Bell P-76A 'Airaconda', 344th Fighter Squadron (343rd FG); Adak/Alaska, 1944

Dizzyfugu · November 06, 2014, 04:49:24 AM

Some background:
Bell's P-76 had its roots in the P-39 Airacobra, one of the principal American fighter aircraft in service when the United States entered World War II.

The Airacobra had an innovative layout, with the engine installed in the center fuselage, behind the pilot, and driving a tractor propeller via a long shaft. It was also the first fighter fitted with a tricycle undercarriage.

1:72 Bell P-76A 'Airaconda', BuNo. 43-04308 of the 344th Fighter Squadron (343rd Fighter Group); Adak Airfield, Aleutian Islands (Alaska), early 1944 (Whif/Kitbashing) by dizzyfugu, on Flickr

1:72 Bell P-76A 'Airaconda', BuNo. 43-04308 of the 344th Fighter Squadron (343rd Fighter Group); Adak Airfield, Aleutian Islands (Alaska), early 1944 (Whif/Kitbashing) by dizzyfugu, on Flickr

Although its mid-engine placement was innovative, the P-39 design was handicapped by the absence of an efficient turbo-supercharger, limiting it to low-altitude work. As such it was rejected by the RAF for use over western Europe and passed over to the USSR where performance at high altitude was less important.

Bell permanently tried to improve the aircraft. Trials of a laminar flow wing (in the XP-39E) and several alternative engines were unsuccessful, so the basic concept was taken into two directions: The mid-engine, gun-through-hub concept was developed further in the overall larger Bell XP-63 Kingcobra, and a radical re-design of the whole aircraft around its basic structure and its power unit, which became the XP-76.

1:72 Bell P-76A 'Airaconda', BuNo. 43-04308 of the 344th Fighter Squadron (343rd Fighter Group); Adak Airfield, Aleutian Islands (Alaska), early 1944 (Whif/Kitbashing) by dizzyfugu, on Flickr

1:72 Bell P-76A 'Airaconda', BuNo. 43-04308 of the 344th Fighter Squadron (343rd Fighter Group); Adak Airfield, Aleutian Islands (Alaska), early 1944 (Whif/Kitbashing) by dizzyfugu, on Flickr

The basic concept was simple: the proven Allison V-1710 engine was to be retained, but the rest of the aircraft was to be lightened and "minimized" wherever possible in order to improve its performance - a similar way Grumman went with the F8F Bearcat.

Anyway, Bell's construction team did not find much options, at least without compromising other factors like rigidity or armament. In a almost desperate move the decison was made to change the aircraft's layout altogether - making the P-39 a pusher aircraft! The Allison V-1710 allowed a simple switch from a pull to a push arrangement, and with a canard layout lots of weight could be saved: the tail section was competely deleted, and the heavy extension shaft and the respective gears for the front propeller became obsolete, too.

1:72 Bell P-76A 'Airaconda', BuNo. 43-04308 of the 344th Fighter Squadron (343rd Fighter Group); Adak Airfield, Aleutian Islands (Alaska), early 1944 (Whif/Kitbashing) by dizzyfugu, on Flickr

1:72 Bell P-76A 'Airaconda', BuNo. 43-04308 of the 344th Fighter Squadron (343rd Fighter Group); Adak Airfield, Aleutian Islands (Alaska), early 1944 (Whif/Kitbashing) by dizzyfugu, on Flickr

Wind tunnel tests confirmed the basic idea, even though the new layout called for several major innovations and new constructions which postponed development and service introduction considerably until late 1943.
These innovation comprised, for instance, the first (moderately) swept wings on an USAAF aircraft, due to CG and atability reasons. Unlike the very similar but bigger Curtiss XP-55 Ascender the XP-76 "Airaconda" had a very good performance, compared to the standard P-39. It was more agile, had a better rate of climb and retained the powerful 37mm cannon, which was highly effective against large air targets as well as ground targets. The gun was complemented by foud 0.5" machine guns, all grouped into the aircraft's nose.

1:72 Bell P-76A 'Airaconda', BuNo. 43-04308 of the 344th Fighter Squadron (343rd Fighter Group); Adak Airfield, Aleutian Islands (Alaska), early 1944 (Whif/Kitbashing) by dizzyfugu, on Flickr

1:72 Bell P-76A 'Airaconda', BuNo. 43-04308 of the 344th Fighter Squadron (343rd Fighter Group); Adak Airfield, Aleutian Islands (Alaska), early 1944 (Whif/Kitbashing) by dizzyfugu, on Flickr

By January 1944 the first service machines, designated P-76A, were delivered to homeland defence units for evaluation, especially against the P-39 as well as the P-40. Anyway, pilots distrusted the very different aircraft. The high tricycle landing caused frequent problems, especially on soggy ground, and several accidents with propeller contacts during exagerrated take-offs did not build the P-76's reputation - even the though the aircraft was basically good and a true step forward from the P-39. But to no avail: no ally would take it, neither Great Britain (having the disappointing P-39 still in mind) nor the Soviet Union.

