Ford Sierra (Mk.I) 1.6L Emaxr (1982-86) Engine 1593cc S4 SOHC Pinto

Registration Number C 58 VLX (London NW)

FORD EUROPE

www.flickr.com/photos/45676495@N05/sets/72157623665118181...

 

Designed by Uwe Bahnsen, Robert Lutz and Patrick le Quément. and developed under the internal code Toni, the Ford Sierra was unveiled at the 1982 British Motorshow as Fords replacement for the much loved Cortina.

Its aerodynamic styling was ahead of its time and as such, many conservative buyers (including company car drivers) at first did not take fondly, and the car was nicknamed as the Blob or Jellymould. Although the Sierra did record almost 160,000 sales in its opening year, sales were hampered by heavy discounting on outgoing Cortinas and sales being diverted to the new Saloon version of the Escort, the Orion.

Early versions suffered from crosswind stability problems, which were addressed in 1985 with the addition of "strakes" (small spoilers), on the rear edge of the rubber seals of the rear-most side windows by 1983 sales were rising and it egained its lead of the market sector in Britain during 1986,

At its launch some of the Sierra's external styling differed depending on the specification. In place of the model's regular two-bar grille, which was unpainted on the lowest specification model, the Ghia featured a narrower blanked-off grille between wider, but still inset, headlights while the front bumper was also restyled and featured combined indicator/foglight units compared to the lower specification model's slimmer but wider indicator units

 

For 1986 the range wqs refreshed with (with more engine options as well as the introduction of a saloon) enjoyed a surge in sales from 1987 The front end was completely revised, with the biggest difference seeing the indicators now positioned above the bumper and to the side of a new headlight design. While the grille again remained blanked-off, UK, Irish and South African versions of the newly introduced saloon bodystyle, featured a unique shallow black grille between the headlights. That apart, all specifications of the Sierra now shared a common front end, compared to the car's original styling. The side windows were made slightly larger with the corners made sharper to increase outward vision. The rear lights were replaced with slimmer but wider models containing separate stop lamps. The saloon got similar rear lights as the revised hatchbacks, though not interchangeable. The rear end of the estate has never changed during the Sierra's lifespan. The interior was slightly modernized.

 

Thankyou for a massive 54,771,904 views

 

Shot 03.07.2016 at Cars in the Park, Beacon Park, Lichfield REF 121-157

 

Valor is stability, not of legs and arms, but of courage and the soul. ~Michel de Montaigne

 

As I remember my dad and those who have served our country this Veterans Day, I can't help but feel that for my dad, things have now come full circle.

 

I received and email this week and have been in contact with the United States Navy, as they have requested to use an image of mine - one that is posted here on Flickr- a "Sailors Christmas"- www.flickr.com/photos/karenhunnicutt/5289072208/ to use as the theme, including as the cover of their program, on their website and projected as the backdrop, for their annual United States Naval Band holiday concert held at DAR Constitution Hall in Washington DC!

 

Besides using my image and credit to me, they may include the story of my Dad, and that folks, makes this all worth it to me. Most of you know that my dad was orphaned during the depression and by the grace of God and a scheming aunt, who changed his birth certificate, he joined the Navy at 15. He spent the next 21 years serving aboard the USS Ranger and a sub chaser in the north Atlantic, he was in Japan and was a member of the forces that helped liberate Norway at the end of WWII. He served in Korea and retired in 1972. The Navy gave him a home, stability and opportunity and next to God and his family, there was nothing more that he loved. To know that my image will represent all of the good that my father instilled in me, is beyond comprehension and I am humbled and completely overwhelmed at this honor.

 

PHILIPPINE SEA (July 21, 2020) From left, HMAS Arunta (FFH 151), HMAS Hobart (DDG 39), USS Mustin (DDG 89), HMAS Canberra (L02), USS Ronald Reagan (CVN 76), HMAS Sirius (O 266), USS Antietam (CG 54), JS Teruzuki (DD 116) and HMAS Stuart (FFH 153) steam in formation during a trilateral exercise. Trilateral exercises between the JMSDF, ADF and U.S. Navy support shared goals of peace and stability while enhancing regional security and the right of all nations to trade, communicate, and choose their destiny in a free and open Indo-Pacific region. (U.S. Navy photo by Mass Communication Specialist 2nd Class Codie L. Soule)

Modern running shoes feature many fantastic designs and characteristics. A running shoe is your single most important piece of equipment as a runner. Therefore, a running shoe that provides good support, flexibility, grip, and stability are absolutely crucial. Motion control and stability...

 

Best Stability Running Shoes

I captured this shot with my Pixel 6 phone but without a tripod. It was about 7 AM and I was walking to my office at the time, which is the building on the right. I think the moon would have been sharper if I had more stability. . . I will probably try this shot again with a tripod and my DSLR and also expose for the moon then adjust the overall light in Adobe Lightroom.

"Green is the color of nature. It symbolizes growth, harmony, freshness, and fertility. Dark green is also commonly associated with money. Green has great healing power. It is the most restful color for the human eye; it can improve vision. Green suggests stability and endurance. "

 

Think Green ...

  

One solution for improving the stability of these 15-passenger vans: add a set of duals on the rear. Doesn't look great, but probably does the job.

Barclays Global Investors, San Francisco

Nature's magnificent structure, the tree combines two elements to achieve strength and balance. Trees, have a single, superbly engineered material, wood and are ingeniously designed to combine strength and flexibility. They can respond to their environment and change their design accordingly. This allows them to support their canopy of leaves using a bare minimum of structural material.

 

We are no different, our limbs hold us, or we find a way if they fail, our bodies and minds change through time, supporting our thoughts, ideas and dreams. We too have a persistent need to grow and endevour to remain stable, throughout of lives. Keep rooted, use creativity for your own pleasure and grow.

 

www.sharoncooper.co.uk

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SEXT IS ASSOCIATED with the stillness and peace of noon, but it also evokes crisis and danger. Crisis is always a purification if we understand it correctly. The very word “crisis” comes from a root that means sifting out. Crisis is a separation, a sifting out of that which is viable and can go on from that which is dead and has to be left behind.

-Music of Silence: A Sacred Journey Through the Hours of the Day

Brother David Steindl-Rast, Sharon Lebell, and Kathleen Norris

  

EAST CHINA SEA (Aug. 4, 2020) Boatswain’s Mate Seaman Valentina Imokhai, from New York, operates the ship’s helm during a full power engine run aboard the amphibious dock landing ship USS Germantown (LSD 42). Germantown, part of America Expeditionary Strike Group, is operating in the 7th Fleet area of operations to enhance interoperability with allies and partners, and serves as a ready response force to defend peace and stability in the Indo-Pacific region. (U.S. Navy photo by Mass Communication Specialist 2nd Class Taylor DiMartino)

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A catamaran is a multi-hulled watercraft featuring two parallel hulls of equal size. It is a geometry-stabilized craft, deriving its stability from its wide beam, rather than from a ballasted keel as with a monohull boat.

 

Catamarans typically have less hull volume, smaller displacement, and shallower draft than monohulls of comparable length.

 

The two hulls combined also often have a smaller hydrodynamic resistance than comparable monohulls, requiring less propulsive power from either sails or motors. The catamaran's wider stance on the water can reduce both heeling and wave-induced motion, as compared with a monohull, and can give reduced wakes.

 

Sailing Catamarans have evolved from the small boats that you see in races on the shoreline into large ocean-going cruisers capable of carrying dozens of people. Catamarans have become increasingly popular because they are faster, more stable and can carry more loads than their monohull counterparts.

 

Resources: Wikipedia; Deepsailing.com/blog/sailing-a-catamaran

  

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Thank-you for your visit, and please know that any faves or comments are always greatly appreciated!

 

Sonja

KLAX (Los Angeles International Airport) - 23 SEP 2016

 

Ethiopian Airlines "Addis Ababa" ET-AOR (FLT ETH505) climbing out from RWY 25R for a 9 hour 20 minute flight to Dublin Int'l (DUB/EIDW).

 

Below the front door is a special graphic that commemorates the 50 year anniversary as of 2013, when President Kwame Nkrumah of Ghana on 25 MAY 1963 said “Africa must unite or perish” at the First Conference of African Independent States in Addis Ababa, Ethiopia, when 31 Africa Heads of State signed the Charter of the Organisation of African Unity (OAU) which main objective was to rid Africa from colonial domination. The OAU Charter of 1963 envisaged to “harness the natural and human resources of our continent to the total advancement of our peoples in all spheres of human endeavour”.

 

Fifty years after, the mission is accomplished. Africa enjoys its total liberation and its unity, enjoys an unprecedented economic rise, enjoys more and more democracy and good governance, peace and stability just to mention a few achievements.

 

Fifty years after the First Conference of African Independents States, on 25th May 2013, Africa will celebrate the 50th anniversary of the founding of the Organisation of African Unity (OAU). The celebration of the Golden Jubilee will be the occasion to pay tribute to the Founders of African Unity and to the Fighters who liberated Africa from the yoke of colonialism. It will constitute an unprecedented opportunity to take stock of 50 years of achievements while paving the way for the next 50 years.

 

As captured in the theme adopted for the celebration of the Golden Jubilee of the OAU-AU, “Pan-Africanism and African Renaissance”, the year 2013 will constitute a unique opportunity not only to praise the achievements gained from our unity and solidarity, the values that underpin pan Africanism but will also provide Africa with a chance for renaissance and outline its vision and mission for 2063.

 

Within this year of celebration, sons and daughters from within and outside Africa are called to bring closer to reality the Vision of the AU for “an integrated, prosperous and peaceful Africa, driven by its own citizens and representing a dynamic force in global arena”.

 

First flight: 12 SEP 2012

Delivery to Ethiopian Airlines: 03 OCT 2012 as ET-AOR

Named: "Addis Ababa"

Fleet number: OR

Special graphic: 2013, Year of Pan Africanism and African Renaissance

Aircraft based at Addis Ababa Bole International Airport (ADD/HAAB)

Strobist Info:

 

....look at the Photo :)

See more photos of this, and the Wikipedia article.

 

Details, quoting from Smithsonian National Air and Space Museum | Lockheed P-38J-10-LO Lightning

 

In the P-38 Lockheed engineer Clarence "Kelly" Johnson and his team of designers created one of the most successful twin-engine fighters ever flown by any nation. From 1942 to 1945, U. S. Army Air Forces pilots flew P-38s over Europe, the Mediterranean, and the Pacific, and from the frozen Aleutian Islands to the sun-baked deserts of North Africa. Lightning pilots in the Pacific theater downed more Japanese aircraft than pilots flying any other Allied warplane.

 

Maj. Richard I. Bong, America's leading fighter ace, flew this P-38J-10-LO on April 16, 1945, at Wright Field, Ohio, to evaluate an experimental method of interconnecting the movement of the throttle and propeller control levers. However, his right engine exploded in flight before he could conduct the experiment.

 

Transferred from the United States Air Force.

 

Manufacturer:

Lockheed Aircraft Company

 

Date:

1943

 

Country of Origin:

United States of America

 

Dimensions:

Overall: 390 x 1170cm, 6345kg, 1580cm (12ft 9 9/16in. x 38ft 4 5/8in., 13988.2lb., 51ft 10 1/16in.)

 

Materials:

All-metal

 

Physical Description:

Twin-tail boom and twin-engine fighter; tricycle landing gear.

 

Long Description:

From 1942 to 1945, the thunder of P-38 Lightnings was heard around the world. U. S. Army pilots flew the P-38 over Europe, the Mediterranean, and the Pacific; from the frozen Aleutian Islands to the sun-baked deserts of North Africa. Measured by success in combat, Lockheed engineer Clarence "Kelly" Johnson and a team of designers created the most successful twin-engine fighter ever flown by any nation. In the Pacific Theater, Lightning pilots downed more Japanese aircraft than pilots flying any other Army Air Forces warplane.

 

Johnson and his team conceived this twin-engine, single-pilot fighter airplane in 1936 and the Army Air Corps authorized the firm to build it in June 1937. Lockheed finished constructing the prototype XP-38 and delivered it to the Air Corps on New Year's Day, 1939. Air Corps test pilot and P-38 project officer, Lt. Benjamin S. Kelsey, first flew the aircraft on January 27. Losing this prototype in a crash at Mitchel Field, New York, with Kelsey at the controls, did not deter the Air Corps from ordering 13 YP-38s for service testing on April 27. Kelsey survived the crash and remained an important part of the Lightning program. Before the airplane could be declared ready for combat, Lockheed had to block the effects of high-speed aerodynamic compressibility and tail buffeting, and solve other problems discovered during the service tests.

 

The most vexing difficulty was the loss of control in a dive caused by aerodynamic compressibility. During late spring 1941, Air Corps Major Signa A. Gilke encountered serious trouble while diving his Lightning at high-speed from an altitude of 9,120 m (30,000 ft). When he reached an indicated airspeed of about 515 kph (320 mph), the airplane's tail began to shake violently and the nose dropped until the dive was almost vertical. Signa recovered and landed safely and the tail buffet problem was soon resolved after Lockheed installed new fillets to improve airflow where the cockpit gondola joined the wing center section. Seventeen months passed before engineers began to determine what caused the Lightning's nose to drop. They tested a scale model P-38 in the Ames Laboratory wind tunnel operated by the NACA (National Advisory Committee for Aeronautics) and found that shock waves formed when airflow over the wing leading edges reached transonic speeds. The nose drop and loss of control was never fully remedied but Lockheed installed dive recovery flaps under each wing in 1944. These devices slowed the P-38 enough to allow the pilot to maintain control when diving at high-speed.

 

Just as the development of the North American P-51 Mustang, Republic P-47 Thunderbolt, and the Vought F4U Corsair (see NASM collection for these aircraft) pushed the limits of aircraft performance into unexplored territory, so too did P-38 development. The type of aircraft envisioned by the Lockheed design team and Air Corps strategists in 1937 did not appear until June 1944. This protracted shakedown period mirrors the tribulations suffered by Vought in sorting out the many technical problems that kept F4U Corsairs off U. S. Navy carrier decks until the end of 1944.

 

Lockheed's efforts to trouble-shoot various problems with the design also delayed high-rate, mass production. When Japan attacked Pearl Harbor, the company had delivered only 69 Lightnings to the Army. Production steadily increased and at its peak in 1944, 22 sub-contractors built various Lightning components and shipped them to Burbank, California, for final assembly. Consolidated-Vultee (Convair) subcontracted to build the wing center section and the firm later became prime manufacturer for 2,000 P-38Ls but that company's Nashville plant completed only 113 examples of this Lightning model before war's end. Lockheed and Convair finished 10,038 P-38 aircraft including 500 photo-reconnaissance models. They built more L models, 3,923, than any other version.

 

To ease control and improve stability, particularly at low speeds, Lockheed equipped all Lightnings, except a batch ordered by Britain, with propellers that counter-rotated. The propeller to the pilot's left turned counter-clockwise and the propeller to his right turned clockwise, so that one propeller countered the torque and airflow effects generated by the other. The airplane also performed well at high speeds and the definitive P-38L model could make better than 676 kph (420 mph) between 7,600 and 9,120 m (25,000 and 30,000 ft). The design was versatile enough to carry various combinations of bombs, air-to-ground rockets, and external fuel tanks. The multi-engine configuration reduced the Lightning loss-rate to anti-aircraft gunfire during ground attack missions. Single-engine airplanes equipped with power plants cooled by pressurized liquid, such as the North American P-51 Mustang (see NASM collection), were particularly vulnerable. Even a small nick in one coolant line could cause the engine to seize in a matter of minutes.

 

The first P-38s to reach the Pacific combat theater arrived on April 4, 1942, when a version of the Lightning that carried reconnaissance cameras (designated the F-4), joined the 8th Photographic Squadron based in Australia. This unit launched the first P-38 combat missions over New Guinea and New Britain during April. By May 29, the first 25 P-38s had arrived in Anchorage, Alaska. On August 9, pilots of the 343rd Fighter Group, Eleventh Air Force, flying the P-38E, shot down a pair of Japanese flying boats.

 

Back in the United States, Army Air Forces leaders tried to control a rumor that Lightnings killed their own pilots. On August 10, 1942, Col. Arthur I. Ennis, Chief of U. S. Army Air Forces Public Relations in Washington, told a fellow officer "… Here's what the 4th Fighter [training] Command is up against… common rumor out there that the whole West Coast was filled with headless bodies of men who jumped out of P-38s and had their heads cut off by the propellers." Novice Lightning pilots unfamiliar with the correct bailout procedures actually had more to fear from the twin-boom tail, if an emergency dictated taking to the parachute but properly executed, Lightning bailouts were as safe as parachuting from any other high-performance fighter of the day. Misinformation and wild speculation about many new aircraft was rampant during the early War period.

 

Along with U. S. Navy Grumman F4F Wildcats (see NASM collection) and Curtiss P-40 Warhawks (see NASM collection), Lightnings were the first American fighter airplanes capable of consistently defeating Japanese fighter aircraft. On November 18, men of the 339th Fighter Squadron became the first Lightning pilots to attack Japanese fighters. Flying from Henderson Field on Guadalcanal, they claimed three during a mission to escort Boeing B-17 Flying Fortress bombers (see NASM collection).

