Time. Despite the change in the ceremony time, and temperatures of 102 °F (39 °C), 10,000 people were present for the President's speech, in which he avoided mentioning the name of former President Hoover, who was not invited to the ceremony. To mark the occasion, a three-cent stamp was issued by the United States Post Office Department—bearing the name "Boulder Dam", the official name of the dam between 1933 and 1947. After the ceremony, Roosevelt made the first visit by any American president to Las Vegas.
Most work had been completed by the dedication, and Six Companies negotiated with the government through late 1935 and early 1936 to settle all claims and arrange for the formal transfer of the dam to the Federal Government. The parties came to an agreement and on March 1, 1936, Secretary Ickes formally accepted the dam on behalf of the government. Six Companies was not required to complete work on one item, a concrete plug for one of the bypass tunnels, as the tunnel had to be used to take in irrigation water until the powerhouse went into operation.
There were 112 deaths reported as associated with the construction of the dam. The first was Bureau of Reclamation employee Harold Connelly who died on May 15, 1921, after falling from a barge while surveying the Colorado River for an ideal spot for the dam. Surveyor John Gregory ("J.G.") Tierney, who drowned on December 20, 1922, in a flash flood while looking for an ideal spot for the dam was the second person. The official list's final death occurred on December 20, 1935, when Patrick Tierney, electrician's helper and the son of J.G. Tierney, fell from one of the two Arizona-side intake towers. Included in the fatality list are three workers who took their own lives on site, one in 1932 and two in 1933. Of the 112 fatalities, 91 were Six Companies employees, three were Bureau of Reclamation employees, and one was a visitor to the site; the remainder were employees of various contractors not part of Six Companies.
Ninety-six of the deaths occurred during construction at the site. Not included in the official number of fatalities were deaths that were recorded as pneumonia. Workers alleged that this diagnosis was a cover for death from carbon monoxide poisoning (brought on by the use of gasoline-fueled vehicles in the diversion tunnels), and a classification used by Six Companies to avoid paying compensation claims. The site's diversion tunnels frequently reached 140 °F (60 °C), enveloped in thick plumes of vehicle exhaust gases. A total of 42 workers were recorded as having died from pneumonia and were not included in the above total; none were listed as having died from carbon monoxide poisoning. No deaths of non-workers from pneumonia were recorded in Boulder City during the construction period.
The initial plans for the facade of the dam, the power plant, the outlet tunnels and ornaments clashed with the modern look of an arch dam. The Bureau of Reclamation, more concerned with the dam's functionality, adorned it with a Gothic-inspired balustrade and eagle statues. This initial design was criticized by many as being too plain and unremarkable for a project of such immense scale, so Los Angeles-based architect Gordon B. Kaufmann, then the supervising architect to the Bureau of Reclamation, was brought in to redesign the exteriors. Kaufmann greatly streamlined the design and applied an elegant Art Deco style to the entire project. He designed sculpted turrets rising seamlessly from the dam face and clock faces on the intake towers set for the time in Nevada and Arizona—both states are in different time zones, but since Arizona does not observe daylight saving time, the clocks display the same time for more than half the year.
At Kaufmann's request, Denver artist Allen Tupper True was hired to handle the design and decoration of the walls and floors of the new dam. True's design scheme incorporated motifs of the Navajo and Pueblo tribes of the region. Although some were initially opposed to these designs, True was given the go-ahead and was officially appointed consulting artist. With the assistance of the National Laboratory of Anthropology, True researched authentic decorative motifs from Indian sand paintings, textiles, baskets and ceramics. The images and colors are based on Native American visions of rain, lightning, water, clouds, and local animals—lizards, serpents, birds—and on the Southwestern landscape of stepped mesas. In these works, which are integrated into the walkways and interior halls of the dam, True also reflected on the machinery of the operation, making the symbolic patterns appear both ancient and modern.
With the agreement of Kaufmann and the engineers, True also devised for the pipes and machinery an innovative color-coding which was implemented throughout all BOR projects. True's consulting artist job lasted through 1942; it was extended so he could complete design work for the Parker, Shasta and Grand Coulee dams and power plants. True's work on the Hoover Dam was humorously referred to in a poem published in The New Yorker, part of which read, "lose the spark, and justify the dream; but also worthy of remark will be the color scheme".
Complementing Kaufmann and True's work, sculptor Oskar J. W. Hansen designed many of the sculptures on and around the dam. His works include the monument of dedication plaza, a plaque to memorialize the workers killed and the bas-reliefs on the elevator towers. In his words, Hansen wanted his work to express "the immutable calm of intellectual resolution, and the enormous power of trained physical strength, equally enthroned in placid triumph of scientific accomplishment", because "the building of Hoover Dam belongs to the sagas of the daring." Hansen's dedication plaza, on the Nevada abutment, contains a sculpture of two winged figures flanking a flagpole.
Surrounding the base of the monument is a terrazzo floor embedded with a "star map". The map depicts the Northern Hemisphere sky at the moment of President Roosevelt's dedication of the dam. This is intended to help future astronomers, if necessary, calculate the exact date of dedication. The 30-foot-high (9.1 m) bronze figures, dubbed "Winged Figures of the Republic", were both formed in a continuous pour. To put such large bronzes into place without marring the highly polished bronze surface, they were placed on ice and guided into position as the ice melted. Hansen's bas-relief on the Nevada elevator tower depicts the benefits of the dam: flood control, navigation, irrigation, water storage, and power. The bas-relief on the Arizona elevator depicts, in his words, "the visages of those Indian tribes who have inhabited mountains and plains from ages distant."
Excavation for the powerhouse was carried out simultaneously with the excavation for the dam foundation and abutments. The excavation of this U-shaped structure located at the downstream toe of the dam was completed in late 1933 with the first concrete placed in November 1933. Filling of Lake Mead began February 1, 1935, even before the last of the concrete was poured that May. The powerhouse was one of the projects uncompleted at the time of the formal dedication on September 30, 1935; a crew of 500 men remained to finish it and other structures. To make the powerhouse roof bombproof, it was constructed of layers of concrete, rock, and steel with a total thickness of about 3.5 feet (1.1 m), topped with layers of sand and tar.
In the latter half of 1936, water levels in Lake Mead were high enough to permit power generation, and the first three Allis Chalmers built Francis turbine-generators, all on the Nevada side, began operating. In March 1937, one more Nevada generator went online and the first Arizona generator by August. By September 1939, four more generators were operating, and the dam's power plant became the largest hydroelectricity facility in the world. The final generator was not placed in service until 1961, bringing the maximum generating capacity to 1,345 megawatts at the time. Original plans called for 16 large generators, eight on each side of the river, but two smaller generators were installed instead of one large one on the Arizona side for a total of 17. The smaller generators were used to serve smaller communities at a time when the output of each generator was dedicated to a single municipality, before the dam's total power output was placed on the grid and made arbitrarily distributable.
Before water from Lake Mead reaches the turbines, it enters the intake towers and then four gradually narrowing penstocks which funnel the water down towards the powerhouse. The intakes provide a maximum hydraulic head (water pressure) of 590 ft (180 m) as the water reaches a speed of about 85 mph (140 km/h). The entire flow of the Colorado River usually passes through the turbines. The spillways and outlet works (jet-flow gates) are rarely used. The jet-flow gates, located in concrete structures 180 feet (55 m) above the river and also at the outlets of the inner diversion tunnels at river level, may be used to divert water around the dam in emergency or flood conditions, but have never done so, and in practice are used only to drain water from the penstocks for maintenance. Following an uprating project from 1986 to 1993, the total gross power rating for the plant, including two 2.4 megawatt Pelton turbine-generators that power Hoover Dam's own operations is a maximum capacity of 2080 megawatts. The annual generation of Hoover Dam varies. The maximum net generation was 10.348 TWh in 1984, and the minimum since 1940 was 2.648 TWh in 1956. The average power generated was 4.2 TWh/year for 1947–2008. In 2015, the dam generated 3.6 TWh.
The amount of electricity generated by Hoover Dam has been decreasing along with the falling water level in Lake Mead due to the prolonged drought since year 2000 and high demand for the Colorado River's water. By 2014 its generating capacity was downrated by 23% to 1592 MW and was providing power only during periods of peak demand. Lake Mead fell to a new record low elevation of 1,071.61 feet (326.63 m) on July 1, 2016, before beginning to rebound slowly. Under its original design, the dam would no longer be able to generate power once the water level fell below 1,050 feet (320 m), which might have occurred in 2017 had water restrictions not been enforced. To lower the minimum power pool elevation from 1,050 to 950 feet (320 to 290 m), five wide-head turbines, designed to work efficiently with less flow, were installed.[102] Water levels were maintained at over 1,075 feet (328 m) in 2018 and 2019, but fell to a new record low of 1,071.55 feet (326.61 m) on June 10, 2021[104] and were projected to fall below 1,066 feet (325 m) by the end of 2021.
Control of water was the primary concern in the building of the dam. Power generation has allowed the dam project to be self-sustaining: proceeds from the sale of power repaid the 50-year construction loan, and those revenues also finance the multimillion-dollar yearly maintenance budget. Power is generated in step with and only with the release of water in response to downstream water demands.
Lake Mead and downstream releases from the dam also provide water for both municipal and irrigation uses. Water released from the Hoover Dam eventually reaches several canals. The Colorado River Aqueduct and Central Arizona Project branch off Lake Havasu while the All-American Canal is supplied by the Imperial Dam. In total, water from Lake Mead serves 18 million people in Arizona, Nevada, and California and supplies the irrigation of over 1,000,000 acres (400,000 ha) of land.
In 2018, the Los Angeles Department of Water and Power (LADWP) proposed a $3 billion pumped-storage hydroelectricity project—a "battery" of sorts—that would use wind and solar power to recirculate water back up to Lake Mead from a pumping station 20 miles (32 km) downriver.
Electricity from the dam's powerhouse was originally sold pursuant to a fifty-year contract, authorized by Congress in 1934, which ran from 1937 to 1987. In 1984, Congress passed a new statute which set power allocations to southern California, Arizona, and Nevada from the dam from 1987 to 2017. The powerhouse was run under the original authorization by the Los Angeles Department of Water and Power and Southern California Edison; in 1987, the Bureau of Reclamation assumed control. In 2011, Congress enacted legislation extending the current contracts until 2067, after setting aside 5% of Hoover Dam's power for sale to Native American tribes, electric cooperatives, and other entities. The new arrangement began on October 1, 2017.
The dam is protected against over-topping by two spillways. The spillway entrances are located behind each dam abutment, running roughly parallel to the canyon walls. The spillway entrance arrangement forms a classic side-flow weir with each spillway containing four 100-foot-long (30 m) and 16-foot-wide (4.9 m) steel-drum gates. Each gate weighs 5,000,000 pounds (2,300 metric tons) and can be operated manually or automatically. Gates are raised and lowered depending on water levels in the reservoir and flood conditions. The gates cannot entirely prevent water from entering the spillways but can maintain an extra 16 ft (4.9 m) of lake level.
Water flowing over the spillways falls dramatically into 600-foot-long (180 m), 50-foot-wide (15 m) spillway tunnels before connecting to the outer diversion tunnels and reentering the main river channel below the dam. This complex spillway entrance arrangement combined with the approximate 700-foot (210 m) elevation drop from the top of the reservoir to the river below was a difficult engineering problem and posed numerous design challenges. Each spillway's capacity of 200,000 cu ft/s (5,700 m3/s) was empirically verified in post-construction tests in 1941.
The large spillway tunnels have only been used twice, for testing in 1941 and because of flooding in 1983. Both times, when inspecting the tunnels after the spillways were used, engineers found major damage to the concrete linings and underlying rock. The 1941 damage was attributed to a slight misalignment of the tunnel invert (or base), which caused cavitation, a phenomenon in fast-flowing liquids in which vapor bubbles collapse with explosive force. In response to this finding, the tunnels were patched with special heavy-duty concrete and the surface of the concrete was polished mirror-smooth. The spillways were modified in 1947 by adding flip buckets, which both slow the water and decrease the spillway's effective capacity, in an attempt to eliminate conditions thought to have contributed to the 1941 damage. The 1983 damage, also due to cavitation, led to the installation of aerators in the spillways. Tests at Grand Coulee Dam showed that the technique worked, in principle.
There are two lanes for automobile traffic across the top of the dam, which formerly served as the Colorado River crossing for U.S. Route 93. In the wake of the September 11 terrorist attacks, authorities expressed security concerns and the Hoover Dam Bypass project was expedited. Pending the completion of the bypass, restricted traffic was permitted over Hoover Dam. Some types of vehicles were inspected prior to crossing the dam while semi-trailer trucks, buses carrying luggage, and enclosed-box trucks over 40 ft (12 m) long were not allowed on the dam at all, and were diverted to U.S. Route 95 or Nevada State Routes 163/68. The four-lane Hoover Dam Bypass opened on October 19, 2010. It includes a composite steel and concrete arch bridge, the Mike O'Callaghan–Pat Tillman Memorial Bridge, 1,500 ft (460 m) downstream from the dam. With the opening of the bypass, through traffic is no longer allowed across Hoover Dam; dam visitors are allowed to use the existing roadway to approach from the Nevada side and cross to parking lots and other facilities on the Arizona side.
Hoover Dam opened for tours in 1937 after its completion but following Japan's attack on Pearl Harbor on December 7, 1941, it was closed to the public when the United States entered World War II, during which only authorized traffic, in convoys, was permitted. After the war, it reopened September 2, 1945, and by 1953, annual attendance had risen to 448,081. The dam closed on November 25, 1963, and March 31, 1969, days of mourning in remembrance of Presidents Kennedy and Eisenhower. In 1995, a new visitors' center was built, and the following year, visits exceeded one million for the first time. The dam closed again to the public on September 11, 2001; modified tours were resumed in December and a new "Discovery Tour" was added the following year. Today, nearly a million people per year take the tours of the dam offered by the Bureau of Reclamation. Increased security concerns by the government have led to most of the interior structure's being inaccessible to tourists. As a result, few of True's decorations can now be seen by visitors. Visitors can only purchase tickets on-site and have the options of a guided tour of the whole facility or only the power plant area. The only self-guided tour option is for the visitor center itself, where visitors can view various exhibits and enjoy a 360-degree view of the dam.
The changes in water flow and use caused by Hoover Dam's construction and operation have had a large impact on the Colorado River Delta. The construction of the dam has been implicated in causing the decline of this estuarine ecosystem. For six years after the construction of the dam, while Lake Mead filled, virtually no water reached the mouth of the river. The delta's estuary, which once had a freshwater-saltwater mixing zone stretching 40 miles (64 km) south of the river's mouth, was turned into an inverse estuary where the level of salinity was higher close to the river's mouth.
The Colorado River had experienced natural flooding before the construction of the Hoover Dam. The dam eliminated the natural flooding, threatening many species adapted to the flooding, including both plants and animals. The construction of the dam devastated the populations of native fish in the river downstream from the dam. Four species of fish native to the Colorado River, the Bonytail chub, Colorado pikeminnow, Humpback chub, and Razorback sucker, are listed as endangered.
During the years of lobbying leading up to the passage of legislation authorizing the dam in 1928, the press generally referred to the dam as "Boulder Dam" or as "Boulder Canyon Dam", even though the proposed site had shifted to Black Canyon. The Boulder Canyon Project Act of 1928 (BCPA) never mentioned a proposed name or title for the dam. The BCPA merely allows the government to "construct, operate, and maintain a dam and incidental works in the main stream of the Colorado River at Black Canyon or Boulder Canyon".
When Secretary of the Interior Ray Wilbur spoke at the ceremony starting the building of the railway between Las Vegas and the dam site on September 17, 1930, he named the dam "Hoover Dam", citing a tradition of naming dams after Presidents, though none had been so honored during their terms of office. Wilbur justified his choice on the ground that Hoover was "the great engineer whose vision and persistence ... has done so much to make [the dam] possible". One writer complained in response that "the Great Engineer had quickly drained, ditched, and dammed the country."
After Hoover's election defeat in 1932 and the accession of the Roosevelt administration, Secretary Ickes ordered on May 13, 1933, that the dam be referred to as Boulder Dam. Ickes stated that Wilbur had been imprudent in naming the dam after a sitting president, that Congress had never ratified his choice, and that it had long been referred to as Boulder Dam. Unknown to the general public, Attorney General Homer Cummings informed Ickes that Congress had indeed used the name "Hoover Dam" in five different bills appropriating money for construction of the dam. The official status this conferred to the name "Hoover Dam" had been noted on the floor of the House of Representatives by Congressman Edward T. Taylor of Colorado on December 12, 1930, but was likewise ignored by Ickes.
When Ickes spoke at the dedication ceremony on September 30, 1935, he was determined, as he recorded in his diary, "to try to nail down for good and all the name Boulder Dam." At one point in the speech, he spoke the words "Boulder Dam" five times within thirty seconds. Further, he suggested that if the dam were to be named after any one person, it should be for California Senator Hiram Johnson, a lead sponsor of the authorizing legislation. Roosevelt also referred to the dam as Boulder Dam, and the Republican-leaning Los Angeles Times, which at the time of Ickes' name change had run an editorial cartoon showing Ickes ineffectively chipping away at an enormous sign "HOOVER DAM", reran it showing Roosevelt reinforcing Ickes, but having no greater success.
In the following years, the name "Boulder Dam" failed to fully take hold, with many Americans using both names interchangeably and mapmakers divided as to which name should be printed. Memories of the Great Depression faded, and Hoover to some extent rehabilitated himself through good works during and after World War II. In 1947, a bill passed both Houses of Congress unanimously restoring the name "Hoover Dam." Ickes, who was by then a private citizen, opposed the change, stating, "I didn't know Hoover was that small a man to take credit for something he had nothing to do with."
Hoover Dam was recognized as a National Historic Civil Engineering Landmark in 1984. It was listed on the National Register of Historic Places in 1981 and was designated a National Historic Landmark in 1985, cited for its engineering innovations.
Scientists Investigate Light-Emitting Bubbles
Michael D. Wheeler
LOS ANGELES --
What do sound waves, water bubbles and photons have in common? They are the primary players in sonoluminescence, a phenomenon in which the tiny bubbles created by intense acoustic fields in water emit light as they collapse.
It also spurred Gary A. Williams from the University of California and his colleagues to conduct experiments in sonoluminescence. They focused on creating single-bubble luminescence in alcohol and nitrogen at cryogenic temperatures, but they found it difficult to trap the bubbles. They tried another approach: using focused laser pulses to induce cavitation.
In experiments that they described in the May 21 issue of Physical Review Letters, the researchers created bubbles in water with 6-ns, 600-mJ pulses from an Nd:YAG laser. The water absorbed the energy from the focused pulse, creating a bubble that expanded to 2 mm in diameter before it collapsed.
The key to analyzing the luminescence was a Roper Scientific spectrometer with intensified CCD readout capabilities. "The CCD allows us to record a range of 200 nm of the spectrum on each shot," Williams explained. "Because the luminescence is only about 108 photons from each bubble, the intensifier stage of the CCD proved crucial in boosting the signal."