1:72 Bell P-76A 'Airaconda', BuNo. 43-04308 of the 344th Fighter Squadron (343rd Fighter Group); Adak Airfield, Aleutian Islands (Alaska), early 1944 (Whif/Kitbashing) by dizzyfugu, on Flickr

1:72 Bell P-76A 'Airaconda', BuNo. 43-04308 of the 344th Fighter Squadron (343rd Fighter Group); Adak Airfield, Aleutian Islands (Alaska), early 1944 (Whif/Kitbashing) by dizzyfugu, on Flickr

The P-76's career was short, though. The machines were too late for the Aleutian Campaign, and none saw real combat action. Furthermore, more capable aircraft had entered the scene in the meantime, like the P-47 and the P-51, so the P-76 was primarily used for combat training on the USA mainland.

Only about 80 of this unique aircraft were built, before production switched to the more conventional P-63 Kingcobra.

1:72 Bell P-76A 'Airaconda', BuNo. 43-04308 of the 344th Fighter Squadron (343rd Fighter Group); Adak Airfield, Aleutian Islands (Alaska), early 1944 (Whif/Kitbashing) by dizzyfugu, on Flickr

General characteristics:
Crew: One
Length: 26 ft 10 1/2 in (8.2 m)
Wingspan: 31 ft 3 in (9,54 m)
Height: 13 ft (3.96 m)
Wing area: 190 sq ft (17.71 m²)
Empty weight: 4.900lb (2.225 kg)
Loaded weight: 6.530 lb (2.965 kg)
Max. takeoff weight: 7.709 lb (3.500 kg)

Powerplant:
1× Allison V-1710-47R liquid-cooled V12 engine, 1,325 hp (955 kW),
driving a four-blade pusehr propeller

Performance:
Maximum speed: 390 mph at 19,300 ft (628 km/h)
Range: 635 mi (1,020 km)
Service ceiling: 35,000 ft (10,700 m)
Rate of climb: 3,750 ft/min (19 m/s)
Wing loading: 34.6 lb/sq ft (169 kg/m²)
Power/mass: 0.16 hp/lb (0.27 kW/kg)
Time to climb: 15,000 in 4.5 min at 160 mph (260 km/h).

Armament:
1x 1.5 cal. (37 mm) M4 cannon in the nose with 30 rounds of HE-T ammunition
4x .50 cal. (12.7 mm) Browning M2 machine guns, nose-mounted with 200 RPG
Up to 1.000 lb or ordnance, including a drop tank or (rarely used) a single 1.000 lb bomb on
a centerline pylon; alternatively two 500 lb (230 kg) bombs under the wings or six unguided
HVAR missiles.

The kit and its assembly:
This shinden-esque whif aircraft was spawned by a series of P-39 CG illustrations - modified skins for a flight simulator which depicted the Airacobra as a pusher with a canard layout. This looked very interesting, and since I had a Hobby Boss P-39Q in the stash with no real plan until now, I gave the inspiration green light and turned on the saw.

The CGs already showed some inplausibilities, though - all perspectives were carefully taken from a shallow side perspective, hiding problematic areas! So, soon it became clear that my build could not be a 1:1 copy of the virtual art, because that would either not be possible, or simply look poor in hardware form.

As consequence, the simple P-39 pusher conversion idea turned into a major kitbash and body sculpting job, that somehow looked more and more like a diminuitive Kyushu J7W Shinden!?

What went into the thing:
● Central fuselage with engine, cockpit and front end of a Hobby Boss P-39
● Wings from a revell Me 262
● Horizontal stabilizers from an Italeri Fw 190
● The twin fins are stabilizers from the Me 262, too
● The propeller comes from the MPM P-47H kit
● Landing gear was scratched from the spares box

1:72 Bell P-76A 'Airaconda', BuNo. 43-04308 of the 344th Fighter Squadron (343rd Fighter Group); Adak Airfield, Aleutian Islands (Alaska), early 1944 (Whif/Kitbashing) - WiP by dizzyfugu, on Flickr

1:72 Bell P-76A 'Airaconda', BuNo. 43-04308 of the 344th Fighter Squadron (343rd Fighter Group); Adak Airfield, Aleutian Islands (Alaska), early 1944 (Whif/Kitbashing) - WiP by dizzyfugu, on Flickr

A lucky find were the Me 262 wings: they perfectly fit in depth onto the Airacobra's fuselage, and they added the "modern" look I was looking for. The original wings were simply to straight and deep, proportions would hardly work. Unfortunatly this meant that the cutouts on the wings for the Me 262's engine nacelles had to be filled, and that the landing gear wells had to be improvised, too. The wings roots had to be re-sculpted, too, since the Me 262 wings are much thinner than the P-39's.