 

On April 18, 1943, fourteen P-38 pilots from the 70th and the 339th Fighter Squadrons, 347th Fighter Group, accomplished one of the most important Lightning missions of the war. American ULTRA cryptanalysts had decoded Japanese messages that revealed the timetable for a visit to the front by the commander of the Imperial Japanese Navy, Admiral Isoroku Yamamoto. This charismatic leader had crafted the plan to attack Pearl Harbor and Allied strategists believed his loss would severely cripple Japanese morale. The P-38 pilots flew 700 km (435 miles) at heights from 3-15 m (10-50 feet) above the ocean to avoid detection. Over the coast of Bougainville, they intercepted a formation of two Mitsubishi G4M BETTY bombers (see NASM collection) carrying the Admiral and his staff, and six Mitsubishi A6M Zero fighters (see NASM collection) providing escort. The Lightning pilots downed both bombers but lost Lt. Ray Hine to a Zero.

 

In Europe, the first Americans to down a Luftwaffe aircraft were Lt. Elza E. Shahan flying a 27th Fighter Squadron P-38E, and Lt. J. K. Shaffer flying a Curtiss P-40 (see NASM collection) in the 33rd Fighter Squadron. The two flyers shared the destruction of a Focke-Wulf Fw 200C-3 Condor maritime strike aircraft over Iceland on August 14, 1942. Later that month, the 1st fighter group accepted Lightnings and began combat operations from bases in England but this unit soon moved to fight in North Africa. More than a year passed before the P-38 reappeared over Western Europe. While the Lightning was absent, U. S. Army Air Forces strategists had relearned a painful lesson: unescorted bombers cannot operate successfully in the face of determined opposition from enemy fighters. When P-38s returned to England, the primary mission had become long-range bomber escort at ranges of about 805 kms (500 miles) and at altitudes above 6,080 m (20,000 ft).

 

On October 15, 1943, P-38H pilots in the 55th Fighter Group flew their first combat mission over Europe at a time when the need for long-range escorts was acute. Just the day before, German fighter pilots had destroyed 60 of 291 Eighth Air Force B-17 Flying Fortresses (see NASM collection) during a mission to bomb five ball-bearing plants at Schweinfurt, Germany. No air force could sustain a loss-rate of nearly 20 percent for more than a few missions but these targets lay well beyond the range of available escort fighters (Republic P-47 Thunderbolt, see NASM collection). American war planners hoped the long-range capabilities of the P-38 Lightning could halt this deadly trend, but the very high and very cold environment peculiar to the European air war caused severe power plant and cockpit heating difficulties for the Lightning pilots. The long-range escort problem was not completely solved until the North American P-51 Mustang (see NASM collection) began to arrive in large numbers early in 1944.

 

Poor cockpit heating in the H and J model Lightnings made flying and fighting at altitudes that frequently approached 12,320 m (40,000 ft) nearly impossible. This was a fundamental design flaw that Kelly Johnson and his team never anticipated when they designed the airplane six years earlier. In his seminal work on the Allison V-1710 engine, Daniel Whitney analyzed in detail other factors that made the P-38 a disappointing airplane in combat over Western Europe.

 

• Many new and inexperienced pilots arrived in England during December 1943, along with the new J model P-38 Lightning.

 

• J model rated at 1,600 horsepower vs. 1,425 for earlier H model Lightnings. This power setting required better maintenance between flights. It appears this work was not done in many cases.

 

• During stateside training, Lightning pilots were taught to fly at high rpm settings and low engine manifold pressure during cruise flight. This was very hard on the engines, and not in keeping with technical directives issued by Allison and Lockheed.

 

• The quality of fuel in England may have been poor, TEL (tetraethyl lead) fuel additive appeared to condense inside engine induction manifolds, causing detonation (destructive explosion of fuel mixture rather than controlled burning).

 

• Improved turbo supercharger intercoolers appeared on the J model P-38. These devices greatly reduced manifold temperatures but this encouraged TEL condensation in manifolds during cruise flight and increased spark plug fouling.

 

Using water injection to minimize detonation might have reduced these engine problems. Both the Republic P-47 Thunderbolt and the North American P-51 Mustang (see NASM collection) were fitted with water injection systems but not the P-38. Lightning pilots continued to fly, despite these handicaps.

 

During November 1942, two all-Lightning fighter groups, the 1st and the 14th, began operating in North Africa. In the Mediterranean Theater, P-38 pilots flew more sorties than Allied pilots flying any other type of fighter. They claimed 608 enemy a/c destroyed in the air, 123 probably destroyed and 343 damaged, against the loss of 131 Lightnings.

 

In the war against Japan, the P-38 truly excelled. Combat rarely occurred above 6,080 m (20,000 ft) and the engine and cockpit comfort problems common in Europe never plagued pilots in the Pacific Theater. The Lightning's excellent range was used to full advantage above the vast expanses of water. In early 1945, Lightning pilots of the 12th Fighter Squadron, 18th Fighter Group, flew a mission that lasted 10 ½ hours and covered more than 3,220 km (2,000 miles). In August, P-38 pilots established the world's long-distance record for a World War II combat fighter when they flew from the Philippines to the Netherlands East Indies, a distance of 3,703 km (2,300 miles). During early 1944, Lightning pilots in the 475th Fighter Group began the 'race of aces.' By March, Lieutenant Colonel Thomas J. Lynch had scored 21 victories before he fell to antiaircraft gunfire while strafing enemy ships. Major Thomas B. McGuire downed 38 Japanese aircraft before he was killed when his P-38 crashed at low altitude in early January 1945. Major Richard I. Bong became America's highest scoring fighter ace (40 victories) but died in the crash of a Lockheed P-80 (see NASM collection) on August 6, 1945.

 

Museum records show that Lockheed assigned the construction number 422-2273 to the National Air and Space Museum's P-38. The Army Air Forces accepted this Lightning as a P-38J-l0-LO on November 6, 1943, and the service identified the airplane with the serial number 42-67762. Recent investigations conducted by a team of specialists at the Paul E. Garber Facility, and Herb Brownstein, a volunteer in the Aeronautics Division at the National Air and Space Museum, have revealed many hitherto unknown aspects to the history of this aircraft.

 

Brownstein examined NASM files and documents at the National Archives. He discovered that a few days after the Army Air Forces (AAF) accepted this airplane, the Engineering Division at Wright Field in Dayton, Ohio, granted Lockheed permission to convert this P-38 into a two-seat trainer. The firm added a seat behind the pilot to accommodate an instructor who would train civilian pilots in instrument flying techniques. Once trained, these test pilots evaluated new Lightnings fresh off the assembly line.

 

In a teletype sent by the Engineering Division on March 2, 1944, Brownstein also discovered that this P-38 was released to Colonel Benjamin S. Kelsey from March 3 to April 10, 1944, to conduct special tests. This action was confirmed the following day in a cable from the War Department. This same pilot, then a Lieutenant, flew the XP-38 across the United States in 1939 and survived the crash that destroyed this Lightning at Mitchel Field, New York. In early 1944, Kelsey was assigned to the Eighth Air Force in England and he apparently traveled to the Lockheed factory at Burbank to pick up the P-38. Further information about these tests and Kelsey's involvement remain an intriguing question.

 

One of Brownstein's most important discoveries was a small file rich with information about the NASM Lightning. This file contained a cryptic reference to a "Major Bong" who flew the NASM P-38 on April 16, 1945, at Wright Field. Bong had planned to fly for an hour to evaluate an experimental method of interconnecting the movement of the throttle and propeller control levers. His flight ended after twenty-minutes when "the right engine blew up before I had a chance [to conduct the test]." The curator at the Richard I. Bong Heritage Center confirmed that America's highest scoring ace made this flight in the NASM P-38 Lightning.

 

Working in Building 10 at the Paul E. Garber Facility, Rob Mawhinney, Dave Wilson, Wil Lee, Bob Weihrauch, Jim Purton, and Heather Hutton spent several months during the spring and summer of 2001 carefully disassembling, inspecting, and cleaning the NASM Lightning. They found every hardware modification consistent with a model J-25 airplane, not the model J-10 painted in the data block beneath the artifact's left nose. This fact dovetails perfectly with knowledge uncovered by Brownstein. On April 10, the Engineering Division again cabled Lockheed asking the company to prepare 42-67762 for transfer to Wright Field "in standard configuration." The standard P-38 configuration at that time was the P-38J-25. The work took several weeks and the fighter does not appear on Wright Field records until May 15, 1944. On June 9, the Flight Test Section at Wright Field released the fighter for flight trials aimed at collecting pilot comments on how the airplane handled.

 

Wright Field's Aeromedical Laboratory was the next organization involved with this P-38. That unit installed a kit on July 26 that probably measured the force required to move the control wheel left and right to actuate the power-boosted ailerons installed in all Lightnings beginning with version J-25. From August 12-16, the Power Plant Laboratory carried out tests to measure the hydraulic pump temperatures on this Lightning. Then beginning September 16 and lasting about ten days, the Bombing Branch, Armament Laboratory, tested type R-3 fragmentation bomb racks. The work appears to have ended early in December. On June 20, 1945, the AAF Aircraft Distribution Office asked that the Air Technical Service Command transfer the Lightning from Wright Field to Altus Air Force Base, Oklahoma, a temporary holding area for Air Force museum aircraft. The P-38 arrived at the Oklahoma City Air Depot on June 27, 1945, and mechanics prepared the fighter for flyable storage.

 

Airplane Flight Reports for this Lightning also describe the following activities and movements:

 

6-21-45 Wright Field, Ohio, 5.15 hours of flying.

6-22-45Wright Field, Ohio, .35 minutes of flying by Lt. Col. Wendel [?] J. Kelley and P. Shannon.

6-25-45Altus, Oklahoma, .55 hours flown, pilot P. Shannon.

6-27-45Altus, Oklahoma, #2 engine changed, 1.05 hours flown by Air Corps F/O Ralph F. Coady.

10-5-45 OCATSC-GCAAF (Garden City Army Air Field, Garden City, Kansas), guns removed and ballast added.

10-8-45Adams Field, Little Rock, Arkansas.

10-9-45Nashville, Tennessee,

5-28-46Freeman Field, Indiana, maintenance check by Air Corps Capt. H. M. Chadhowere [sp]?

7-24-46Freeman Field, Indiana, 1 hour local flight by 1st Lt. Charles C. Heckel.

7-31-46 Freeman Field, Indiana, 4120th AAF Base Unit, ferry flight to Orchard Place [Illinois] by 1st Lt. Charles C. Heckel.

 

On August 5, 1946, the AAF moved the aircraft to another storage site at the former Consolidated B-24 bomber assembly plant at Park Ridge, Illinois. A short time later, the AAF transferred custody of the Lightning and more than sixty other World War II-era airplanes to the Smithsonian National Air Museum. During the early 1950s, the Air Force moved these airplanes from Park Ridge to the Smithsonian storage site at Suitland, Maryland.

 

• • •

 

Quoting from Wikipedia | Lockheed P-38 Lightning:

 

The Lockheed P-38 Lightning was a World War II American fighter aircraft built by Lockheed. Developed to a United States Army Air Corps requirement, the P-38 had distinctive twin booms and a single, central nacelle containing the cockpit and armament. Named "fork-tailed devil" by the Luftwaffe and "two planes, one pilot" by the Japanese, the P-38 was used in a number of roles, including dive bombing, level bombing, ground-attack, photo reconnaissance missions, and extensively as a long-range escort fighter when equipped with drop tanks under its wings.

 

The P-38 was used most successfully in the Pacific Theater of Operations and the China-Burma-India Theater of Operations as the mount of America's top aces, Richard Bong (40 victories) and Thomas McGuire (38 victories). In the South West Pacific theater, the P-38 was the primary long-range fighter of United States Army Air Forces until the appearance of large numbers of P-51D Mustangs toward the end of the war. The P-38 was unusually quiet for a fighter, the exhaust muffled by the turbo-superchargers. It was extremely forgiving, and could be mishandled in many ways, but the rate of roll was too slow for it to excel as a dogfighter. The P-38 was the only American fighter aircraft in production throughout American involvement in the war, from Pearl Harbor to Victory over Japan Day.

 

Variants: Lightning in maturity: P-38J

 

The P-38J was introduced in August 1943. The turbo-supercharger intercooler system on previous variants had been housed in the leading edges of the wings and had proven vulnerable to combat damage and could burst if the wrong series of controls were mistakenly activated. In the P-38J model, the streamlined engine nacelles of previous Lightnings were changed to fit the intercooler radiator between the oil coolers, forming a "chin" that visually distinguished the J model from its predecessors. While the P-38J used the same V-1710-89/91 engines as the H model, the new core-type intercooler more efficiently lowered intake manifold temperatures and permitted a substantial increase in rated power. The leading edge of the outer wing was fitted with 55 gal (208 l) fuel tanks, filling the space formerly occupied by intercooler tunnels, but these were omitted on early P-38J blocks due to limited availability.

 

The final 210 J models, designated P-38J-25-LO, alleviated the compressibility problem through the addition of a set of electrically-actuated dive recovery flaps just outboard of the engines on the bottom centerline of the wings. With these improvements, a USAAF pilot reported a dive speed of almost 600 mph (970 km/h), although the indicated air speed was later corrected for compressibility error, and the actual dive speed was lower. Lockheed manufactured over 200 retrofit modification kits to be installed on P-38J-10-LO and J-20-LO already in Europe, but the USAAF C-54 carrying them was shot down by an RAF pilot who mistook the Douglas transport for a German Focke-Wulf Condor. Unfortunately the loss of the kits came during Lockheed test pilot Tony LeVier's four-month morale-boosting tour of P-38 bases. Flying a new Lightning named "Snafuperman" modified to full P-38J-25-LO specs at Lockheed's modification center near Belfast, LeVier captured the pilots' full attention by routinely performing maneuvers during March 1944 that common Eighth Air Force wisdom held to be suicidal. It proved too little too late because the decision had already been made to re-equip with Mustangs.

 

The P-38J-25-LO production block also introduced hydraulically-boosted ailerons, one of the first times such a system was fitted to a fighter. This significantly improved the Lightning's rate of roll and reduced control forces for the pilot. This production block and the following P-38L model are considered the definitive Lightnings, and Lockheed ramped up production, working with subcontractors across the country to produce hundreds of Lightnings each month.

 

Noted P-38 pilots

 

Richard Bong and Thomas McGuire

 

The American ace of aces and his closest competitor both flew Lightnings as they tallied 40 and 38 victories respectively. Majors Richard I. "Dick" Bong and Thomas J. "Tommy" McGuire of the USAAF competed for the top position. Both men were awarded the Medal of Honor.

 

McGuire was killed in air combat in January 1945 over the Philippines, after racking up 38 confirmed kills, making him the second-ranking American ace. Bong was rotated back to the United States as America's ace of aces, after making 40 kills, becoming a test pilot. He was killed on 6 August 1945, the day the atomic bomb was dropped on Japan, when his P-80 Shooting Star jet fighter flamed out on takeoff.

 

Charles Lindbergh

 

The famed aviator Charles Lindbergh toured the South Pacific as a civilian contractor for United Aircraft Corporation, comparing and evaluating performance of single- and twin-engined fighters for Vought. He worked to improve range and load limits of the F4U Corsair, flying both routine and combat strafing missions in Corsairs alongside Marine pilots. In Hollandia, he attached himself to the 475th FG flying P-38s so that he could investigate the twin-engine fighter. Though new to the machine, he was instrumental in extending the range of the P-38 through improved throttle settings, or engine-leaning techniques, notably by reducing engine speed to 1,600 rpm, setting the carburetors for auto-lean and flying at 185 mph (298 km/h) indicated airspeed which reduced fuel consumption to 70 gal/h, about 2.6 mpg. This combination of settings had been considered dangerous; it was thought it would upset the fuel mixture and cause an explosion. Everywhere Lindbergh went in the South Pacific, he was accorded the normal preferential treatment of a visiting colonel, though he had resigned his Air Corps Reserve colonel's commission three years before. While with the 475th, he held training classes and took part in a number of Army Air Corps combat missions. On 28 July 1944, Lindbergh shot down a Mitsubishi Ki-51 "Sonia" flown expertly by the veteran commander of 73rd Independent Flying Chutai, Imperial Japanese Army Captain Saburo Shimada. In an extended, twisting dogfight in which many of the participants ran out of ammunition, Shimada turned his aircraft directly toward Lindbergh who was just approaching the combat area. Lindbergh fired in a defensive reaction brought on by Shimada's apparent head-on ramming attack. Hit by cannon and machine gun fire, the "Sonia's" propeller visibly slowed, but Shimada held his course. Lindbergh pulled up at the last moment to avoid collision as the damaged "Sonia" went into a steep dive, hit the ocean and sank. Lindbergh's wingman, ace Joseph E. "Fishkiller" Miller, Jr., had also scored hits on the "Sonia" after it had begun its fatal dive, but Miller was certain the kill credit was Lindbergh's. The unofficial kill was not entered in the 475th's war record. On 12 August 1944 Lindbergh left Hollandia to return to the United States.

 

Charles MacDonald

 

The seventh-ranking American ace, Charles H. MacDonald, flew a Lightning against the Japanese, scoring 27 kills in his famous aircraft, the Putt Putt Maru.

