North American Mustang VII (P-51N) - a radial alternative...

Dizzyfugu · March 17, 2016, 12:02:44 PM

To some it might be heresy and and an unholy alliance, but: yes, you can mate a sleek Mustang with a late WWII radial engine in the 2.000 hp class like the British Centaurus!

1:72 North American "Mustang VII" (P-51N); "FL-Y/NT982" of 81 Squadron, Royal Air Force South East Asia Command; Chittagong area, June 1945, (Whif/Matchbox kit conversion) by dizzyfugu, on Flickr

Some background:
The North American Aviation P-51 Mustang was an American long-range, single-seat fighter and fighter-bomber used during World War II, the Korean War and other conflicts.
The Mustang was conceived, designed and built by North American Aviation (NAA) in response to a specification issued directly to NAA by the British Purchasing Commission. The prototype NA-73X airframe was rolled out on 9 September 1940, 102 days after the contract was signed and, with an engine installed, first flew on 26 October.

The Mustang was originally designed to use the Allison V-1710 engine, which had limited high-altitude performance. It was first flown operationally by the Royal Air Force (RAF) as a tactical-reconnaissance aircraft and fighter-bomber (Mustang Mk I).
The addition of the Rolls-Royce Merlin to the P-51B/C (Mustang Mk III) model transformed the Mustang's performance at altitudes above 15,000 ft, giving it a much better performance that matched or bettered almost all of the Luftwaffe's fighters at altitude.
The definitive USAF version, which saw use in any late WWII theatre, the P-51D (Mustang Mk IV), was powered by the Packard V-1650-7, a license-built version of the Rolls-Royce Merlin 60 series two-stage two-speed supercharged engine, and armed with six .50 caliber (12.7 mm) M2 Browning machine guns.

1:72 North American "Mustang VII" (P-51N); "FL-Y/NT982" of 81 Squadron, Royal Air Force South East Asia Command; Chittagong area, June 1945, (Whif/Matchbox kit conversion) by dizzyfugu, on Flickr

1:72 North American "Mustang VII" (P-51N); "FL-Y/NT982" of 81 Squadron, Royal Air Force South East Asia Command; Chittagong area, June 1945, (Whif/Matchbox kit conversion) by dizzyfugu, on Flickr

Anyway, the Mustang's development was kept up by North American as well as in Great Britain. There, the Mustang was developed into the Mustang V (a lightweight fighter of which only one prototype reached England), the Mustang VI (a high altitude fighter version which was produced in small numbers and kept in RAF service until 1951) and the Mustang VII, a radical modification for the South East Asia Command.

The Mustang VII was intended as a replacement for the Hawker Hurricanes and early Spitfire variants deployed to India and Burma. One of these types' biggest concerns had been the engine, or, more specifically, its cooling system. The Merlin's liquid cooled system had been designed for the mild European climate, but, in the hot and humid Asian environment, the aircraft frequently faced engine problems. An air-cooled, radial engine was regarded as the more appropriate means of propulsion, and with the Bristol Centaurus a powerful option was readily available and earmarked for the Hawker Tempest.

1:72 North American "Mustang VII" (P-51N); "FL-Y/NT982" of 81 Squadron, Royal Air Force South East Asia Command; Chittagong area, June 1945, (Whif/Matchbox kit conversion) by dizzyfugu, on Flickr

1:72 North American "Mustang VII" (P-51N); "FL-Y/NT982" of 81 Squadron, Royal Air Force South East Asia Command; Chittagong area, June 1945, (Whif/Matchbox kit conversion) by dizzyfugu, on Flickr

Apart from the new engine and cowling, the Mustang VII prototypes were similar to the P-51D. The Centaurus engine was tightly cowled and the exhaust stacks were grouped behind and on either side of the engine. Behind these were air outlets with automatic sliding "gills".
New air intakes on the inner leading edges of both wings fed the carburetor and an oil cooler. The radial engine installation owed much to examinations of a captured Focke-Wulf Fw 190, and was clean and effective. The bigger frontal area was partly compensated by the removal of the Mustang's characteristic, ventral radiator tunnel.
This modification also kept the overall increment of weight to only ~90 lb (41 kg) – even though the aircraft became remarkably nose-heavy and handled much different from the Merlin-powered versions. Longitudinal stability also deteriorated slightly.