Another problem was the fuselage's relative length - with the tail cut off, it's just too short in order to take canards on the nose - that was already recognizable in the CGs where the front fuselage had been stretched.

1:72 Bell P-76A 'Airaconda', BuNo. 43-04308 of the 344th Fighter Squadron (343rd Fighter Group); Adak Airfield, Aleutian Islands (Alaska), early 1944 (Whif/Kitbashing) - WiP by dizzyfugu, on Flickr

I did the same, with two measures: Firstly, a 10mm plug was inserted in front of the cockpit - a massive lump of putty that was sanded into shape. Furthermore, just glueing the spinner onto the nose would not yield a proper look. So I added a P-38 nose (Airfix kit) that was reduced in height and re-scuplted the lower fuselage, adding depth. As a consequence, the front wheel well moved forward and had to be re-shaped, too. Lots of messy putty work!

1:72 Bell P-76A 'Airaconda', BuNo. 43-04308 of the 344th Fighter Squadron (343rd Fighter Group); Adak Airfield, Aleutian Islands (Alaska), early 1944 (Whif/Kitbashing) - WiP by dizzyfugu, on Flickr

A third dubious section was the propeller, or better its interesction with the fuselage. Again, the CGs did not yield any potential solution. Since pusher props call for ground clearance I decided to fix the propeller axis so high that the spinner would be flush with the aircraft's spine - the pointed XP-47H propeller (It's one massive piece, with lots of flash...) was perfect and finally found a good and unexpected use. As per usual I built a metal axis construction with a styrene tube adapter inside the fuselage for the propeller, so that it can spin freely.

In order to shape a more or less elegant transition from the oval P-39 fuselage to the round spinner I added another plug, about 5mm long and again sculpted from putty.

1:72 Bell P-76A 'Airaconda', BuNo. 43-04308 of the 344th Fighter Squadron (343rd Fighter Group); Adak Airfield, Aleutian Islands (Alaska), early 1944 (Whif/Kitbashing) - WiP by dizzyfugu, on Flickr

1:72 Bell P-76A 'Airaconda', BuNo. 43-04308 of the 344th Fighter Squadron (343rd Fighter Group); Adak Airfield, Aleutian Islands (Alaska), early 1944 (Whif/Kitbashing) - WiP by dizzyfugu, on Flickr

With that in place the overall proprotions became clearer. Next step was to clip the Me 262 wings, so that the span would match the fuselage length, and I had to devise a way to mount fins. The CG just used the P-39's stabilizers, vertically placed on the wings' trailing edge. But, again, this does not work well in hardware form. These "fins" are much too tall, and just mounting them in that place looks rather awkward.

My solution was then to add small carrier booms - actually these a massive, modern 500 lb bombs without fins, placed on the trailing edges and protruding. This makes a more plausible and stable-looking base for fins, IMHO, and after several options (including P-51 and P-47 stabilizers)I used trimmed Me 262 stabilizers. Their sweeped leading edge matches the wings' shape just well - and the Fw 190 stabilizers which were glued to the nose as canards also look in-style, and overall more modern than the P-39's rounded wing shapes.

Slowly the P-76 took more and more shape, and I was surprised how much it started to resemble the Kyushu Shinden, which was a bigger aircraft, though.

1:72 Bell P-76A 'Airaconda', BuNo. 43-04308 of the 344th Fighter Squadron (343rd Fighter Group); Adak Airfield, Aleutian Islands (Alaska), early 1944 (Whif/Kitbashing) - WiP by dizzyfugu, on Flickr

1:72 Bell P-76A 'Airaconda', BuNo. 43-04308 of the 344th Fighter Squadron (343rd Fighter Group); Adak Airfield, Aleutian Islands (Alaska), early 1944 (Whif/Kitbashing) - WiP by dizzyfugu, on Flickr

Painting and markings:
A weird aircraft needs IMHO a rather subtle paint scheme, so I settled for a standard USAAF livery with overall Olive Drab upper sides, some Medium Green blotches on all wing surfaces and Neutral Grey undersides.

As basic colors I used Modelmaster's ANA 613 for the upper surfaces and FS 36231 (instead of the true Neutral Grey FS 36173) for the lower sides; the green blotches are frequently quoted as FS 34096, but this is IMHO too "green", the tone has a rather blue-ish hue. So I went for a more a yellow-ish tone and settled for Humbrol 102 (Army Green). All tones were later lightened and weathered through dry-painting (also highlighting some panels) and a black ink wash - both tones somewhat came closer to each other through this treatment, but I think this happened on real world aircraft, too?