The bubbles displayed a molecular OH* band at 310 nm, which approximates a 7800-K blackbody spectrum. This suggests a strong connection between the emission from single and multiple bubbles, because the same molecular band is observed in the latter.
7.62x63mm HV-APDS experimental battle rifle.
May 31st, 2044. The FH-106 is finished. Now we just need a test subject for combat evaluation... We don't need it alive - we just need one of those VM-1s to test out the power of the HV-APDS.
~ Translated excerpt from the Hochwald Armament Research Center lead designer.
A battle rifle designed to combat HAWS and VM-1s constantly being deployed in Old Haven, and is intended for town militia and federal military use.
The 7.62x63mm Hyper-Velocity Armor Piercing Discarding Sabot rounds that the FH-106 fires has a velocity rivaling general purpose gauss guns, allowing the round to easily pierce the reinforced armor found on the aforementioned threats. However, due to the round traveling at a very high speed, it limits bullet yaw and cavitation, reducing lethality against soft targets.
Regardless, it has very low recoil for a battle rifle, even when fired full-auto at 850 RPM. This allows users to place tight groups within a fairly short period of time.
Other features include a 30 round magazine, left-folding stock, RIS handguard, grenade leaf sight and compensator.
.50 cal magnetically assisted anti-biological gun.
"Guaranteed to put down your neighbourhood abomination, or your money back!"
- Informal advertisement from GC Kinetics.
A high-power sidearm jointly developed by GC Kinetics, Archwell Defense, and Barton Precision Industries (with GC spearheading the project), at the behest of the International Security and Defense Force (ISDF).
The rising threats of humanoid autonomous combat systems (HACS) saw the development of anti-HACS weapons being carried out on a massive scale by many arms manufacturers. The MAG-50 is one of many weapons produced from this surge, featuring a revolutionary armor-piercing frangible round.
Due to the HACS' ability to withstand an immense amount of damage courtesy of experimental armor, accelerated regeneration, extensive use of pain inhibitors and several other factors, the aforementioned round was designed to neutralize most (if not all) inherent advantages within a single strike.
The .50 cal. APFN-EMADS (Armor Piercing Fragmenting Necro-toxin, Electro-Magnetically Assisted Discarding Sabot) round deals with the HACS enhanced combat abilities in three phases: First, the primary armor piercing module punches through most conventional anti-ballistic armor thanks to an increased muzzle velocity (courtesy of the magnetically powered barrel). Next, upon reaching the optimal location for fragmentation, the round ejects eight shards, which, in conjunction with the primary module, greatly increases the chances of striking a vital area (such as the heart or brain) - the shards themselves possess excellent yawing cavitation to maximize damage dealt. Finally, once the shards have settled, a necro-toxin is released from the primary module, inhibiting natural healing factors and generally making the target more susceptible to conventional fire.
Since the rounds do not rely on gunpowder to propel each round, the MAG-50 boasts excellent recoil control, which makes follow up shots easy. However, due to the size of each round, magazine capacity is limited to just eight rounds.
Other features include a match barrel, illuminated sights, and a laser aiming module.
Frontal sail looks like a kite while the sail at the rear looks like a wind surfer sail.
Het voorste zeil lijkt op een kite en het achterste op een windsurfzeil.
Via via onder andere deze schepen ontstonden Spailboat en Orbites strai; voor toepassing van harde wind. www.flickr.com/photos/spailingstrailing.
The front line of the frontal sail is not directly established by the mast. The front line of this sail is an extra rod. Anyway, it is complex, stable sailing.
With stable wind users there is sufficient energy for enough liquefied hydrogen, and or ammonia, NH3, for the whole world.
The kinetic energy from wind counts quadratically with the wind speed, so that, four times more wind provides sixteen times more energy. Formula ( 1 ). Energy_kinetic in Joule = (1/2) * M * v^2. M is mass in kG and velocity in m/s.
Places for wind farms are where the wind is. These places are in general far from home so that the problem is how to bring the energy homewards. with the new media there is no problem. the new media are, ammonia, NH3 or LH2; liquefied and safe hydrogen.
The energy extracted from the wind is, of course, mostly, electricity. Bringing the wind energy homewards is firsly done by making liquefied hydrogen, LH2, from ( marine- ) water. Or ammonia, NH3.
Omdat de energie uit wind kwadratisch telt, ten opzichte van de windsnelheid, levert vier keer snellere wind, zestien keer zoveel energie. Sneller gaan werkt kwadratisch, zodat het wijs is om storm te zoeken. Harde wind doet zich voornamelijk voor vlakbij de arctische polen. De afgenomen energie is, vooral, natuurlijk, elektriciteit. Om de energie naar huis te brengen wordt er bijvoorbeeld waterstof gemaakt van ( zee- ) water.
Stable sailing leads to using storms. Stable sailing comes up with rings; possibly spanning in a Maglev bed. Stable sailing comes from kite surfing and wind surfing. The course sailed is, half wind. Half wind is the course flat to the wind. In case we go over the equator, a theoretical ring comes up. From here we go back to axis. The future windturbines do not need rings in all versions because, smaller and stronger wind turbines, with axis, can also be equipped for storm. Screws under boats, for instance the big ocean liners, are suitable wind mills for storms. The conclusion according to wind surfers is to use high winds. Until now, the rich countries forget storms, because they only take the low wind speed range at home in account. Or, in other words, (rich) countries forget the arctic poles.
The most important thing to understand from wind surfers and this shown boat is that storm is wind too. So, first of all must be understood that using wind is done where the wind blows. Near the Arctic Poles and on oceans. The picture shows high winds and a composition which is able to use it. The boat goes over the so called -and very famous- half wind course. What we see is windsurfing on the half winds course.
Stabiel zeilen leidt tot gebruik van storm. Stabiel zeilen komt met een ring waarin de bladen zijn gestoken en, de as van waaruit de bladen ontspruiten, is weg. De as komt later wel weer terug want de kleinere windturbines voor storm kunnen ook met as worden uitgevoerd. Het ontwerpproces ging echter via windsurfen en kitesurfen naar windturbines met ringen. Ringen lageren kan beter met Maglev. Toen we eenmaal in storm stonden kwam de as weer terug in windturbines.
Windsurfen / kitesurfen >> ring_wind-molen ( Orbites strai ) >> storm.
In storm kunnen dan weer geaste ( met wieken komende vanuit assen ) windturbines worden geplaatst, zodat windsurfen en ringen er eigenlijk alleen maar waren om de storm ( terug ) te vinden. We hebben nu eenmaal veel storm op de aarde en die moeten we gebruiken.
Verder, met ringen, die worden gelagerd met Maglev, ontstaat plotseling een ontwerppad richting mechanische vliegende schotels. Te zien op pagina 21a en 21b.
Zijsprong. Ringen gelagerd met Maglev leiden tot VLIEGENDE SCHOTELS. Die bestaan uit vier ringen. Waarvan de buitenste ding een doos is, die stilstaat, of heel licht spint, net als de centrale ring, die ook deze karakteristieken heeft.
Vervolg zijsprong, vliegende schotels. De centrale ring, een bel, staat ofwel stil, ofwel spint heel langzaam. De tweede ring spint heel snel en smijt, periodiek, massa in de rondte. De derde ring vangt de massa op, en brengt het in stilstand naar de centrale bel. Deze derde ring pendelt tussen de centrale ring en de vliedende ring in; met ofwel dezelfde snelheid als de tweede ring, tijdens het opvangen van de massa, meestal kwik, ofwel, die van de centrale ring en, dan, dus, stilstaat. De pendel-ring is essentieel, want, deze zogenaamde pendel-ring brengt het kwik terug naar de centrale ring.
Vervolg zijsprong vliegende schotels. Vanaf de zijkanten, rondom, wordt het kwik naar het centrum vervoerd. We hebben een mechanische vliegende schotel die gebaseerd is op een kite-, en, windsurfer, in de halve windse koers.
Einde zijsprong vliegende schotel. Kwik rondslingeren, spinnen, in een conus die dan draait, met een noodgang, is, mechanica. Er is dus een mechanische variant op de vliegende schotel, die echt kan werken.
Terug naar het windsurfen en spelen. Heel hard door water gaan levert problemen op en het grootste probleem heet: cavitatie. Zwaarden door water slepen levert cavitatie op. Dit zijn luchtbelletjes rondom de zwaarden als gevolg van de hoge snelheden en de onderdruk. De luchtbelletjes laten zien dat het water over de zwaarden, ""kookt"". Er is dus een analogie tussen slepen door water en slepen over land. Slepen, immers, ging beter met wielen eronder. Na het slepende mes kwamen de glas-snijders en, blik-openers, met cirkel-snijrand; in water snijden vergt een diep snijdend mes. Want, de tegenkracht op de zeilen wordt gemaakt door de watervoerende delen. Een zwaard-wiel, wordt, net als de genoemde wiel-snijders, met de snijdende rand aan de onderkant, door water gedreven. Maar ook kunnen dan drijvende wielen als, zijnde de boot zelf, of, aan de boot, omrollen en deze boten duwen minder water weg. Via windsurfen kwam vlieger-surfen en via de snelheid kwamen wielen voor door water.
Eigenlijk staat er, dat snelheid komt door de stabiliteit. Stabiliteit leidt tot wielen voor door water. De stabiliteit kenmerkt zich door de positie van het zeil, respectievelijk, vleugel, die dan als een vlieger, respectievelijk, kite, staat opgesteld.
Alleen, dan is de koers niet meer arbitrair. Wind-surfen gaat het beste, half wind; net als Vikingschepen en de typen zoals afgebeeld in de bijgaande tekening. Want, de lift-lijn, van het voorste zeil aan de ra, schiet rechtstreeks door de blokkade erop; en zelfs kan de lift-lijn in Speelboten beneden de zwaarden uitkomen, zodat de boot aan de lijzijde wordt opgetild. De ogen in het zeil kijken dan, als het ware, naar waar de draden zouden uitkomen, indien het een vlieger zou zijn.
Er is geen arm meer, zodat geldt: Actie, is, Reactie. Ofwel, F_actie, is, F_reactie. Ter opheldering van hoe het was, binnen zeilboten: Moment is kracht maal arm, ofwel, M = F a, in. Nm. De ogen keken, als gevolg van een hellende mast waaraan de zeilen hingen, naar de lucht. De lift werkt verkeerd, bij langsgetuigde zeilboten. Stabiel betekent, constructief ; het kan nu sterk genoeg worden gemaakt. Ter opheldering; zeilboten flippen, ook met een sterke zeilboot. Sterker, met een sterke boot wordt hij log, onhandelbaar, en slaat nog steeds om.
Een mast op een zeilboot kan natuurlijk ook heel sterk worden gemaakt, maar, nog steeds flipt de zeilboot; slaat de zeilboot, om. Een zeilboot is een naam, voor een specifieke soort zeilboot. Net als vliegtuig en wiel slaan de benamingen op de inmiddels bekende waardeloze inhoud. Speelboten kunnen vleugels dragen met de ogen van de zeilen naar de reactie gericht. De mast, 5, komt uit de mast-manipulator, 3, en voor de rest zit alles in de mast; ten behoeve van het ophouden van een of, meerdere, vleugels, 6; met de hulp, overigens, van maar zes variabelen.
Minimaal drie lijnen, 7, lopen naar de vleugel, 6. Ik gebruik er vier, naar elk hoekpunt, en in een reactie op een schift, staat een lijn, van de vier lijnen, dan los. Dus, de reflex, werkt door op drie draden: geblokt door drie lijnen.
De reflex neemt drie variabelen. De, gewone, controle van de vleugel geschiedt natuurlijk wel met alle-vier de lijnen. Maar, het gaat, hier, specifiek, om de reactie; natuurlijk.
En, vooral, in, de mast-manipulator, 3, omdat de zeilboot moet vliegen en moet zeilen. Vliegen, dat moet stabiel. Een zeilboot vliegt niet, want men kan niet met een half span vliegen. Vlieger-surfen is als windsurfen, maar dan snijdt de giek het span door-de-midden. Een wind-surf-zeil is daarom zo klein want, het deel onder de, GIEK, is, direct afhankelijk van de grootte van de windsurfer. Een hele grote windsurfer, zou nog grotere zeilen vast kunnen houden.
Maar een windsurfer is een mens. Een mens is, zeg even, 200 cm en gemiddeld, 160, a, 190. Dus, willen we een span in de lucht houden, dan moet ze worden opgehouden, door uitzetconstructies, welke universeel zijn, de uitvinding, deze show, alsof de draden uit komen, respectievelijk, ontspruiten vanuit de zwaartepunten van de zwaarden. Een vleugel-span, met straks wellicht elke helft gearticuleerd aan een bol aan de mast, kan, net zo goed, voor een gebalanceerde compositie, zorgen. Stabiele, Speel-boten, tillen vanzelf de boot uit het water. En, zelfs zo dat aanvankelijk de vleugel de boot bijna helemaal optilt, wat dan impliceert dat de zijwaartse-lift-kracht-component, vector 10, dan heel klein is. De vectorvoorstellingen staan op pagina 14.
Als de mast dan flauw opligt en, de vleugels staan op opwaartse lift, dan wordt de lei-zijde als eerste opgetild; door Vector 11. Alhoewel dit misleidend zou kunnen zijn kunnen, want, vector 11, is alleen te zien in de configuratie ten tijde van maximale werking. Dan is, vector 11, gelijk aan het eigen gewicht, minus, de opwaartse werking van de zwaard-wielen. Die deels planeren, aan de onderkant van het drijfvolume van de rol-drijvers. De rol-drijvers zijn ook de zwaard-wielen, het best te omschrijven als een snijrand die om de rol-drijver heen loopt. De snijrand wordt relatief groot. Voor tegenwerking tegen zijwaarts gerichte lift-kracht. Groot en sterk. Zo kunnen we windsurfen in storm. Omdat de massa dan lekker snel beweegt is er veel kinetische energie aan boord. De volgende logische stap, is / was, om schoepen tegen het water aan te laten lopen; voor / ten behoeve van de opwekking van elektriciteit en dan, ten behoeve van transport, bijvoorbeeld, vloeibare waterstof, die gekoeld is op, minus, 260 graden Celsius.
Storm is energie voor waterstof uit water. Ook zeewater. CYCLOON-BENUTTING, WATTs. We hebben waterstof uit zeewater, met storm als energiebron!
Geen vervuiling. Uitmuntend ( Zowel thuis, als elders, verschijnen E-ringen / Orbites strai voor storm. Over stormachtige wateren verschijnen Speelboten. Zowel de lift-krachten, inwerkende op de E-ringen, als liftkrachten, inwerkend op de vleugels op Spel-boten, worden normaal overgedragen op de behuizing, grond, respectievelijk, water ) is, ( we spreken gewoon over een tijd die komt en eindeloos is, op aarde al 400.000.000 jaar; om de bouwwerken en werktuigen en alles wat voorheen staal en plastic was, uit super-composieten op te trekken / te bouwen.
Super-composieten, met metaal-coating, gaan lang mee. Volgens de, TU-Delft, zelfs oneindig. Dan,
De snelheden van Speelboten zijn net zo hoog als die van windsurfers. Wielen voor door over water zijn zwaardwielen. Speelboten hebben deze. Zwaardwielen, die draaien, spinnen, aan snelle boards, laten het water, “heel”. Zie show.
Cavitatie is bubbeltjes van lucht in het water om de door water gesleepte toestanden, zoals zwaarden en roeren. De wind komt hier van links.
Olie wordt de belangrijkste grondstof in super-composieten. Super-composieten zijn beter dan staal. De waterstof verdrijft de olie, en de olie, in de vorm van super-composieten, verdrijft de staal.
Windsurfers en vlieger-surfers gaan heel hard, bijna, 100, 60 - 80 km / hr. Surfen maakt snelheid, op een ongelofelijke manier, en, windsurfen maakt op een nog fantastischer manier nog meer snelheid en gaan ook vliegen. En dit in een verrassend logisch lijkende respons van de mens op een surfplank.
Composities als deze, alsmede Spailboat, kunnen werken in storm op zee. Windsurfen en vlieger-surfen gaan alleen maar snel. Surfen gaat ook half wind, omdat de golffronten ook haaks op de wind lopen; op open zee, ons werkterrein, is geen diffractie en is er ook geen refractie van de golven, te herkennen als golffronten
Dwars op de wind is, heen en terug zonder tegen de wind in terrein te winnen. En, gaan nergens heen. De golven worden niet systematisch overgegaan. Storm is harde wind. E= (1 / 2) M v^2, in Watts. Waarin; E, is, Energie, in Watts, M, is, massa, in, K g, en, v, is, snelheid, in, meter / sec.
Twee weken storm, in Nederland, is energie, gelijk aan ongeveer drie maanden wind, kracht drie. Storm en waterstof gaan hand in hand. Sterker, wind en waterstof horen bij elkaar, omdat de wind niet constant blaast.
Thuis worden de stormen, energie-pieken, afgevlakt met, waterstof, en elders wordt alle windenergie, via de elektriciteit opgewekt door de E-ringen, omgezet in, waterstof.
Het windsurfen kan in storm. Dan gaan we naar storm.
We gebruiken wat we hebben. De energie uit storm. Net als een stekker, gaan we naar de polen.
De polen. En dan blijkt dat een schroef van een onderzeeër ook voldoet. Dus ook met assen omdraaiende windturbines kunnen draaien in storm.
De uitvinding van de landbouw. Typisch. Exemplarisch. Een kringloop, net als waterstof uit storm, want storm is een rest van verbranding van fossiele brandstoffen. Landbouw; vruchtbare grond. Vruchtbare grond is, grond, prut, aarde, gemengd met mest. Gewassen groeien goed op bemeste grond. We eten de gewassen op. Voor ons zijn gewassen, voedsel, energie. We groeien dus onze energie, voedsel, op bemeste grond.
Er is sprake van een kringloop. Het restproduct van voedsel is, mest. Storm is dus als het ware mest, want, sinds de stoommachine loopt het overgrote deel van onze machines, motoren, energiecentrales op fossiele brandstoffen, zoals olie, kolen en gas. Verteerd en verwerkt geeft verbranding van fossiele brandstoffen, stormachtige wind. Eerder is al genoemd dat een kerncentrale nog immer een stoommachine is. Echter, het afval-product van kernenergie valt overal buiten deze verhandeling. Het afvalproduct, “mest”, van de overige genoemde energiecentrales en motoren, is, warming. De verwarmde aarde en oceanen, geven meer wind. Storm, harde wind, cyclonen, zijn een restproduct van onze verteerde energie. Storm, is, dus, als mest, waarop nieuw leven kan groeien.
Met, E-, en, Speel Boten, kan storm worden gebruikt, waarmee cyclus rond is. E-rondje. waarin een uiteinde van het blad dat met duizend kilometer per uur beweegt, indien los gelaten, in eerste instantie, weg spatten in de richting loodrecht op de wind. Het gaat dus over wind-energie-omzetters.