The first Mustang Mk. VIII, PE883, flew on 28 June 1944 powered by a Centaurus I (2,000 hp/1,490 kW) driving a four-blade propeller, followed by the second, PE884. From the start, the Mustang VII was "tropicalized" for service in the South-East Asian theatre.

Orders were placed in September 1944 for 300 Mustang VIIs, and they were directly deployed to India and Burma. There, the Mustang VII replaced the Spitfire II and Vs in the fighter role, relegating the new RAF Thunderbolts in the region to ground attack, a task for which that type was well suited.

1:72 North American "Mustang VII" (P-51N); "FL-Y/NT982" of 81 Squadron, Royal Air Force South East Asia Command; Chittagong area, June 1945, (Whif/Matchbox kit conversion) by dizzyfugu, on Flickr

1:72 North American "Mustang VII" (P-51N); "FL-Y/NT982" of 81 Squadron, Royal Air Force South East Asia Command; Chittagong area, June 1945, (Whif/Matchbox kit conversion) by dizzyfugu, on Flickr

Once the Mustang VIIs were cleared for use, they were used against the Japanese in Burma by four RAF squadrons of the South East Asia Command from India. Operations with army support (operating as "cab ranks" to be called in when needed), attacks on enemy airfields and lines of communication, and escort sorties.
They proved devastating in tandem with Thunderbolts during the Japanese breakout attempt at the Sittang Bend in the final months of the war. The Mustangs were armed with two 500 lb (227 kg) bombs or, in some cases, British RP-3 rocket projectiles. The Mustang VIIs also flew escort for RAF Liberators in the bombing of Rangoon.

The type remained in RAF service until October 1946. After that the RAF passed 60 machines to the Indian Air Force in 1947, together with other piston fighters.

1:72 North American "Mustang VII" (P-51N); "FL-Y/NT982" of 81 Squadron, Royal Air Force South East Asia Command; Chittagong area, June 1945, (Whif/Matchbox kit conversion) by dizzyfugu, on Flickr

1:72 North American "Mustang VII" (P-51N); "FL-Y/NT982" of 81 Squadron, Royal Air Force South East Asia Command; Chittagong area, June 1945, (Whif/Matchbox kit conversion) by dizzyfugu, on Flickr

General characteristics:
Crew: 1
Length: 32 ft 8 1/4 in (9.97 m)
Wingspan: 48 ft 9½ in (14.90 m)
Height: 14 ft 6 in (4.39 m)
Wing area: 235 sq ft (21.83 m²)
Airfoil: NAA/NACA 45-100 / NAA/NACA 45-100
Empty weight: 7,725 lb (3,505 kg)
Loaded weight: 9,290 lb (4,220 kg)
Max. takeoff weight: 12,200 lb (5,515 kg)
Maximum fuel capacity: 419 US gal (349 imp gal; 1,590 l)

Powerplant:
1× Bristol Centaurus 1 18-cylinder twin-row radial engine, 2,000 hp (1,490 kW) at take-off

Performance:
Maximum speed: 432 mph (695 km/h) at 18,400 ft (5,608 m)
Cruise speed: 362 mph (315 kn, 580 km/h)
Range: 740 mi (1,190 km) on internal fuel
Service ceiling: 36,500 ft (11,125 m)
Rate of climb: 4,700 ft/min (23.9 m/s)

Armament:
4× 0.787 caliber (20mm) Hispano Mk. II cannons with 200 RPG in the outer wings
Underwing hardpoints for up to 2.000 lb (907 kg) of external ordnance,
including drop tanks, a pair of bombs of up to 1.000 lb (454 kg) caliber, or six unguided missiles

The kit and its assembly:
This conversion was based on the rather academic question: how could a Mustang with a radial engine look like? A weird idea, if you look at the sleek aircraft. But then there was the rather handsome Fw 190 A/F, the Hawker Tempest carried both liquid-cooled and air-cooled engines, and I saw a model of a Merlin Spitfire mated with a Fw 190 BMW engine some time ago. So, why not re-do the Mustang?

Working things out was complex, though. Initially I wanted to graft an R-2800 onto the Mustang's nose – I had a spare fuselage from a late Italeri F4U at hand, as well as a Matchbox P-51D... After some measuring I was certain: yes, this transplant could work!