1:72 Bell P-76A 'Airaconda', BuNo. 43-04308 of the 344th Fighter Squadron (343rd Fighter Group); Adak Airfield, Aleutian Islands (Alaska), early 1944 (Whif/Kitbashing) - WiP by dizzyfugu, on Flickr

The only colorful highlight is a yellow nose.

All interior surfaces were painted in zinc chromate primer: on top of an olive green base (Humbrol 159) some dry-painting with Modelmaster's Zinc Chromate Green was added.

1:72 Bell P-76A 'Airaconda', BuNo. 43-04308 of the 344th Fighter Squadron (343rd Fighter Group); Adak Airfield, Aleutian Islands (Alaska), early 1944 (Whif/Kitbashing) - WiP by dizzyfugu, on Flickr

Markings were puzzled together from various sources. The red-rimmed Stars-And-Bars were AFAIK still in use in late 1943, and they add some contrast to the otherwise simple aircraft. The white stripes were used as ID markings in the Aleutian theatre - another small individual note. Otherwise, P-40's of the 344th FS/343rd FG were used as benchmarks.

1:72 Bell P-76A 'Airaconda', BuNo. 43-04308 of the 344th Fighter Squadron (343rd Fighter Group); Adak Airfield, Aleutian Islands (Alaska), early 1944 (Whif/Kitbashing) by dizzyfugu, on Flickr

1:72 Bell P-76A 'Airaconda', BuNo. 43-04308 of the 344th Fighter Squadron (343rd Fighter Group); Adak Airfield, Aleutian Islands (Alaska), early 1944 (Whif/Kitbashing) by dizzyfugu, on Flickr

In the end, and interesting experiment that shows that CG ideas must not translate well into model kit hardware form. Nevertheless, the P-76 looks interesting - at some times I thought it would look rather German or like an aircraft from Captain America or the 'The Sky Crawlers' anime movie?

Librarian · November 06, 2014, 05:04:19 AM

That's worked out superbly well. Seems so logical too, wonder if Bell ever did studies. Nice and dirty, those Pacific P-39s ended up much like that. Congrats

.

NARSES2 · November 06, 2014, 07:14:24 AM

I love watching the "coming together" pics

Tophe · November 06, 2014, 08:16:59 AM

And it's almost a twin-boomer, I love it!

TallEng · November 06, 2014, 08:17:48 AM

Another master piece from the Master of quick kit bashes

Interesting looking design. Much better looking than the Curtiss Ascender

Regards
Keith

Captain Canada · November 06, 2014, 08:30:11 AM

Nice ! Just looks right...balanced, fast, well armed. Beauty.

Weaver · November 06, 2014, 09:28:05 AM

Nice one, that looks really good. It's interesting how your logical development process ended up producing something that resembled a real-world solution, i.e. the Shinden.

Looking at this, an idea popped into my head for a canard Flitzer for some reason....

PR19_Kit · November 06, 2014, 09:57:21 AM

An 'in combat' pic between a Shinden and a P-76A would be rather good.............

Old Wombat · November 06, 2014, 10:16:23 PM

That's really good, Dizz!

Quote from: PR19_Kit on November 06, 2014, 09:57:21 AM
An 'in combat' pic between a Shinden and a P-76A would be rather good.............

Seconded!

zenrat · November 07, 2014, 12:17:27 AM

Inspiring. Where's that Academy P39...

Dizzyfugu · November 07, 2014, 05:04:19 AM

Thank you very much everyone, glad you like it! What I find very interesting during whiffing aircraft like this is that I seem to encounter similar problems as real world engineers, so that things evolve into something that looks similar to a real world aircraft. It was not intended, but at some point I was amazed that the P-76 looked a lot like a small-scale J7W... and how balanced this thing turned out. Canard aircraft can look wacky at at times, but this one has very convincing proportions.

Furthermore, as a motivation to PR19_kit, there's also an option to build a high altitude version of this since I had to considerably clip the Me 262 wings - I considered such a version, but then settled on a standard aircraft. There's potential in this one, even though building it was rather messy. Half of the kit is putty...

Scooterman · November 07, 2014, 06:14:27 AM

very good indeed!

Hotte · November 07, 2014, 11:17:41 AM

Very sexy Bell

Hotte

Dizzyfugu · November 07, 2014, 11:21:07 AM

Quote from: Flyer on November 07, 2014, 06:07:05 AM
Has given me some inspiration for my P-39 as I have not progressed with it.

Very good...!

Again, many thanks!