 

Robin Olds

 

Main article: Robin Olds

 

Robin Olds was the last P-38 ace in the Eighth Air Force and the last in the ETO. Flying a P-38J, he downed five German fighters on two separate missions over France and Germany. He subsequently transitioned to P-51s to make seven more kills. After World War II, he flew F-4 Phantom IIs in Vietnam, ending his career as brigadier general with 16 kills.

 

Clay Tice

 

A P-38 piloted by Clay Tice was the first American aircraft to land in Japan after VJ-Day, when he and his wingman set down on Nitagahara because his wingman was low on fuel.

 

Antoine de Saint-Exupéry

 

Noted aviation pioneer and writer Antoine de Saint-Exupéry vanished in a F-5B-1-LO, 42-68223, c/n 2734, of Groupe de Chasse II/33, out of Borgo-Porreta, Bastia, Corsica, a reconnaissance variant of the P-38, while on a flight over the Mediterranean, from Corsica to mainland France, on 31 July 1944. His health, both physical and mental (he was said to be intermittently subject to depression), had been deteriorating and there had been talk of taking him off flight status. There have been suggestions (although no proof to date) that this was a suicide rather than an aircraft failure or combat loss. In 2000, a French scuba diver found the wreckage of a Lightning in the Mediterranean off the coast of Marseille, and it was confirmed in April 2004 as Saint-Exupéry's F-5B. No evidence of air combat was found. In March 2008, a former Luftwaffe pilot, Horst Rippert from Jagdgruppe 200, claimed to have shot down Saint-Exupéry.

 

Adrian Warburton

 

The RAF's legendary photo-recon "ace", Wing Commander Adrian Warburton DSO DFC, was the pilot of a Lockheed P-38 borrowed from the USAAF that took off on 12 April 1944 to photograph targets in Germany. W/C Warburton failed to arrive at the rendezvous point and was never seen again. In 2003, his remains were recovered in Germany from his wrecked USAAF P-38 Lightning.

 

• • • • •

 

Quoting Smithsonian National Air and Space Museum | Boeing B-29 Superfortress "Enola Gay":

 

Boeing's B-29 Superfortress was the most sophisticated propeller-driven bomber of World War II and the first bomber to house its crew in pressurized compartments. Although designed to fight in the European theater, the B-29 found its niche on the other side of the globe. In the Pacific, B-29s delivered a variety of aerial weapons: conventional bombs, incendiary bombs, mines, and two nuclear weapons.

 

On August 6, 1945, this Martin-built B-29-45-MO dropped the first atomic weapon used in combat on Hiroshima, Japan. Three days later, Bockscar (on display at the U.S. Air Force Museum near Dayton, Ohio) dropped a second atomic bomb on Nagasaki, Japan. Enola Gay flew as the advance weather reconnaissance aircraft that day. A third B-29, The Great Artiste, flew as an observation aircraft on both missions.

 

Transferred from the United States Air Force.

 

Manufacturer:

Boeing Aircraft Co.

Martin Co., Omaha, Nebr.

 

Date:

1945

 

Country of Origin:

United States of America

 

Dimensions:

Overall: 900 x 3020cm, 32580kg, 4300cm (29ft 6 5/16in. x 99ft 1in., 71825.9lb., 141ft 15/16in.)

 

Materials:

Polished overall aluminum finish

 

Physical Description:

Four-engine heavy bomber with semi-monoqoque fuselage and high-aspect ratio wings. Polished aluminum finish overall, standard late-World War II Army Air Forces insignia on wings and aft fuselage and serial number on vertical fin; 509th Composite Group markings painted in black; "Enola Gay" in black, block letters on lower left nose.

Terrace Falls Reserve

Blue Mountains National Park.

 

The Blue Mtns received some torrential rain for a couple of days, so it was a great time time to explore the waterfalls in the mid mountains area.

These waterfalls only flow strongly after decent rain.

I waited for a day after the rain finished to so that all the sediment that normally turns the water an ugly brown would’ve settled back down.

 

My friend Bez and I headed down into the Reserve and we were met by a rainforest wetland.

The waterfalls were flowing like I’d never seen them before, and there was water and mud everywhere.

The walking track had a temporary creek running thru it and all the usually dry creek crossings became tricky & slippery wades.

There were cascades tumbling down where previously there were none.

The cliffs were ‘weeping’ moisture which made it quite a refreshing walk.

And of course, the wet brought out the leeches in force.

 

The conditions were exhilarating but made for challenging photography.

The torrent of water that was flowing down the creeks was creating a fine mist that continually covered camera lenses.

This mist also created a rather hazy washed-out looking landscape.

All the usual spots for waterfall compositions were now under water, and the force of the water played havoc with tripod stability.

Also the amount of water made longer exposures trick due to over-exposure.

 

We reached the Bedford Ck junction and Bez had to head off for a family function.

I continued left towards Bedford Pool and headed upstream on un-named creek that headed towards Pyramid Falls.

This gully is normally pretty dry but was alive with flowing water with temporary cascades and rivulets flowing in all directions.

It was certainly quite a memorable day with conditions that are pretty rare for these parts.

 

Stability Diffusion

Different forms of fluctuations of the terrestrial gravity field are observed by gravity experiments. For example, atmospheric pressure fluctuations generate a gravity-noise foreground in measurements with super-conducting gravimeters. Gravity changes caused by high-magnitude earthquakes have been detected with the satellite gravity experiment GRACE, and we expect high-frequency terrestrial gravity fluctuations produced by ambient seismic fields to limit the sensitivity of ground-based gravitational-wave (GW) detectors. Accordingly, terrestrial gravity fluctuations are considered noise and signal depending on the experiment. Here, we will focus on ground-based gravimetry. This field is rapidly progressing through the development of GW detectors. The technology is pushed to its current limits in the advanced generation of the LIGO and Virgo detectors, targeting gravity strain sensitivities better than 10−23 Hz−1/2 above a few tens of a Hz. Alternative designs for GW detectors evolving from traditional gravity gradiometers such as torsion bars, atom interferometers, and superconducting gradiometers are currently being developed to extend the detection band to frequencies below 1 Hz. The goal of this article is to provide the analytical framework to describe terrestrial gravity perturbations in these experiments. Models of terrestrial gravity perturbations related to seismic fields, atmospheric disturbances, and vibrating, rotating or moving objects, are derived and analyzed. The models are then used to evaluate passive and active gravity noise mitigation strategies in GW detectors, or alternatively, to describe their potential use in geophysics. The article reviews the current state of the field, and also presents new analyses especially with respect to the impact of seismic scattering on gravity perturbations, active gravity noise cancellation, and time-domain models of gravity perturbations from atmospheric and seismic point sources. Our understanding of terrestrial gravity fluctuations will have great impact on the future development of GW detectors and high-precision gravimetry in general, and many open questions need to be answered still as emphasized in this article.

 

Keywords: Terrestrial gravity, Newtonian noise, Wiener filter, Mitigation

Go to:

Introduction

In the coming years, we will see a transition in the field of high-precision gravimetry from observations of slow lasting changes of the gravity field to the experimental study of fast gravity fluctuations. The latter will be realized by the advanced generation of the US-based LIGO [1] and Europe-based Virgo [7] gravitational-wave (GW) detectors. Their goal is to directly observe for the first time GWs that are produced by astrophysical sources such as inspiraling and merging neutron-star or black-hole binaries. Feasibility of the laser-interferometric detector concept has been demonstrated successfully with the first generation of detectors, which, in addition to the initial LIGO and Virgo detectors, also includes the GEO600 [119] and TAMA300 [161] detectors, and several prototypes around the world. The impact of these projects onto the field is two-fold. First of all, the direct detection of GWs will be a milestone in science opening a new window to our universe, and marking the beginning of a new era in observational astronomy. Second, several groups around the world have already started to adapt the technology to novel interferometer concepts [60, 155], with potential applications not only in GW science, but also geophysics. The basic measurement scheme is always the same: the relative displacement of test masses is monitored by using ultra-stable lasers. Progress in this field is strongly dependent on how well the motion of the test masses can be shielded from the environment. Test masses are placed in vacuum and are either freely falling (e.g., atom clouds [137]), or suspended and seismically isolated (e.g., high-quality glass or crystal mirrors as used in all of the detectors listed above). The best seismic isolations realized so far are effective above a few Hz, which limits the frequency range of detectable gravity fluctuations. Nonetheless, low-frequency concepts are continuously improving, and it is conceivable that future detectors will be sufficiently sensitive to detect GWs well below a Hz [88].

 

Terrestrial gravity perturbations were identified as a potential noise source already in the first concept laid out for a laser-interferometric GW detector [171]. Today, this form of noise is known as “terrestrial gravitational noise”, “Newtonian noise”, or “gravity-gradient noise”. It has never been observed in GW detectors, but it is predicted to limit the sensitivity of the advanced GW detectors at low frequencies. The most important source of gravity noise comes from fluctuating seismic fields [151]. Gravity perturbations from atmospheric disturbances such as pressure and temperature fluctuations can become significant at lower frequencies [51]. Anthropogenic sources of gravity perturbations are easier to avoid, but could also be relevant at lower frequencies [163]. Today, we only have one example of a direct observation of gravity fluctuations, i.e., from pressure fluctuations of the atmosphere in high-precision gravimeters [128]. Therefore, almost our entire understanding of gravity fluctuations is based on models. Nonetheless, potential sensitivity limits of future large-scale GW detectors need to be identified and characterized well in advance, and so there is a need to continuously improve our understanding of terrestrial gravity noise. Based on our current understanding, the preferred option is to construct future GW detectors underground to avoid the most dominant Newtonian-noise contributions. This choice was made for the next-generation Japanese GW detector KAGRA, which is currently being constructed underground at the Kamioka site [17], and also as part of a design study for the Einstein Telescope in Europe [140, 139]. While the benefit from underground construction with respect to gravity noise is expected to be substantial in GW detectors sensitive above a few Hz [27], it can be argued that it is less effective at lower frequencies [88].

 

Alternative mitigation strategies includes coherent noise cancellation [42]. The idea is to monitor the sources of gravity perturbations using auxiliary sensors such as microphones and seismometers, and to use their data to generate a coherent prediction of gravity noise. This technique is successfully applied in gravimeters to reduce the foreground of atmospheric gravity noise using collocated pressure sensors [128]. It is also noteworthy that the models of the atmospheric gravity noise are consistent with observations. This should give us some confidence at least that coherent Newtonian-noise cancellation can also be achieved in GW detectors. It is evident though that a model-based prediction of the performance of coherent noise cancellation schemes is prone to systematic errors as long as the properties of the sources are not fully understood. Ongoing experiments at the Sanford Underground Research Facility with the goal to characterize seismic fields in three dimensions are expected to deliver first data from an underground seismometer array in 2015 (see [89] for results from an initial stage of the experiment). While most people would argue that constructing GW detectors underground is always advantageous, it is still necessary to estimate how much is gained and whether the science case strongly profits from it. This is a complicated problem that needs to be answered as part of a site selection process.

 

More recently, high-precision gravity strainmeters have been considered as monitors of geophysical signals [83]. Analytical models have been calculated, which allow us to predict gravity transients from seismic sources such as earthquakes. It was suggested to implement gravity strainmeters in existing earthquake-early warning systems to increase warning times. It is also conceivable that an alternative method to estimate source parameters using gravity signals will improve our understanding of seismic sources. Potential applications must still be investigated in greater detail, but the study already demonstrates that the idea to use GW technology to realize new geophysical sensors seems feasible. As explained in [49], gravitational forces start to dominate the dynamics of seismic phenomena below about 1 mHz (which coincides approximately with a similar transition in atmospheric dynamics where gravity waves start to dominate over other forms of oscillations [164]). Seismic isolation would be ineffective below 1 mHz since the gravitational acceleration of a test mass produced by seismic displacement becomes comparable to the seismic acceleration itself. Therefore, we claim that 10 mHz is about the lowest frequency at which ground-based gravity strainmeters will ever be able to detect GWs, and consequently, modelling terrestrial gravity perturbations in these detectors can focus on frequencies above 10 mHz.

 

This article is divided into six main sections. Section 2 serves as an introduction to gravity measurements focussing on the response mechanisms and basic properties of gravity sensors. Section 3 describes models of gravity perturbations from ambient seismic fields. The results can be used to estimate noise spectra at the surface and underground. A subsection is devoted to the problem of noise estimation in low-frequency GW detectors, which differs from high-frequency estimates mostly in that gravity perturbations are strongly correlated between different test masses. In the low-frequency regime, the gravity noise is best described as gravity-gradient noise. Section 4 is devoted to time domain models of transient gravity perturbations from seismic point sources. The formalism is applied to point forces and shear dislocations. The latter allows us to estimate gravity perturbations from earthquakes. Atmospheric models of gravity perturbations are presented in Section 5. This includes gravity perturbations from atmospheric temperature fields, infrasound fields, shock waves, and acoustic noise from turbulence. The solution for shock waves is calculated in time domain using the methods of Section 4. A theoretical framework to calculate gravity perturbations from objects is given in Section 6. Since many different types of objects can be potential sources of gravity perturbations, the discussion focusses on the development of a general method instead of summarizing all of the calculations that have been done in the past. Finally, Section 7 discusses possible passive and active noise mitigation strategies. Due to the complexity of the problem, most of the section is devoted to active noise cancellation providing the required analysis tools and showing limitations of this technique. Site selection is the main topic under passive mitigation, and is discussed in the context of reducing environmental noise and criteria relevant to active noise cancellation. Each of these sections ends with a summary and a discussion of open problems. While this article is meant to be a review of the current state of the field, it also presents new analyses especially with respect to the impact of seismic scattering on gravity perturbations (Sections 3.3.2 and 3.3.3), active gravity noise cancellation (Section 7.1.3), and timedomain models of gravity perturbations from atmospheric and seismic point sources (Sections 4.1, 4.5, and 5.3).

 

Even though evident to experts, it is worth emphasizing that all calculations carried out in this article have a common starting point, namely Newton’s universal law of gravitation. It states that the attractive gravitational force equation M1 between two point masses m1, m2 is given by

 

equation M21

where G = 6.672 × 10−11 N m2/kg2 is the gravitational constant. Eq. (1) gives rise to many complex phenomena on Earth such as inner-core oscillations [156], atmospheric gravity waves [157], ocean waves [94, 177], and co-seismic gravity changes [122]. Due to its importance, we will honor the eponym by referring to gravity noise as Newtonian noise in the following. It is thereby clarified that the gravity noise models considered in this article are non-relativistic, and propagation effects of gravity changes are neglected. While there could be interesting scenarios where this approximation is not fully justified (e.g., whenever a gravity perturbation can be sensed by several sensors and differences in arrival times can be resolved), it certainly holds in any of the problems discussed in this article. We now invite the reader to enjoy the rest of the article, and hope that it proves to be useful.

 

Go to:

Gravity Measurements

In this section, we describe the relevant mechanisms by which a gravity sensor can couple to gravity perturbations, and give an overview of the most widely used measurement schemes: the (relative) gravimeter [53, 181], the gravity gradiometer [125], and the gravity strainmeter. The last category includes the large-scale GW detectors Virgo [6], LIGO [91], GEO600 [119], KAGRA [17], and a new generation of torsion-bar antennas currently under development [13]. Also atom interferometers can potentially be used as gravity strainmeters in the future [62]. Strictly speaking, none of the sensors only responds to a single field quantity (such as changes in gravity acceleration or gravity strain), but there is always a dominant response mechanism in each case, which justifies to give the sensor a specific name. A clear distinction between gravity gradiometers and gravity strainmeters has never been made to our knowledge. Therefore the sections on these two measurement principles will introduce a definition, and it is by no means the only possible one. Later on in this article, we almost exclusively discuss gravity models relevant to gravity strainmeters since the focus lies on gravity fluctuations above 10 mHz. Today, the sensitivity near 10 mHz of gravimeters towards gravity fluctuations is still competitive to or exceeds the sensitivity of gravity strainmeters, but this is likely going to change in the future so that we can expect strainmeters to become the technology of choice for gravity observations above 10 mHz [88]. The following sections provide further details on this statement. Space-borne gravity experiments such as GRACE [167] will not be included in this overview. The measurement principle of GRACE is similar to that of gravity strainmeters, but only very slow changes of Earth gravity field can be observed, and for this reason it is beyond the scope of this article.

 

The different response mechanisms to terrestrial gravity perturbations are summarized in Section 2.1. While we will identify the tidal forces acting on the test masses as dominant coupling mechanism, other couplings may well be relevant depending on the experiment. The Shapiro time delay will be discussed as the only relativistic effect. Higher-order relativistic effects are neglected. All other coupling mechanisms can be calculated using Newtonian theory including tidal forces, coupling in static non-uniform gravity fields, and coupling through ground displacement induced by gravity fluctuations. In Sections 2.2 to 2.4, the different measurement schemes are explained including a brief summary of the sensitivity limitations (choosing one of a few possible experimental realizations in each case). As mentioned before, we will mostly develop gravity models relevant to gravity strainmeters in the remainder of the article. Therefore, the detailed discussion of alternative gravimetry concepts mostly serves to highlight important differences between these concepts, and to develop a deeper understanding of the instruments and their role in gravity measurements.