E = M C ^2 voor licht, Einstein. Kent iedereen. Massa in beweging is energie.
E = 1 / 2 M v^2 op aarde, van een massa. Zelfde strekking, massa in beweging is energie.
Energie is massa in beweging.
Energie, oude situatie &t;&t; Stoom-turbines lopen op stoom. Ook kern-energie is, nog steeds, een stoom-machine. Ongelooflijk, zo simpel. Echter, wind kan ook ronde dingen laten draaien. Eerder werd al herinnerd dat de naam, ""Wiel"", staat voor ronde dingen. Een ring om een as, wordt vervolgens een velg genoemd. Die velg, de ring om de as, kan ook buitenom worden gelagerd, en dan is het wiel een ring geworden. Geen assen meer, met wieken direct erin, maar, wieken, bladen, vleugels, starre zeilen, in ringen, die dan mogelijk rollen in assen, respectievelijk, wielen, met, assen. Wind is bewegende lucht en drijft massa voort via vleugels.
De vleugels kunnen nu niet meer stuk omdat ze in een ring zitten. Ik vraag U met klem om U te verplaatsen naar, 400 jaar, geleden. Toen was er nood. Die nood is er nu ook. We hebben nu eenmaal water en energie nodig. Veel zeewater moet zoet water worden. Simpel, omdat de zeewater-spiegel moet dalen en er zoet water nodig is in de woestijnen. Al met al kan men stellen dat er een meter van de zeespiegel af moet, en dat er zoet-water nodig is in de woestijnen. Kortom: de, armen krijgen water, en het, Westen, krijgt zijn zeespiegel-daling. Energie uit zeewater.
Intussen is het natuurlijk een misvatting dat speciale assen met wieken erin voor storm, niet aangepast kunnen worden. Dit kan wel. Zelfs ook tot aan de maximale wind, 560 km / hour. Een windmolen voor storm zal kleiner zijn. Met een korte mast. En, een grote as. En korte wieken. Ergens onderweg vergeleek ik schroeven van onderzeeërs met geschikte windmolens voor echt keiharde wind, 500 km / uur. De energie is ver van huis, dus hebben we bijvoorbeeld waterstof nodig.
Waterstof, nabij de polen is, voor het grootste deel voor transport naar huis en voor opslag van de harde wind.
Waterstof-reactors en de buffering, opslag, van de, waterstof, in speciale met Indium uitgevoerde opslagtanks, leiden tot genoeg energie, altijd, en overal. Althans, indien men opereert in storm, wat impliceert dat men nabij de polen of, in tropische stormen en orkanen is.
Het wiel voor door over het water, zou, indien er dan toch over: “het wiel opnieuw uitvinden”, zou worden gesproken, het, ZWAARDWIEL, zijn om de cavitatie te voorkomen. Cavitatie komt, eigenlijk alleen maar, voor, in de half-wind-koers. Speel Boten hebben zwaardwielen. Zwaardwiel komt voort uit de vrijetijdsbesteding windsurfen. De half-wind-koers is te bevaren door wind-, en, vlieger-surfers. Half-wind is de zogenaamde, “race-koers”.
En racen door water leidt tot zwaardwielen onder de boot. Maar ook leidt racen over een bepaalde lijn, de evenaar, tot een ring. Met, E-, kan hanteerbare energie worden gehaald uit storm. Magnetische velden- sporen voor, -treinen, hebben energie nodig om te zweven, zodat het wiel niet meer nodig is op land. En, grote ringen kunnen ook met behulp van Magnetische sporen. Kortom, als er energie in overvloed is, kunnen de lagers wrijvingsloos hun werk doen; met behulp van, magnetische lift. Met de komst van energie uit storm komen ze er dus, er komt wrijvingsloos leven, en er komt paradijs, op aarde, omdat spelen energie oplevert. alles wat we nodig hadden was een speelboot, en hieruit kwam een ring, en daarna vliegende schotels.
Zo mogelijk verdwijnen de wielen op land; omdat er met de enorme hoeveelheid energie uit storm met Magnetische lagers kan worden gewerkt. Magnetisme, “vreet”, energie en, storm levert, meer dan genoeg, energie. Storm geeft snelheid aan de dragers van de bladen in / aan stabiele wind-omzetters.
Snelheid te water leidt tot lucht bubbeltjes; vooral om de water-appendages, zoals, roeren en zwaarden. In water gaan zwaarden, vinnen, onder wind- surf-boards, vaak te snel, en hierdoor metamorphosen, zwaarden, tot, zwaard-wielen. Zwaard-wielen verschijnen te water om cavitatie te voorkomen onder hoge snelheden, maar ook, om turbines aan te drijven die aan boord zijn.
Wat ik verwacht is dat, ter land, de wielen minder vanzelfsprekend worden en, dat, er, dus, meer met magnetische lagers wordt gewerkt; omdat het wrijvingsloos is, waardoor de onderdelen niet slijten. Trajecten, sporen, en, met, magnetisch gelagerde ringen, komen, logischerwijs, door de energie die nu voorhanden is, in plaats van het bekende wiel, met as.
Ter zee komen de wielen weer terug, in de vorm van zwaardwielen. En, wieken aan assen, respectievelijk, wind-turbines, verdwijnen, want, bladen, die worden vastgehouden door ringen, werken in storm. Ringen komen voor assen en wielen en wielen komen voor zwaarden. Een ring, kan buitenom worden gelagerd met, ook, magnetische velden, Maglev, genoemd. Zo'n ring kan ook plat staan, met zijn gezicht naar de aarde. De ( ronde- ) doos, waarin de ring zit, kan vacuüm worden getrokken. Een ring in een vacuüm-omhulsel, kan wel wrijvingsloos gefixeerd draaien, ten opzichte van de doos, en, een wiel met as niet.
De as verbindt het wiel namelijk met de doos. En de lagers worden warm. Kortom, een wiel met as kan niet heel snel draaien, spinnen; ook al is het in vacuüm. Er is wrijving op de as. Een ring in een vacuümdoos kan dus wel wrijvingsloos draaien. De lagering wordt verzorgd door magneten. Wellicht worden assen zelf ook met Magneten gelagerd, en dan, kan er, natuurlijk, ook door wielen in vacuüm heel snel worden gespind. Pagina 21a en 21b.
Als nu, hypothetisch, de ring met enorme snelheid draait, wat kan, in vacuüm, zonder wrijving, dan kan er in deze hypothese een ring draaien die eruit ziet als een vliegende disk, frisbee. Als er dan nog een ring binnen in de ring zit, kan deze ring stilstaan ten opzichte van de de doos. De frisbee-ring draait dan met bv, 40.000 km / hour, aan het randje, terwijl de centrale ring terug draait met dezelfde snelheid, en dus stilstaat, ten opzichte van de doos. Als er nu kwik wordt weggeslingerd door, de ziedende ring dan, ontstaat er anti-zwaartekracht. In plaats dat de conus stilstaat, en een soort lava weg spuugt, zoals in raketten, draait de conus met een noodgang: eventueel een soort lava in de rondte slingerend. In een later stadium kwam kwik als medium om de hoek kijken. Het in de rondte geslingerde medium is dus geen lava meer, maar kwik.
De centrale ring heeft een vangscherm om een medium dat, niet exploderende is in het luchtledige, dus, met genoeg eigen spanning, een soort lava, bijvoorbeeld, op te vangen en in stilstand weer terug te voeren naar de as, om vervolgens wederom te worden weggeslingerd door de ring; in de vorm van een frisbee; gemaakt, net als de doos waarin de ring zweeft, van super-composieten, met Magnetische velden voor de lagering, en met, metaal-coating als schilletje. Het is een vliegende schotel. Vliegende schotels kunnen zelfs ook deels uit hout geconstrueerd worden. Hieruit volgt dat metaal niet langer nodig is voor constructies, edoch wel zeker als coating.
Ringen met wieken en Speel Boot met wielen / Storm / energiebron, I.
Assen en Wielen / Kolen, Olie / energiebron, I.
Energiebron, I, is nodig om uit zeewater waterstof te halen.
Windsurfen, half-wind, ligt aan de basis van, Orbites strai / E-ring. Zowel, vlieger-surfers, als, E-ring, zijn stabiel. Stabiel zeilen opent de half-wind-koers omdat de lift-krachten rechtstreeks door de zwaarden worden gejast. Speel Boot, respectievelijk, wind-surf-machines, gaan vervolgens zo snel gaan dat zwaard-wielen, in plaats van (steek-) zwaarden, ontstonden. Met het gebruik van storm krijgen wielen dus een andere invulling. Een zwaard-wiel, onder Speel Boot, snijdt / rijdt door het water met de onderkant. De assen van zwaard-wielen lopen naar waterstof-reactors voor de aanmaak van, waterstof.
Als er dus harde wind, storm, aan de basis staat, dan ontstaan er wielen voor door water en ringen met wieken. Speel Boot en later, in, 2008, E-ring, zijn gevolgen van de zoektocht om, zeilen als vliegers, op te houden. Spinnen op wind en, zeilen, kunnen dan zonder excentriciteit. Er is nu geen wringing meer op de assen in wind-gebruikers en er wordt niet meer omgeslagen met zeilboten.
Actie, is, gelijk, reactie. Storm is, de energie om van water veilige vloeibare waterstof te maken; ook nog eens in, `oneindige`, hoeveelheden. Er is alleen maar energie nodig om uit zeewater waterstof te maken. Vloeibare waterstof heeft een soortelijke massa van, 200 KG / m^3. Een volle Speel Boot is geen probleem.
De eerste vlieger-surfers: Een scheef hangend, zich, in de halve-wind-koers, voort banend, Vikingschip lijkt op de tentoonstelling van een vlieger-surfer. De lift-kracht werkt de surfer scheef omhoog; net als het Viking-zeil. Ook Viking-schepen worden namelijk scheef opgetild in de half-wind-koers. Vliegen kon de mens toen al. Heel hard in de half-wind-koers zeilen leidde tot E-ring. E-ring, voor storm, hebben ringen, in plaats van assen, waaraan de bladen hangen. E-ring en Speel Boot zijn voor storm. Speelboten slaan niet om en E-ring laten de lagers koud. Dit, doordat de krachten-overbrenging eerst is genormaliseerd.
Het geval kukelt niet meer omver. In water leidt stabiel zeilen tot hoge snelheden en hierdoor ontstonden, in water, wielen, om te rollen.
Met de koppeling van alle wind, ongeacht boven water of land, waar ook ter wereld, zoals de ruwe veertigste lengtegraad, furieuze vijftigste -, en, schreeuwende zestigste lengtegraad,. aan de productie, opslag en transport van waterstof volgt de nieuwe reformatie! Nederland kan opnieuw een reformatie over vier generaties doorvoeren, om nu de wereld opnieuw te bevrijden.
Waterstof, komt in plaats van olie, kolen en gas, als brandstof. De olie wordt de voornaamste grondstof voor bouwmateriaal, super-composieten. Water kan uit zeewater worden gemaakt, met behulp van de energie uit wind, ook storm. Hout komt terug als bouwmateriaal door de irrigatie. Zeewater kan water worden, en ook waterstof, als er maar energie is. En, energie is er in de vorm van harde wind. Warming maakte de wind furieuzer.
Metaal, met name, staal, voor constructies stopt op den duur, loopt sterk terug, maar, metaal zal blijven voor coating. Echter, de constructies worden van hout, vlas en carbon-fibers, respectievelijk, super-composieten.
Energie uit storm komt door de normalisatie van de lift, door wind in de zeilen, met de grond / water. Storm, wedijvert met duizenden kerncentrales. Ofwel, olie-, gas-, kolen-, en kernenergie zijn tussenstappen geweest. Er is werk genoeg voor alle mensen op aarde.
In plaats van centrales, wordt de energie-voorziening gedaan door E-ringen, en, Speel-Boten, die waterstof-reactors aandrijven. Alle problemen worden opgelost, met een ring, waarin de wieken gestoken zijn. Van vrijheid kwam een ring. Want, windsurfen leidt tot een ring. Het doel van windsurfen is, het windsurfen; de snelheid. Windsurfen en catamarans werden uitgevonden na, 1945, na, WOII, de tijd in de geschiedenis dat er vrije tijd was. Het motief was altijd om van, A, naar, B, te gaan met, aanvankelijk, stenen. Piramide-bouw; onzin. We zijn Nomaden en we reizen in de rondte. Windsurfen doet niet aan het aandoen van bestemmingen.
Als de zee zegt, dit is de juiste koers, met de golven, dan is het zo. Alleen, als er gezeild [ surf ] wordt met de golven dan blijft men globaal gezien op dezelfde plek. Geen, B, dus. Half-wind koersen: haaks op de wind, en, na eindeloos heen en weer gaan zijn we nog steeds in, A. En dit, dient, volgens onze beschaafde regels, geen doel. In plaats van een as, met wieken, is er nu een stelsel, met in elk stelsel een ring met assen die de ringen inhangen.
Cyclonen kunnen worden benut. Industriële revolutie, smog, smog maakt de lucht dikker en broeit lekker. Warmer zeewater, meer wind. Wind, ook storm, respectievelijk, met name, storm, is de input voor, E-ringen, en, mogelijk, zeer grote stabiele zeilboten, Spailboat, levert genoeg energie voor de aanmaak van waterstof uit zeewater. Stabiliteit in de energie-huishouding van de planeet. Geen roofbouw en geen vervuiling meer, maar, een sluitende begroting. Zeewater wordt zoet water. Vies water wordt schoon water. Energie kan water schoon maken, dus, is, het voedsel-probleem ( ook ) opgelost.
Woestijnen kunnen worden bevloeid. Bijvoorbeeld Noord-Afrika heeft dan weer Savanna's, zoals het daar vroeger was, voordat de Egyptenaren alles hadden vernietigd voor onder andere de piramides. Een normale uitvinding, hetgeen dan direct een vondst is, en helemaal geen uitvinding, Normaal doen gebeurt, eens per duizend jaar. Deze, E-ring, is zoiets. Terug naar de rollende stammen onder de stenen. Het waren de slaven die dit ontdekten, want zij moesten immers de boel op sleeptouw nemen. Vanzelf ontstond uit de stam, het wiel, met een as. een as, zoals in een stoom machine, en nu in kern centrales, is dus via het verkeerde motief.
Onze windmolens hebben dus een as, waarin de wieken gestoken zijn. We dachten immers zo. Een wiel heeft een as; gewoonte-recht. Maar, er kan maar een beperkt aantal wieken in een as, en, de as vliegt in de fik als het echt gaat waaien. Er is veel meer ruimte in een ring, om een groot aantal bladen in te steken. Eerder leerden de piramide- en de kerken-bouw dat er stabiliteit moet zijn van evenwicht; eer men groot kon gaan bouwen. Een as met wieken is niet stabiel en dus kan er niet worden opgeschaald.
Ringen, net als de assen, verdragen de wieken, en staan stijf van de spanningen, maar de lagering ( van de ringen ) -wielen met assen-stelsels of, magnetische lift-systemen-, voelen daar niets van. De ophanging van de, E-ringen, respectievelijk, de lagering van de E-ring, worden door een centrische kracht benaderd. De energie van de vervuiling kan rechtstreeks terug worden gebruikt. En hier begint een dwaling, althans, indien ik die niet zou opmerken. want, eenmaal in storm, dan kan ook een schroef van een onderzeeër op staan.
Before the airplane showed up, we called flying what birds, winged insects and bats did. already can be distinguished here, because, there are also flying fish, squirrels, frogs, snakes and the rest which I forget. the flights of flying fish, falling frogs, squirrels and snakes, are another type of flying than the birds and insects. it is for sure that for planes birds served as the example. later came the helicopter and it had been based clearly more on an insect, probably a dragonfly.
voordat het vliegtuig kwam, noemden we vliegen hetgeen vogels en gevleugelde insecten deden. nu al kan er onderscheid worden gemaakt, want, er zijn ook vliegende vissen, eekhoorns, kikkers, slangen en de rest die ik vergeet. de vluchten van vliegende vissen, vallende kikkers, eekhoorns en slangen, zijn een ander soort van vliegen dan de vogels en insecten. ik kan me zo voorstellen dat voor vliegtuigen vogels als voorbeeld dienden. later kwam de helikopter en die was duidelijk meer gebaseerd op een insect, een libel denk ik.
as from now flying is therefore presented as the flaunting piece of birds and bats. flying is in fact therefore in this context the control over the articulation of wings. to couple directly to full imagination; a swarm of birds, in a storm or, fall winds or other type turbulent air trends. another show is the flight of for example an albatross, only actively moving the wings occasionally. of course, it is best for birds to save as much energy as possible and to glide as much as they can with the wings, but, in case of a swarm in a storm, is it necessary, to fly!?
vanaf nu wordt vliegen dus voorgesteld als het pronkstuk van vogels. vliegen is dus in deze context eigenlijk de controle hebben over vleugels. om direct de verbeelding aan te spreken stel ik een hele zwerm vogels voor, in een storm, valwind of ander soort turbulente luchtstromingen. een andere voorstelling is de koele vlucht van bijvoorbeeld een Albatros, die zo weinig mogelijk met zijn vleugels wiekt. natuurlijk is het zaak voor vogels om zo weinig mogelijk te slaan met de vleugels, maar, in geval van een zwerm in een storm, is het nodig, om, te vliegen!?