1:72 North American "Mustang VII" (P-51N); "FL-Y/NT982" of 81 Squadron, Royal Air Force South East Asia Command; Chittagong area, June 1945, (Whif/Matchbox kit conversion) by dizzyfugu, on Flickr

Said and done, the Corsair's front section including the engine was cut out and tailored to fit over the shortened Mustang nose which lost its Merlin. At first I retained the original belly radiator, since it would be a convenient fairing for the oil coolers. The project made good progress, but... the result did not look good, because the R-2800 is rather wide. The aircraft looked very tadpole-like.
So, while in the middle of body sculpting, I decided to change the project, switching to a British Centaurus - a featureless piece from a PM Model Sea Fury with some more changes.

The Centaurus' selling point was the more slender cowling, and it goes well onto a F4U's nose section, proven by several conversions of this kind. In order to keep the aircraft as slender as possible I removed the belly tunnel and re-located the oil coolers and air intakes into the wing roots, closer to the engine and more like the installation on the Tempest or the Sea Fury. These extended wing root fairings were created from sprue pieces and putty.

1:72 North American "Mustang VII" (P-51N); "FL-Y/NT982" of 81 Squadron, Royal Air Force South East Asia Command; Chittagong area, June 1945, (Whif/Matchbox kit conversion) by dizzyfugu, on Flickr

1:72 North American "Mustang VII" (P-51N); "FL-Y/NT982" of 81 Squadron, Royal Air Force South East Asia Command; Chittagong area, June 1945, (Whif/Matchbox kit conversion) by dizzyfugu, on Flickr

It is amazing how this further modification changed the Mustang's look – the thing reminds a lot of a La-9/11 now, even though wings, tail and most of the fuselage, including the canopy, were not modified at all? I am also reminded of the F8F Bearcat?
Furthermore, after the new propeller (cuffed blades from a P-47 Thunderbolt, IIRC, with trimmed tips) with a massive spinner from a Hawker Tempest was mounted on its metal axis, this mutant Mustang looked more and more like a Reno Unlimited Class racer? Weird, but sexy!

Otherwise, only minor things were changed, e. g. the landing gear covers were replaced through 0.5mm styrene sheet, a dashboard was added to the cockpit and the thick canopy cut into two pieces. The six 0.5" machine guns were replaced by four short Hispano cannons made from brass.

1:72 North American "Mustang VII" (P-51N); "FL-Y/NT982" of 81 Squadron, Royal Air Force South East Asia Command; Chittagong area, June 1945, (Whif/Matchbox kit conversion) by dizzyfugu, on Flickr

Painting and markings:
With the Centaurus implant the background story and the operator idea changed. I used this opportunity to paint the aircraft in a late/post WWII SEAC livery – inspired by P-47s operated in this region.

The bare metal finish with dark blue ID stripes and the SEAC roundels already looked nice, but as a twist I incorporated remnants of a former Dark Green/Dark Earth camouflage, on the fuselage and the wings' leading edges, as anti-glare panels, while the area in front of the cockpit was painted in opaque dark olive drab – a practice to be found on several RAF aircraft of that time are area.

1:72 North American "Mustang VII" (P-51N); "FL-Y/NT982" of 81 Squadron, Royal Air Force South East Asia Command; Chittagong area, June 1945, (Whif/Matchbox kit conversion) by dizzyfugu, on Flickr

1:72 North American "Mustang VII" (P-51N); "FL-Y/NT982" of 81 Squadron, Royal Air Force South East Asia Command; Chittagong area, June 1945, (Whif/Matchbox kit conversion) by dizzyfugu, on Flickr

The interior surface were painted with USAF Cockpit Green (Humbrol 224 and 150) and slightly dry-brushed, then the whole kit received a basic coat of Revell Acrylic Aluminum. Later, some panels were painted with different shades of Aluminum and Steel (including Metallizer and normal metallic paint). Some wet sanding blurred the outlines and enhanced the worn look.