 

Gravity response mechanisms

 

Gravity acceleration and tidal forces We will start with the simplest mechanism of all, the acceleration of a test mass in the gravity field. Instruments that measure the acceleration are called gravimeters. A test mass inside a gravimeter can be freely falling such as atom clouds [181] or, as suggested as possible future development, even macroscopic objects [72]. Typically though, test masses are supported mechanically or magnetically constraining motion in some of its degrees of freedom. A test mass suspended from strings responds to changes in the horizontal gravity acceleration. A test mass attached at the end of a cantilever with horizontal equilibrium position responds to changes in vertical gravity acceleration. The support fulfills two purposes. First, it counteracts the static gravitational force in a way that the test mass can respond to changes in the gravity field along a chosen degree of freedom. Second, it isolates the test mass from vibrations. Response to signals and isolation performance depend on frequency. If the support is modelled as a linear, harmonic oscillator, then the test mass response to gravity changes extends over all frequencies, but the response is strongly suppressed below the oscillators resonance frequency. The response function between the gravity perturbation δg(ω) and induced test mass acceleration δa(ω) assumes the form

equation M32

where we have introduced a viscous damping parameter γ, and ω0 is the resonance frequency. Well below resonance, the response is proportional to ω2, while it is constant well above resonance. Above resonance, the supported test mass responds like a freely falling mass, at least with respect to “soft” directions of the support. The test-mass response to vibrations δα(ω) of the support is given by

 

equation M43

This applies for example to horizontal vibrations of the suspension points of strings that hold a test mass, or to vertical vibrations of the clamps of a horizontal cantilever with attached test mass. Well above resonance, vibrations are suppressed by ω−2, while no vibration isolation is provided below resonance. The situation is somewhat more complicated in realistic models of the support especially due to internal modes of the mechanical system (see for example [76]), or due to coupling of degrees of freedom [121]. Large mechanical support structures can feature internal resonances at relatively low frequencies, which can interfere to some extent with the desired performance of the mechanical support [173]. While Eqs. (2) and (3) summarize the properties of isolation and response relevant for this paper, details of the readout method can fundamentally impact an instrument’s response to gravity fluctuations and its susceptibility to seismic noise, as explained in Sections 2.2 to 2.4.

 

Next, we discuss the response to tidal forces. In Newtonian theory, tidal forces cause a relative acceleration δg12(ω) between two freely falling test masses according to

 

equation M54

where equation M6 is the Fourier amplitude of the gravity potential. The last equation holds if the distance r12 between the test masses is sufficiently small, which also depends on the frequency. The term equation M7 is called gravity-gradient tensor. In Newtonian approximation, the second time integral of this tensor corresponds to gravity strain equation M8, which is discussed in more detail in Section 2.4. Its trace needs to vanish in empty space since the gravity potential fulfills the Poisson equation. Tidal forces produce the dominant signals in gravity gradiometers and gravity strainmeters, which measure the differential acceleration or associated relative displacement between two test masses (see Sections 2.3 and 2.4). If the test masses used for a tidal measurement are supported, then typically the supports are designed to be as similar as possible, so that the response in Eq. (2) holds for both test masses approximately with the same parameter values for the resonance frequencies (and to a lesser extent also for the damping). For the purpose of response calibration, it is less important to know the parameter values exactly if the signal is meant to be observed well above the resonance frequency where the response is approximately equal to 1 independent of the resonance frequency and damping (here, “well above” resonance also depends on the damping parameter, and in realistic models, the signal frequency also needs to be “well below” internal resonances of the mechanical support).

 

Shapiro time delay Another possible gravity response is through the Shapiro time delay [19]. This effect is not universally present in all gravity sensors, and depends on the readout mechanism. Today, the best sensitivities are achieved by reflecting laser beams from test masses in interferometric configurations. If the test mass is displaced by gravity fluctuations, then it imprints a phase shift onto the reflected laser, which can be observed in laser interferometers, or using phasemeters. We will give further details on this in Section 2.4. In Newtonian gravity, the acceleration of test masses is the only predicted response to gravity fluctuations. However, from general relativity we know that gravity also affects the propagation of light. The leading-order term is the Shapiro time delay, which produces a phase shift of the laser beam with respect to a laser propagating in flat space. It can be calculated from the weak-field spacetime metric (see chapter 18 in [124]):

equation M95

Here, c is the speed of light, ds is the so-called line element of a path in spacetime, and equation M10. Additionally, for this metric to hold, motion of particles in the source of the gravity potential responsible for changes of the gravity potential need to be much slower than the speed of light, and also stresses inside the source must be much smaller than its mass energy density. All conditions are fulfilled in the case of Earth gravity field. Light follows null geodesics with ds2 = 0. For the spacetime metric in Eq. (5), we can immediately write

 

equation M116

As we will find out, this equation can directly be used to calculate the time delay as an integral along a straight line in terms of the coordinates equation M12, but this is not immediately clear since light bends in a gravity field. So one may wonder if integration along the proper light path instead of a straight line yields additional significant corrections. The so-called geodesic equation must be used to calculate the path. It is a set of four differential equations, one for each coordinate t, equation M13 in terms of a parameter λ. The weak-field geodesic equation is obtained from the metric in Eq. (5):

 

equation M147

where we have made use of Eq. (6) and the slow-motion condition equation M15. The coordinates equation M16 are to be understood as functions of λ. Since the deviation of a straight path is due to a weak gravity potential, we can solve these equations by perturbation theory introducing expansions equation M17 and t = t(0) +t(1) + …. The superscript indicates the order in ψ/c2. The unperturbed path has the simple parametrization

 

equation M188

We have chosen integration constants such that unperturbed time t(0) and parameter λ can be used interchangeably (apart from a shift by t0). Inserting these expressions into the right-hand side of Eq. (7), we obtain

 

equation M199

As we can see, up to linear order in equation M20, the deviation equation M21 is in orthogonal direction to the unperturbed path equation M22, which means that the deviation can be neglected in the calculation of the time delay. After some transformations, it is possible to derive Eq. (6) from Eq. (9), and this time we find explicitly that the right-hand-side of the equation only depends on the unperturbed coordinates1. In other words, we can integrate the time delay along a straight line as defined in Eq. (8), and so the total phase integrated over a travel distance L is given by

 

equation M2310

In static gravity fields, the phase shift doubles if the light is sent back since not only the direction of integration changes, but also the sign of the expression substituted for dt/dλ.

 

Gravity induced ground motion As we will learn in Section 3, seismic fields produce gravity perturbations either through density fluctuations of the ground, or by displacing interfaces between two materials of different density. It is also well-known in seismology that seismic fields can be affected significantly by self-gravity. Self-gravity means that the gravity perturbation produced by a seismic field acts back on the seismic field. The effect is most significant at low frequency where gravity induced acceleration competes against acceleration from elastic forces. In seismology, low-frequency seismic fields are best described in terms of Earth’s normal modes [55]. Normal modes exist as toroidal modes and spheroidal modes. Spheroidal modes are influenced by self-gravity, toroidal modes are not. For example, predictions of frequencies and shapes of spheroidal modes based on Earth models such as PREM (Preliminary Reference Earth Model) [68] are inaccurate if self-gravity effects are excluded. What this practically means is that in addition to displacement amplitudes, gravity becomes a dynamical variable in the elastodynamic equations that determine the normal-mode properties. Therefore, seismic displacement and gravity perturbation cannot be separated in normal-mode formalism (although self-gravity can be neglected in calculations of spheroidal modes at sufficiently high frequency).

In certain situations, it is necessary or at least more intuitive to separate gravity from seismic fields. An exotic example is Earth’s response to GWs [67, 49, 47, 30, 48]. Another example is the seismic response to gravity perturbations produced by strong seismic events at large distance to the source as described in Section 4. It is more challenging to analyze this scenario using normal-mode formalism. The sum over all normal modes excited by the seismic event (each of which describing a global displacement field) must lead to destructive interference of seismic displacement at large distances (where seismic waves have not yet arrived), but not of the gravity amplitudes since gravity is immediately perturbed everywhere. It can be easier to first calculate the gravity perturbation from the seismic perturbation, and then to calculate the response of the seismic field to the gravity perturbation at larger distance. This method will be adopted in this section. Gravity fields will be represented as arbitrary force or tidal fields (detailed models are presented in later sections), and we simply calculate the response of the seismic field. Normal-mode formalism can be avoided only at sufficiently high frequencies where the curvature of Earth does not significantly influence the response (i.e., well above 10 mHz). In this section, we will model the ground as homogeneous half space, but also more complex geologies can in principle be assumed.

 

Gravity can be introduced in two ways into the elastodynamic equations, as a conservative force −∇ψ [146, 169], or as tidal strain The latter method was described first by Dyson to calculate Earth’s response to GWs [67]. The approach also works for Newtonian gravity, with the difference that the tidal field produced by a GW is necessarily a quadrupole field with only two degrees of freedom (polarizations), while tidal fields produced by terrestrial sources are less constrained. Certainly, GWs can only be fully described in the framework of general relativity, which means that their representation as a Newtonian tidal field cannot be used to explain all possible observations [124]. Nonetheless, important here is that Dyson’s method can be extended to Newtonian tidal fields. Without gravity, the elastodynamic equations for small seismic displacement can be written as

 

equation M2411

where equation M25 is the seismic displacement field, and equation M26 is the stress tensor [9]. In the absence of other forces, the stress is determined by the seismic field. In the case of a homogeneous and isotropic medium, the stress tensor for small seismic displacement can be written as

 

equation M2712

The quantity equation M28 is known as seismic strain tensor, and λ, μ are the Lamé constants (see Section 3.1). Its trace is equal to the divergence of the displacement field. Dyson introduced the tidal field from first principles using Lagrangian mechanics, but we can follow a simpler approach. Eq. (12) means that a stress field builds up in response to a seismic strain field, and the divergence of the stress field acts as a force producing seismic displacement. The same happens in response to a tidal field, which we represent as gravity strain equation M29. A strain field changes the distance between two freely falling test masses separated by equation M30 by equation M312. For sufficiently small distances L, the strain field can be substituted by the second time integral of the gravity-gradient tensor equation M32. If the masses are not freely falling, then the strain field acts as an additional force. The corresponding contribution to the material’s stress tensor can be written

 

equation M3313

Since we assume that the gravity field is produced by a distant source, the local contribution to gravity perturbations is neglected, which means that the gravity potential obeys the Laplace equation, equation M34. Calculating the divergence of the stress tensor according to Eq. (11), we find that the gravity term vanishes! This means that a homogeneous and isotropic medium does not respond to gravity strain fields. However, we have to be more careful here. Our goal is to calculate the response of a half-space to gravity strain. Even if the half-space is homogeneous, the Lamé constants change discontinuously across the surface. Hence, at the surface, the divergence of the stress tensor reads

 

equation M3514

In other words, tidal fields produce a force onto an elastic medium via gradients in the shear modulus (second Lamé constant). The gradient of the shear modulus can be written in terms of a Dirac delta function, equation M36, for a flat surface at z = 0 with unit normal vector equation M37. The response to gravity strain fields is obtained applying the boundary condition of vanishing surface traction, equation M38:

 

equation M3915

Once the seismic strain field is calculated, it can be used to obtain the seismic stress, which determines the displacement field equation M40 according to Eq. (11). In this way, one can for example calculate that a seismometer or gravimeter can observe GWs by monitoring surface displacement as was first calculated by Dyson [67].

 

Coupling in non-uniform, static gravity fields If the gravity field is static, but non-uniform, then displacement equation M41 of the test mass in this field due to a non-gravitational fluctuating force is associated with a changing gravity acceleration according to

equation M4216

We introduce a characteristic length λ, over which gravity acceleration varies significantly. Hence, we can rewrite the last equation in terms of the associated test-mass displacement ζ

 

equation M4317

where we have neglected directional dependence and numerical factors. The acceleration change from motion in static, inhomogeneous fields is generally more significant at low frequencies. Let us consider the specific case of a suspended test mass. It responds to fluctuations in horizontal gravity acceleration. The test mass follows the motion of the suspension point in vertical direction (i.e., no seismic isolation), while seismic noise in horizontal direction is suppressed according to Eq. (3). Accordingly, it is possible that the unsuppressed vertical (z-axis) seismic noise ξz(t) coupling into the horizontal (x-axis) motion of the test mass through the term ∂xgz = ∂zgx dominates over the gravity response term in Eq. (2). Due to additional coupling mechanisms between vertical and horizontal motion in real seismic-isolation systems, test masses especially in GW detectors are also isolated in vertical direction, but without achieving the same noise suppression as in horizontal direction. For example, the requirements on vertical test-mass displacement for Advanced LIGO are a factor 1000 less stringent than on the horizontal displacement [22]. Requirements can be set on the vertical isolation by estimating the coupling of vertical motion into horizontal motion, which needs to take the gravity-gradient coupling of Eq. (16) into account. Although, because of the frequency dependence, gravity-gradient effects are more significant in low-frequency detectors, such as the space-borne GW detector LISA [154].

 

Next, we calculate an estimate of gravity gradients in the vicinity of test masses in large-scale GW detectors, and see if the gravity-gradient coupling matters compared to mechanical vertical-to-horizontal coupling.

 

One contribution to gravity gradients will come from the vacuum chamber surrounding the test mass. We approximate the shape of the chamber as a hollow cylinder with open ends (open ends just to simplify the calculation). In our calculation, the test mass can be offset from the cylinder axis and be located at any distance to the cylinder ends (we refer to this coordinate as height). The gravity field can be expressed in terms of elliptic integrals, but the explicit solution is not of concern here. Instead, let us take a look at the results in Figure ​Figure1.1. Gravity gradients ∂zgx vanish if the test mass is located on the symmetry axis or at height L/2. There are also two additional ∂zgx = 0 contour lines starting at the symmetry axis at heights ∼ 0.24 and ∼0.76. Let us assume that the test mass is at height 0.3L, a distance 0.05L from the cylinder axis, the total mass of the cylinder is M = 5000 kg, and the cylinder height is L = 4 m. In this case, the gravity-gradient induced vertical-to-horizontal coupling factor at 20 Hz is

 

equation M4418

This means that gravity-gradient induced coupling is extremely weak, and lies well below estimates of mechanical coupling (of order 0.001 in Advanced LIGO3). Even though the vacuum chamber was modelled with a very simple shape, and additional asymmetries in the mass distribution around the test mass may increase gravity gradients, it still seems very unlikely that the coupling would be significant. As mentioned before, one certainly needs to pay more attention when calculating the coupling at lower frequencies. The best procedure is of course to have a 3D model of the near test-mass infrastructure available and to use it for a precise calculation of the gravity-gradient field.

 

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Figure 1

Gravity gradients inside hollow cylinder. The total height of the cylinder is L, and M is its total mass. The radius of the cylinder is 0.3L. The axes correspond to the distance of the test mass from the symmetry axis of the cylinder, and its height above one of the cylinders ends. The plot on the right is simply a zoom of the left plot into the intermediate heights.

Gravimeters

 

Gravimeters are instruments that measure the displacement of a test mass with respect to a non-inertial reference rigidly connected to the ground. The test mass is typically supported mechanically or magnetically (atom-interferometric gravimeters are an exception), which means that the test-mass response to gravity is altered with respect to a freely falling test mass. We will use Eq. (2) as a simplified response model. There are various possibilities to measure the displacement of a test mass. The most widespread displacement sensors are based on capacitive readout, as for example used in superconducting gravimeters (see Figure ​Figure22 and [96]). Sensitive displacement measurements are in principle also possible with optical readout systems; a method that is (necessarily) implemented in atom-interferometric gravimeters [137], and prototype seismometers [34] (we will explain the distinction between seismometers and gravimeters below). As will become clear in Section 2.4, optical readout is better suited for displacement measurements over long baselines, as required for the most sensitive gravity strain measurements, while the capacitive readout should be designed with the smallest possible distance between the test mass and the non-inertial reference [104].

 

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Figure 2

Sketch of a levitated sphere serving as test mass in a superconducting gravimeter. Dashed lines indicate magnetic field lines. Coils are used for levitation and precise positioning of the sphere. Image reproduced with permission from [96]; copyright by Elsevier.

Let us take a closer look at the basic measurement scheme of a superconducting gravimeter shown in Figure ​Figure2.2. The central part is formed by a spherical superconducting shell that is levitated by superconducting coils. Superconductivity provides stability of the measurement, and also avoids some forms of noise (see [96] for details). In this gravimeter design, the lower coil is responsible mostly to balance the mean gravitational force acting on the sphere, while the upper coil modifies the magnetic gradient such that a certain “spring constant” of the magnetic levitation is realized. In other words, the current in the upper coil determines the resonance frequency in Eq. (2).