So, what is in fact flying? flying is the not stationary position of wings with respect to the fuselage of the bird. because, a flying fish or a falling squirrel or flat snake fly also but, there is another source for flying than clapping the wings. a flying fish, for instance, is launched from the water by swimming speed and a falling flat snake or squirrel really do not fly to the other side, but glide over the air. and this to slide comes already in neighbourhood of what albatrosses dearest doing. from time to time clap with the wings and for the rest use the albatrosses the thermals but also, the pushed up air as a result of sea-waves.
hier wil ik U hebben ; wat is nu eigenlijk vliegen? natuurlijk is dat hetgeen vogels doen door het wieken van de vleugels ten opzichte van de romp van de vogel. want, een vliegende vis of een vallende eekhoorn of platte slang vliegen ook wel, maar, er is ook spraken van een andere aandrijving dan de kracht van de klappende vleugels. een vliegende vis wordt als het ware uit het water afgeschoten en een vallende platte slang of eekhoorn vliegen niet echt naar de overkant, maar glijden, en dit glijden komt al in buurt van wat Albatrossen het liefste doen. af en toe een slagje om op hoogte te blijven en voor de rest gebruiken de Albatrossen de thermiek maar ook, de opgestuwde lucht als gevolg van zee golven.
dan, een vliegtuig. het stond natuurlijk groots in de krant rond, 1900AD. de mensheid kan vliegen! maar, was dat ook zo? de vleugels stonden star, zonder articulatie zoals vogels, vleermuizen en -honden en dat wel degelijk hebben, aan de romp, en van vliegen was eigenlijk geen sprake, want, het valt onder vallen, glijden, met in plaats van de zwaartekracht als aandrijvende kracht, een motor, de propeller. een vliegtuig is dus meer te vergelijken met een vallende platte slang of, die speciale eekhoorn of kikker. met andere woorden, zonder een motor, en zonder een valhoogte kunnen platte slangen, eekhoorns en, vliegtuigen, niet vliegen! een vliegtuig is dus in feite geen vliegtuig, maar een luchtglijder. zonder een motor en zonder een valhoogte kan er niet worden gevlogen door luchtglijders.
then, an airplane. massive in the newspaper around, 1900AD: humanity can fly! but, was this in fact the case? the airplane got airborne and covered a distance by using the air as carrier of the mass. true, of course. and in a way, we can call that phenomenon, ‘’’’flying’’’’, but, of course! However, after looking closer to this kind of flying, we will see that this kind of flying is in fact more like falling or, air gliding; like flat snakes and squirrels do, when covering distance by falling. only birds and winged insects can take off caused by the motion of the wings with respect to the fuselage. the wings at the fuselage of an airplane are without articulation, such as birds have indeed. so, flying, like birds do, was in fact not copied. flying, gliding, like airplanes do, without wings articulated to the fuselages, need a propeller or, compulsion other than the motion of the wings with respect to the fuselage and therefore it falls under, falling, or, gliding; like the flat snakes and squirrels do when falling, gliding over the air beneath, from one tree to another or, in any way a point lower than take off height. So, without wings actively used for airborne power, the flying of airplanes falls under: falling, gliding, with, instead of the gravitation as operating strength for the earlier mentioned air gliders, such as flat snakes and squirrels, an engine; the aircraft’s propeller. an air plane, which uses compulsion other than the movements of the wings with respect to the fuselage, is, therefore, to compare with falling flat snakes or, special flying squirrels or, special flying frogs; the last with those nice toes spreading out creating so a fall screen. in other words, without an engine and without a fall altitude, the airplanes fly like flat snakes, squirrels and those nice frogs. not like a bird, at all! an airplane is therefore in fact not a flying thing, but an air glider. without an engine and, without a falling height, so, without a ‘’’’pull’’’’, air gliders cannot be flown.
laat staan dat er met een zwerm vliegtuigen kan worden gevlogen in een storm, want, dat noem ik nu vliegen! of beter, de kunst van vliegen. windsurfers en kitesurfers, daarentegen, kunnen dat wel. ze vliegen soms ook zelfs alhoewel dit ook gebeurt door middel van een aanvangssnelheid; net als een vliegende vis in feite. het gemaakte punt is dus deze: windsurfers en kitesurfers hebben vleugels die gearticuleerd zijn ten opzichte van de romp, respectievelijk voortgang van het board. articulatie is dat de vleugels niet star zijn verbonden met de romp.
And then, what about a swarm flying airplanes, only inches apart from each other, in a storm or, in turbulent airflows or, under fall winds? I mean, that is what I want to call flying! anticipating by means of articulating the wings with respect to the bodies and so, also anticipating with respect to the other birds in the swarm and at the same time with respect to the always differing motions of the air in storms. wind - and kite surfers, on the other hand, can do this, very well in fact. the participation on the ever changing angles of attack in the wings is also done with the articulation of the wings, sails, with respect to the hulls, fuselages, bodies, boards. wind - and kite surfing are therefore bird-like. the triviality now comes with this: also wind - and kite surfers do, sometimes, cover distances through air; which was called flying in the first place, but, in this new definition this kind of flying is air gliding indeed! the actual flying prior to the ‘’’’jump’’’’ is the wind surfing; just like a flying fish uses the swimming just before the air glide. these flying fish cannot wing themselves up to keep on flying for a long time. And neither can snakes, squirrels and frogs. this kind of flying is therefore in fact, not flying, but, gliding on air. the point is therefore: wind - and kite surfers have wings which are articulated with respect to the fuselage, respectively to the board. articulation is that the wings are not rigidly linked with the fuselage but with ball-and-sockets / articular joints.
Wind- en kitesurfers hebben geen motor en ook geen valhoogte waardoor glijden vervalt en plaats maakt voor, vliegen!? een vliegtuig vliegt dus niet maar glijdt terwijl wind- en kitesurfers wel als vogels vliegen. als dan mijn verhaal is inbegrepen in deze positionering. vliegen door vogels wordt gedaan door de articulatie van de vleugels en wind- en kitesurfen ook.
Wind - and kite surfing are, because of this articulation, very difficult. It is, therefore, no surprise that wind - and kite surfing are not yet embedded in modern science, because, the art of flying is not for sale! the rich cannot buy this art, so, it is just not here. for once, this is the way the system is build up. make, sale. wind surf riggings and boards are, with respect to sailing boats, absurdly cheap and the speed to reach is no less than, 100km/hr, but still, we never see wind surfers in sailing boat regatta’s. so many times I have mentioned the revolution and this is why: sailing is going from, A, to, B. sailing was going somewhere, to make war and for trading. wind - and kite surfing are going nowhere but fast. regatta’s nearly exclude the half wind sailing course! so, there is no place for a wind surfer in regatta’s. the rules make low wind courses and high wind courses and exclude this way the entrance of wind surfing for speed. there was this song: Street Fighting Man, in where the ever repeating lines were; in the sleepy rich world, there is no place for, Street Fighting Man. Anyway, in the world, the rich make, there is no place for wind surfing / wind-surf-man. TIME OR A STAND, oh, too BIG, well, anyway; time for a stand; I call it revolution. The revolution for using the wind, instead of oil, gas, coals, uranuim, and, plutonium. Storms, notably the outcome of using oil, gas, wood, and, coals! By, also, planes, indeed. Global Warming, led to more wind and higher sea waves, exactly the two to use by wind surfers. exactly, child’s play! how beautiful do you want to have it? avoiding war is to be done with child’s play. the grownups at the top of the, Pyramid, rather play a different game, but, of course; they rather go to war for, oil, otherwise, their airplanes cannot glide and their cars would not run! the facts are that the population is now so big, that this world of the happy few is ending real fast. the thing is, in history these days, that we cannot make war any more over nothing, whereas the rich always had this trick in the sleeve to get rid of the young men, which were threatening the Kingdoms. the rage could always be tempered, by taking the young out in a war with the neighbours. So, now the rich seek to go to war outside. And yes, they are successful. Iran, is, ready for, war. Bingo. Game on. But, what if the children of the, West, gave Iran, water, which is the result of burning, LH2? what if we use the human skill to make energy instead of war? And what about the first paragraphs of the three most important books, where we all are called to walk away from the, Pyramid / or, The System / the Pyramid, is the enemy. The system let us fight. Wake up, please. We do not wnat to fight, we are all brothers and sisters. The issue we face as mankind is to straighten out a few tiny things. Where in the, Bible, Moses, doubts, God, there is no doubt by, Moses, in the, Quran. Iran, me West, give you water! Please. Wind surfing is going through these paths. The problem is not oil, as I showed you earlier, no, the problem with energy is, that, the rich, the system, cannot buy the skill to wind surf. On the other hand is oil for, for instance air gliding, for sale. Brutal and this proves this point. Flying, well, now called, air gliding an airplane is a brutal act. Air gliding has, in fact, nothing to do with flying, like birds do. So, making war over oil is brutal, and, stupid. Wind surfing for energy is the revolution of today. Let the children play. This means that, the articulation, of the wings, with respect to the boards, can only be coordinated and, controlled, by human power. And, of course, human power is the complex combination of the muscles and the brain. Articulation of the wings with planes, demands : ‘’’’Science’’’’; the same as articulation of guns in war! Air anti-aircraft guns, such as the, Goal Keeper, and guns on tanks are, articulated: just like the wings. attached, with the joints under the rig, at the boards, in the very hands of the wind surfer. Wind surfing is, art: The War Industry.
The aim, originally, is, to replace the human handler by mechanics, just like in war the humans whom held the guns were replaced by tanks and anti-aircraft guns et cetera. Because, how large can the barrel of a gun be, if directly in the hands of a soldier? War for oil, versus, Peace with oil. Oil is plastic, and, oil is the base material for mechanical wind -, and, kite surfer, which arouse energy. The technique for, war, proves to be the same such as those for, peace; if / in case, with, the wind made, speed of the wind -, and, kite surfer, is producing energy, ending up with, LH2; in order to bring it home from the remote places. Mass in motion and then elecrtrifying the whole santamacram. Energy is mass in motion. Storm and swell are mass in motionis is all. As said, just look at the pictures. Open up. Let the energy in.
Het doel is om de mens te vervangen als drager / behandelaar van de vleugels, net zoals in oorlog de mens werd vervangen door kanonnen en luchtafweergeschut et cetera. want, hoe groot kan een loop van een geweer nu eenmaal zijn, indien rechtstreeks in de handen van een soldaat? Hoe groot zijn die windsurf-zeilen en de kites; rechtstreeks in de handen van de mens? …….. ik bedoel: toen het geweer in de handen kwam van de techniek, veranderde / vergrootte, het geweer in / tot een kanon, en dus, voor vrede is het nodig dat de wind-, en kitesurf-zeilen, in de handen van de techniek komen. Dan vergroten zich de zeilen precies zo als de grootte van de geweren groter werd. En, zo, is er meer massa dat kan windsurfen. Juist nodig voor energie: Om energie te halen uit wind is het dus zaak dat de techniek de zaak, de zeilen, onder handen neemt. de situatie in de wereld is zo dat, er weer oorlog dreigt en dat, het weer gaat om energie, getuige de schermutselingen in het, Midden-Oosten. in plaats dat er slaven worden gedreven, hetgeen verbranding van fossiele brandstoffen en gebruik van kernenergie zijn, kunnen de mensen hun techniek gebruiken om energie op te wekken. Er is namelijk ´´´´iets´´´´ te doen (net zoals oorlog maken iets is in feite voor energie, olie) tussen de soorten van energie. aan de ene kant stormt het en aan de kant is er energie nodig. >> Nu is die storm mede een gevolg van juist ons energie verbruik. global warming maakte de lucht dikker, warmde zo de aarde op, en de warmere wateren en dikkere lucht zorgden voor meer wind. Meer wind leidt tot hogere golven. wind en golven. pak dat nu eens letterlijk op, en dan volgt: wind surf! so not war, spail.
wind-surfen gebeurt met plastic, olie dus, en zet de wind om in snel windsurfende massa. Massa maal snelheid is, energie. met energie hoeven we niet naar de oorlog te gaan. het ging om olie, toch? het ging er toch om dat het volk zijn brood krijgt? LH2, of, stikstof of, elektriciteit zijn energie, het tegenwoordige brood.
Olie is plastic, respectievelijk, super-composieten, en is de mechanische wind- en kitesurfer die energie opwekt.
Oorlog is zodoende niet slim, en vrede wel. oorlog en vrede. beide impliceren namelijk de kunst van de drie dimensionale behandeling, van ofwel een geweer ofwel een vleugel. ofwel leren vliegen als vogels is wat de mensheid moet doen, voor vrede, omdat vrede hangt om energie. via energie kan namelijk zeewater worden gezuiverd. met water kan er worden geïrrigeerd, voor voedsel voor bossen en zo meer.
The energy of moving air, wind, counting for windturbines
( 2 ) C ( wind-e ) in, Watt / m^2 =
0,5 * air ( = 1,24 K g/m^3 ) * ( wind speed, in m/s )^3
The kinetic energy of moving mass ( 1 ) :
( 1 ) E_kin = ( 1 / 2 ) M v^2, in J. M, is, mass in, Kg, v, is, speed, in m/s.
Claiming the 5 m/s – 20 m/s, wind-regime, as usual, by conventional modern wind turbines. Claiming the 20 m/s – 55 m/s, wind-regime can from now be done by the New products. Future wind farms use storm too.
The worlds' energy demand, world wide: 0,5 Z J/yr, source Wikipedia. Het totale energieverbruik door mensen op aarde is ongeveer 0,5 Z J/jaar, volgens Wikipedia.
Big wheels under boats make harbors unnecessary. The new fuel, LH2, leads to oil as left over, for building materials.
Efficiency is no longer an issue. Food, water, fish, wild life, preservation of the planet is the gain. Life itself, is crucial.
The philosophy is with nature. Storm using for making hydrogen out of marine water is, with nature.
The earliest fore-and-aft rig was the spritsail, appearing in the 2nd century BC in the Aegean Sea on small Greek craft. The lateen sail originated during the early Roman empire in the Mediterranean Sea. It gradually evolved out of the dominant square rig by setting the sails more along the line of the keel rather than athwartship, while tailoring the luff and leech. The windjammers were the last breed of a large commercial sailing vessel, and they were designed well after the Industrial Revolution, using modern materials, such as iron and steel, on their construction and scientific methods on their design.
The quest I took on was, to position the wing as kite, with still the massive control over the wing, like, the wind-surfer has over wind-surfer-sails. Spailboat is a stable sailing craft, with monolithic control over the remote-, as kite standing, wing; without the driving mechanisms, for controlling the wings, far from deck. Sailing, without capsizing, implies an upwards working lift-component, making the stable sailing craft to climb, a bit, out of the water. Sailing without capsizing reaches the cavitation speed-barrier. Cavitation is related to the speed of the, through water, dragged items, like swords, ruthers and under-water-ship. Image is dating from *ca. 1650 - ca. 1707
This loose sail on the horizontal beam which, crosses the mast, looks like -, and certainly works as, a kite. This boat does not flip over, no, it tends to fly. This is the situation in a gale, where the sail works as kite. The, Flying Dutchman, wondered around and went nowhere. This is, half wind. Forewards and backwards along the same line is, ending up, over and over again, at the same spot on the Sea; problably the South Pacific. And, one simple calculation, Lift = 1 / 2 times density air, times square value of the speed, in N / m^2 shows, that the Flying Dutchman was able to get airborn, in, 10 Bft, under the condition that the boat was sailing half wind; going with enormous speed in between the waves along the gangways. Of Course.
Stabiel zeilen kan half wind. Half winds zeilen kan alleen als de zeilboten gaan vliegen omdat, de vleugel dan als een kite staat opgesteld. Spailing geeft mogelijk meer dan genoeg energie. Er werken dan veel mensen voor energie.
Verder, energie opwekken met kites, respectievelijk zeilen of vleugels, spelen, staat los van transport, respectievelijk een bestemming. hiermee is gezegd dat transportboten nog immer op motorkracht varen. geen kites aan boten, want dat is, onzin. Kites zijn alleen geschikt in voor de windse koersen en halve windse koersen. Spelen doet men voor energie, werken gebeurt met motoren, draaiend op waterstof, gemaakt met spelen. Spailen. de motoren draaien op waterstof, gemaakt met de in deze show getoonde apparaten. waterstof. of ammoniak, NH3.
Van-de-weg- / koers-afs: Vikingschepen voeren in twee weken met, 70 Km / hr, naar, Groenland. Half wind. Rond, 700AD bestond er nog niet zoiets als ergens heen moeten, van de baas / systeem / top van de Piramide. De Vikingen waren de Baas en voeren uit, als de wind gunstig was. Lekker tussen de golven in. In de gangpaden. Maar natuurlijk! Of Course! Ze gingen als het gunstig weer was. Vikingschepen zijn ook van de koers-afs. een koers, half wind. Geen geprik en geen geval. Zeilboten met, de zeilen aan horizontale ra's, zie afbeelding, kunnen echter wel opereren in storm! Natuurlijk, er wordt dan wel successievelijk gereefd. De, maanrakers(moonraker) -dit zijn de bovenste zeilen, aan de bovenste ra's- worden als eerste gereefd. Successievelijk worden zeilen onder de maanrakers gereefd. Totdat alleen het voorste zeil aan de onderste ra zeil draagt. Ingewikkelde zeilschepen zijn te moeilijk gebleken voor NL. De zeilen, aan de ra's, werken de lift, in een lage koers, dit zijn koersen lager dan halve-wind, deels omhoog. De zeilboot, met zeilen aan de ra's, wordt in storm, ook deels opgelifd. De koers ligt, tussen, halve-wind en voor-de-wind, in. De boot gaat schever als er wordt opgestuurd. De scheefstand van een mast, met eraan, ra's, zorgt voor het ontwikkelen van ook trekkracht in de mast. De zeilen werken de boot steeds minder omver, en steeds meer wordt er door de zeilen aan de ra's, bij aanzienlijke scheefstand, aan de mast getrokken, zodat de boot gaat vliegen!? Een scheefgaand vikingschip -, en een scheefstaande zeilboot met ra's, in de half-windse koers, hebben precies dezelfde configuratie als de moderne kites. Ook een kite trekt de kite-surfer omhoog, naast dat natuurlijk de kite-surfer dwars wordt getrokken, iets dat wordt verhinderd door het board en de skeggen onder het board. Met harde wind zeilen, heeft als consequentie dat er geen bestemming ( meer ) is. Het achterste zeiltje, een plaatje, lijkt dan op een windsurf-zeil.
Deze boten vielen niet ""om"", ( jargon, voor omslaan ) maar gingen, werkelijk, bijna, vliegen. de koers van deze boten was, echter, niet arbitrair, zoals de latere zeilboten met de zeilen direct aan de masten, wel de hogere koersen konden aanvaarden. net als vikingschepen, mijn icoontje, voeren zeilboten met de zeilen aan ra's eigenlijk alleen maar half wind, en voor de wind. ja, ja, ze liepen wel ietsje hoger dan halve wind, goed dan. toch kan gesteld worden dat ze aan de wind niet liepen. daarom kwamen er andere zeilboten die wel aan de wind konden lopen. echter, dan slaan ze wel om in halve wind. halve wind, is, haaks op de wind. een wiek gaat half wind. vroeger zeilden de boten met zeilen aan de ra's pas uit als de wind gunstig was. toen werd tijd geld, en toen was het afgelopen met wachten op goede wind. waar het al die tijd over gaat is het motief. toen geld nog tijd was, windsurfde men. in vrijheid ontdekte men dit weer, alleen, nu heette het windsurfen en kitesurfen. wind surfen en kite surfen, net als deze getoonde boten, gaan half wind. Pythagoras komt dan kijken, a^2 + b^2 = c^2. de rechte hoek ligt in de definitie van half wind. met zeilen in de halve winds koers geldt : Snelheid schijnbare wind is wortel uit w^2 + v^2. Net als de wiek die hanteert.
als U in het slootje / meertje achter kijkt dan zal U zien dat de wind de golven stuwt. en dat halve wind precies langs de golven loopt, plat op de wind, natuurlijk, zodat er een gootje ontstaat, zodat, er, geen, bobbels zijn, ook niet als het stormt. de bobbels, de golven, zijn er wel degelijk in storm, maar, de koersen, respectievelijk half wind en voor de wind, impliceren koersen met de golven mee, in geval van voor de wind, en in een golfdal, in geval van half wind. Land
ORBITes strai / Windriaan turbines
Spailcrafts
Water
Spailboat
leading to
a hydrogen society, with plastic, respectively glued carbon fibers with for instance epoxy and hemp fibered polypropylene structures and transportation means.
