1:72 Spectrum SA-550 (modified Cessna 337) “Pelican”; aircraft “N669PD” of the Los Angeles Police Department Air Support Division, Special Flight Section (SFS); California (USA), 2001 (What-if/modified Arii kit)

+++ DISCLAIMER +++

Nothing you see here is real, even though the conversion or the presented background story might be based on historical facts. BEWARE!

 

 

Some background:

The Cessna Model 336 and 337 “Skymaster” were American twin-engine civil utility aircraft built in a unique push-pull configuration. Their engines were mounted in the nose and rear of its pod-style fuselage. Twin booms extended aft of the wings to the vertical stabilizers, with the rear engine between them. The horizontal stabilizer was aft of the pusher propeller, mounted between and connecting the two booms.

 

The first Skymaster, Model 336, had fixed landing gear and initially flew on February 28, 1961. It went into production in May 1963 with 195 being produced through mid-1964. In February 1965, Cessna introduced the larger Model 337 Super Skymaster with more powerful engines, retractable landing gear, and a dorsal air scoop for the rear engine (the "Super" prefix was subsequently dropped from the name). In 1966, the turbocharged T337 was introduced, and in 1973, the pressurized P337G entered production.

The type was very prolific and Cessna built 2.993 Skymasters of all variants, including 513 military O-2 (nicknamed "Oscar Deuce") versions from 1967 onwards. The latter featured underwing ordnance hard points to hold unguided rockets, gun pods or flares, and served in the forward air control (FAC) role and psychological operations (PSYOPS) by the US military between 1967 and 2010. Production in America ended in 1982, but was continued by Reims in France, with the FTB337 STOL and the military FTMA “Milirole”.

 

Both civil and military Cessna 336/337 version had long service careers, and some were considerably modified for new operators and uses. Among the most drastic conversions was the Spectrum SA-550, built by Spectrum Aircraft Corporation of Van Nuys, California, in the mid-1980s: Spectrum took the 336/337 airframe and removed the front engine, lengthened the nose to maintain the center of gravity, and replaced the rear piston engine with a pusher turboprop which offered more power than the combined pair of original petrol engines. The Spectrum SA-550 conversion also came together with an optional modernization package that prolonged the airframes’ service life, so that modified machines could well serve on for 20 years or more.

 

This drastic conversion was executed for both military and civil operators. The best-known military SA-550s were six former USAF O-2A airframes, which had been transferred to the U.S. Navy in 1983 for use as range controllers with VA-122 at NAS Lemoore, California. These aircraft were operationally nicknamed “Pelican”, due to the characteristic new nose shape, and the name unofficially caught on.

However, the SA-550 package was only adopted sporadically by private operators, but it became quite popular among several major police and fire departments. Typical duties for these machines included border/drug patrol, surveillance/observation duties (e.g. traffic, forest fire) and special tasks, including drug interdiction as well for SAR missions and undercover operations like narcotics and serialized criminal investigations. Some SA-550s were accordingly modified and individually outfitted with suitable sensors, including IR/low light cameras, searchlights, and internal auxiliary tanks. None were armed, even though some aircraft featured underwing hardpoints for external extra tanks, flare dispensers for nocturnal operations or smoke charge dispensers for ground target marking to guide water bombers to hidden forest fires.

 

The type’s versatility, low noise level, high travel speed and good loitering time in the operational area at low speed proved to be vital assets for these public service operators and justified its relatively high maintenance costs. A handful of the modernized Spectrum SA-550 machines were still in active service after the Millennium, primarily in the USA.