 

Capacitor plates are distributed around the sphere. Whenever a force acts on the sphere, the small signal produced in the capacitive readout is used to immediately cancel this force by a feedback coil. In this way, the sphere is kept at a constant location with respect to the external frame. This illustrates a common concept in all gravimeters. The displacement sensors can only respond to relative displacement between a test mass and a surrounding structure. If small gravity fluctuations are to be measured, then it is not sufficient to realize low-noise readout systems, but also vibrations of the surrounding structure forming the reference frame must be as small as possible. In general, as we will further explore in the coming sections, gravity fluctuations are increasingly dominant with decreasing frequency. At about 1 mHz, gravity acceleration associated with fluctuating seismic fields become comparable to seismic acceleration, and also atmospheric gravity noise starts to be significant [53]. At higher frequencies, seismic acceleration is much stronger than typical gravity fluctuations, which means that the gravimeter effectively operates as a seismometer. In summary, at sufficiently low frequencies, the gravimeter senses gravity accelerations of the test mass with respect to a relatively quiet reference, while at higher frequencies, the gravimeter senses seismic accelerations of the reference with respect to a test mass subject to relatively small gravity fluctuations. In superconducting gravimeters, the third important contribution to the response is caused by vertical motion ξ(t) of a levitated sphere against a static gravity gradient (see Section 2.1.4). As explained above, feedback control suppresses relative motion between sphere and gravimeter frame, which causes the sphere to move as if attached to the frame or ground. In the presence of a static gravity gradient ∂zgz, the motion of the sphere against this gradient leads to a change in gravity, which alters the feedback force (and therefore the recorded signal). The full contribution from gravitational, δa(t), and seismic, equation M45, accelerations can therefore be written

 

equation M4619

It is easy to verify, using Eqs. (2) and (3), that the relative amplitude of gravity and seismic fluctuations from the first two terms is independent of the test-mass support. Therefore, vertical seismic displacement of the reference frame must be considered fundamental noise of gravimeters and can only be avoided by choosing a quiet measurement site. Obviously, Eq. (19) is based on a simplified support model. One of the important design goals of the mechanical support is to minimize additional noise due to non-linearities and cross-coupling. As is explained further in Section 2.3, it is also not possible to suppress seismic noise in gravimeters by subtracting the disturbance using data from a collocated seismometer. Doing so inevitably turns the gravimeter into a gravity gradiometer.

 

Gravimeters target signals that typically lie well below 1 mHz. Mechanical or magnetic supports of test masses have resonance frequencies at best slightly below 10 mHz along horizontal directions, and typically above 0.1 Hz in the vertical direction [23, 174]4. Well below resonance frequency, the response function can be approximated as equation M47. At first, it may look as if the gravimeter should not be sensitive to very low-frequency fluctuations since the response becomes very weak. However, the strength of gravity fluctuations also strongly increases with decreasing frequency, which compensates the small response. It is clear though that if the resonance frequency was sufficiently high, then the response would become so weak that the gravity signal would not stand out above other instrumental noise anymore. The test-mass support would be too stiff. The sensitivity of the gravimeter depends on the resonance frequency of the support and the intrinsic instrumental noise. With respect to seismic noise, the stiffness of the support has no influence as explained before (the test mass can also fall freely as in atom interferometers).

 

For superconducting gravimeters of the Global Geodynamics Project (GGP) [52], the median spectra are shown in Figure ​Figure3.3. Between 0.1 mHz and 1 mHz, atmospheric gravity perturbations typically dominate, while instrumental noise is the largest contribution between 1 mHz and 5 mHz [96]. The smallest signal amplitudes that have been measured by integrating long-duration signals is about 10−12 m/s2. A detailed study of noise in superconducting gravimeters over a larger frequency range can be found in [145]. Note that in some cases, it is not fit to categorize seismic and gravity fluctuations as noise and signal. For example, Earth’s spherical normal modes coherently excite seismic and gravity fluctuations, and the individual contributions in Eq. (19) have to be understood only to accurately translate data into normal-mode amplitudes [55].

 

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Figure 3

Median spectra of superconducting gravimeters of the GGP. Image reproduced with permission from [48]; copyright by APS.

Gravity gradiometers

 

It is not the purpose of this section to give a complete overview of the different gradiometer designs. Gradiometers find many practical applications, for example in navigation and resource exploration, often with the goal to measure static or slowly changing gravity gradients, which do not concern us here. For example, we will not discuss rotating gradiometers, and instead focus on gradiometers consisting of stationary test masses. While the former are ideally suited to measure static or slowly changing gravity gradients with high precision especially under noisy conditions, the latter design has advantages when measuring weak tidal fluctuations. In the following, we only refer to the stationary design. A gravity gradiometer measures the relative acceleration between two test masses each responding to fluctuations of the gravity field [102, 125]. The test masses have to be located close to each other so that the approximation in Eq. (4) holds. The proximity of the test masses is used here as the defining property of gradiometers. They are therefore a special type of gravity strainmeter (see Section 2.4), which denotes any type of instrument that measures relative gravitational acceleration (including the even more general concept of measuring space-time strain).

 

Gravity gradiometers can be realized in two versions. First, one can read out the position of two test masses with respect to the same rigid, non-inertial reference. The two channels, each of which can be considered a gravimeter, are subsequently subtracted. This scheme is for example realized in dual-sphere designs of superconducting gravity gradiometers [90] or in atom-interferometric gravity gradiometers [159].

 

It is schematically shown in Figure ​Figure4.4. Let us first consider the dual-sphere design of a superconducting gradiometer. If the reference is perfectly stiff, and if we assume as before that there are no cross-couplings between degrees of freedom and the response is linear, then the subtraction of the two gravity channels cancels all of the seismic noise, leaving only the instrumental noise and the differential gravity signal given by the second line of Eq. (4). Even in real setups, the reduction of seismic noise can be many orders of magnitude since the two spheres are close to each other, and the two readouts pick up (almost) the same seismic noise [125]. This does not mean though that gradiometers are necessarily more sensitive instruments to monitor gravity fields. A large part of the gravity signal (the common-mode part) is subtracted together with the seismic noise, and the challenge is now passed from finding a seismically quiet site to developing an instrument with lowest possible intrinsic noise.

 

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Figure 4

Basic scheme of a gravity gradiometer for measurements along the vertical direction. Two test masses are supported by horizontal cantilevers (superconducting magnets, …). Acceleration of both test masses is measured against the same non-inertial reference frame, which is connected to the ground. Each measurement constitutes one gravimeter. Subtraction of the two channels yields a gravity gradiometer.

The atom-interferometric gradiometer differs in some important details from the superconducting gradiometer. The test masses are realized by ultracold atom clouds, which are (nearly) freely falling provided that magnetic shielding of the atoms is sufficient, and interaction between atoms can be neglected. Interactions of a pair of atom clouds with a laser beam constitute the basic gravity gradiometer scheme. Even though the test masses are freely falling, the readout is not generally immune to seismic noise [80, 18]. The laser beam interacting with the atom clouds originates from a source subject to seismic disturbances, and interacts with optics that require seismic isolation. Schemes have been proposed that could lead to a large reduction of seismic noise [178, 77], but their effectiveness has not been tested in experiments yet. Since the differential position (or tidal) measurement is performed using a laser beam, the natural application of atom-interferometer technology is as gravity strainmeter (as explained before, laser beams are favorable for differential position measurements over long baselines). Nonetheless, the technology is currently insufficiently developed to realize large-baseline experiments, and we can therefore focus on its application in gradiometry. Let us take a closer look at the response of atom-interferometric gradiometers to seismic noise. In atom-interferometric detectors (excluding the new schemes proposed in [178, 77]), one can show that seismic acceleration δα(ω) of the optics or laser source limits the sensitivity of a tidal measurement according to

 

equation M4820

where L is the separation of the two atom clouds, and is the speed of light. It should be emphasized that the seismic noise remains, even if all optics and the laser source are all linked to the same infinitely stiff frame. In addition to this noise term, other coupling mechanisms may play a role, which can however be suppressed by engineering efforts. The noise-reduction factor ωL/c needs to be compared with the common-mode suppression of seismic noise in superconducting gravity gradiometers, which depends on the stiffness of the instrument frame, and on contamination from cross coupling of degrees-of-freedom. While the seismic noise in Eq. (20) is a fundamental noise contribution in (conventional) atom-interferometric gradiometers, the noise suppression in superconducting gradiometers depends more strongly on the engineering effort (at least, we venture to claim that common-mode suppression achieved in current instrument designs is well below what is fundamentally possible).

 

To conclude this section, we discuss in more detail the connection between gravity gradiometers and seismically (actively or passively) isolated gravimeters. As we have explained in Section 2.2, the sensitivity limitation of gravimeters by seismic noise is independent of the mechanical support of the test mass (assuming an ideal, linear support). The main purpose of the mechanical support is to maximize the response of the test mass to gravity fluctuations, and thereby increase the signal with respect to instrumental noise other than seismic noise. Here we will explain that even a seismic isolation of the gravimeter cannot overcome this noise limitation, at least not without fundamentally changing its response to gravity fluctuations. Let us first consider the case of a passively seismically isolated gravimeter. For example, we can imagine that the gravimeter is suspended from the tip of a strong horizontal cantilever. The system can be modelled as two oscillators in a chain, with a light test mass m supported by a heavy mass M representing the gravimeter (reference) frame, which is itself supported from a point rigidly connected to Earth. The two supports are modelled as harmonic oscillators. As before, we neglect cross coupling between degrees of freedom. Linearizing the response of the gravimeter frame and test mass for small accelerations, and further neglecting terms proportional to m/M, one finds the gravimeter response to gravity fluctuations:

 

equation M4921

Here, ω1, γ1 are the resonance frequency and damping of the gravimeter support, while ω2, γ2 are the resonance frequency and damping of the test-mass support. The response and isolation functions R(·), S(·) are defined in Eqs. (2) and (3). Remember that Eq. (21) is obtained as a differential measurement of test-mass acceleration versus acceleration of the reference frame. Therefore, δg1(ω) denotes the gravity fluctuation at the center-of-mass of the gravimeter frame, and δg2(ω) at the test mass. An infinitely stiff gravimeter suspension, ω1 → ∞, yields R(ω; ω1, γ1) = 0, and the response turns into the form of the non-isolated gravimeter. The seismic isolation is determined by

 

equation M5022

We can summarize the last two equations as follows. At frequencies well above ω1, the seismically isolated gravimeter responds like a gravity gradiometer, and seismic noise is strongly suppressed. The deviation from the pure gradiometer response ∼ δg2(ω) − δg1(ω) is determined by the same function S(ω; ω1, γ1) that describes the seismic isolation. In other words, if the gravity gradient was negligible, then we ended up with the conventional gravimeter response, with signals suppressed by the seismic isolation function. Well below ω1, the seismically isolated gravimeter responds like a conventional gravimeter without seismic-noise reduction. If the centers of the masses m (test mass) and M (reference frame) coincide, and therefore δg1(ω) = δg2(ω), then the response is again like a conventional gravimeter, but this time suppressed by the isolation function S(ω; ω1, γ1).

 

Let us compare the passively isolated gravimeter with an actively isolated gravimeter. In active isolation, the idea is to place the gravimeter on a stiff platform whose orientation can be controlled by actuators. Without actuation, the platform simply follows local surface motion. There are two ways to realize an active isolation. One way is to place a seismometer next to the platform onto the ground, and use its data to subtract ground motion from the platform. The actuators cancel the seismic forces. This scheme is called feed-forward noise cancellation. Feed-forward cancellation of gravity noise is discussed at length in Section 7.1, which provides details on its implementation and limitations. The second possibility is to place the seismometer together with the gravimeter onto the platform, and to suppress seismic noise in a feedback configuration [4, 2]. In the following, we discuss the feed-forward technique as an example since it is easier to analyze (for example, feedback control can be unstable [4]). As before, we focus on gravity and seismic fluctuations. The seismometer’s intrinsic noise plays an important role in active isolation limiting its performance, but we are only interested in the modification of the gravimeter’s response. Since there is no fundamental difference in how a seismometer and a gravimeter respond to seismic and gravity fluctuations, we know from Section 2.2 that the seismometer output is proportional to δg1(ω) − δα(ω), i.e., using a single test mass for acceleration measurements, seismic and gravity perturbations contribute in the same way. A transfer function needs to be multiplied to the acceleration signals, which accounts for the mechanical support and possibly also electronic circuits involved in the seismometer readout. To cancel the seismic noise of the platform that carries the gravimeter, the effect of all transfer functions needs to be reversed by a matched feed-forward filter. The output of the filter is then equal to δg1(ω) − δα(ω) and is added to the motion of the platform using actuators cancelling the seismic noise and adding the seismometer’s gravity signal. In this case, the seismometer’s gravity signal takes the place of the seismic noise in Eq. (3). The complete gravity response of the actively isolated gravimeter then reads

 

equation M5123

The response is identical to a gravity gradiometer, where ω2, γ2 are the resonance frequency and damping of the gravimeter’s test-mass support. In reality, instrumental noise of the seismometer will limit the isolation performance and introduce additional noise into Eq. (23). Nonetheless, Eqs. (21) and (23) show that any form of seismic isolation turns a gravimeter into a gravity gradiometer at frequencies where seismic isolation is effective. For the passive seismic isolation, this means that the gravimeter responds like a gradiometer at frequencies well above the resonance frequency ω1 of the gravimeter support, while it behaves like a conventional gravimeter below ω1. From these results it is clear that the design of seismic isolations and the gravity response can in general not be treated independently. As we will see in Section 2.4 though, tidal measurements can profit strongly from seismic isolation especially when common-mode suppression of seismic noise like in gradiometers is insufficient or completely absent.

 

Gravity strainmeters

 

Gravity strain is an unusual concept in gravimetry that stems from our modern understanding of gravity in the framework of general relativity. From an observational point of view, it is not much different from elastic strain. Fluctuating gravity strain causes a change in distance between two freely falling test masses, while seismic or elastic strain causes a change in distance between two test masses bolted to an elastic medium. It should be emphasized though that we cannot always use this analogy to understand observations of gravity strain [106]. Fundamentally, gravity strain corresponds to a perturbation of the metric that determines the geometrical properties of spacetime [124]. We will briefly discuss GWs, before returning to a Newtonian description of gravity strain.

 

Gravitational waves are weak perturbations of spacetime propagating at the speed of light. Freely falling test masses change their distance in the field of a GW. When the length of the GW is much larger than the separation between the test masses, it is possible to interpret this change as if caused by a Newtonian force. We call this the long-wavelength regime. Since we are interested in the low-frequency response of gravity strainmeters throughout this article (i.e., frequencies well below 100 Hz), this condition is always fulfilled for Earth-bound experiments. The effect of a gravity-strain field equation M52 on a pair of test masses can then be represented as an equivalent Newtonian tidal field

 

equation M5324

Here, equation M54 is the relative acceleration between two freely falling test masses, L is the distance between them, and equation M55 is the unit vector pointing from one to the other test mass, and equation M56 its transpose. As can be seen, the gravity-strain field is represented by a 3 × 3 tensor. It contains the space-components of a 4-dimensional metric perturbation of spacetime, and determines all properties of GWs5. Note that the strain amplitude h in Eq. (24) needs to be multiplied by 2 to obtain the corresponding amplitude of the metric perturbation (e.g., the GW amplitude). Throughout this article, we define gravity strain as h = ΔL/L, while the effect of a GW with amplitude aGW on the separation of two test mass is determined by aGW = 2ΔL/L.

 

The strain field of a GW takes the form of a quadrupole oscillation with two possible polarizations commonly denoted × (cross)-polarization and +(plus)-polarization. The arrows in Figure ​Figure55 indicate the lines of the equivalent tidal field of Eq. (24).

 

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Figure 5

Polarizations of a gravitational wave.

Consequently, to (directly) observe GWs, one can follow two possible schemes: (1) the conventional method, which is a measurement of the relative displacement of suspended test masses typically carried out along two perpendicular baselines (arms); and (2) measurement of the relative rotation between two suspended bars. Figure ​Figure66 illustrates the two cases. In either case, the response of a gravity strainmeter is obtained by projecting the gravity strain tensor onto a combination of two unit vectors, equation M57 and equation M58, that characterize the orientation of the detector, such as the directions of two bars in a rotational gravity strain meter, or of two arms of a conventional gravity strain meter. This requires us to define two different gravity strain projections. The projection for the rotational strain measurement is given by

 

equation M5925

where the subscript × indicates that the detector responds to the ×-polarization assuming that the x, y-axes (see Figure ​Figure5)5) are oriented along two perpendicular bars. The vectors equation M60 and equation M61 are rotated counter-clockwise by 90° with respect to equation M62 and equation M63. In the case of perpendicular bars equation M64 and equation M65. The corresponding projection for the conventional gravity strain meter reads

 

equation M6626

The subscript + indicates that the detector responds to the +-polarization provided that the x, y-axes are oriented along two perpendicular baselines (arms) of the detector. The two schemes are shown in Figure ​Figure6.6. The most sensitive GW detectors are based on the conventional method, and distance between test masses is measured by means of laser interferometry. The LIGO and Virgo detectors have achieved strain sensitivities of better than 10−22 Hz−1/2 between about 50 Hz and 1000 Hz in past science runs and are currently being commissioned in their advanced configurations [91, 7]. The rotational scheme is realized in torsion-bar antennas, which are considered as possible technology for sub-Hz GW detection [155, 69]. However, with achieved strain sensitivity of about 10−8 Hz−1/2 near 0.1 Hz, the torsion-bar detectors are far from the sensitivity we expect to be necessary for GW detection [88].

 

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Figure 6

Sketches of the relative rotational and displacement measurement schemes.