Water will be purified, as we have enough energy, once the hydrogen, nitrogen and, even, pressed ordinary air! are made with wind and solar power.
The input is making all of these components.
To start with
Hydrogen based society study
Hydrogen motors
Hydrogen containers
Hydrogen carriers,
Working out the windsurf formula, by making 18 prototypes, which are on paper and worked out.
E_rounds / ORBITes strai / Windriaan come from wind - and kite surfing. The course wind surfers sail is, half wind; this course is, by the way, former useless; wind surfing is useless. but, it goes fast. and, mass in motion is energy. modern sailing boats are in fact the killing of the half wind courses. and, because of that, the steam machines on ships had a free way. older sailing boats, see image, with sails on horizontal beams at the masts sailed best, half wind.
when time became money, all changed. the half wind course disappeared. this part of history goes again over half wind gsailing courses. goinh
g nowhere, but fast. just play. which means speel in Dutch. Just make alle move.
because, half wind means maximum speed. and, energy is mass in motion.
E_kinetic, is, 1 / 2 M v^2, in words, a half times the MASS times SQUARED VALUE SPEED.
Mass in KG and v, velocity, speed, in m /s. Energy is in Watts. NICE HEY, PRODUCING ( enough, sufficient ) WATTS, WITH WIND?
wind increased because of Watt. James Watt's steam machine led to combustion engines, power plants driven by coals and gas. global warming is because of Watt.
Spailcrafts, Spailboats, and, E-rings, are for ( using ) high winds, storms, cyclones. Spailcrafts, and, E-rings, are for, respectively, over / on, land, and, Spailboats, for, over water; at the windiest places on earth. Of course, windy places are there where the sea is relatively warm, with respect to the air temperature. We all know that water can not be colder than zero, degrees, Celsius, because, then water freezes into ice. Only a few know that water can stay liquid at minus, two, degrees, Celsius.
All the same, in this context, because, cyclones and, very heavy storms, are caused by the difference between the sea -, and, the air temperature. Near the arctic poles is always a very big temperature difference between air and water, feeding storms.
High winds, and, low temperatures, make these places remote and do, explicitly, not invite us. Conventional wind mills are shut down, when the wind speed over tops, 25 m/s. These wind speeds rule, for at least three months a year, over the windiest places on earth.
This means that we can go where the wind is; which implies that the energy-crisis is to an end. We make hydrogen and burn it. Water (marine-) goes in, and (fresh-) water comes out. It was not normal to use oil, gas and coals, because there are leaks in the equations. Oil goes in, we burn it, and smoke and filthy shit comes out. Using fossil fuels is a kind of slavery. The slave is, mother earth, and, when mamma gets angry, she rages. The thickening of the atmosphere gave us even more wind. The house hold of the planet can be a normal equation. We can calm the planet, by tempering the rage of her. The intermediate and, also fuel on itself, is, hydrogen. With hydrogen in the running, also solar power can be used in remote deserts, because the hydrogen propels the carriers. When hydrogen is in, oil is out, and that is nice, because oil is good construction. Steel stops. Carbon-fibers come and so will cars form, “plastic”, with, retractable, and out spreading, spoilers. Plastic means, in this context, super composites. And, the market learned us that huge amounts, say, all the cars, all the planes and, all the rest, drive the costs down. Using wind is the input for the house hold of the planet. It is no longer so, that we need slaves, like gas, oil, coals. We have wind. However, we did not have stable machines, strong enough, to withstand the high winds. It says all that we call heavy winds: '''' destructive.'''' In fact, high winds are, ''''constructive''''. When cyclones hit our living grounds, Spailboats, go out on sea, to tame them and, E-rings, on land, suck the rest out. Wind is here and we made some more because we warmed up the planet. This equation was never balanced, because, we never used storms. Using storms is simple. However, we need all the technology we have, because operating in storms is full of action. We can use the earth, that is what I say, but we need technology. Above hydrogen stands an input energy. Exactly this, the input energy, is, what is accomplished. Stable converters for wind are here. It is a fact that we have an input for enough hydrogen. Enough hydrogen is possible because we live on earth, with a lot of water. Result: Cars from plastic. Plastic is, carbon fibers, glued together with for instance epoxy. Plastic Fantastic. Super-composites. Wood comes back because of irrigation in former deserts. Via wind comes hydrogen.
Via hydrogen comes the sun. Sun is, H. What was the problem? The problem was the energy to make hydrogen. I sometimes wonder why I try to write this down. So obvious all together >> marine water, we do not have get to another solar system, it here here.. They, the life from there, come here, off course.., Big compositions, like big insects, mostly monocoque, are possible, and, of course, the future. Big Spailboats are the forerunners on Space Crafts. Big transportation wagons, may have wheels of over ten meters in diameter. Big wheels under boats make harbors unnecessary. Amphibious with, LH2, and, plastic. Size and fuel. The bigger the size the more water comes out from the exaust. The new fuel, LH2, leads to oil as left over, for building materials.
Storms are, via stable wind users, energy for, for instance, the making of ( electrolyses process ) LH2, from ( marine - ) water. energy. water. food.
Remote controlled wing which is, as a kite, in the air. Kite means / stands for more than the kite alone. In fact. the wing is in the air, pulling and, this pulling happens in a normal way. A kite on only wires / steering lines / bridles, directs its e lift to the point of origin from where the wires are coming from. With a mast for main bridles, the lift can be directed right through the dagger boards / swords. Until now, with a kite, any kite, in fact, is held up with wires. And wires automatically hold the kite in just this way, as is pointed out earlier, so that the force / lift from the wing / kite is pulling at the mass, which mass / the kite surfer!, is holding these wires. The mass for holding the wing in the air is a kite-surfer. What is just said is, that, stable sailing is, nothing more than, holding a wing in the air, in such a way that the arm is taken out. The lift from a kite on only wires, shoots almost through the dagger boards. A kite on a mast, for main bridles, can / might / has the possibility to shoot right through the cumulated blocking force in the water created by the dagger boards / swords. dagger boards : " as if the wires to the kite are now coming from out the water around the swords, dagger boards."" The cumulated lift shooits through the cumulated water blockage force, brought up by the dagger boards / swords / wheels. Lining up the action -, with the reaction force, is ike builidng. So, kite surfing and windsurfing fall under, art of construction, like the Pyramids / churches / dams / buildings. One of the first big compositions, was, of course, the tower of Babel. and some what later the insanly Pyramids.
But, still, a Pyramide is a stable construction. A Pyramide also shoots its own weight, the force, right through the core of the foundation; blocking so this force in reaction. Within kite-surfing, the foundation of the compostion is, the blocking force on the lift in the water; created by the dagger boards / swords, where the action force comes from the kite / wing. The rig, on SB, controls kites / wings, and since we have this, we can direct / force the lift, in order to pull at the blocking force ( in the water brought up by the swords / dagger boards ). :: Then, professor M. Donze came in, so to speak, and put me on track over land : Spailtrain : The rig is on special train. Looping it makes Orbites strai. Windriaan is stable and strong.
Hoover Dam is a concrete arch-gravity dam in the Black Canyon of the Colorado River, on the border between the U.S. states of Nevada and Arizona. It was constructed between 1931 and 1936 during the Great Depression and was dedicated on September 30, 1935, by President Franklin D. Roosevelt. Its construction was the result of a massive effort involving thousands of workers, and cost over one hundred lives. It was referred to as Hoover Dam after President Herbert Hoover in bills passed by Congress during its construction, but was named Boulder Dam by the Roosevelt administration. The Hoover Dam name was restored by Congress in 1947.
Since about 1900, the Black Canyon and nearby Boulder Canyon had been investigated for their potential to support a dam that would control floods, provide irrigation water and produce hydroelectric power. In 1928, Congress authorized the project. The winning bid to build the dam was submitted by a consortium named Six Companies, Inc., which began construction of the dam in early 1931. Such a large concrete structure had never been built before, and some of the techniques were unproven. The torrid summer weather and lack of facilities near the site also presented difficulties. Nevertheless, Six Companies turned the dam over to the federal government on March 1, 1936, more than two years ahead of schedule.
Hoover Dam impounds Lake Mead, the largest reservoir in the United States by volume when full. The dam is located near Boulder City, Nevada, a municipality originally constructed for workers on the construction project, about 30 mi (48 km) southeast of Las Vegas, Nevada. The dam's generators provide power for public and private utilities in Nevada, Arizona, and California. Hoover Dam is a major tourist attraction; nearly a million people tour the dam each year. The heavily traveled U.S. Route 93 (US 93) ran along the dam's crest until October 2010, when the Hoover Dam Bypass opened.
As the United States developed the Southwest, the Colorado River was seen as a potential source of irrigation water. An initial attempt at diverting the river for irrigation purposes occurred in the late 1890s, when land speculator William Beatty built the Alamo Canal just north of the Mexican border; the canal dipped into Mexico before running to a desolate area Beatty named the Imperial Valley. Though water from the Imperial Canal allowed for the widespread settlement of the valley, the canal proved expensive to operate. After a catastrophic breach that caused the Colorado River to fill the Salton Sea, the Southern Pacific Railroad spent $3 million in 1906–07 to stabilize the waterway, an amount it hoped in vain would be reimbursed by the federal government. Even after the waterway was stabilized, it proved unsatisfactory because of constant disputes with landowners on the Mexican side of the border.
As the technology of electric power transmission improved, the Lower Colorado was considered for its hydroelectric-power potential. In 1902, the Edison Electric Company of Los Angeles surveyed the river in the hope of building a 40-foot (12 m) rock dam which could generate 10,000 horsepower (7,500 kW). However, at the time, the limit of transmission of electric power was 80 miles (130 km), and there were few customers (mostly mines) within that limit. Edison allowed land options it held on the river to lapse—including an option for what became the site of Hoover Dam.
In the following years, the Bureau of Reclamation (BOR), known as the Reclamation Service at the time, also considered the Lower Colorado as the site for a dam. Service chief Arthur Powell Davis proposed using dynamite to collapse the walls of Boulder Canyon, 20 miles (32 km) north of the eventual dam site, into the river. The river would carry off the smaller pieces of debris, and a dam would be built incorporating the remaining rubble. In 1922, after considering it for several years, the Reclamation Service finally rejected the proposal, citing doubts about the unproven technique and questions as to whether it would, in fact, save money.
Soon after the dam was authorized, increasing numbers of unemployed people converged on southern Nevada. Las Vegas, then a small city of some 5,000, saw between 10,000 and 20,000 unemployed descend on it. A government camp was established for surveyors and other personnel near the dam site; this soon became surrounded by a squatters' camp. Known as McKeeversville, the camp was home to men hoping for work on the project, together with their families. Another camp, on the flats along the Colorado River, was officially called Williamsville, but was known to its inhabitants as "Ragtown". When construction began, Six Companies hired large numbers of workers, with more than 3,000 on the payroll by 1932 and with employment peaking at 5,251 in July 1934. "Mongolian" (Chinese) labor was prevented by the construction contract, while the number of black people employed by Six Companies never exceeded thirty, mostly lowest-pay-scale laborers in a segregated crew, who were issued separate water buckets.
As part of the contract, Six Companies, Inc. was to build Boulder City to house the workers. The original timetable called for Boulder City to be built before the dam project began, but President Hoover ordered work on the dam to begin in March 1931 rather than in October. The company built bunkhouses, attached to the canyon wall, to house 480 single men at what became known as River Camp. Workers with families were left to provide their own accommodations until Boulder City could be completed, and many lived in Ragtown. The site of Hoover Dam endures extremely hot weather, and the summer of 1931 was especially torrid, with the daytime high averaging 119.9 °F (48.8 °C). Sixteen workers and other riverbank residents died of heat prostration between June 25 and July 26, 1931.
The Industrial Workers of the World (IWW or "Wobblies"), though much-reduced from their heyday as militant labor organizers in the early years of the century, hoped to unionize the Six Companies workers by capitalizing on their discontent. They sent eleven organizers, several of whom were arrested by Las Vegas police. On August 7, 1931, the company cut wages for all tunnel workers. Although the workers sent the organizers away, not wanting to be associated with the "Wobblies", they formed a committee to represent them with the company. The committee drew up a list of demands that evening and presented them to Crowe the following morning. He was noncommittal. The workers hoped that Crowe, the general superintendent of the job, would be sympathetic; instead, he gave a scathing interview to a newspaper, describing the workers as "malcontents".
On the morning of the 9th, Crowe met with the committee and told them that management refused their demands, was stopping all work, and was laying off the entire work force, except for a few office workers and carpenters. The workers were given until 5 p.m. to vacate the premises. Concerned that a violent confrontation was imminent, most workers took their paychecks and left for Las Vegas to await developments. Two days later, the remainder were talked into leaving by law enforcement. On August 13, the company began hiring workers again, and two days later, the strike was called off. While the workers received none of their demands, the company guaranteed there would be no further reductions in wages. Living conditions began to improve as the first residents moved into Boulder City in late 1931.
A second labor action took place in July 1935, as construction on the dam wound down. When a Six Companies manager altered working times to force workers to take lunch on their own time, workers responded with a strike. Emboldened by Crowe's reversal of the lunch decree, workers raised their demands to include a $1-per-day raise. The company agreed to ask the Federal government to supplement the pay, but no money was forthcoming from Washington. The strike ended.
Before the dam could be built, the Colorado River needed to be diverted away from the construction site. To accomplish this, four diversion tunnels were driven through the canyon walls, two on the Nevada side and two on the Arizona side. These tunnels were 56 ft (17 m) in diameter. Their combined length was nearly 16,000 ft, or more than 3 miles (5 km). The contract required these tunnels to be completed by October 1, 1933, with a $3,000-per-day fine to be assessed for any delay. To meet the deadline, Six Companies had to complete work by early 1933, since only in late fall and winter was the water level in the river low enough to safely divert.
Tunneling began at the lower portals of the Nevada tunnels in May 1931. Shortly afterward, work began on two similar tunnels in the Arizona canyon wall. In March 1932, work began on lining the tunnels with concrete. First the base, or invert, was poured. Gantry cranes, running on rails through the entire length of each tunnel were used to place the concrete. The sidewalls were poured next. Movable sections of steel forms were used for the sidewalls. Finally, using pneumatic guns, the overheads were filled in. The concrete lining is 3 feet (1 m) thick, reducing the finished tunnel diameter to 50 ft (15 m). The river was diverted into the two Arizona tunnels on November 13, 1932; the Nevada tunnels were kept in reserve for high water. This was done by exploding a temporary cofferdam protecting the Arizona tunnels while at the same time dumping rubble into the river until its natural course was blocked.
Following the completion of the dam, the entrances to the two outer diversion tunnels were sealed at the opening and halfway through the tunnels with large concrete plugs. The downstream halves of the tunnels following the inner plugs are now the main bodies of the spillway tunnels. The inner diversion tunnels were plugged at approximately one-third of their length, beyond which they now carry steel pipes connecting the intake towers to the power plant and outlet works. The inner tunnels' outlets are equipped with gates that can be closed to drain the tunnels for maintenance.
To protect the construction site from the Colorado River and to facilitate the river's diversion, two cofferdams were constructed. Work on the upper cofferdam began in September 1932, even though the river had not yet been diverted. The cofferdams were designed to protect against the possibility of the river's flooding a site at which two thousand men might be at work, and their specifications were covered in the bid documents in nearly as much detail as the dam itself. The upper cofferdam was 96 ft (29 m) high, and 750 feet (230 m) thick at its base, thicker than the dam itself. It contained 650,000 cubic yards (500,000 m3) of material.
When the cofferdams were in place and the construction site was drained of water, excavation for the dam foundation began. For the dam to rest on solid rock, it was necessary to remove accumulated erosion soils and other loose materials in the riverbed until sound bedrock was reached. Work on the foundation excavations was completed in June 1933. During this excavation, approximately 1,500,000 cu yd (1,100,000 m3) of material was removed. Since the dam was an arch-gravity type, the side-walls of the canyon would bear the force of the impounded lake. Therefore, the side-walls were also excavated to reach virgin rock, as weathered rock might provide pathways for water seepage. Shovels for the excavation came from the Marion Power Shovel Company.
The men who removed this rock were called "high scalers". While suspended from the top of the canyon with ropes, the high-scalers climbed down the canyon walls and removed the loose rock with jackhammers and dynamite. Falling objects were the most common cause of death on the dam site; the high scalers' work thus helped ensure worker safety. One high scaler was able to save a life in a more direct manner: when a government inspector lost his grip on a safety line and began tumbling down a slope towards almost certain death, a high scaler was able to intercept him and pull him into the air. The construction site had become a magnet for tourists. The high scalers were prime attractions and showed off for the watchers. The high scalers received considerable media attention, with one worker dubbed the "Human Pendulum" for swinging co-workers (and, at other times, cases of dynamite) across the canyon. To protect themselves against falling objects, some high scalers dipped cloth hats in tar and allowed them to harden. When workers wearing such headgear were struck hard enough to inflict broken jaws, they sustained no skull damage. Six Companies ordered thousands of what initially were called "hard boiled hats" (later "hard hats") and strongly encouraged their use.
The cleared, underlying rock foundation of the dam site was reinforced with grout, forming a grout curtain. Holes were driven into the walls and base of the canyon, as deep as 150 feet (46 m) into the rock, and any cavities encountered were to be filled with grout. This was done to stabilize the rock, to prevent water from seeping past the dam through the canyon rock, and to limit "uplift"—upward pressure from water seeping under the dam. The workers were under severe time constraints due to the beginning of the concrete pour. When they encountered hot springs or cavities too large to readily fill, they moved on without resolving the problem. A total of 58 of the 393 holes were incompletely filled. After the dam was completed and the lake began to fill, large numbers of significant leaks caused the Bureau of Reclamation to examine the situation. It found that the work had been incompletely done, and was based on less than a full understanding of the canyon's geology. New holes were drilled from inspection galleries inside the dam into the surrounding bedrock. It took nine years (1938–47) under relative secrecy to complete the supplemental grout curtain.
The first concrete was poured into the dam on June 6, 1933, 18 months ahead of schedule. Since concrete heats and contracts as it cures, the potential for uneven cooling and contraction of the concrete posed a serious problem. Bureau of Reclamation engineers calculated that if the dam were to be built in a single continuous pour, the concrete would take 125 years to cool, and the resulting stresses would cause the dam to crack and crumble. Instead, the ground where the dam would rise was marked with rectangles, and concrete blocks in columns were poured, some as large as 50 ft square (15 m) and 5 feet (1.5 m) high. Each five-foot form contained a set of 1-inch (25 mm) steel pipes; cool river water would be poured through the pipes, followed by ice-cold water from a refrigeration plant. When an individual block had cured and had stopped contracting, the pipes were filled with grout. Grout was also used to fill the hairline spaces between columns, which were grooved to increase the strength of the joints.
