+++ DISCLAIMER +++
Nothing you see here is real, even though the conversion or the presented background story might be based on historical facts. BEWARE!
The P-51H (NA-126) was the final production Mustang, embodying the experience gained in the development of the lightweight XP-51F and XP-51G aircraft. This aircraft, brought the development of the Mustang to a peak as one of the fastest production piston-engine fighters to see service in WWII.
In July of 1943, U.S. Army approved a contract with North American Aviation to design and build a lightweight P-51. Designated NA-105, 5 aircraft were to be built and tested. Edgar Schmued, chief of design at NAA, began this design early in 1943. He, in February of 1943, left the U.S. on a two-month trip to England. He was to visit the Supermarine factory and the Rolls Royce factory to work on his lightweight project.
Rolls Royce had designed a new version of the Merlin, the RM.14.SM, which was proposed to increase the manifold pressure to 120 (from 67 max) and thus improve military emergency horsepower to 2,200. Schmued was very eager to use this powerplant, since the new Merlin was not heavier than the earlier models. In order to exploit the new engine to the maximum, he visited the engineers at Rolls Royce in Great Britain. However, British fighters were by tendency lighter than their U.S. counterparts and Schmued also asked for detailed weight statements from Supermarine concerning the Spitfire. Supermarine did not have such data, so they started weighing all the parts they could get a hold of and made a report. It revealed that the British had design standards that were not as strict in some areas as the U.S, and American landing gear, angle of attack and side engine design loads were by tendency higher. When Schmued returned, he began a new design of the P-51 Mustang that used British design loads, shaving off weight on any part that could yield. The result was an empty weight reduction by 600 pounds, what would directly translate into more performance.
This design effort led to a number of lightweight Mustang prototypes, designated XP-51F, XP-51G and XP-51J. After their testing, the production version, NA-126 a.k.a. P-51H, was closest to the XP-51F. The project began in April 1944 and an initial contract for 1,000 P-51Hs was approved on June 30, 1944, which was soon expanded.
The P-51H used the V-1650-9 engine, a modified version of the new Merlin RM.14.SM that included Simmons automatic supercharger boost control with water injection, allowing War Emergency Power as high as 2,218 hp (1,500 kW) and a continuous output of up to 1,490 hp (1.070 kW).
Even though the P-51H looked superficially like a slightly modified P-51D, it was effectively a completely new design. External differences to the P-51D included lengthening and deepening the fuselage and increasing the height of the tailfin, which reduced, together with a lower fuel load in the fuselage tank, the tendency to yaw. The landing gear was simplified and lightened. The canopy resembled the P-51D bubble top style, over a raised pilot’s position. The armament was retained but service access to the guns and ammunition was improved, including the introduction of ammunition cassettes that made reloading easier and quicker. With the new airframe several hundred pounds lighter, extra power, and a more streamlined radiator, the P-51H was faster than the P-51D, able to reach 472 mph (760 km/h; 410 kn) at 21,200 ft (6,500 m), making it one of the fastest piston engine aircraft in WWII.
The high-performance P-51H was designed to complement the P-47N as the primary aircraft for the invasion of Japan, with 2,000 ordered to be manufactured at NAA’s Inglewood plant. Variants of the P-51H with different versions of the Merlin engine were produced in limited numbers, too, in order to ramp up production and deliveries to frontline units. These included the P-51L, which was similar to the P-51H but utilized the V-1650-11 engine with a modified fuel system, rated at maximum 2,270 hp (1,690 kW), and the P-51M, or NA-124. The P-51M, of which a total of 1629 was ordered, was built in Dallas and utilized the V-1650-9A engine. This variant was optimized for operations at low and medium altitude and lacked water injection, producing less maximum power at height. However, it featured attachment points for up to ten unguided HVAR missiles under the outer wings as well as improved armor protection for the pilot against low-caliber weapons esp. from ground troops, which ate up some of the light structure’s weight benefit.