Let us now return to the discussion of the previous sections on the role of seismic isolation and its impact on gravity response. Gravity strainmeters profit from seismic isolation more than gravimeters or gravity gradiometers. We have shown in Section 2.2 that seismically isolated gravimeters are effectively gravity gradiometers. So in this case, seismic isolation changes the response of the instrument in a fundamental way, and it does not make sense to talk of seismically isolated gravimeters. Seismic isolation could in principle be beneficial for gravity gradiometers (i.e., the acceleration of two test masses is measured with respect to a common rigid, seismically isolated reference frame), but the common-mode rejection of seismic noise (and gravity signals) due to the differential readout is typically so high that other instrumental noise becomes dominant. So it is possible that some gradiometers would profit from seismic isolation, but it is not generally true. Let us now consider the case of a gravity strainmeter. As explained in Section 2.3, we distinguish gradiometers and strainmeters by the distance of their test masses. For example, the distance of the LIGO or Virgo test masses is 4 km and 3 km respectively. Seismic noise and terrestrial gravity fluctuations are insignificantly correlated between the two test masses within the detectors’ most sensitive frequency band (above 10 Hz). Therefore, the approximation in Eq. (4) does not apply. Certainly, the distinction between gravity gradiometers and strainmeters remains somewhat arbitrary since at any frequency the approximation in Eq. (4) can hold for one type of gravity fluctuation, while it does not hold for another. Let us adopt a more practical definition at this point. Whenever the design of the instrument places the test masses as distant as possible from each other given current technology, then we call such an instrument strainmeter. In the following, we will discuss seismic isolation and gravity response for three strainmeter designs, the laser-interferometric, atom-interferometric, and superconducting strainmeters. It should be emphasized that the atom-interferometric and superconducting concepts are still in the beginning of their development and have not been realized yet with scientifically interesting sensitivities.

 

Laser-interferometric strainmeters The most sensitive gravity strainmeters, namely the large-scale GW detectors, use laser interferometry to read out the relative displacement between mirror pairs forming the test masses. Each test mass in these detectors is suspended from a seismically isolated platform, with the suspension itself providing additional seismic isolation. Section 2.1.1 introduced a simplified response and isolation model based on a harmonic oscillator characterized by a resonance frequency ω0 and viscous damping γ6. In a multi-stage isolation and suspension system as realized in GW detectors (see for example [37, 121]), coupling between multiple oscillators cannot be neglected, and is fundamental to the seismic isolation performance, but the basic features can still be explained with the simplified isolation and response model of Eqs. (2) and (3). The signal output of the interferometer is proportional to the relative displacement between test masses. Since seismic noise is approximately uncorrelated between two distant test masses, the differential measurement itself cannot reject seismic noise as in gravity gradiometers. Without seismic isolation, the dominant signal would be seismic strain, i.e., the distance change between test masses due to elastic deformation of the ground, with a value of about 10−15 Hz−1/2 at 50 Hz (assuming kilometer-scale arm lengths). At the same time, without seismically isolated test masses, the gravity signal can only come from the ground response to gravity fluctuations as described in Section 2.1.3, and from the Shapiro time delay as described in Section 2.1.2.

 

www.ncbi.nlm.nih.gov/pmc/articles/PMC5256008/

The Basílica i Temple Expiatori de la Sagrada Família Spanish: Templo Expiatorio de la Sagrada Familia; English: Basilica and Expiatory Church of the Holy Family) is a large Roman Catholic church in Barcelona, designed by Catalan architect Antoni Gaudí (1852–1926). Gaudí's work on the building is part of a UNESCO World Heritage Site, and in November 2010 Pope Benedict XVI consecrated and proclaimed it a minor basilica, as distinct from a cathedral, which must be the seat of a bishop.

 

In 1882 construction of Sagrada Família commenced under architect Francisco Paula de Villar until 1883, when Gaudí became involved when Francisco resigned as the head architect.Taking over the project, Gaudí transformed it with his architectural and engineering style, combining Gothic and curvilinear Art Nouveau forms. Gaudí devoted his last years to the project, and at the time of his death at age 73 in 1926, less than a quarter of the project was complete.

 

Sagrada Familia's construction progressed slowly, as it relied on private donations and was interrupted by the Spanish Civil War, only to resume intermittent progress in the 1950s. Construction passed the midpoint in 2010 with some of the project's greatest challenges remaining and an anticipated completion date of 2026, the centenary of Gaudí's death.

 

The basílica has a long history of dividing the citizens of Barcelona: over the initial possibility it might compete with Barcelona's cathedral, over Gaudí's design itself, over the possibility that work after Gaudí's death disregarded his design, and the 2007 proposal to build an underground tunnel of Spain's high-speed rail link to France which could disturb its stability. Describing Sagrada Família, art critic Rainer Zerbst said, "It is probably impossible to find a church building anything like it in the entire history of art" and Paul Goldberger describes it as, "The most extraordinary personal interpretation of Gothic architecture since the Middle Ages." Wikipedia

Purple combines the stability of blue and the energy of red. Why is it so difficult to catch this color ?

 

from the SRGC Scottish Rock Garden Club seed exchange

PHILIPPINE SEA (Aug. 22, 2022) Capt. John Kiefaber, commanding officer of amphibious assault carrier USS Tripoli (LHA 7), prepares to board an MH-60S Sea Hawk, assigned to Helicopter Sea Combat Squadron (HSC) 23, aboard Tripoli. Tripoli is operating in U.S. 7th Fleet to enhance interoperability with allies and partners and serve as a ready response force to defend peace and maintain stability in the Indo-Pacific region. (U.S. Navy photo by Mass Communication Specialist 2nd Class Malcolm Kelley)

SASEBO, Japan (Aug. 9, 2020) Landing craft, air cushion 30, assigned to Naval Beach Unit 7, prepares to enter the well deck of the amphibious dock landing ship USS Germantown (LSD 42) as the ship conducts amphibious operations. Germantown, part of the America Expeditionary Strike Group, is operating in the 7th Fleet area of operations to enhance interoperability with allies and partners, and serves as a ready response force to defend peace and stability in the Indo-Pacific region. (U.S. Navy photo by Mass Communication Specialist 2nd Class Taylor DiMartino)

Bright sunny day on the beach. Neat drift wood

Originally late C14, although not much of that remains except for the windows, and even they are much restored. Two major Victorian restorations preceded at 2000 one resulting from a late 1990s fire. This shot was taken under a full moon which was battling, not always successfully, with heavy cloud. The church has been transferred from the Diocese of Salisbury into the possession of the Pilsdon Community, an ecumenical community with an Anglican foundation, based in the farm next door. Pilsdon is an sustainable community which offers a place of stability to people recovering from addiction or simply from the strain of life.

Tony Southgate's masterwork of downforce and stability for the 3.5 liter V10 era of Group C, doing battle against the Peugeot 905 and Jaguar XJR14. Cornering speeds were so fast and the g-forces so high that several drivers broke their ribs.

Must attribute with link to: www.ptpioneer.com

Abdominal exercise crunch stability Ball

SOUTH CHINA SEA (Oct. 6, 2019) - The aircraft carrier USS Ronald Reagan (CVN 76), left, and the amphibious assault ship USS Boxer (LHD 6) and ships from the Ronald Reagan Carrier Strike Group (CSG) and the Boxer Amphibious Ready Group (ARG) are underway in formation while conducting security and stability operations in the U.S. 7th Fleet area of operations. U.S. 7th Fleet is the largest numbered fleet in the world, and the U.S. Navy has operated in the Indo-Pacific region for more than 70 years, providing credible, ready forces to help preserve peace and prevent conflict. (U.S. Navy photo by Mass Communication Specialist 2nd Class Erwin Jacob V. Miciano) 191006-N-VI515-0396

 

** Interested in following U.S. Indo-Pacific Command? Engage and connect with us at www.facebook.com/indopacom | twitter.com/INDOPACOM |

www.instagram.com/indopacom | www.flickr.com/photos/us-pacific-command; | www.youtube.com/user/USPacificCommand | www.pacom.mil/ **

 

The New Farm Powerhouse was built in 1928 to provide power for Brisbane’s expanding tram network and power and lighting for the suburbs of Toowong, Ithaca and Yeerongpilly. The Powerhouse was designed by Roy Rusden Ogg, the architect for the Brisbane City Council’s Tramways Department. He was also responsible for the design of eight Tramways substations. In 1929 the first section of the stores building was constructed.

 

The Powerhouse was constructed in two stages in response to increasing demand for power supply. The first stage comprised the turbine room and boiler house. In 1934 the turbine room was extended and the switch house, the portion facing the River was built. The stores building was also extended in this year. An additional bay to the boiler house was added in 1936 along with a staff accommodation wing. A major and final extension to the boiler house was completed in 1940.

 

During the post-War years the Powerhouse operated at peak capacity. In 1963, operations of the Powerhouse were passed over to the Southern Electric Authority, later to become the South East Queensland Electricity Board (SEQEB). The powerhouse was decommissioned in 1971 when it was superseded by the Swanbank Power Station. SEQEB continued to occupy the site as a works depot. Generating plant and ancillary structures were removed in the late 1970s. Fears about the security and stability of the boiler house section led to its partial demolition in 1984. In 1989 most of the Powerhouse site was transferred to the Brisbane City Council.

 

In the years after it was made redundant the structure was subject to neglect and vandalism. In the years prior to its conversion it was occasionally the venue for dramatic theatre and rave events.

 

In 1991 the Urban Renewal Task Force recommended a review of the structural and financial feasibility of retaining the New Farm powerhouse for public or residential purposes. Subsequently the Brisbane City Council initiated the proposed development of the powerhouse into a cultural and performing arts venue. The Powerhouse arts complex brief was developed through extensive public consultation and with direction form the Urban Renewal Task Force. A collaborative team of Architects with specific experience – City Design (theatres), Cox Rayner (urban design) and Allom Lovell (conservation) developed the design. Construction commenced early in 1999 and the complex was completed in 2000.

 

Source: Brisbane City Council Heritage Register.

shot in the twilight from the Q1 observation deck. Managed to find a window that I could eliminate the glare and get a suitable stability for the longer exposure. Just the tight balance fading natural light and introduced ambient street lighting..

lukecaseyphotography.com/

 

Wall Street Journal

Navy Day in New York, 1945

The biggest display of military might the nation had ever seen.

By Elliot Rosenberg

Oct. 26, 2015 6:48 pm ET

 

Seventy years ago, on Oct. 27, 1945, New York City was the site of the most spectacular homefront display of American military might the nation had ever seen. Navy Day was in effect a monumental victory lap, coming seven weeks after the signing of the Japanese surrender in Tokyo Bay aboard the USS Missouri.

 

Now the “Big Mo” and other stars and supporting players from the Pacific Fleet had come home. Along a six-mile stretch of the Hudson River, 47 warships gathered—battleships, aircraft carriers, cruisers, destroyers, submarines and submarine chasers.

 

President Truman was there. So was I. About 3.5 million people crowded along Manhattan’s West Side, with another 1.5 million viewing from New Jersey, according to press reports. Joining the USS Missouri, with its 16-inch turret guns bristling from its 56,000-ton frame, were the USS New York (an older battle wagon) and the USS Enterprise, the only aircraft carrier that had been active from Pearl Harbor to V-J Day.

 

At midafternoon, President Truman boarded a destroyer for a two-hour review of the assembled firepower. Twenty-one-gun salutes boomed from many of the vessels. Overhead, 1,200 Hellcat and Corsair fighters, Avenger torpedo planes and Helldiver bombers circled in 12-mile ovals. For half-hour spells on two successive nights the ships turned on their 24-inch and 36-inch searchlights, sending brilliant blue-white beams, with millions in candle power, flashing across the sky and illuminating the city’s skyscrapers. No fireworks display could compare.

 

Many of the ships initially moored at piers along the river, welcoming visitors, and tens of thousands clambered aboard. The Missouri was the biggest celebrity; visitors especially wanted to see a small starboard-deck plaque that read: “Over this spot on 2 September 1945 the instrument of formal surrender of Japan to the Allied Powers was signed.”

 

By the time my father was off work and able to take me to see the naval display, the ships had left their piers and lined up in mid-river. Navy launches ferried civilians to visit them, and my father and I were among the lucky ones.

 

I would have preferred to see the Big Mo, but the Enterprise was a worthy consolation prize. I marveled at being aboard an aircraft carrier, previously known only through movies like “Wing and a Prayer” and “Thirty Seconds Over Tokyo.” The rectangular expanse of the flight deck. The squadrons of planes bunched together, wings folded. The rows of antiaircraft guns lining its rim. A large poster provided some Enterprise statistics: 911 Japanese planes shot down, 71 ships sunk, 192 more ships damaged or sunk.

 

After Oct. 27, the Navy fleet gradually dispersed. Elsewhere that fall, the Soviet Union was scrambling to develop an atomic bomb, and the Korean peninsula was about to be sliced at something called the 38th Parallel. Vietnam was still a faraway French outpost in Indochina. And Afghanistan and Iraq barely registered in the mind of at least one New York schoolboy, who had witnessed Navy Day and come away certain that America could still lick any international bully on the planet.

 

Mr. Rosenberg is the author, with Louis Eisenstein, of “A Stripe of Tammany’s Tiger” (Cornell University, 2013 paperback).

 

From Wikipedia, the free encyclopedia

 

History

United States

Name:USS Midway

Namesake:Battle of Midway

Ordered:1 August 1942

Builder:Newport News Shipbuilding

Laid down:27 October 1943

Launched:20 March 1945

Commissioned:10 September 1945

Decommissioned:11 April 1992

In service:1945

Out of service:1992

Stricken:17 March 1997

Nickname(s):Midway Magic

Status:Museum ship at the USS Midway Museum in San Diego, California

Notes:Only carrier museum in the United States from WW2 that is not of the Essex class

General characteristics

Class and type:Midway-class aircraft carrier

Displacement:

 

45,000 tons at commissioning

64,000 tons at decommissioning

 

Length:1,001 ft (305 m)[1]

Beam:

 

121 ft (37 m)

136 ft (41 m), 238 ft (73 m) at flight deck after modernization

 

Draft:34.5 ft (10.5 m)

Propulsion:12 boilers, four Westinghouse geared Steam turbines[2]

Speed:33 kn (61 km/h; 38 mph)

Complement:4,104 officers and men

Armament:

 

As Built:

18 × 5"/54 caliber Mark 16 guns,

84 × Bofors 40 mm guns,

68 × Oerlikon 20 mm cannons

After Refit:

2 8-cell Sea Sparrow launchers,

2 Phalanx CIWS

 

Aircraft carried:137 theoretical, 100 (1940s–50s), 70 (Vietnam–retirement)

 

USS Midway (CVB/CVA/CV-41) is an aircraft carrier, formerly of the United States Navy, the lead ship of her class. Commissioned a week after the end of World War II, Midway was the largest ship in the world until 1955, as well as the first U.S. aircraft carrier too big to transit the Panama Canal. She operated for 47 years, during which time she saw action in the Vietnam War and served as the Persian Gulf flagship in 1991's Operation Desert Storm. Decommissioned in 1992, she is now a museum ship at the USS Midway Museum, in San Diego, California, and is the only remaining inactive U.S. aircraft carrier that is not an Essex-class aircraft carrier.

 

Service history

 

Midway was laid down 27 October 1943 in Shipway 11 at Newport News Shipbuilding Co., Newport News, Virginia; launched 20 March 1945, sponsored by Mrs. Bradford William Ripley, Jr.; and commissioned on 10 September 1945 (eight days after the Surrender of Japan) with Captain Joseph F. Bolger in command.

 

After shakedown in the Caribbean, Midway joined the U.S. Atlantic Fleet training schedule, with Norfolk as her homeport. From 20 February 1946, she was the flagship for Carrier Division 1. In March, she participated in Operation Frostbite testing the Ryan FR Fireball and helicopter rescue techniques for cold-weather operations in the Labrador Sea. In September 1947, a captured German V-2 rocket was test-fired from the flight deck in Operation Sandy, the first large-rocket launch from a moving platform, and the only moving-platform launch for a V-2. While the rocket lifted off, she then tilted and broke up at 15,000 feet (4,600 m).[3]

 

On 29 October 1947, Midway sailed for the first of her annual deployments with the 6th Fleet in the Mediterranean. Between deployments, Midway trained and received alterations to accommodate heavier aircraft as they were developed.

 

In June 1951, Midway operated in the Atlantic off the Virginia Capes during carrier suitability tests of the F9F-5 Panther. On 23 June, as Cdr. George Chamberlain Duncan attempted a landing in BuNo 125228, a downdraft just aft of the stern caused Duncan to crash. His plane's forward fuselage broke away and rolled down the deck, and he suffered burns. Footage of the crash has been used in several films, including Men of the Fighting Lady, Midway, and The Hunt for Red October.[4]

 

In 1952, the ship participated in Operation Mainbrace, North Sea maneuvers with NATO forces. Midway had an angled runway painted on the flight deck in May for touch-and-go landings following the pioneering trials of the technique aboard HMS Triumph. Successful demonstration of the possibilities caused widespread adoption of the angled flight deck in future aircraft carrier construction and modifications of existing carriers.[3] On 1 October, the ship was redesignated CVA-41.