The concrete was delivered in huge steel buckets 7 feet high (2.1 m) and almost 7 feet in diameter; Crowe was awarded two patents for their design. These buckets, which weighed 20 short tons (18.1 t; 17.9 long tons) when full, were filled at two massive concrete plants on the Nevada side, and were delivered to the site in special railcars. The buckets were then suspended from aerial cableways which were used to deliver the bucket to a specific column. As the required grade of aggregate in the concrete differed depending on placement in the dam (from pea-sized gravel to 9 inches [230 mm] stones), it was vital that the bucket be maneuvered to the proper column. When the bottom of the bucket opened up, disgorging 8 cu yd (6.1 m3) of concrete, a team of men worked it throughout the form. Although there are myths that men were caught in the pour and are entombed in the dam to this day, each bucket deepened the concrete in a form by only 1 inch (25 mm), and Six Companies engineers would not have permitted a flaw caused by the presence of a human body.
A total of 3,250,000 cubic yards (2,480,000 cubic meters) of concrete was used in the dam before concrete pouring ceased on May 29, 1935. In addition, 1,110,000 cu yd (850,000 m3) were used in the power plant and other works. More than 582 miles (937 km) of cooling pipes were placed within the concrete. Overall, there is enough concrete in the dam to pave a two-lane highway from San Francisco to New York. Concrete cores were removed from the dam for testing in 1995; they showed that "Hoover Dam's concrete has continued to slowly gain strength" and the dam is composed of a "durable concrete having a compressive strength exceeding the range typically found in normal mass concrete". Hoover Dam concrete is not subject to alkali–silica reaction (ASR), as the Hoover Dam builders happened to use nonreactive aggregate, unlike that at downstream Parker Dam, where ASR has caused measurable deterioration.
With most work finished on the dam itself (the powerhouse remained uncompleted), a formal dedication ceremony was arranged for September 30, 1935, to coincide with a western tour being made by President Franklin D. Roosevelt. The morning of the dedication, it was moved forward three hours from 2 p.m. Pacific time to 11 a.m.; this was done because Secretary of the Interior Harold L. Ickes had reserved a radio slot for the President for 2 p.m. but officials did not realize until the day of the ceremony that the slot was for 2 p.m. Eastern Time. Despite the change in the ceremony time, and temperatures of 102 °F (39 °C), 10,000 people were present for the President's speech, in which he avoided mentioning the name of former President Hoover, who was not invited to the ceremony. To mark the occasion, a three-cent stamp was issued by the United States Post Office Department—bearing the name "Boulder Dam", the official name of the dam between 1933 and 1947. After the ceremony, Roosevelt made the first visit by any American president to Las Vegas.
Most work had been completed by the dedication, and Six Companies negotiated with the government through late 1935 and early 1936 to settle all claims and arrange for the formal transfer of the dam to the Federal Government. The parties came to an agreement and on March 1, 1936, Secretary Ickes formally accepted the dam on behalf of the government. Six Companies was not required to complete work on one item, a concrete plug for one of the bypass tunnels, as the tunnel had to be used to take in irrigation water until the powerhouse went into operation.
There were 112 deaths reported as associated with the construction of the dam. The first was Bureau of Reclamation employee Harold Connelly who died on May 15, 1921, after falling from a barge while surveying the Colorado River for an ideal spot for the dam. Surveyor John Gregory ("J.G.") Tierney, who drowned on December 20, 1922, in a flash flood while looking for an ideal spot for the dam was the second person. The official list's final death occurred on December 20, 1935, when Patrick Tierney, electrician's helper and the son of J.G. Tierney, fell from one of the two Arizona-side intake towers. Included in the fatality list are three workers who took their own lives on site, one in 1932 and two in 1933. Of the 112 fatalities, 91 were Six Companies employees, three were Bureau of Reclamation employees, and one was a visitor to the site; the remainder were employees of various contractors not part of Six Companies.
Ninety-six of the deaths occurred during construction at the site. Not included in the official number of fatalities were deaths that were recorded as pneumonia. Workers alleged that this diagnosis was a cover for death from carbon monoxide poisoning (brought on by the use of gasoline-fueled vehicles in the diversion tunnels), and a classification used by Six Companies to avoid paying compensation claims. The site's diversion tunnels frequently reached 140 °F (60 °C), enveloped in thick plumes of vehicle exhaust gases. A total of 42 workers were recorded as having died from pneumonia and were not included in the above total; none were listed as having died from carbon monoxide poisoning. No deaths of non-workers from pneumonia were recorded in Boulder City during the construction period.
The initial plans for the facade of the dam, the power plant, the outlet tunnels and ornaments clashed with the modern look of an arch dam. The Bureau of Reclamation, more concerned with the dam's functionality, adorned it with a Gothic-inspired balustrade and eagle statues. This initial design was criticized by many as being too plain and unremarkable for a project of such immense scale, so Los Angeles-based architect Gordon B. Kaufmann, then the supervising architect to the Bureau of Reclamation, was brought in to redesign the exteriors. Kaufmann greatly streamlined the design and applied an elegant Art Deco style to the entire project. He designed sculpted turrets rising seamlessly from the dam face and clock faces on the intake towers set for the time in Nevada and Arizona—both states are in different time zones, but since Arizona does not observe daylight saving time, the clocks display the same time for more than half the year.
At Kaufmann's request, Denver artist Allen Tupper True was hired to handle the design and decoration of the walls and floors of the new dam. True's design scheme incorporated motifs of the Navajo and Pueblo tribes of the region. Although some were initially opposed to these designs, True was given the go-ahead and was officially appointed consulting artist. With the assistance of the National Laboratory of Anthropology, True researched authentic decorative motifs from Indian sand paintings, textiles, baskets and ceramics. The images and colors are based on Native American visions of rain, lightning, water, clouds, and local animals—lizards, serpents, birds—and on the Southwestern landscape of stepped mesas. In these works, which are integrated into the walkways and interior halls of the dam, True also reflected on the machinery of the operation, making the symbolic patterns appear both ancient and modern.
With the agreement of Kaufmann and the engineers, True also devised for the pipes and machinery an innovative color-coding which was implemented throughout all BOR projects. True's consulting artist job lasted through 1942; it was extended so he could complete design work for the Parker, Shasta and Grand Coulee dams and power plants. True's work on the Hoover Dam was humorously referred to in a poem published in The New Yorker, part of which read, "lose the spark, and justify the dream; but also worthy of remark will be the color scheme".
Complementing Kaufmann and True's work, sculptor Oskar J. W. Hansen designed many of the sculptures on and around the dam. His works include the monument of dedication plaza, a plaque to memorialize the workers killed and the bas-reliefs on the elevator towers. In his words, Hansen wanted his work to express "the immutable calm of intellectual resolution, and the enormous power of trained physical strength, equally enthroned in placid triumph of scientific accomplishment", because "the building of Hoover Dam belongs to the sagas of the daring." Hansen's dedication plaza, on the Nevada abutment, contains a sculpture of two winged figures flanking a flagpole.
Surrounding the base of the monument is a terrazzo floor embedded with a "star map". The map depicts the Northern Hemisphere sky at the moment of President Roosevelt's dedication of the dam. This is intended to help future astronomers, if necessary, calculate the exact date of dedication. The 30-foot-high (9.1 m) bronze figures, dubbed "Winged Figures of the Republic", were both formed in a continuous pour. To put such large bronzes into place without marring the highly polished bronze surface, they were placed on ice and guided into position as the ice melted. Hansen's bas-relief on the Nevada elevator tower depicts the benefits of the dam: flood control, navigation, irrigation, water storage, and power. The bas-relief on the Arizona elevator depicts, in his words, "the visages of those Indian tribes who have inhabited mountains and plains from ages distant."
Excavation for the powerhouse was carried out simultaneously with the excavation for the dam foundation and abutments. The excavation of this U-shaped structure located at the downstream toe of the dam was completed in late 1933 with the first concrete placed in November 1933. Filling of Lake Mead began February 1, 1935, even before the last of the concrete was poured that May. The powerhouse was one of the projects uncompleted at the time of the formal dedication on September 30, 1935; a crew of 500 men remained to finish it and other structures. To make the powerhouse roof bombproof, it was constructed of layers of concrete, rock, and steel with a total thickness of about 3.5 feet (1.1 m), topped with layers of sand and tar.
In the latter half of 1936, water levels in Lake Mead were high enough to permit power generation, and the first three Allis Chalmers built Francis turbine-generators, all on the Nevada side, began operating. In March 1937, one more Nevada generator went online and the first Arizona generator by August. By September 1939, four more generators were operating, and the dam's power plant became the largest hydroelectricity facility in the world. The final generator was not placed in service until 1961, bringing the maximum generating capacity to 1,345 megawatts at the time. Original plans called for 16 large generators, eight on each side of the river, but two smaller generators were installed instead of one large one on the Arizona side for a total of 17. The smaller generators were used to serve smaller communities at a time when the output of each generator was dedicated to a single municipality, before the dam's total power output was placed on the grid and made arbitrarily distributable.
Before water from Lake Mead reaches the turbines, it enters the intake towers and then four gradually narrowing penstocks which funnel the water down towards the powerhouse. The intakes provide a maximum hydraulic head (water pressure) of 590 ft (180 m) as the water reaches a speed of about 85 mph (140 km/h). The entire flow of the Colorado River usually passes through the turbines. The spillways and outlet works (jet-flow gates) are rarely used. The jet-flow gates, located in concrete structures 180 feet (55 m) above the river and also at the outlets of the inner diversion tunnels at river level, may be used to divert water around the dam in emergency or flood conditions, but have never done so, and in practice are used only to drain water from the penstocks for maintenance. Following an uprating project from 1986 to 1993, the total gross power rating for the plant, including two 2.4 megawatt Pelton turbine-generators that power Hoover Dam's own operations is a maximum capacity of 2080 megawatts. The annual generation of Hoover Dam varies. The maximum net generation was 10.348 TWh in 1984, and the minimum since 1940 was 2.648 TWh in 1956. The average power generated was 4.2 TWh/year for 1947–2008. In 2015, the dam generated 3.6 TWh.
The amount of electricity generated by Hoover Dam has been decreasing along with the falling water level in Lake Mead due to the prolonged drought since year 2000 and high demand for the Colorado River's water. By 2014 its generating capacity was downrated by 23% to 1592 MW and was providing power only during periods of peak demand. Lake Mead fell to a new record low elevation of 1,071.61 feet (326.63 m) on July 1, 2016, before beginning to rebound slowly. Under its original design, the dam would no longer be able to generate power once the water level fell below 1,050 feet (320 m), which might have occurred in 2017 had water restrictions not been enforced. To lower the minimum power pool elevation from 1,050 to 950 feet (320 to 290 m), five wide-head turbines, designed to work efficiently with less flow, were installed.[102] Water levels were maintained at over 1,075 feet (328 m) in 2018 and 2019, but fell to a new record low of 1,071.55 feet (326.61 m) on June 10, 2021[104] and were projected to fall below 1,066 feet (325 m) by the end of 2021.
Control of water was the primary concern in the building of the dam. Power generation has allowed the dam project to be self-sustaining: proceeds from the sale of power repaid the 50-year construction loan, and those revenues also finance the multimillion-dollar yearly maintenance budget. Power is generated in step with and only with the release of water in response to downstream water demands.
Lake Mead and downstream releases from the dam also provide water for both municipal and irrigation uses. Water released from the Hoover Dam eventually reaches several canals. The Colorado River Aqueduct and Central Arizona Project branch off Lake Havasu while the All-American Canal is supplied by the Imperial Dam. In total, water from Lake Mead serves 18 million people in Arizona, Nevada, and California and supplies the irrigation of over 1,000,000 acres (400,000 ha) of land.
In 2018, the Los Angeles Department of Water and Power (LADWP) proposed a $3 billion pumped-storage hydroelectricity project—a "battery" of sorts—that would use wind and solar power to recirculate water back up to Lake Mead from a pumping station 20 miles (32 km) downriver.
Electricity from the dam's powerhouse was originally sold pursuant to a fifty-year contract, authorized by Congress in 1934, which ran from 1937 to 1987. In 1984, Congress passed a new statute which set power allocations to southern California, Arizona, and Nevada from the dam from 1987 to 2017. The powerhouse was run under the original authorization by the Los Angeles Department of Water and Power and Southern California Edison; in 1987, the Bureau of Reclamation assumed control. In 2011, Congress enacted legislation extending the current contracts until 2067, after setting aside 5% of Hoover Dam's power for sale to Native American tribes, electric cooperatives, and other entities. The new arrangement began on October 1, 2017.
The dam is protected against over-topping by two spillways. The spillway entrances are located behind each dam abutment, running roughly parallel to the canyon walls. The spillway entrance arrangement forms a classic side-flow weir with each spillway containing four 100-foot-long (30 m) and 16-foot-wide (4.9 m) steel-drum gates. Each gate weighs 5,000,000 pounds (2,300 metric tons) and can be operated manually or automatically. Gates are raised and lowered depending on water levels in the reservoir and flood conditions. The gates cannot entirely prevent water from entering the spillways but can maintain an extra 16 ft (4.9 m) of lake level.
Water flowing over the spillways falls dramatically into 600-foot-long (180 m), 50-foot-wide (15 m) spillway tunnels before connecting to the outer diversion tunnels and reentering the main river channel below the dam. This complex spillway entrance arrangement combined with the approximate 700-foot (210 m) elevation drop from the top of the reservoir to the river below was a difficult engineering problem and posed numerous design challenges. Each spillway's capacity of 200,000 cu ft/s (5,700 m3/s) was empirically verified in post-construction tests in 1941.
The large spillway tunnels have only been used twice, for testing in 1941 and because of flooding in 1983. Both times, when inspecting the tunnels after the spillways were used, engineers found major damage to the concrete linings and underlying rock. The 1941 damage was attributed to a slight misalignment of the tunnel invert (or base), which caused cavitation, a phenomenon in fast-flowing liquids in which vapor bubbles collapse with explosive force. In response to this finding, the tunnels were patched with special heavy-duty concrete and the surface of the concrete was polished mirror-smooth. The spillways were modified in 1947 by adding flip buckets, which both slow the water and decrease the spillway's effective capacity, in an attempt to eliminate conditions thought to have contributed to the 1941 damage. The 1983 damage, also due to cavitation, led to the installation of aerators in the spillways. Tests at Grand Coulee Dam showed that the technique worked, in principle.
There are two lanes for automobile traffic across the top of the dam, which formerly served as the Colorado River crossing for U.S. Route 93. In the wake of the September 11 terrorist attacks, authorities expressed security concerns and the Hoover Dam Bypass project was expedited. Pending the completion of the bypass, restricted traffic was permitted over Hoover Dam. Some types of vehicles were inspected prior to crossing the dam while semi-trailer trucks, buses carrying luggage, and enclosed-box trucks over 40 ft (12 m) long were not allowed on the dam at all, and were diverted to U.S. Route 95 or Nevada State Routes 163/68. The four-lane Hoover Dam Bypass opened on October 19, 2010. It includes a composite steel and concrete arch bridge, the Mike O'Callaghan–Pat Tillman Memorial Bridge, 1,500 ft (460 m) downstream from the dam. With the opening of the bypass, through traffic is no longer allowed across Hoover Dam; dam visitors are allowed to use the existing roadway to approach from the Nevada side and cross to parking lots and other facilities on the Arizona side.
Hoover Dam opened for tours in 1937 after its completion but following Japan's attack on Pearl Harbor on December 7, 1941, it was closed to the public when the United States entered World War II, during which only authorized traffic, in convoys, was permitted. After the war, it reopened September 2, 1945, and by 1953, annual attendance had risen to 448,081. The dam closed on November 25, 1963, and March 31, 1969, days of mourning in remembrance of Presidents Kennedy and Eisenhower. In 1995, a new visitors' center was built, and the following year, visits exceeded one million for the first time. The dam closed again to the public on September 11, 2001; modified tours were resumed in December and a new "Discovery Tour" was added the following year. Today, nearly a million people per year take the tours of the dam offered by the Bureau of Reclamation. Increased security concerns by the government have led to most of the interior structure's being inaccessible to tourists. As a result, few of True's decorations can now be seen by visitors. Visitors can only purchase tickets on-site and have the options of a guided tour of the whole facility or only the power plant area. The only self-guided tour option is for the visitor center itself, where visitors can view various exhibits and enjoy a 360-degree view of the dam.
The changes in water flow and use caused by Hoover Dam's construction and operation have had a large impact on the Colorado River Delta. The construction of the dam has been implicated in causing the decline of this estuarine ecosystem. For six years after the construction of the dam, while Lake Mead filled, virtually no water reached the mouth of the river. The delta's estuary, which once had a freshwater-saltwater mixing zone stretching 40 miles (64 km) south of the river's mouth, was turned into an inverse estuary where the level of salinity was higher close to the river's mouth.
The Colorado River had experienced natural flooding before the construction of the Hoover Dam. The dam eliminated the natural flooding, threatening many species adapted to the flooding, including both plants and animals. The construction of the dam devastated the populations of native fish in the river downstream from the dam. Four species of fish native to the Colorado River, the Bonytail chub, Colorado pikeminnow, Humpback chub, and Razorback sucker, are listed as endangered.
During the years of lobbying leading up to the passage of legislation authorizing the dam in 1928, the press generally referred to the dam as "Boulder Dam" or as "Boulder Canyon Dam", even though the proposed site had shifted to Black Canyon. The Boulder Canyon Project Act of 1928 (BCPA) never mentioned a proposed name or title for the dam. The BCPA merely allows the government to "construct, operate, and maintain a dam and incidental works in the main stream of the Colorado River at Black Canyon or Boulder Canyon".
When Secretary of the Interior Ray Wilbur spoke at the ceremony starting the building of the railway between Las Vegas and the dam site on September 17, 1930, he named the dam "Hoover Dam", citing a tradition of naming dams after Presidents, though none had been so honored during their terms of office. Wilbur justified his choice on the ground that Hoover was "the great engineer whose vision and persistence ... has done so much to make [the dam] possible". One writer complained in response that "the Great Engineer had quickly drained, ditched, and dammed the country."
After Hoover's election defeat in 1932 and the accession of the Roosevelt administration, Secretary Ickes ordered on May 13, 1933, that the dam be referred to as Boulder Dam. Ickes stated that Wilbur had been imprudent in naming the dam after a sitting president, that Congress had never ratified his choice, and that it had long been referred to as Boulder Dam. Unknown to the general public, Attorney General Homer Cummings informed Ickes that Congress had indeed used the name "Hoover Dam" in five different bills appropriating money for construction of the dam. The official status this conferred to the name "Hoover Dam" had been noted on the floor of the House of Representatives by Congressman Edward T. Taylor of Colorado on December 12, 1930, but was likewise ignored by Ickes.