Most P-51H and L were issued to USAF units, while the P-51M and some Hs were delivered to allied forces in the Pacific TO, namely Australia and New Zealand. Only a few aircraft arrived in time to become operational until the end of hostilities, and even less became actually involved in military actions during the final weeks of fighting in the Pacific.
The RAAF received only a handful P-51Hs, since Commonwealth Aircraft Corporation (CAC) had recently started license production of the P-51D (as CA-18) and the RAAF rather focused on this type. However, there were plans in early 1945 to build the P-51H locally as the CA-21, too, but this never came to fruition.
New Zealand ordered a total of 370 P-51 Mustangs of different variants to supplement its Vought F4U Corsairs in the PTO, which were primarily used as fighter-bombers. Scheduled deliveries were for an initial batch of 30 P-51Ds, followed by 137 more P-51Ds and 203 P-51Ms. The first RNZAF P-51Ms arrived in April 1945 and were allocated to 3 Squadron as well as to the Flight Leaders School in Ardmore (near Auckland in Northern New Zealand) for conversion training. The machines arrived as knocked-down kits via ship in natural metal finish, but the operational machines were, despite undisputed Allied air superiority, immediately camouflaged in field workshops to protect the airframes from the harsh and salty environment, esp. on the New Guinean islands. The RNZAF Mustangs also received quick identification markings in the form of white tail surfaces and white bands on the wings and in front of and behind the cockpit, in order to avoid any confusion with the Japanese Ki-61 “Hien” (Tony) and Ki-84 (Frank) fighters which had a similar silhouette and frequently operated in a natural metal finish.
During the final weeks of the conflict, the RNZAF only scored three air victories: two Japanese reconnaissance flying boats were downed and a single Ki-84 fighter was shot down in a dogfight over Bougainville. Most combat situations of 3 Squadron were either fighter escorts for F4U fighter bombers or close air support and attacks against Japanese strongholds or supply ships.
After the war, many USAF P-51Hs were immediately retired or handed over to reserve units. The surviving P-51Js were, due to their smaller production numbers, were mostly donated to foreign air forces in the course of the Fifties, in order to standardize the US stock. Despite its good performance, the P-51H/J/M did not take part in the Korean War. Instead, the (by the time re-designated) F-51D was selected, as it was available in much greater numbers and had a better spares supply situation. It was considered as a proven commodity and perceived to be stouter against ground fire – a misconception, because the vulnerable ventral liquid cooling system caused heavy losses from ground fire. The alternative P-47 would have been a more effective choice. The last American F-51H Mustangs were retired from ANG units in 1957, but some of its kin in foreign service soldiered on deep into the Sixties. The F-51D even lasted into the Eigthies in military service!
After the end of hostilities in the PTO, the RNZAF’s forty-two operational P-51Ms met different fates: The twenty-six survivors, which had reached frontline service in New Guinea, were directly scrapped on site, because their transfer back to New Zealand was not considered worthwhile. Those used for training in New Zealand were stored, together with the delivered P-51Ds, or, together with yet unbuilt kits, sent back to the United States.
In 1951, when New Zealand’s Territorial Air Force (TAF) was established, only the stored P-51D Mustangs were revived and entered service in the newly established 1 (Auckland), 2 (Wellington), 3 (Canterbury), and 4 (Otago) squadrons. Due to the small number, lack of spares and communality with the P-51D, the remaining mothballed RNZAF F-51Ms were eventually scrapped, too.