 

 

General characteristics:

Crew: 1 + 3 passengers (up to 5 passengers possible in special seat configuration)

Length: 32 ft 6½ in (9.94 m)

Wingspan: 38 ft ¾ in (11.62 m)

Height: 9 ft 2 in (2.79 m)

Wing area: 201 sq ft (18.81 m²)

Aspect ratio: 7.18:1

Airfoil: NACA 2412 at root, NACA 2409 at tip

Empty weight: 2,655 lb (1,204 kg)

Max takeoff weight: 4,400 lb (1,996 kg)

Fuel capacity: 92 US gal (77 imp gal; 350 l) normal,

128 US gal (107 imp gal; 480 l) with auxiliary tank

in the cabin instead of two passenger seats

 

Powerplant:

1× Pratt & Whitney PT6A-27 turboprop engine, delivering 550 shp (410 kW) and

driving a four-blade McCauley fully-feathering, constant-speed propeller, 6 ft 4 in (1.93 m) diameter

 

Performance:

Maximum speed: 199 mph (320 km/h, 173 kn) at sea level

Cruise speed: 144 mph (232 km/h, 125 kn) at 10,000 ft (3,000 m) (econ cruise)

Stall speed: 69 mph (111 km/h, 60 kn)

Range: 1421 mi (2.288 km, 1.243 nmi) at 10.000 ft (3.050 m) altitude and economy cruise

Service ceiling: 19,500 ft (5,900 m)

Rate of climb: 1,200 ft/min (6.1 m/s)

Takeoff distance to 50 ft (15m): 1,545 ft (471 m)

Landing distance from 50 ft (15m): 1,650 ft (500 m)

 

 

The kit and its assembly:

This build is the combination of ingredients that had already been stashed away for a long time, and the “Red Lights” Group Build at whatifmodellers.com in early 2021 was a good motivator and occasion to finally put everything together.

 

The basis is an ARII 1:72 Cessna T337 model kit – I had purchased it long ago with the expectation to create a military Skymaster from it, but I was confused by a fixed landing gear which would make it a 336? Well, without a further concrete plan the kit preliminarily landed in The Stash™…

However, the ARII model features the optional observation windows in the doors on the starboard side, in the form of a complete(!) fuselage half, so that it lends itself to a police or firefighter aircraft of some sort. This idea was furthermore fueled by a decal sheet that I had been given from a friend, left over from a 1:72 Italeri JetRanger, with three optional police helicopter markings.

The final creative element was the real-world “Pelican” conversion of six O-2As for the US Navy, as mentioned in the background above: the front engine was replaced with a longer nose and the engine configuration changed to a pusher-only aircraft with a single powerful turboprop engine. This looked so odd that I wanted to modify the ARII Cessna in a similar fashion, too, and all these factors came together in this model.

 

My Arii Cessna 337 kit is a re-boxing from 2009, but its origins date back to Eidai in 1972 and that’s just what you get: a vintage thing with some flash and sinkholes, raised (but fine) surface details and pretty crude seams with bulges and gaps. Some PSR is direly necessary, esp. the fit of the fuselage halves is cringeworthy. The clear parts were no source of joy, either; especially the windscreen turned out to be thick, very streaky (to a degree that I’d almost call it opaque!) and even not fully molded! The side glazing was also not very clear. I tried to improve the situation through polishing, but if the basis is already poor, there’s little you can do about it. Hrmpf.

 

However, the kit was built mostly OOB, including the extra O-2 glazing in the lower doors, but with some mods. One is a (barely visible) extra tank in the cabin’s rear, plus a pilot and an observer figure placed into the tight front seats. The extended “Pelican” nose was a lucky find – I was afraid that I had had to sculpt a nose from scratch with 2C putty. But I found a radome from a Hasegawa RA-5C, left over from a model I built in the Eighties and that has since long fallen apart. However, this nose fitted almost perfectly in size and shape, I just “blunted” the tip a little. Additionally, both the hull in front of the dashboard and the Vigilante radome were filled with as many lead beads as possible to keep the nose down.

 

The kit’s OOB spatted, fixed landing gear was retained – even though it is dubious for a Cessna 337, because this type had a fully retractable landing gear, and the model has the landing gear covers actually molded into the lower fuselage. On the other side, the Cessna 336’s fixed landing gear looks quite different, too! However, this is a what-if model, and a fixed landing gear might have been a measure to reduce maintenance costs?