When Ickes spoke at the dedication ceremony on September 30, 1935, he was determined, as he recorded in his diary, "to try to nail down for good and all the name Boulder Dam." At one point in the speech, he spoke the words "Boulder Dam" five times within thirty seconds. Further, he suggested that if the dam were to be named after any one person, it should be for California Senator Hiram Johnson, a lead sponsor of the authorizing legislation. Roosevelt also referred to the dam as Boulder Dam, and the Republican-leaning Los Angeles Times, which at the time of Ickes' name change had run an editorial cartoon showing Ickes ineffectively chipping away at an enormous sign "HOOVER DAM", reran it showing Roosevelt reinforcing Ickes, but having no greater success.
In the following years, the name "Boulder Dam" failed to fully take hold, with many Americans using both names interchangeably and mapmakers divided as to which name should be printed. Memories of the Great Depression faded, and Hoover to some extent rehabilitated himself through good works during and after World War II. In 1947, a bill passed both Houses of Congress unanimously restoring the name "Hoover Dam." Ickes, who was by then a private citizen, opposed the change, stating, "I didn't know Hoover was that small a man to take credit for something he had nothing to do with."
Hoover Dam was recognized as a National Historic Civil Engineering Landmark in 1984. It was listed on the National Register of Historic Places in 1981 and was designated a National Historic Landmark in 1985, cited for its engineering innovations.
Hoover Dam is a concrete arch-gravity dam in the Black Canyon of the Colorado River, on the border between the U.S. states of Nevada and Arizona. It was constructed between 1931 and 1936 during the Great Depression and was dedicated on September 30, 1935, by President Franklin D. Roosevelt. Its construction was the result of a massive effort involving thousands of workers, and cost over one hundred lives. It was referred to as Hoover Dam after President Herbert Hoover in bills passed by Congress during its construction, but was named Boulder Dam by the Roosevelt administration. The Hoover Dam name was restored by Congress in 1947.
Since about 1900, the Black Canyon and nearby Boulder Canyon had been investigated for their potential to support a dam that would control floods, provide irrigation water and produce hydroelectric power. In 1928, Congress authorized the project. The winning bid to build the dam was submitted by a consortium named Six Companies, Inc., which began construction of the dam in early 1931. Such a large concrete structure had never been built before, and some of the techniques were unproven. The torrid summer weather and lack of facilities near the site also presented difficulties. Nevertheless, Six Companies turned the dam over to the federal government on March 1, 1936, more than two years ahead of schedule.
Hoover Dam impounds Lake Mead, the largest reservoir in the United States by volume when full. The dam is located near Boulder City, Nevada, a municipality originally constructed for workers on the construction project, about 30 mi (48 km) southeast of Las Vegas, Nevada. The dam's generators provide power for public and private utilities in Nevada, Arizona, and California. Hoover Dam is a major tourist attraction; nearly a million people tour the dam each year. The heavily traveled U.S. Route 93 (US 93) ran along the dam's crest until October 2010, when the Hoover Dam Bypass opened.
As the United States developed the Southwest, the Colorado River was seen as a potential source of irrigation water. An initial attempt at diverting the river for irrigation purposes occurred in the late 1890s, when land speculator William Beatty built the Alamo Canal just north of the Mexican border; the canal dipped into Mexico before running to a desolate area Beatty named the Imperial Valley. Though water from the Imperial Canal allowed for the widespread settlement of the valley, the canal proved expensive to operate. After a catastrophic breach that caused the Colorado River to fill the Salton Sea, the Southern Pacific Railroad spent $3 million in 1906–07 to stabilize the waterway, an amount it hoped in vain would be reimbursed by the federal government. Even after the waterway was stabilized, it proved unsatisfactory because of constant disputes with landowners on the Mexican side of the border.
As the technology of electric power transmission improved, the Lower Colorado was considered for its hydroelectric-power potential. In 1902, the Edison Electric Company of Los Angeles surveyed the river in the hope of building a 40-foot (12 m) rock dam which could generate 10,000 horsepower (7,500 kW). However, at the time, the limit of transmission of electric power was 80 miles (130 km), and there were few customers (mostly mines) within that limit. Edison allowed land options it held on the river to lapse—including an option for what became the site of Hoover Dam.
In the following years, the Bureau of Reclamation (BOR), known as the Reclamation Service at the time, also considered the Lower Colorado as the site for a dam. Service chief Arthur Powell Davis proposed using dynamite to collapse the walls of Boulder Canyon, 20 miles (32 km) north of the eventual dam site, into the river. The river would carry off the smaller pieces of debris, and a dam would be built incorporating the remaining rubble. In 1922, after considering it for several years, the Reclamation Service finally rejected the proposal, citing doubts about the unproven technique and questions as to whether it would, in fact, save money.
Soon after the dam was authorized, increasing numbers of unemployed people converged on southern Nevada. Las Vegas, then a small city of some 5,000, saw between 10,000 and 20,000 unemployed descend on it. A government camp was established for surveyors and other personnel near the dam site; this soon became surrounded by a squatters' camp. Known as McKeeversville, the camp was home to men hoping for work on the project, together with their families. Another camp, on the flats along the Colorado River, was officially called Williamsville, but was known to its inhabitants as "Ragtown". When construction began, Six Companies hired large numbers of workers, with more than 3,000 on the payroll by 1932 and with employment peaking at 5,251 in July 1934. "Mongolian" (Chinese) labor was prevented by the construction contract, while the number of black people employed by Six Companies never exceeded thirty, mostly lowest-pay-scale laborers in a segregated crew, who were issued separate water buckets.
As part of the contract, Six Companies, Inc. was to build Boulder City to house the workers. The original timetable called for Boulder City to be built before the dam project began, but President Hoover ordered work on the dam to begin in March 1931 rather than in October. The company built bunkhouses, attached to the canyon wall, to house 480 single men at what became known as River Camp. Workers with families were left to provide their own accommodations until Boulder City could be completed, and many lived in Ragtown. The site of Hoover Dam endures extremely hot weather, and the summer of 1931 was especially torrid, with the daytime high averaging 119.9 °F (48.8 °C). Sixteen workers and other riverbank residents died of heat prostration between June 25 and July 26, 1931.
The Industrial Workers of the World (IWW or "Wobblies"), though much-reduced from their heyday as militant labor organizers in the early years of the century, hoped to unionize the Six Companies workers by capitalizing on their discontent. They sent eleven organizers, several of whom were arrested by Las Vegas police. On August 7, 1931, the company cut wages for all tunnel workers. Although the workers sent the organizers away, not wanting to be associated with the "Wobblies", they formed a committee to represent them with the company. The committee drew up a list of demands that evening and presented them to Crowe the following morning. He was noncommittal. The workers hoped that Crowe, the general superintendent of the job, would be sympathetic; instead, he gave a scathing interview to a newspaper, describing the workers as "malcontents".
On the morning of the 9th, Crowe met with the committee and told them that management refused their demands, was stopping all work, and was laying off the entire work force, except for a few office workers and carpenters. The workers were given until 5 p.m. to vacate the premises. Concerned that a violent confrontation was imminent, most workers took their paychecks and left for Las Vegas to await developments. Two days later, the remainder were talked into leaving by law enforcement. On August 13, the company began hiring workers again, and two days later, the strike was called off. While the workers received none of their demands, the company guaranteed there would be no further reductions in wages. Living conditions began to improve as the first residents moved into Boulder City in late 1931.
A second labor action took place in July 1935, as construction on the dam wound down. When a Six Companies manager altered working times to force workers to take lunch on their own time, workers responded with a strike. Emboldened by Crowe's reversal of the lunch decree, workers raised their demands to include a $1-per-day raise. The company agreed to ask the Federal government to supplement the pay, but no money was forthcoming from Washington. The strike ended.
Before the dam could be built, the Colorado River needed to be diverted away from the construction site. To accomplish this, four diversion tunnels were driven through the canyon walls, two on the Nevada side and two on the Arizona side. These tunnels were 56 ft (17 m) in diameter. Their combined length was nearly 16,000 ft, or more than 3 miles (5 km). The contract required these tunnels to be completed by October 1, 1933, with a $3,000-per-day fine to be assessed for any delay. To meet the deadline, Six Companies had to complete work by early 1933, since only in late fall and winter was the water level in the river low enough to safely divert.
Tunneling began at the lower portals of the Nevada tunnels in May 1931. Shortly afterward, work began on two similar tunnels in the Arizona canyon wall. In March 1932, work began on lining the tunnels with concrete. First the base, or invert, was poured. Gantry cranes, running on rails through the entire length of each tunnel were used to place the concrete. The sidewalls were poured next. Movable sections of steel forms were used for the sidewalls. Finally, using pneumatic guns, the overheads were filled in. The concrete lining is 3 feet (1 m) thick, reducing the finished tunnel diameter to 50 ft (15 m). The river was diverted into the two Arizona tunnels on November 13, 1932; the Nevada tunnels were kept in reserve for high water. This was done by exploding a temporary cofferdam protecting the Arizona tunnels while at the same time dumping rubble into the river until its natural course was blocked.
Following the completion of the dam, the entrances to the two outer diversion tunnels were sealed at the opening and halfway through the tunnels with large concrete plugs. The downstream halves of the tunnels following the inner plugs are now the main bodies of the spillway tunnels. The inner diversion tunnels were plugged at approximately one-third of their length, beyond which they now carry steel pipes connecting the intake towers to the power plant and outlet works. The inner tunnels' outlets are equipped with gates that can be closed to drain the tunnels for maintenance.
To protect the construction site from the Colorado River and to facilitate the river's diversion, two cofferdams were constructed. Work on the upper cofferdam began in September 1932, even though the river had not yet been diverted. The cofferdams were designed to protect against the possibility of the river's flooding a site at which two thousand men might be at work, and their specifications were covered in the bid documents in nearly as much detail as the dam itself. The upper cofferdam was 96 ft (29 m) high, and 750 feet (230 m) thick at its base, thicker than the dam itself. It contained 650,000 cubic yards (500,000 m3) of material.
When the cofferdams were in place and the construction site was drained of water, excavation for the dam foundation began. For the dam to rest on solid rock, it was necessary to remove accumulated erosion soils and other loose materials in the riverbed until sound bedrock was reached. Work on the foundation excavations was completed in June 1933. During this excavation, approximately 1,500,000 cu yd (1,100,000 m3) of material was removed. Since the dam was an arch-gravity type, the side-walls of the canyon would bear the force of the impounded lake. Therefore, the side-walls were also excavated to reach virgin rock, as weathered rock might provide pathways for water seepage. Shovels for the excavation came from the Marion Power Shovel Company.
The men who removed this rock were called "high scalers". While suspended from the top of the canyon with ropes, the high-scalers climbed down the canyon walls and removed the loose rock with jackhammers and dynamite. Falling objects were the most common cause of death on the dam site; the high scalers' work thus helped ensure worker safety. One high scaler was able to save a life in a more direct manner: when a government inspector lost his grip on a safety line and began tumbling down a slope towards almost certain death, a high scaler was able to intercept him and pull him into the air. The construction site had become a magnet for tourists. The high scalers were prime attractions and showed off for the watchers. The high scalers received considerable media attention, with one worker dubbed the "Human Pendulum" for swinging co-workers (and, at other times, cases of dynamite) across the canyon. To protect themselves against falling objects, some high scalers dipped cloth hats in tar and allowed them to harden. When workers wearing such headgear were struck hard enough to inflict broken jaws, they sustained no skull damage. Six Companies ordered thousands of what initially were called "hard boiled hats" (later "hard hats") and strongly encouraged their use.
The cleared, underlying rock foundation of the dam site was reinforced with grout, forming a grout curtain. Holes were driven into the walls and base of the canyon, as deep as 150 feet (46 m) into the rock, and any cavities encountered were to be filled with grout. This was done to stabilize the rock, to prevent water from seeping past the dam through the canyon rock, and to limit "uplift"—upward pressure from water seeping under the dam. The workers were under severe time constraints due to the beginning of the concrete pour. When they encountered hot springs or cavities too large to readily fill, they moved on without resolving the problem. A total of 58 of the 393 holes were incompletely filled. After the dam was completed and the lake began to fill, large numbers of significant leaks caused the Bureau of Reclamation to examine the situation. It found that the work had been incompletely done, and was based on less than a full understanding of the canyon's geology. New holes were drilled from inspection galleries inside the dam into the surrounding bedrock. It took nine years (1938–47) under relative secrecy to complete the supplemental grout curtain.
The first concrete was poured into the dam on June 6, 1933, 18 months ahead of schedule. Since concrete heats and contracts as it cures, the potential for uneven cooling and contraction of the concrete posed a serious problem. Bureau of Reclamation engineers calculated that if the dam were to be built in a single continuous pour, the concrete would take 125 years to cool, and the resulting stresses would cause the dam to crack and crumble. Instead, the ground where the dam would rise was marked with rectangles, and concrete blocks in columns were poured, some as large as 50 ft square (15 m) and 5 feet (1.5 m) high. Each five-foot form contained a set of 1-inch (25 mm) steel pipes; cool river water would be poured through the pipes, followed by ice-cold water from a refrigeration plant. When an individual block had cured and had stopped contracting, the pipes were filled with grout. Grout was also used to fill the hairline spaces between columns, which were grooved to increase the strength of the joints.
The concrete was delivered in huge steel buckets 7 feet high (2.1 m) and almost 7 feet in diameter; Crowe was awarded two patents for their design. These buckets, which weighed 20 short tons (18.1 t; 17.9 long tons) when full, were filled at two massive concrete plants on the Nevada side, and were delivered to the site in special railcars. The buckets were then suspended from aerial cableways which were used to deliver the bucket to a specific column. As the required grade of aggregate in the concrete differed depending on placement in the dam (from pea-sized gravel to 9 inches [230 mm] stones), it was vital that the bucket be maneuvered to the proper column. When the bottom of the bucket opened up, disgorging 8 cu yd (6.1 m3) of concrete, a team of men worked it throughout the form. Although there are myths that men were caught in the pour and are entombed in the dam to this day, each bucket deepened the concrete in a form by only 1 inch (25 mm), and Six Companies engineers would not have permitted a flaw caused by the presence of a human body.
A total of 3,250,000 cubic yards (2,480,000 cubic meters) of concrete was used in the dam before concrete pouring ceased on May 29, 1935. In addition, 1,110,000 cu yd (850,000 m3) were used in the power plant and other works. More than 582 miles (937 km) of cooling pipes were placed within the concrete. Overall, there is enough concrete in the dam to pave a two-lane highway from San Francisco to New York. Concrete cores were removed from the dam for testing in 1995; they showed that "Hoover Dam's concrete has continued to slowly gain strength" and the dam is composed of a "durable concrete having a compressive strength exceeding the range typically found in normal mass concrete". Hoover Dam concrete is not subject to alkali–silica reaction (ASR), as the Hoover Dam builders happened to use nonreactive aggregate, unlike that at downstream Parker Dam, where ASR has caused measurable deterioration.
With most work finished on the dam itself (the powerhouse remained uncompleted), a formal dedication ceremony was arranged for September 30, 1935, to coincide with a western tour being made by President Franklin D. Roosevelt. The morning of the dedication, it was moved forward three hours from 2 p.m. Pacific time to 11 a.m.; this was done because Secretary of the Interior Harold L. Ickes had reserved a radio slot for the President for 2 p.m. but officials did not realize until the day of the ceremony that the slot was for 2 p.m. Eastern Time. Despite the change in the ceremony time, and temperatures of 102 °F (39 °C), 10,000 people were present for the President's speech, in which he avoided mentioning the name of former President Hoover, who was not invited to the ceremony. To mark the occasion, a three-cent stamp was issued by the United States Post Office Department—bearing the name "Boulder Dam", the official name of the dam between 1933 and 1947. After the ceremony, Roosevelt made the first visit by any American president to Las Vegas.
Most work had been completed by the dedication, and Six Companies negotiated with the government through late 1935 and early 1936 to settle all claims and arrange for the formal transfer of the dam to the Federal Government. The parties came to an agreement and on March 1, 1936, Secretary Ickes formally accepted the dam on behalf of the government. Six Companies was not required to complete work on one item, a concrete plug for one of the bypass tunnels, as the tunnel had to be used to take in irrigation water until the powerhouse went into operation.
There were 112 deaths reported as associated with the construction of the dam. The first was Bureau of Reclamation employee Harold Connelly who died on May 15, 1921, after falling from a barge while surveying the Colorado River for an ideal spot for the dam. Surveyor John Gregory ("J.G.") Tierney, who drowned on December 20, 1922, in a flash flood while looking for an ideal spot for the dam was the second person. The official list's final death occurred on December 20, 1935, when Patrick Tierney, electrician's helper and the son of J.G. Tierney, fell from one of the two Arizona-side intake towers. Included in the fatality list are three workers who took their own lives on site, one in 1932 and two in 1933. Of the 112 fatalities, 91 were Six Companies employees, three were Bureau of Reclamation employees, and one was a visitor to the site; the remainder were employees of various contractors not part of Six Companies.
Ninety-six of the deaths occurred during construction at the site. Not included in the official number of fatalities were deaths that were recorded as pneumonia. Workers alleged that this diagnosis was a cover for death from carbon monoxide poisoning (brought on by the use of gasoline-fueled vehicles in the diversion tunnels), and a classification used by Six Companies to avoid paying compensation claims. The site's diversion tunnels frequently reached 140 °F (60 °C), enveloped in thick plumes of vehicle exhaust gases. A total of 42 workers were recorded as having died from pneumonia and were not included in the above total; none were listed as having died from carbon monoxide poisoning. No deaths of non-workers from pneumonia were recorded in Boulder City during the construction period.
The initial plans for the facade of the dam, the power plant, the outlet tunnels and ornaments clashed with the modern look of an arch dam. The Bureau of Reclamation, more concerned with the dam's functionality, adorned it with a Gothic-inspired balustrade and eagle statues. This initial design was criticized by many as being too plain and unremarkable for a project of such immense scale, so Los Angeles-based architect Gordon B. Kaufmann, then the supervising architect to the Bureau of Reclamation, was brought in to redesign the exteriors. Kaufmann greatly streamlined the design and applied an elegant Art Deco style to the entire project. He designed sculpted turrets rising seamlessly from the dam face and clock faces on the intake towers set for the time in Nevada and Arizona—both states are in different time zones, but since Arizona does not observe daylight saving time, the clocks display the same time for more than half the year.
At Kaufmann's request, Denver artist Allen Tupper True was hired to handle the design and decoration of the walls and floors of the new dam. True's design scheme incorporated motifs of the Navajo and Pueblo tribes of the region. Although some were initially opposed to these designs, True was given the go-ahead and was officially appointed consulting artist. With the assistance of the National Laboratory of Anthropology, True researched authentic decorative motifs from Indian sand paintings, textiles, baskets and ceramics. The images and colors are based on Native American visions of rain, lightning, water, clouds, and local animals—lizards, serpents, birds—and on the Southwestern landscape of stepped mesas. In these works, which are integrated into the walkways and interior halls of the dam, True also reflected on the machinery of the operation, making the symbolic patterns appear both ancient and modern.