Length: 33’ 4” (10.173 m)
Wingspan: 37‘ (11.28 m)
Height: 13‘ 8” (4.17 m) with tail wheel on ground, vertical propeller blade
Wing area: 235 sq ft (21.83 m²)
Airfoil: NAA/NACA 45-100 / NAA/NACA 45-100
Empty weight: 7.180 lb (3,260 kg)
Gross weight: 9,650 lb (4,381 kg)
Max takeoff weight: 11,800 lb (5,357 kg)
Fuel capacity: 255 US gal (212 imp gal; 964 l)
Aspect ratio: 5.83
1× Packard (Rolls Royce) V-1650-9A Merlin 12-cylinder liquid cooled engine, delivering 1,380 hp
(1,030 kW) at sea level, driving a 4-blade constant-speed Aeroproducts 11′ 1" Unimatic propeller
Maximum speed: 465 mph (750 km/h; 407 kn) at 18,000 ft (5,500 m)
Cruise speed: 362 mph (583 km/h, 315 kn)
Stall speed: 100 mph (160 km/h, 87 kn)
Range: 855 mi (1,375 km, 747 nm) with internal fuel
1,200 mi (1,930 km, 1,050 nmi) with external tanks
Service ceiling: 30,100 ft (9,200 m)
Rate of climb: 3,200 ft/min (16.3 m/s) at sea level
Wing loading: 30.5 lb/sq ft (149 kg/m²)
Power/mass: 0.19 hp/lb (315 W/kg)
Lift-to-drag ratio: 14.6
Recommended Mach limit 0.8
6× 0.50 caliber (12.7mm) AN/M2 Browning machine guns with a total of 1,880 rounds
2× underwing hardpoints for drop tanks or bombs of 500 pounds (227 kg) caliber each,
or 6 or 10 5” (127 mm) T64 HVAR rockets
The kit and its assembly:
A relatively simple project, a whiffy color variant based on RS Model’s 1:72 P-51H kit – which I quickly turned into a P-51M, which was planned as mentioned in the background, but never produced in real life.
The model was strictly built OOB, and while this short-run kit goes together quite well, I encountered some problems along the way:
– There are massive and long ejector pin markers, sometimes in very confined locations like the radiator intake. Without a mini drill, getting rid of them is very difficult
– Somehow the instructions for the cockpit are not correct; I put the parts into place as indicated, and the pilot’s seat ended up way too far forward in the fuselage
– The canopy, while clear, is pretty thick and just a single piece, so that you have to cut the windscreen off by yourself if you want to show the otherwise very nice cockpit.
– The separated windscreen section itself includes a piece of the cowling in front of the window panes, which makes its integration into the fuselage a tricky affair. However, this IMHO not-so-perfect construction became a minor blessing because the separated windscreen turned out to be a little too narrow for the fuselage – it had to be glued forcibly to the fuselage (read: with superglue), and the section in front of the window panes offered enough hidden area to safely apply the glue on the clear piece.
– While there are some resin parts included like weighted wheels, it is beyond me why tiny bits like the underwing pitot or most delicate landing gear parts have been executed in resin, as flat parts of a resin block that makes it IMHO impossible to cut them out from.
– The tail wheel is a messy three-piece construction of resin and IP parts, with a flimsy strut that’s prone to break already upon cutting the part from the IP sprue. Furthermore, there’s no proper location inside of the fuselage to mount it. Guess and glue!
– The fit of the stabilizers is doubtful; it’s probably best to get rid of their locator pins and glue them directly onto the fuselage
– The propeller consists of a centerpiece with the blades, which is enclosed by two spinner halves (front and back). This results in a visible seam between them that is not easy to fill/PSR away
On the positive side I must say that the engraved surface details, the cockpit interior and the landing gear are very nice, and there is even the complete interior of the radiator and its tunnel included. PSR requirements are also few, even though you won’t get along well without cosmetic bodywork.
The only personal modification is a styrene tube inside of the nose for the propeller, which was mounted onto a metal axis for free rotation; OOB, the propeller is not moveable at all and is to be glued directly to the fuselage.
While the kit comes with optional ordnance (six HVARs or a pair of 500 lb bombs, both in resin), I just used the bomb pylons and left them empty, for a clean look.