 

Midway cleared Norfolk 27 December 1954 for a world cruise, sailing via the Cape of Good Hope for Taiwan, where she became the first large carrier in the 7th Fleet for operations in the Western Pacific until 28 June 1955.[3] During these operations, Midway pilots flew cover for the evacuation from the Quemoy-Matsu crisis[5] from the Tachen Islands of 15,000 Chinese nationalist troops and 20,000 Chinese civilians, along with their livestock.

Apartheid Incident

 

Controversy arose during the cruise when Midway docked in Cape Town, South Africa. Democratic senator Herbert Lehman sent a telegram to Secretary of the Navy Charles Thomas when he learned of a supposed United States Navy plan to segregate 400 non-European members of the crew of Midway while she was in Cape Town. Fellow Democrat senator Hubert Humphrey soon joined Lehman, additionally sending a letter to the Secretary of State John Foster Dulles, asking that "immediate steps be taken to see that equal treatment is given to American service personnel allowed shore leave in South Africa, or eliminate Cape Town as a port of call", and that: "To me this is a shocking of discrimination that should not be tolerated by our Government. Every American soldier or sailor is an American regardless of race, colour or creed, and is entitled to be respected and treated as such anywhere in the world."[6]

 

An anonymous Navy official stated that the Department of the Navy did not know of the arrangements that were to be made between the officers of Midway and South African authorities, and that African-American members of the crew would not be segregated while still aboard Midway.[6]

 

Clarence Mitchell Jr. also urged Thomas not to allow Midway to dock at Cape Town. James H. Smith Jr., Acting Secretary of the Navy at the time, replied that the stop at Cape Town was merely to "satisfy an operational logistic requirement" and that it was customary to observe local laws and regulations while visiting foreign ports.[6]

 

Captain Reynold Delos Hogle of Midway stated that while in port, Midway would be United States territory and federal United States laws would apply. In the end, the crew of Midway were not made to abide by Apartheid, saying that "At Hartleyvale this afternoon and at the concert to-night, European and non-European members of the crew have been asked to attend. There will be no segregation whatsoever".[6]

Modernizations

 

On 28 June 1955, the ship sailed for Puget Sound Naval Shipyard, where Midway underwent an extensive modernization program (SCB-110, similar to SCB-125 for the Essex-class carriers). Midway received an enclosed hurricane bow, an aft deck-edge elevator, an angled flight deck, and steam catapults, returning to service on 30 September 1957.[3]

 

Home ported at Alameda, California, Midway began annual deployments bringing McDonnell F3H Demons, North American FJ-4 Furys, Vought F-8 Crusaders, Douglas A-1 Skyraiders, and Douglas A-3 Skywarriors to the 7th Fleet in 1958, and into the South China Sea during the Laotian Crisis of spring 1961. During the 1962 deployment, Midway recorded her 100,000th arrested landing[3] as the ship's aircraft tested the air defense systems of Japan, Korea, Okinawa, the Philippines, and Taiwan. Midway again sailed for the Far East 6 March 1965, and from mid-April flew strikes against military and logistics installations in North and South Vietnam including the first combat use of AGM-12 Bullpup air-to-surface missiles. On 17 June 1965 two VF-21 McDonnell Douglas F-4 Phantom IIs flying from Midway were credited with the first confirmed MiG kills of the Vietnam conflict using AIM-7 Sparrow missiles to down two MiG-17s. Three days later, four of Midway's A-1 Skyraiders used the Thach Weave to down an attacking MiG-17.[3]

 

Midway lost an F-4 Phantom and two A-4 Skyhawks to North Vietnamese S-75 Dvina surface-to-air missiles before returning to Alameda on 23 November to enter San Francisco Bay Naval Shipyard on 11 February 1966 for a massive modernization (SCB-101.66), which proved expensive and controversial. The flight deck was enlarged from 2.8 to 4 acres (11,300 to 16,200 square metres (122,000 to 174,000 sq ft)), and the angle of the flight deck landing area was increased to 13.5 degrees. The elevators were enlarged, moved, and given almost double the weight capacity. Midway also received new steam catapults, arresting gear, and a centralized air conditioning plant. Cost overruns raised the price of this program from $88 million to US$202 million, and precluded a similar modernization planned for Franklin D. Roosevelt. After Midway was finally recommissioned on 31 January 1970, it was found that the modifications had hurt the ship's seakeeping capabilities and ability to conduct air operations in rough seas, which made further modifications necessary to correct the problem.[3]

Return to Vietnam

 

Midway returned to Vietnam and on 18 May 1971, after relieving Hancock on Yankee Station, began single carrier operations. Midway departed Yankee Station on 5 June, completing the vessel's final line period on 31 October 1971, and returned to the ship's homeport on 6 November 1971.

Midway en route to South-East Asia in April 1972

 

Midway, with embarked Carrier Air Wing 5 (CVW 5), again departed Alameda for operations off Vietnam on 10 April 1972. On 11 May, aircraft from Midway, along with those from Coral Sea, Kitty Hawk, and Constellation, continued laying naval mines off North Vietnamese ports, including Thanh Hóa, Đồng Hới, Vinh, Hon Gai, Quang Khe, and Cam Pha as well as other approaches to Haiphong. Ships that were in port in Haiphong had been advised that the mining would take place and that the mines would be armed 72 hours later.

 

Midway continued Vietnam operations during Operation Linebacker throughout the summer of 1972. On 7 August 1972, an HC-7 Det 110 helicopter, flying from Midway, and aided by planes from the carrier and from Saratoga, searched for the pilot of an A-7 Corsair II aircraft from Saratoga, who had been downed the previous day by a surface-to-air missile about 20 mi (32 km) inland, northwest of Vinh. Flying over mountains, the HC-7 helicopter spotted the downed aviator with her searchlight and, under heavy ground fire, retrieved him and returned to an LPD off the coast. This was the deepest penetration of a rescue helicopter into North Vietnam since 1968. By the end of 1972, HC-7 Det 110 had rescued 48 pilots, 35 in combat conditions.

 

On 5 October 1973, Midway, with CVW 5, put into Yokosuka, Japan, marking the first forward-deployment of a complete carrier task group in a Japanese port, the result of an accord arrived at on 31 August 1972 between the U.S. and Japan. The move allowed sailors to live with their families when in port; more strategically, it allowed three carriers to stay in the Far East even as the economic situation demanded the reduction of carriers in the fleet. CVW 5 became based at the nearby Naval Air Facility Atsugi.[3]

 

For service in Vietnam from 30 April 1972, to 9 February 1973, Midway and CVW 5 received the Presidential Unit Citation from Richard Nixon. It read:

 

For extraordinary heroism and outstanding performance of duty in action against enemy forces in Southeast Asia from 30 April 1972 to 9 February 1973. During this crucial period of the Vietnam conflict, USS MIDWAY and embarked Attack Carrier Air Wing FIVE carried out devastating aerial attacks against enemy installations, transportation, and lines of communications in the face of extremely heavy opposition including multi-calibre antiaircraft artillery fire and surface-to-air missiles. Displaying superb airmanship and unwavering courage, MIDWAY/CVW-5 pilots played a significant role in lifting the prolonged sieges at An Lộc, Kon Tum, and Quảng Trị and in carrying out the concentrated aerial strikes against the enemy's industrial heartland which eventually resulted in a cease-fire. By their excellent teamwork, dedication, and sustained superior performance, the officers and men of MIDWAY and Attack Carrier Air Wing FIVE reflected great credit upon themselves and upheld the highest traditions of the United States Naval Service."[7]

 

Aircraft from Midway made the first MIG kills in the Vietnam War, and the last air-to-air victory of the war. On 17 June 1965, aviators of Midway's Attack Carrier Wing 2, VF-21 downed the first two MiGs credited to U.S. forces in Southeast Asia.[8] On 12 January 1973 a combat aircraft from Midway made the last air-to-air victory of the Vietnam War.[8]

Operation Frequent Wind

 

On 19 April 1975, after North Vietnam had overrun two-thirds of South Vietnam, Midway, along with Coral Sea, Hancock, Enterprise and Okinawa, were sent to the waters off South Vietnam. Ten days later, U.S. 7th Fleet forces carried out the Operation Frequent Wind evacuation. Midway, which had offloaded half of the ship's regular combat air wing at NS Subic Bay, Philippines, steamed to Thailand and took aboard eight CH-53 from 21st Special Operations Squadron and two HH-53 helicopters from 40th Aerospace Rescue and Recovery Squadron.[9] As Saigon fell to the North Vietnamese, these helicopters ferried hundreds of U.S. personnel and Vietnamese people to Midway and other U.S. ships in the South China Sea.

 

On 29 April 1975, Republic of Vietnam Air Force (RVNAF) Major Buang-Ly (also spelled Buang Lee) loaded his wife and five children into a two-seat Cessna O-1 Bird Dog and took off from Con Son Island. After evading enemy ground fire, Buang headed out to the South China Sea, found Midway, and began to circle overhead with his landing lights turned on. Midway's crew unsuccessfully attempted to contact the aircraft on emergency frequencies. When a spotter reported that there were at least four people in the two-seater aircraft, all thoughts of forcing the pilot to ditch alongside were abandoned. After three tries, Major Buang managed to drop a note from a low pass over the deck: "Can you move the helicopter to the other side, I can land on your runway, I can fly for one hour more, we have enough time to move. Please rescue me! Major Buang, wife and 5 child." Captain Larry Chambers, the ship's commanding officer, ordered that the arresting wires be removed and that any helicopters that could not be safely and quickly moved should be pushed over the side. He called for volunteers, and soon every available seaman was on deck to help. An estimated US$10 million worth of UH-1 Huey helicopters were pushed overboard. With a 500-foot (150 m) ceiling, 5-mile (8.0 km) visibility, light rain, and 15 knots (28 km/h; 17 mph) of surface wind, Chambers ordered the ship to make 25 knots (46 km/h; 29 mph) into the wind. Warnings about the dangerous downdrafts created behind a steaming carrier were transmitted blind in both Vietnamese and English. To make matters worse, five more UH-1s landed and cluttered up the deck. Without hesitation, Chambers ordered them scuttled as well. Captain Chambers recalled that the aircraft cleared the ramp and touched down on center line at the normal touchdown point. Had he been equipped with a tailhook he could have bagged a number 3 wire. He bounced once and came stop abeam of the island, amid a wildly cheering, arms-waving flight deck crew.[10]

 

Buang was escorted to the bridge where Chambers congratulated him on his outstanding airmanship and his bravery in risking everything on a gamble beyond the point of no return without knowing for certain a carrier would be where he needed it. The crew of Midway was so impressed that they established a fund to help him and his family get settled in the United States.[11] The O-1 that Major Buang landed is now on display at the Naval Aviation Museum in Pensacola, Florida.[12] Major Buang became the first Vietnamese pilot ever to land on an aircraft carrier deck.

 

Upon completion of ferrying people to other ships, Midway returned to Thailand and disembarked the Air Force helicopters at U-Tapao Royal Thai Navy Airfield. The CH-53s then airlifted over 50 RVNAF aircraft to the ship.[13] With almost 100 helicopters and aircraft of the former RVNAF aboard, the ship steamed to Guam where the aircraft and helicopters were offloaded in twenty-four hours. While transiting back to the Philippines to pick up the ship's air wing, Midway was rerouted to act as a floating airfield in support of special operation forces rescuing the SS Mayagüez. Midway picked up the ship's regular air wing again a month later when the aircraft carrier returned NAS Cubi Point, Philippines.

After Vietnam

 

On 21 August 1976, a Navy task force headed by Midway made a show of force off the coast of Korea in response to an unprovoked attack on two U.S. Army officers who were killed by North Korean guards on 18 August. (The U.S. response to this incident was Operation Paul Bunyan). Midway's response was in support of a U.S. demonstration of military concern vis-à-vis North Korea.

 

Midway relieved Constellation as the Indian Ocean contingency carrier on 16 April 1979. This unscheduled deployment was due to USS Ranger colliding with tanker Liberian Fortune near the Straits of Malacca, with Midway taking over Ranger's mission while she went in for repair. Midway and her escorts continued a significant American naval presence in the oil-producing region of the Arabian Sea and Persian Gulf. On 18 November, the aircraft carrier arrived in the northern part of the Arabian Sea in connection with the continuing hostage crisis in Iran. Militant followers of the Ayatollah Khomeini, who had come to power following the overthrow of the Shah, seized the U.S. Embassy in Tehran on 4 November and held 63 U.S. citizens hostage. Midway was joined 21 November by Kitty Hawk, and both carriers, along with their escort ships, were joined by Nimitz and her escorts on 22 January 1980. Midway was relieved by Coral Sea on 5 February.[3]

Missions in the 1980s

 

Following a period in Yokosuka, Midway relieved Coral Sea 30 May 1980 on standby south of the Cheju-Do Islands in the Sea of Japan following the potential of civil unrest in the Republic of Korea.

 

While transiting the passage between Palawan Island of the Philippines and the coast of Northern Borneo on 29 July, the Panamanian merchant ship Cactus collided with Midway. Cactus was 450 nautical miles (830 km) southwest of Subic Bay and headed to Singapore. The collision occurred near the liquid oxygen plant and two sailors working in the plant were killed and three were injured. Midway sustained light damage and three F-4 Phantom aircraft parked on the flight deck were also damaged.[8]

 

On 17 August, Midway relieved Constellation to begin another Indian Ocean deployment and to complement the Dwight D. Eisenhower task group still on contingency duty in the Arabian Sea. Midway spent a total of 118 consecutive days in the Indian Ocean during 1980.

 

On 16 March 1981, an A-6 Intruder from VA-115 aboard Midway sighted a downed civilian helicopter in the South China Sea. Midway immediately dispatched HC-1 Det 2 helicopters to the scene. All 17 people aboard the downed helicopter were rescued and brought aboard the carrier. The chartered civilian helicopter was also plucked out of the water and lifted to Midway's flight deck.

 

On 25 March 1986, the final carrier launching of a Navy fleet F-4S Phantom II took place off Midway during flight operations in the East China Sea. The Phantoms were replaced by the new F/A-18 Hornets.

 

Midway continued serving in the western Pacific throughout the 1980s. In order to alleviate persistent seakeeping issues, Midway received hull blisters in 1986. During her 1986 refit (named "Extended Incremental Selected Repair Availability"), blisters were added to improve the ship's stability. The modification proved unsuccessful, and actually increased the ship's instability in rough seas. She took water over the flight deck during excessive rolls in moderate seas, thereby hampering flight operations. Before another $138 million refit was approved to rectify the stability problems, it was even proposed to decommission Midway. Nevertheless, she had earned herself the nickname "Rock'n Roll carrier". During a typhoon while in the Sea of Japan during the Olympic Games in Korea, October 8, 1988, Midway, which was not supposed to be able to survive more than 24 degrees of roll, sustained a 26 degree roll and withstood it.

 

On 30 October 1989 an F/A-18 Hornet aircraft from Midway mistakenly dropped a 500 pounds (227 kilograms) general-purpose bomb on the deck of Reeves during training exercises in the Indian Ocean, creating a 5-foot (1.5 m) hole in the bow, sparking small fires, and injuring five sailors. Reeves was 32 miles (51 km) south of Diego Garcia at the time of the incident.[14]

 

Disaster struck Midway on 20 June 1990. While conducting routine flight operations approximately 125 nautical miles (232 km; 144 mi) northeast of Japan, the ship was badly damaged by two onboard explosions. These explosions led to a fire that raged more than ten hours. In addition to damage to the ship's hull, two crew members were killed and 9 others were wounded;[15] one of the injured later died of his injuries.[16] All 11 crewmen belonged to the at sea fire-fighting team known as the Flying Squad. When Midway entered Yokosuka Harbor the next day, 12 Japanese media helicopters flew in circles and hovered about 150 feet (46 m) above the flight deck. Three bus loads of reporters were waiting on the pier. About 30 minutes after Midway cast her first line, more than 100 international print and electronic journalists charged over the brow to cover the event. The news media made a major issue out of the incident, as it happened amid several other military accidents. It was thought that the accident would lead to the ship's immediate retirement due to her age, but instead Midway was retained to fight in one last major conflict.

Operation Desert Storm and the 1990s

 

On 2 August 1990, Iraq invaded neighboring Kuwait and U.S. forces moved into Saudi Arabia as part of Operation Desert Shield to protect that country against invasion by Iraq. On 1 November 1990, Midway was again on station in the North Arabian Sea being the carrier of Battle Force Zulu (which included warships from the US, Australia, and other countries), relieving Independence. On 15 November, the aircraft carrier participated in Operation Imminent Thunder, an eight-day combined amphibious landing exercise in northeastern Saudi Arabia which involved about 1,000 U.S. Marines, 16 warships, and more than 1,100 aircraft. Meanwhile, the United Nations set an ultimatum deadline of 15 January 1991 for Iraq to withdraw from Kuwait.

 

Operation Desert Storm began the next day, and the Navy launched 228 sorties from Midway and Ranger in the Persian Gulf, from Theodore Roosevelt en route to the Gulf, and from John F. Kennedy, Saratoga, and America in the Red Sea. In addition, the Navy launched more than 100 Tomahawk missiles from nine ships in the Mediterranean Sea, the Red Sea, and the Persian Gulf. Desert Storm officially ended 27 February, and Midway departed the Persian Gulf on 11 March 1991 and returned to Yokosuka.