With the agreement of Kaufmann and the engineers, True also devised for the pipes and machinery an innovative color-coding which was implemented throughout all BOR projects. True's consulting artist job lasted through 1942; it was extended so he could complete design work for the Parker, Shasta and Grand Coulee dams and power plants. True's work on the Hoover Dam was humorously referred to in a poem published in The New Yorker, part of which read, "lose the spark, and justify the dream; but also worthy of remark will be the color scheme".
Complementing Kaufmann and True's work, sculptor Oskar J. W. Hansen designed many of the sculptures on and around the dam. His works include the monument of dedication plaza, a plaque to memorialize the workers killed and the bas-reliefs on the elevator towers. In his words, Hansen wanted his work to express "the immutable calm of intellectual resolution, and the enormous power of trained physical strength, equally enthroned in placid triumph of scientific accomplishment", because "the building of Hoover Dam belongs to the sagas of the daring." Hansen's dedication plaza, on the Nevada abutment, contains a sculpture of two winged figures flanking a flagpole.
Surrounding the base of the monument is a terrazzo floor embedded with a "star map". The map depicts the Northern Hemisphere sky at the moment of President Roosevelt's dedication of the dam. This is intended to help future astronomers, if necessary, calculate the exact date of dedication. The 30-foot-high (9.1 m) bronze figures, dubbed "Winged Figures of the Republic", were both formed in a continuous pour. To put such large bronzes into place without marring the highly polished bronze surface, they were placed on ice and guided into position as the ice melted. Hansen's bas-relief on the Nevada elevator tower depicts the benefits of the dam: flood control, navigation, irrigation, water storage, and power. The bas-relief on the Arizona elevator depicts, in his words, "the visages of those Indian tribes who have inhabited mountains and plains from ages distant."
Excavation for the powerhouse was carried out simultaneously with the excavation for the dam foundation and abutments. The excavation of this U-shaped structure located at the downstream toe of the dam was completed in late 1933 with the first concrete placed in November 1933. Filling of Lake Mead began February 1, 1935, even before the last of the concrete was poured that May. The powerhouse was one of the projects uncompleted at the time of the formal dedication on September 30, 1935; a crew of 500 men remained to finish it and other structures. To make the powerhouse roof bombproof, it was constructed of layers of concrete, rock, and steel with a total thickness of about 3.5 feet (1.1 m), topped with layers of sand and tar.
In the latter half of 1936, water levels in Lake Mead were high enough to permit power generation, and the first three Allis Chalmers built Francis turbine-generators, all on the Nevada side, began operating. In March 1937, one more Nevada generator went online and the first Arizona generator by August. By September 1939, four more generators were operating, and the dam's power plant became the largest hydroelectricity facility in the world. The final generator was not placed in service until 1961, bringing the maximum generating capacity to 1,345 megawatts at the time. Original plans called for 16 large generators, eight on each side of the river, but two smaller generators were installed instead of one large one on the Arizona side for a total of 17. The smaller generators were used to serve smaller communities at a time when the output of each generator was dedicated to a single municipality, before the dam's total power output was placed on the grid and made arbitrarily distributable.
Before water from Lake Mead reaches the turbines, it enters the intake towers and then four gradually narrowing penstocks which funnel the water down towards the powerhouse. The intakes provide a maximum hydraulic head (water pressure) of 590 ft (180 m) as the water reaches a speed of about 85 mph (140 km/h). The entire flow of the Colorado River usually passes through the turbines. The spillways and outlet works (jet-flow gates) are rarely used. The jet-flow gates, located in concrete structures 180 feet (55 m) above the river and also at the outlets of the inner diversion tunnels at river level, may be used to divert water around the dam in emergency or flood conditions, but have never done so, and in practice are used only to drain water from the penstocks for maintenance. Following an uprating project from 1986 to 1993, the total gross power rating for the plant, including two 2.4 megawatt Pelton turbine-generators that power Hoover Dam's own operations is a maximum capacity of 2080 megawatts. The annual generation of Hoover Dam varies. The maximum net generation was 10.348 TWh in 1984, and the minimum since 1940 was 2.648 TWh in 1956. The average power generated was 4.2 TWh/year for 1947–2008. In 2015, the dam generated 3.6 TWh.
The amount of electricity generated by Hoover Dam has been decreasing along with the falling water level in Lake Mead due to the prolonged drought since year 2000 and high demand for the Colorado River's water. By 2014 its generating capacity was downrated by 23% to 1592 MW and was providing power only during periods of peak demand. Lake Mead fell to a new record low elevation of 1,071.61 feet (326.63 m) on July 1, 2016, before beginning to rebound slowly. Under its original design, the dam would no longer be able to generate power once the water level fell below 1,050 feet (320 m), which might have occurred in 2017 had water restrictions not been enforced. To lower the minimum power pool elevation from 1,050 to 950 feet (320 to 290 m), five wide-head turbines, designed to work efficiently with less flow, were installed.[102] Water levels were maintained at over 1,075 feet (328 m) in 2018 and 2019, but fell to a new record low of 1,071.55 feet (326.61 m) on June 10, 2021[104] and were projected to fall below 1,066 feet (325 m) by the end of 2021.
Control of water was the primary concern in the building of the dam. Power generation has allowed the dam project to be self-sustaining: proceeds from the sale of power repaid the 50-year construction loan, and those revenues also finance the multimillion-dollar yearly maintenance budget. Power is generated in step with and only with the release of water in response to downstream water demands.
Lake Mead and downstream releases from the dam also provide water for both municipal and irrigation uses. Water released from the Hoover Dam eventually reaches several canals. The Colorado River Aqueduct and Central Arizona Project branch off Lake Havasu while the All-American Canal is supplied by the Imperial Dam. In total, water from Lake Mead serves 18 million people in Arizona, Nevada, and California and supplies the irrigation of over 1,000,000 acres (400,000 ha) of land.
In 2018, the Los Angeles Department of Water and Power (LADWP) proposed a $3 billion pumped-storage hydroelectricity project—a "battery" of sorts—that would use wind and solar power to recirculate water back up to Lake Mead from a pumping station 20 miles (32 km) downriver.
Electricity from the dam's powerhouse was originally sold pursuant to a fifty-year contract, authorized by Congress in 1934, which ran from 1937 to 1987. In 1984, Congress passed a new statute which set power allocations to southern California, Arizona, and Nevada from the dam from 1987 to 2017. The powerhouse was run under the original authorization by the Los Angeles Department of Water and Power and Southern California Edison; in 1987, the Bureau of Reclamation assumed control. In 2011, Congress enacted legislation extending the current contracts until 2067, after setting aside 5% of Hoover Dam's power for sale to Native American tribes, electric cooperatives, and other entities. The new arrangement began on October 1, 2017.
The dam is protected against over-topping by two spillways. The spillway entrances are located behind each dam abutment, running roughly parallel to the canyon walls. The spillway entrance arrangement forms a classic side-flow weir with each spillway containing four 100-foot-long (30 m) and 16-foot-wide (4.9 m) steel-drum gates. Each gate weighs 5,000,000 pounds (2,300 metric tons) and can be operated manually or automatically. Gates are raised and lowered depending on water levels in the reservoir and flood conditions. The gates cannot entirely prevent water from entering the spillways but can maintain an extra 16 ft (4.9 m) of lake level.
Water flowing over the spillways falls dramatically into 600-foot-long (180 m), 50-foot-wide (15 m) spillway tunnels before connecting to the outer diversion tunnels and reentering the main river channel below the dam. This complex spillway entrance arrangement combined with the approximate 700-foot (210 m) elevation drop from the top of the reservoir to the river below was a difficult engineering problem and posed numerous design challenges. Each spillway's capacity of 200,000 cu ft/s (5,700 m3/s) was empirically verified in post-construction tests in 1941.
The large spillway tunnels have only been used twice, for testing in 1941 and because of flooding in 1983. Both times, when inspecting the tunnels after the spillways were used, engineers found major damage to the concrete linings and underlying rock. The 1941 damage was attributed to a slight misalignment of the tunnel invert (or base), which caused cavitation, a phenomenon in fast-flowing liquids in which vapor bubbles collapse with explosive force. In response to this finding, the tunnels were patched with special heavy-duty concrete and the surface of the concrete was polished mirror-smooth. The spillways were modified in 1947 by adding flip buckets, which both slow the water and decrease the spillway's effective capacity, in an attempt to eliminate conditions thought to have contributed to the 1941 damage. The 1983 damage, also due to cavitation, led to the installation of aerators in the spillways. Tests at Grand Coulee Dam showed that the technique worked, in principle.
There are two lanes for automobile traffic across the top of the dam, which formerly served as the Colorado River crossing for U.S. Route 93. In the wake of the September 11 terrorist attacks, authorities expressed security concerns and the Hoover Dam Bypass project was expedited. Pending the completion of the bypass, restricted traffic was permitted over Hoover Dam. Some types of vehicles were inspected prior to crossing the dam while semi-trailer trucks, buses carrying luggage, and enclosed-box trucks over 40 ft (12 m) long were not allowed on the dam at all, and were diverted to U.S. Route 95 or Nevada State Routes 163/68. The four-lane Hoover Dam Bypass opened on October 19, 2010. It includes a composite steel and concrete arch bridge, the Mike O'Callaghan–Pat Tillman Memorial Bridge, 1,500 ft (460 m) downstream from the dam. With the opening of the bypass, through traffic is no longer allowed across Hoover Dam; dam visitors are allowed to use the existing roadway to approach from the Nevada side and cross to parking lots and other facilities on the Arizona side.
Hoover Dam opened for tours in 1937 after its completion but following Japan's attack on Pearl Harbor on December 7, 1941, it was closed to the public when the United States entered World War II, during which only authorized traffic, in convoys, was permitted. After the war, it reopened September 2, 1945, and by 1953, annual attendance had risen to 448,081. The dam closed on November 25, 1963, and March 31, 1969, days of mourning in remembrance of Presidents Kennedy and Eisenhower. In 1995, a new visitors' center was built, and the following year, visits exceeded one million for the first time. The dam closed again to the public on September 11, 2001; modified tours were resumed in December and a new "Discovery Tour" was added the following year. Today, nearly a million people per year take the tours of the dam offered by the Bureau of Reclamation. Increased security concerns by the government have led to most of the interior structure's being inaccessible to tourists. As a result, few of True's decorations can now be seen by visitors. Visitors can only purchase tickets on-site and have the options of a guided tour of the whole facility or only the power plant area. The only self-guided tour option is for the visitor center itself, where visitors can view various exhibits and enjoy a 360-degree view of the dam.
The changes in water flow and use caused by Hoover Dam's construction and operation have had a large impact on the Colorado River Delta. The construction of the dam has been implicated in causing the decline of this estuarine ecosystem. For six years after the construction of the dam, while Lake Mead filled, virtually no water reached the mouth of the river. The delta's estuary, which once had a freshwater-saltwater mixing zone stretching 40 miles (64 km) south of the river's mouth, was turned into an inverse estuary where the level of salinity was higher close to the river's mouth.
The Colorado River had experienced natural flooding before the construction of the Hoover Dam. The dam eliminated the natural flooding, threatening many species adapted to the flooding, including both plants and animals. The construction of the dam devastated the populations of native fish in the river downstream from the dam. Four species of fish native to the Colorado River, the Bonytail chub, Colorado pikeminnow, Humpback chub, and Razorback sucker, are listed as endangered.
During the years of lobbying leading up to the passage of legislation authorizing the dam in 1928, the press generally referred to the dam as "Boulder Dam" or as "Boulder Canyon Dam", even though the proposed site had shifted to Black Canyon. The Boulder Canyon Project Act of 1928 (BCPA) never mentioned a proposed name or title for the dam. The BCPA merely allows the government to "construct, operate, and maintain a dam and incidental works in the main stream of the Colorado River at Black Canyon or Boulder Canyon".
When Secretary of the Interior Ray Wilbur spoke at the ceremony starting the building of the railway between Las Vegas and the dam site on September 17, 1930, he named the dam "Hoover Dam", citing a tradition of naming dams after Presidents, though none had been so honored during their terms of office. Wilbur justified his choice on the ground that Hoover was "the great engineer whose vision and persistence ... has done so much to make [the dam] possible". One writer complained in response that "the Great Engineer had quickly drained, ditched, and dammed the country."
After Hoover's election defeat in 1932 and the accession of the Roosevelt administration, Secretary Ickes ordered on May 13, 1933, that the dam be referred to as Boulder Dam. Ickes stated that Wilbur had been imprudent in naming the dam after a sitting president, that Congress had never ratified his choice, and that it had long been referred to as Boulder Dam. Unknown to the general public, Attorney General Homer Cummings informed Ickes that Congress had indeed used the name "Hoover Dam" in five different bills appropriating money for construction of the dam. The official status this conferred to the name "Hoover Dam" had been noted on the floor of the House of Representatives by Congressman Edward T. Taylor of Colorado on December 12, 1930, but was likewise ignored by Ickes.
When Ickes spoke at the dedication ceremony on September 30, 1935, he was determined, as he recorded in his diary, "to try to nail down for good and all the name Boulder Dam." At one point in the speech, he spoke the words "Boulder Dam" five times within thirty seconds. Further, he suggested that if the dam were to be named after any one person, it should be for California Senator Hiram Johnson, a lead sponsor of the authorizing legislation. Roosevelt also referred to the dam as Boulder Dam, and the Republican-leaning Los Angeles Times, which at the time of Ickes' name change had run an editorial cartoon showing Ickes ineffectively chipping away at an enormous sign "HOOVER DAM", reran it showing Roosevelt reinforcing Ickes, but having no greater success.
In the following years, the name "Boulder Dam" failed to fully take hold, with many Americans using both names interchangeably and mapmakers divided as to which name should be printed. Memories of the Great Depression faded, and Hoover to some extent rehabilitated himself through good works during and after World War II. In 1947, a bill passed both Houses of Congress unanimously restoring the name "Hoover Dam." Ickes, who was by then a private citizen, opposed the change, stating, "I didn't know Hoover was that small a man to take credit for something he had nothing to do with."
Hoover Dam was recognized as a National Historic Civil Engineering Landmark in 1984. It was listed on the National Register of Historic Places in 1981 and was designated a National Historic Landmark in 1985, cited for its engineering innovations.
Most of the members of the Model Engineering Club in Detroit MI were machinists, tool and die makers, and engineers who worked in the automotive industry in the area. The Detroit News sponsored the club and one of the requirements was that all members must build their own boats and engines to qualify for competition.
Florent Socall designed and built this unique 30cc, 4-cycle, air-cooled over head valve engine to power his model boats. It has a cast aluminum crankcase, gear box, and head with a machined steel cylinder. It burns gasoline on spark ignition and supports an oil tank for internal lubrication; the rockers and valves must be lubricated manually before operation.
An item of interest is the photographic timer mounted to the crankcase and linked to the carburetor. Releasing a tether boat at full throttle often resulted in cavitation and no speed. Mr. Socall modified the timer to hold the throttle on idle and when he released the boat he simultaneously tripped the timer which steadily increased the throttle from idle to full throttle within 5 seconds, thus preventing the possibility of cavitation.
See More Model Boat Engines at: www.flickr.com/photos/15794235@N06/sets/72157641089388694/
See More 1-Cylinder Engines at: www.flickr.com/photos/15794235@N06/albums/72157656174064422
See Our Model Engine Collection at: www.flickr.com/photos/15794235@N06/sets/72157602933346098/
Visit Our Photo Sets at: www.flickr.com/photos/15794235@N06/sets
Courtesy of Paul and Paula Knapp
Miniature Engineering Museum
The Jaguar C-Type (also called the Jaguar XK120-C) is a racing sports car built by Jaguar and sold from 1951 to 1953. The "C" designation stood for "competition".
The car used the running gear of the contemporary XK120 in a lightweight tubular frame and aerodynamic aluminium body. A total of 52 C-Types were built.
The road-going XK120’s 3.4-litre twin-cam, straight-6 engine produced between 160 and 180 bhp (134 kW). The version in the C-Type was originally tuned to around 205 bhp (153 kW). Later C-Types were more powerful, using triple twin-choke Weber carburettors and high-lift camshafts. They were also lighter, and from 1952 braking performance was improved by disc brakes on all four wheels. The lightweight, multi-tubular, triangulated frame was designed by Bob Knight. The aerodynamic body was designed by Malcolm Sayer. Made of aluminium in the barchetta style, it was devoid of road-going items such as carpets, weather equipment and exterior door handles.
[edit]Racing
The C-Type was successful in racing, most notably at the Le Mans 24 hours race, which it won twice.
In 1951 the car won at its first attempt. The factory entered three, whose driver pairings were Stirling Moss and Jack Fairman, Leslie Johnson and 3-times Mille Miglia winner Clemente Biondetti, and the eventual winners, Peter Walker and Peter Whitehead. The Walker/Whitehead car was the only factory entry to finish, the other two retiring with lack of oil pressure. A privately entered XK120, owned by Robert Lawrie, co-driven by Ivan Waller, also completed the race, finishing 11th.
In 1952 Jaguar, worried by a report about the speed of the Mercedes-Benz 300SLs that would run at Le Mans, modified the C-Type’s aerodynamics to increase the top speed. However, the consequent rearrangement of the cooling system made the car vulnerable to overheating.[1] All three retired from the race. The Peter Whitehead/Ian Stewart and Tony Rolt/Duncan Hamilton cars blew head gaskets, and the Stirling Moss/Peter Walker car, the only one not overheating, lost oil pressure after a mechanical breakage.[2] Later testing by Norman Dewis at MIRA after the race proved that it was not the body shape that caused the overheating but mainly the water pump pulley that was undersize, span too fast, caused cavitation and thus the overheating. What the body shape did do though was to create enormous tail lift, which caused the cars to squirrel their way down the Mulsanne (properly called the Hunaudières) straight at speeds over 120mph (200kph). The chassis numbers of the cars were XKC 001, 002 and 011, the latter existing today as a normal C-type, the others being dismantled at the factory. An exact copy of XKC 002 has since been created by CKL Developments in England, complete with FIA papers.
In 1953 a C-Type won again. This time the body was in thinner, lighter aluminium and the original twin H8 sand cast SU carburettors were replaced by three DCO3 40mm Webers, which helped boost power to 220 bhp (164 kW). Philip Porter mentions additional changes:
Further weight was saved by using a rubber bag fuel tank ... lighter electrical equipment and thinner gauge steel for some of the chassis tubes ... [T]he most significant change to the cars was the [switch to] disc brakes.[3]
Duncan Hamilton and Tony Rolt won the race at 105.85 mph {170.34 km/h} – the first time Le Mans had been won at an average of over 100 miles per hour (160 km/h). 1954, the C-Type's final year at Le Mans, saw a fourth place by the Ecurie Francorchamps entry driven by Roger Laurent and Jacques Swater
Balloons exploding with pellet gun fire and precise timing. ;-) You can actually see the pellet just about to exit the green balloon (the "lime") at the right of the frame. The cavitation can just be made out inside the green balloon.
Made in the same way as my others.
©2009 David C. Pearson, M.D.