 

The propeller was replaced with a resin four-blade aftermarket piece (from CMK, probably the best-fitting thing on this build!) on my standard metal axis/styrene tube adapter arrangement. The propeller belongs to a Shorts Tucano, but I think that it works well on the converted Cessna and its powerful pusher engine, even though in the real world, the SA-550 is AFAIK driven by a three-blade prop. For the different engine I also enlarged the dorsal air intake with a 1.5 mm piece of styrene sheet added on top of the molded original air scoop and added a pair of ventral exhaust stubs (scratched from sprue material).

Another addition is a pair of winglets, made from 0.5 mm styrene sheet – an upgrade which I found on several late Cessna 337s in various versions. They just add to the modernized look of the aircraft. For the intended observation role, a hemispherical fairing under the nose hides a 180° camera, and I added some antennae around the hull.

 

However, a final word concerning the model kit itself: nothing fits, be warned! While the kit is a simple affair and looks quite good in the box, assembling it turned out to be a nightmare, with flash, sinkholes, a brittle styrene and gaps everywhere. This includes the clear parts, which are pretty thick and blurry. The worst thing is the windscreen, which is not only EXTRA thick and EXTRA blurry, it was also not completely molded, with gaps on both sides. I tried to get it clearer through manual polishing, but the streaky blurs are integral – no hope for improvement unless you completely replace the parts! If I ever build a Cessna 337/O-2 again, I will give the Airfix kit a try, it can only be better…

 

 

Painting and markings:

The choice between the operator options from the JetRanger sheet was hard, it included Sweden and Italy, but I eventually settled for the LAPD because the livery looks cool and this police department not only operates helicopters, but also some fixed-wing aircraft.

 

I adapted the LAPD’s classic black-and-white police helicopter livery (Gloss White and Black, Humbrol 22 and 21, respectively) to the Cessna and extended it to the wings. At this point – already upset because of the poor fit of the hardware – disaster struck in the form of Humbrol’s 22 turning into a pinkish ivory upon curing! In the tin, the paint and its pigments looked pretty white and “clean”, and I assume that it’s the thinner that caused this change. What a crap! It’s probably the third tin with 22 that causes trouble, even though in different peculiarities!

The result was total rubbish, though, and I tried to rub the paint off as good as possible on the small model with its many windows, the fixed, delicate landing gear and the wing support struts. Then I overpainted the areas with Revell 301 (Semi-matt White). While this enamel yielded the intended pure white tone, the paint itself is rather gooey and not easy to work with, so that the overall finish turned out worse than desired. At least the black paint worked properly. The demarcations were created with black decal stripes (TL Modellbau), because the tiny model left little room for complex masking measures – and I did not risk any more painting accidents.

 

Since the aircraft would be kept shiny and clean, I just did a light black ink washing to emphasize surface details and did a light panel post-shading on the black areas, not for weathering but rather to accent surface structures. No further weathering was done (and necessary).

 

The markings/decals come – as mentioned above – from an Italeri 1:72 JetRanger, but they were augmented with some additional markings, e. g. grey walkways on the wings and “L-A-P-D” in large black letters under the wings, to distract from the poor finish of the white paint around them…

Finally, the kit was sealed overall with Italeri semi-gloss acrylic varnish, just with a matt anti-glare shield in front of the windscreen, which received thin white trim lines (generic decal stripes).

 

 

A challenging build due to the Arii kit’s rather poor basis, the massive rhinoplasty and the crisp paint scheme. However, I like the result – what-if models do not always have to be armed military vehicles, there’s potential in other genres, too. And this mono-engine “Pelican” Skymaster plays its role as a “flying eye” in police service credibly and well. However, this was my first and last Eidai kit…

Done