 

In June 1991, Midway left for her final deployment, this time to the Philippines to take part in Operation Fiery Vigil, which was the evacuation of 20,000 military members including their families from Clark Air Base, on the island of Luzon, after the eruption of Mt. Pinatubo. Midway, along with twenty other U.S. naval ships, ferried the evacuees to the island of Cebu, where they were taken off the ship by helicopter. After taking part in the evacuation, the aircraft carrier once again returned to Yokosuka.

 

Final cruise

 

In August 1991, Midway departed Yokosuka and returned to Pearl Harbor. There, she turned over with Independence, which was to replace Midway as the forward-deployed carrier in Yokosuka. Rear Admiral Joseph Prueher and the staff of Carrier Group ONE cross-decked from Independence. Pruher was the last admiral to break his flag on Midway. She then sailed to Seattle for a port visit. The ship then disembarked "tigers" (guests of crew members) before making her final voyage to San Diego.

 

Midway was decommissioned at Naval Air Station North Island on 11 April 1992 in a ceremony in which the main speaker was Secretary of Defense Dick Cheney. The ship was stricken from the Naval Vessel Register on 17 March 1997. During decommissioning, Midway, her sailors, and their families were filmed for the movie At Sea, a documentary on carrier life shown only at the Navy Museum in Washington, D.C.

 

On 30 September 2003, ex-Midway began her journey from the Navy Inactive Ship Maintenance Facility, Bremerton, Washington, to San Diego, California, in preparation for use as a museum and memorial. The aircraft carrier was docked in early October at the Charles P. Howard Terminal in Oakland, California, while work proceeded on the Broadway Pier in downtown San Diego. On 10 January 2004, the ship was moored at her final location, where she was opened to the public on 7 June 2004 as a museum. In the first year of operation, the museum had 879,281 visitors, double the expected attendance.

 

On 11 November 2012, a college basketball game between the Syracuse Orange and the San Diego State Aztecs was played on the flight deck. The Orange won, 62–49.[17]

 

On 15 July 2015, museum personnel were evacuated from ex-Midway due to smoke caused by an apparent fire. The San Diego fire department responded quickly, but no fire was found, and the museum was able to open for the day on schedule.[18]

Awards and decorations

 

Presidential Unit Citation Joint Meritorious Unit Award Navy Unit Commendation

with three stars Meritorious Unit Commendation

with two stars

Navy E Ribbon with

wreathed Battle "E" device Navy Expeditionary Medal

with three stars China Service Medal American Campaign Medal

World War II Victory Medal Navy Occupation Service Medal National Defense Service Medal

with two stars Armed Forces Expeditionary Medal

with six stars

Vietnam Service Medal

with four stars Southwest Asia Service Medal

with two stars Humanitarian Service Medal Sea Service Deployment Ribbon

with sixteen stars

Republic of Vietnam Meritorious

Unit Citation (Gallantry Cross) Republic of Vietnam Campaign

Medal Kuwait Liberation Medal

(Saudi Arabia) Kuwait Liberation Medal

(Kuwait)

A good friend has this wee beauty parked in his garage awaiting some restoration work , I have hoped to capture it many times in the past however on this occasion the light was right and he had her parked in his drive , this photo is one of a few I took .

  

Vehicle details

 

Vehicle make: VOLKSWAGEN

Date of first registration: January 1973

Year of manufacture: 1972

Cylinder capacity (cc): 1584 cc

CO₂Emissions: Not available

Fuel type: PETROL

Export marker: No

Vehicle status: SORN in place

Vehicle colour: ORANGE

Wheelplan: 2-AXLE-RIGID BODY

 

The Volkswagen Beetle—officially the Volkswagen Type 1, informally in German the Käfer (literally "beetle"), in parts of the English-speaking world the Bug, and known by many other nicknames in other languages—is a two-door, rear-engine economy car, intended for five passengers, that was manufactured and marketed by German automaker Volkswagen (VW) from 1938 until 2003.

 

History of the Volkswagen T1 Beetle

 

Introduction

The VW Beetle has become an iconic vehicle worldwide, and has built a huge loyal following. It is known by numerous names, for example, in Germany it’s a Kafer, in the USA a Bug or salon, England a Beetle etc. As the floor pan and running gear can be used without the body being attached, they became a firm favourite of the kit car builders. They were turned into Porsche 356 replicas, beach buggies, and Nova kit cars to mention just a few. When production stopped in 2003 in Mexico over 21 million air-cooled Volkswagen Beetles had been produced. During eight decades of manufacturing came a whole variety of models, ranging from 25Hp through to the 1303S or Super Beetle with its Independent Rear Suspension (also known as IRS). Salons, sunroof models, cabrios and even specialist versions as police cars, German post office delivery vehicles and in Mexico City, the green and white Beetle taxi, with its missing passengers seat, was a common sight until recently.

 

Personalisation and the custom scene

 

Fashions change and over the years the VW Beetle or Bug has seen styles come and go. The 1950’s saw shiny and standard Beetles as the common style. But by the 1960’s the trend to ‘soup them up’ and build street legal drag racers was taking hold in the USA, especially on the West Coast. This was the time of legends such as Gene Berg and cars such as the Empi Inch Pincher. In the UK, smaller tuning companies such as Speedwell developed carb tuning kits and alloy wheels. By the mid 1970’s the Bug was being used for time trials and autocross racing.

 

This was also the start of a ‘dark’ time for the Beetle customising scene, as the fat whale tailed body kits were fitted, so if you saw it on a dark foggy night, it could look a little like a Porsche 911! However as the whale tail was strapped on, in California they developed what has come to be known as ‘Calook’ or Californian Look. Lowered, smoothed out, de-chromed, alloys, neat interiors and performance engines were the main features of the Calook scene. Luckily by the mid 1980s in the UK, the body kits were out of fashion and the Calook scene took hold, initially from Essex. Since then there have been a variety of fashions, with the VW drag racing scene now in its fourth decade. We’ve seen ‘Old School’ lowered, lots of chrome and accessories, neat and tidy. ‘Rat look’ is almost the polar opposite, with flat mat paint, original and lived in interiors but shares the passion for vintage accessories! Calook in various rebirths has been a steady influence. However, today there seems to be strong move back to ‘stock’.

 

Please Note: When trying to identify a Beetle, bear in mind that on all models (except 1302/1303) most body panels are interchangeable, so if a Beetle has sloping headlights, don’t assume that it is a 1957>1967 model. Many late Beetles have early wings, lights, bonnet, engine lid and front and rear valances, making them, at first glance identical to a 1964 to 1967 model, but generally if it has an external fuel filler cap it is likely to be built between 1968 and 2003.

 

Production history and technical changes

 

Here are the main changes that took place to the Volkswagen Beetle during its eight decades of production.

 

1936 > 1952 ‘Splitscreen Beetle’ The Beetle story started in the early 1930’s, but production started officially in 1936. The Second World War all but stopped production until the British army rebuilt the factory and production commenced of the ‘Splitscreen’ Beetles (named after the shape of the small ‘split’ rear window). These were very basic cars with engines from 985cc (24bhp) to 1131cc (25bhp) but are rare and very desirable.

 

1953 > 1956 ‘Oval Beetle’ Very similar to the Splitscreen, but with the split removed from the rear window making it an oval. Small developments aimed at improving driver comfort and making the Beetle appeal to foreign markets, including a new 1192cc (30bhp) engine.

1957 > 67 Little difference in appearance from the Oval Beetle, the biggest being the rear window, which was enlarged in August 1957 to the large rectangular shape that would remain for the remainder of production. The windscreen and side glass were also enlarged in August 1964. These Beetles still retained the sloping headlights, long bonnet, link and king pin torsion bar front suspension and swing axle torsion bar suspension at the rear and 5 bolt wheels as previous models, but in Aug 1966 the link pins were replaced with ball joints and the wheels used four bolts instead of five. Engine options were now 1192cc (34bhp), 1285cc (40bhp) and in Aug 1966 the 1493cc engine with (44bhp).

 

1968 > 2003 August 1967 saw the first major styling change with upright headlights, a shorter bonnet and engine lid, plus an exterior mounted fuel filler cap. These models retained the torsion bar front suspension and swing axle rear suspension, which remained until the end of Brazilian production in 2003. The only exceptions were the semi-automatic Beetle which came with I.R.S rear suspension and the 1302 and 1303 models which used front coil springs... (see below). Engine options for these were 1192cc (34bhp), 1285cc (44bhp), 1493cc engine with (44bhp) and 1584cc (50bhp).

 

1971 > 72 ‘The 1302 Beetle’ In an effort to make the Beetle more practical and improve sales, VW offered a restyled version alongside the regular Beetle which was badged the 1302 (1285cc) and the 1302S (1584cc). This had a more bulbous front bodywork but retained the flat windscreen and the torsion bar front suspension was replaced with MacPherson struts with coil springs, similar to the VW Golf. The rear suspension was also the much improved I.R.S torsion bar system similar to the Porsche 911 of the same era. These changes improved the handling, ride comfort and stability, plus the front luggage area increased from 5 cu ft to over 9 cu ft, however, the styling proved unpopular and it was replaced after 2 years by the 1303 model.

 

1973 > 80 ‘The 1303 Beetle’ This was a revision of the 1302 Beetle and was available as the 1303A (1192cc) 1303 (1283cc) and the 1303S (1584cc). The only major change was that the flat windscreen was replaced with a more modern curved windscreen, which improved aerodynamics and interior space. This was also sold alongside the regular, torsion bar; flat windscreen Beetle, with the last 1303 was built in 1980.

 

The classic styling of the torsion bar Beetles helped them outlive the improved design of the 1302/1302 ‘Super Beetles’ and production was ended in 2003 to free up factory space for the front engined, water-cooled ‘New Beetle.’

 

German Beetle production chassis numbers

The chassis number is very useful when ordering parts for your Beetle as it gives the date of manufacture, model type. These can be found in two places. Firstly, in the front luggage compartment, by the bonnet lock and secondly, under the rear seat on the central tunnel.

Large View

 

So much of what is best in us is bound up in our love of family, that it remains the measure of our stability because it measures our sense of loyalty. All other pacts of love or fear derive from it and are modeled upon it.

 

~Haniel Long

 

Another beautifully composed piece of music by the legendary film composer Hans Zimmer for the Holiday Sndtrk. A well done video as well...

 

Hans Zimmer- Maestro

 

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SOUTH CHINA SEA (Sept. 6, 2020) Sailors assigned to the forward-deployed amphibious assault ship USS America (LHA 6) refuel an AH-1Z Viper helicopter assigned to the 31st Marine Expeditionary Unit (MEU), Marine Medium Tiltrotor Squadron (VMM) 262 (Reinforced) during a visit, board, search and seizure exercise. America, flagship of the America Amphibious Ready Group, assigned to Amphibious Squadron Eleven, along with the 31st Marine Expeditionary Unit, is operating in the U.S. 7th Fleet area of responsibility to enhance interoperability with allies and partners and serve as a ready response force to defend peace and stability in the Indo-Pacific region. (U.S. Navy photo by Mass Communication Specialist 3rd Class Vincent E. Zline)

PHILIPPINE SEA (Aug. 6, 2020) A CV-22 Osprey tilt-rotor aircraft attached to the Air Force 21st Special Operations Squadron lands on the flight deck of the amphibious assault ship USS America (LHA 6). America, flagship of the America Expeditionary Strike Group, is operating in the U.S. 7th Fleet area of responsibility to enhance interoperability with allies and partners and serve as a ready response force to maintain security and stability in the Indo-Pacific region. (U.S. Navy photo by Mass Communication Specialist 3rd Class Walter Estrada)

PACIFIC OCEAN (Aug. 19, 2020) Landing Craft, Utility 1666, from Navy Beach Unit (NBU) 7 enters the well deck of the amphibious transport dock ship USS New Orleans (LPD 18). New Orleans, part of the America Expeditionary Strike Group, is operating in the U.S. 7th Fleet area of operations to enhance interoperability with allies and partners, and serves as a ready response force to defend security and stability in the Indo-Pacific region. (U.S. Navy photo by Mass Communication Specialist 2nd Class Kelby Sanders)

They are amazingly fast. It took about a week for the boys to figure out how to catch them. Then it was a dozen in one morning once they found the plant that traps drinking water, and evasive geckos.

 

They can hang from perfectly smooth glass, wet or dry, and support their body weight with one toe touching. But the toes are not sticky. They can also climb those surfaces at a meter per second.

 

The nanostructured split-end hairs at the tip of the gecko’s toes exploit weak Van der Waals bonds at the molecular scale, conforming to any surface.

 

The gecko is a simply amazing animal, and it’s not just the nano-adhesive toes. High-speed video studies also shed light on the use of their tail for dynamic stability and flight, inspiring the robo-gecko experiments of Robert Full (see below).

SOUTH CHINA SEA (Sept. 6, 2020) Force Reconnaissance Marines with Command Element, 31st Marine Expeditionary Unit (MEU) fast rope from an MH-60S Seahawk helicopter from the “Archangels” of Helicopter Sea Combat Squadron (HSC) 25, Detachment 6, during a visit, board, search and seizure exercise aboard the amphibious dock landing ship USS Germantown (LSD 42). Germantown, part of the America Amphibious Ready Group assigned to Amphibious Squadron 11, along with the 31st Marine Expeditionary Unit, is operating in the U.S. 7th Fleet area of responsibility to enhance interoperability with allies and partners, and serve as a ready response force to defend peace and stability in the Indo-Pacific region. (U.S. Navy photo by Mass Communication Specialist 2nd Class Taylor DiMartino)

PHILIPPINE SEA (Jan. 27, 2021) Aviation Boatswains Mate (Handling) 3rd Class Russell Edgar, from Salt Lake City, left, and Chief Warrant Officer Brad Anthony, from Anthony, Fla., perform a P-25 drive-through aboard the forward-deployed amphibious assault ship USS America (LHA 6). America, flagship of the America Expeditionary Strike Group, along with the 31st Marine Expeditionary Unit, is operating in the U.S. 7th Fleet area of responsibility to enhance interoperability with allies and partners, serving as a ready response force to defend peace and stability in the Pacific region. (U.S. Navy photo by Mass Communication Specialist Seaman Kelsey Culbertson)

SOUTH CHINA SEA (May 29, 2016) The guided-missile cruiser USS Mobile Bay (CG 53) performs a high-speed turn during a breakaway after completing a replenishment-at-sea. Providing a ready force supporting security and stability in the Indo-Asia-Pacific, Mobile Bay is operating as part of the John C. Stennis Strike Group and Great Green Fleet on a regularly scheduled 7th Fleet deployment. (U.S. Navy photo by Mass Communication Specialist 3rd Class Andre T. Richard)

 

PHILIPPINE SEA (Aug. 13, 2021) U.S. Marines with the 31st Marine Expeditionary Unit (MEU), brace behind cargo during a Helicopter Support Team (HST) exercise aboard amphibious assault ship USS America (LHA 6) in the Philippine Sea. Marines conduct HST training in order to increase proficiency in logistics tasks and enhance the ability to execute potential contingency missions carried out be the 31st MEU. The 31st MEU is operating aboard ships of America Expeditionary Strike Group in the 7th fleet area of operations to enhance interoperability with allies and partners and serve as a ready response force to defend peace and stability in the Indo-Pacific region. (U.S. Marine Corps photo by Lance Cpl. Malik Lewis)

PHILIPPINE SEA (Sept. 1, 2020) The forward-deployed amphibious transport dock USS New Orleans (LPD 18), front right, the amphibious assault ship USS America (LHA 6) and the amphibious dock landing ship USS Germantown (LSD 42) sail in formation. New Orleans, America and Germantown, part of the America Amphibious Ready Group assigned to Amphibious Squadron 11, along with the 31st Marine Expeditionary Unit, are operating in the U.S. 7th Fleet area of responsibility to enhance interoperability with allies and partners and serve as a ready response force to defend peace and stability in the Indo-Pacific region. (U.S. Navy photo by Mass Communication Specialist 3rd Class Walter Estrada)

SOUTH CHINA SEA (Sept. 6, 2020) Force Reconnaissance Marines with Command Element, 31st Marine Expeditionary Unit (MEU) board a CH-53 E Super Stallion helicopter with Marine Medium Tiltrotor Squadron (VMM) 262, for extraction during a visit, board, search and seizure exercise aboard the amphibious dock landing ship USS Germantown (LSD 42). Germantown, part of the America Amphibious Ready Group assigned to Amphibious Squadron 11, along with the 31st Marine Expeditionary Unit, is operating in the U.S. 7th Fleet area of responsibility to enhance interoperability with allies and partners, and serve as a ready response force to defend peace and stability in the Indo-Pacific region. (U.S. Navy photo by Mass Communication Specialist 2nd Class Taylor DiMartino)

EAST CHINA SEA (July 31, 2020) Sailors connect fueling lines to the Ticonderoga-class guided-missile cruiser USS Shiloh (CG 67) from the dry cargo and ammunition ship USNS Alan Shepard (T-AKE-3) during a replenishment-at-sea. Shiloh is forward-deployed to the U.S. 7th Fleet area of operations in support of security and stability in the Indo-Pacific. (U.S. Navy photo by Mass Communication Specialist 3rd Class Isaac Maxwell)