Painting and markings:
Even though the model was a quick build, finding a suitable color concept took a while; I had a whiffy P-51H on my agenda for a long time (since the RS Models kit came out), and my initial plan was to create an Australian aircraft. This gradually changed to an RNZAF aircraft during the last weeks of WWII in the PTO, and evolved from an NMF finish (initial and IMHO most logical idea) through am Aussie-esque green/brown camouflage to a scheme I found for a P-40: a trainer that was based in New Zealand and (re)painted in domestic colors, namely in Foliage Green, Blue Sea Grey and Sky. This might sound like a standard RAF aircraft, but in the end the colors and markings make this Mustang look pretty exotic, just as the P-51H looks like a Mustang that is “not quite right”.
The Foliage Green is Humbrol 195 (Dark Green Satin, actually RAL 6020 Chrome Oxide Green), which offers IMHO a good compromise between the tone’s rather bluish hue and yellow shades – I find it to be a better match than the frequently recommended FS 34092, because RAL 6020 is darker. The RNZAF “Blue Sea Grey”, also known as “Pacific Blue” or “Ocean Blue”, is a more obscure tone, which apparently differed a lot from batch to batch and weathered dramatically from a bluish tone (close to FS 35109 when fresh) to a medium grey. I settled for Humbrol 144 (FS 35164; USN Intermediate Blue), which is rumored to come close to the color in worn state.
The undersides were painted with Humbrol 23 (RAF Duck Egg Blue), which I found to be a suitable alternative to the more greenish RAF Sky, even though it’s a pretty light interpretation.
Tail and spinner were painted white, actually a mix of Humbrol 22 (Gloss White) and 196 (Light Grey, RAL 7035) so that there would be some contrast room left for post-shading with pure white.
The interior of cockpit and landing gear wells was painted with zinc chromate primer yellow (Humbrol 81), while the landing gear struts became Humbrol 56 (Aluminum Dope). The radiator ducts received an interior in aluminum (Revell 99).
In order to simulate wear and tear as well as the makeshift character of the camouflage I painted the wings’ leading edges and some other neuralgic areas in aluminum (Revell 99, too) first, before the basic camouflage tones were added in a somewhat uneven fashion, with the metallized areas showing through.
Once dry, the model received an overall washing with thinned black ink and a through dry-brushing treatment with lighter shades of the basic tones (including Humbrol 30, 122 and 145) for post-panel-shading and weathering, esp. on the upper surfaces.
The decals are a mix from a Rising Decals sheet for various RNZAF aircraft (which turned out to be nicely printed, but rather thin so that they lacked opacity and rigidity), and for the tactical markings I stuck to the RNZAF practice of applying just a simple number or letter code to frontline aircraft instead of full RAF-style letter codes. The latter were used only on aircraft based on home soil, since the RNZAF’s frontline units had a different organization with an aircraft pool allocated to the squadrons. Through maintenance these circulated and were AFAIK not rigidly attached to specific units, hence there was no typical two-letter squadron code applied to them, just single ID letters or numbers, and these were typically painted on the aircraft nose and/or the fin, not on the fuselage next to the roundel. The nose art under the cockpit is a mix of markings from P-40s and F4Us.
The white ID bands on fuselage and wings are simple white decal strips from TL-Modellbau. While this, together with the all-white tail, might be overdone and outdated towards mid-1945, I gave the Kiwi-Mustang some extra markings for a more exciting look – and the aircraft’s profile actually reminds a lot of the Ki-61, so that they definitely make sense.
Towards the finish line, some additional dry-brushing with grey and silver was done, soot stains were added with graphite to the exhaust areas and the machine gun ports, and the model was finally sealed with matt acrylic varnish.
After the recent, massive YA-14 kitbashing project, this Mustang was – despite some challenges of the RS Models kit itself – a simple and quick “relief” project, realized in just a couple of days. Despite being built OOB, the result looks quite exotic, both through the paint scheme with RNZAF colors, but also through the unusual roundels and the striking ID markings (for a Mustang). I was skeptical at first, but the aircraft looks good and the camouflage in RNZAF colors even proved to be effective when set into the right landscape context (beauty pics).
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