1:72 North American "Mustang VII" (P-51N); "FL-Y/NT982" of 81 Squadron, Royal Air Force South East Asia Command; Chittagong area, June 1945, (Whif/Matchbox kit conversion) by dizzyfugu, on Flickr

1:72 North American "Mustang VII" (P-51N); "FL-Y/NT982" of 81 Squadron, Royal Air Force South East Asia Command; Chittagong area, June 1945, (Whif/Matchbox kit conversion) by dizzyfugu, on Flickr

Decals come from various SEAC sheets, including the blue ID stripes on wings and tail. The corresponding blue cowling ring was painted with a mix of Humbrol 15 and 104, and pretty flaky around the engine cowling.
As finishing touches some oil stains were added with Tamiya "Smoke" and some soot stains around the exhausts and the guns were added. Finally, the camouflaged areas were sealed under a matt varnish while the bare metal parts received a semi-gloss acrylic coat.

1:72 North American "Mustang VII" (P-51N); "FL-Y/NT982" of 81 Squadron, Royal Air Force South East Asia Command; Chittagong area, June 1945, (Whif/Matchbox kit conversion) by dizzyfugu, on Flickr

A weird project – one of the few of my models that somehow changed dramatically along the way, even though still true to the original idea of a radial engine Mustang. However, the result was envisioned differently, but I am still happy with the outcome. Even though there's visually little Mustang breed left...

Tophe · March 17, 2016, 12:25:28 PM

Wonderful! This is greatly enriching the P-51 family, thanks.
I will try to draw a profile of it for my collection, thanks!

tc2324 · March 17, 2016, 01:11:56 PM

Nicely done Dizzy.

Bet that would of led to a lot of blue on blue contacts as it looks very much like a Fw 190.

PR19_Kit · March 17, 2016, 01:12:20 PM

I'd have NEVER have said this would have worked if anyone would have suggested it, but it patently does, and VERY well indeed! It's exactly what it says on the tin, a radial engine Mustang.

Very Tempest-like in its look, specially from the front. Excellent work Thomas.

And now for the Merlin engine Corsair, yes?

KiwiZac · March 17, 2016, 04:29:04 PM

I 110% approve of this project. Gorgeous!

comrade harps · March 17, 2016, 05:28:33 PM

Another success!

DogfighterZen · March 17, 2016, 05:51:31 PM

Quote from: tc2324 on March 17, 2016, 01:11:56 PM
Nicely done Dizzy.

Bet that would of led to a lot of blue on blue contacts as it looks very much like a Fw 190.

Exact same feelings here! I thought of an American Fw190! Great work!

Dizzyfugu · March 18, 2016, 01:14:36 AM

Quote from: Tophe on March 17, 2016, 12:25:28 PM
Wonderful! This is greatly enriching the P-51 family, thanks.
I will try to draw a profile of it for my collection, thanks!

That was part of the secret plan!

Glad you like it (and other obviosuly, too!

) - and I wonder that this stunt has not been done before, at least in hardware/model form? Worked much better than expected, and open a lot of whif potential for the post WWII era as a lighter alternative to the Tempest, Fury or even some late Spitfires? I might try that one again (still a PM Model Centaurus left in the spares box...), but with a better Mustang kit, maybe the Academy P-51D.

zenrat · March 18, 2016, 01:44:26 AM

Look Dave, I found your football socks.

As Kit says I does work.
I too think it looks German.

Radial engined Spitfire anyone?

PACOPEPE · March 18, 2016, 02:14:14 AM

Very nice!

It remember me to Boomerang.

Regards
Fran

Dizzyfugu · March 18, 2016, 02:32:34 AM

Quote from: zenrat on March 18, 2016, 01:44:26 AM
Look Dave, I found your football socks.

LOL!

NARSES2 · March 18, 2016, 07:38:50 AM

Does look 190'ish. I think it's the tail for some reason. If you "beefed" the rear up a tad it would look like one of the real world Folland projects IMHO.

Nice build sir

Hotte · March 18, 2016, 11:41:23 AM

Nice Mustang

Hotte

Glenn Gilbertson · March 18, 2016, 12:22:00 PM

Brilliant modelling and oddly believable!

Tophe · March 18, 2016, 10:48:23 PM

Quote from: Tophe on March 17, 2016, 12:25:28 PM
Wonderful! This is greatly enriching the P-51 family, thanks.
I will try to draw a profile of it for my collection, thanks!

Here I am, thanks again!