Profile – North American P-51 Mustang, Part 11

His reflexes were slow, and his combat judgement often suffered in the latter stages of such a mission, making him vulnerable to enemy pilots who attempted to intercept the Mustang. Chances were, those pilots had been in the air for a relatively short period, were alert, fresh and therefore more likely to win if combat took place.

The problem was addressed in 1943 and it soon became clear that the answer lay in a long-range escort fighter capable of carrying two crew members. A two-seat Mustang had already been built, but the second seat (behind the pilot in tandem) was installed at the expense of a large proportion of the Mustang’s internal fuel capacity.

So the idea arose to make a ‘Twin Mustang’, combining two P-51H fuselages joined by a constant-chord centre section, a similar tailplane and elevator and pretty much standard P-51 outer wings. The idea was attractive, not only because North American Aviation’s proposal would meet the requirements set out, but would also save time and development costs as a large part of the aircraft was already in production, and most of the P-51’s tooling, jigging and systems could continue to be used. As a result the USAAF ordered four prototypes in January 1944 and the aircraft was designated the XP-82.

The aircraft that emerged from NAA’s factory and made its first flight on April 15, 1945, was in fact rather more than just two Mustang fuselages joined together, despite its appearance. Considerable detailed redesign had taken place since the idea was first mooted, including the lengthening of the normal P-51 fuselage(s) by some five feet (1. 5m), the relocation of each main undercarriage leg to a point just outboard of each fuselage (from where they retracted inwards to lie across the fuselages), and the removal of the six 0. 50 inch (12. 7mm) Browning machine guns from the outer wings to the new centre section, a structure which was also designed to support various external loads. The outer wings now sported two ordnance hard points per side. Internal fuel capacity was 576 US gallons (480 imp gal/2182 litres), some two-and-half times that of the P-51, while two 31O US gal external tanks more than doubled the Twin Mustang’s fuel capacity again and gave a range of over 2,200 miles (3,500km).

The two crew members were accommodated one in each fuselage in a normal P-51 cockpit, the pilot in the port position and the copilot in the starboard. The pilot’s cockpit had a full range of flight and engine instrumentation while the copilot’s had duplicated controls but only enough instrumentation for emergency or relief flying. The first two XP-82s (manufacturer’s designation NA-120) were powered by 1,380hp (for takeoff) Packard Merlin V-1650-23/25s, these engines being counter-rotating and driving four-bladed propellers and producing a remarkable maximum speed of 482mph (776km/h) at 25,000ft. The third and fourth prototypes were to be designated XP-82As (NA-123) but were not completed. These aircraft would have been powered by two similarly rotating Allison V-1710-119 engines with a takeoff rating of 1,500hp, but both NAA and the USAAF preferred the Merlin installation.

Allison-powered production models would be built later, but for now it was to be the Merlin which would provide the Twin Mustang’s motive power in the initial production model, the P-82B, 500 of which had been ordered in March 1944.

Only 20 of these were completed before the war ended and the contract was cancelled. However, several new versions came about as a result of converting some of those 20 aircraft. One became the P-82C night fighter with its SCR-720 radar mounted in a bulbous pod under the centre-section and another was converted to the P-82D, also a night fighter with similarly mounted APS-4 radar. In these versions, the right-hand cockpit became a radar operator’s station. One or two were also converted to photo/reconnaissance aircraft and assigned to appropriate units for testing while others were used to test various armament installations.

However these roles were not to mark the end of a brief operational career for the P-82 (or F-82 as it was redesignated in 1948) as tests of the two night fighter conversions had shown the aircraft to be distinctly superior to the Northrop P-61 Black Widow, then the USAAF’s primary ‘all weather’ fighter.

In December 1945 the USAAF ordered a total of 100 Twin Mustangs for long-range escort duties under the designation F-82E and followed that in the second half of 1946 with orders for two night fighter variants, the F-82F with SCR-720 radar (100) and F-82G (50) with APS-4 radar.

These new models were similar to the P-82 initial version but with one major difference – the Packard Merlin engines were replaced with a new counter-rotating version of the Allison engine, the V-1710-143/145 series rated at 1,600hp for takeoff and 1,930hp at altitude with water/alcohol augmentation.

Deliveries of the F-82E began early in 1948, most of them going to the 27th Fighter Group at McChord Field, Washington, where the basis of their training was the possible escorting of Boeing B-29 and B-50 Superfortresses on raids into the Soviet Union.

The F-82F and G models were delivered between 1948 and early 1949, although nine and five, respectively, were ccompleted as F-82Hs with special cold weather equipment for service with the 449th Fighter Squadron based in Alaska. This unit was also the last to operate the Twin Mustang.

Despite being very much an interim type pending the arrival of its jet-powered successors, the F-82 served a useful role with what was by then known as the United States Air Force. And it did see active service, recording the first USAF victory of the Korean conflict when a 68th Fighter Squadron F-82G flown by Lt William Hudson shot down a North Korean Yak-9 piston-engined fighter on June 27, 1950 near Seoul.

A Yak-11 and La-7 were also claimed by F-82 crews on that same day, but soon after the Twin Mustangs were withdrawn from the Korean battle zone (while their single-engined predecessors remained) and sent to Japan to see out their operational days by providing the air defence of that country

A Cavalier Approach

Although North American Aviation ceased production of the P-51 Mustang after VJ day, the type continued in widespread service with various air arms for some years after, most being equipped from USAF stocks. Australia, of course, built the Mustang under licence (described later) but the list of other postwar users was an extensive one: the Soviet Union, Italy, Canada, Sweden, Switzerland, Taiwan, New Zealand, France, the Philippines and Indonesia all taking delivery of Mustangs in the immediate postwar period.

Numerous South American countries also received P-51Os under the terms of the Rio Pact: Bolivia, Cuba, Haiti, Guatemala, Uruguay, Dominica, Honduras and El Salvador among them. Many of these countries retained their Mustangs until the early 1970s, and two of them – Honduras and El Salvador – used their aircraft in combat against each other as late as 1969.

The incident was the so-called ‘Football War’ and came about as a result of fierce battles between players and spectators on and off the field during the World Cup elimination play-offs between the two countries. Blood was shed over the roll of a soccer ball – ostensibly anyway – though this was just a manifestation of deeper-rooted tensions between the two countries.

Mustangs covertly obtained from Sweden also fought for Israel during its War of Independence of 1948, while in the Netherlands East Indies in 1948 and 1949, the type fought in the battles that would result in the creation of the Republic of Indonesia.

The Mustang came into its own once again during the Korean conflict of 1950-53. The range, endurance and airfield requirement shortcomings of the first generation of jets made them unsuitable for most ground attack missions and the Mustang (now designated F-51) was put to work once again not only by the Americans but also by the Australians, whose 77 Squadron used the type there until re-equipping with Gloster Meteors.

After World War 11, civilian interest in the Mustang increased as war surplus stocks became available. The type was ideally suited to the Bendix Trophy-type races which restarted after the war and continue to this day in the form of events such as the

Unlimiteds at Reno. The 1946 Bendix Trophy race from Cleveland to California was won by famous aviator Paul Mantz, whose P-51D averaged a stunning 535. 5mph (700. 8km/h) over the 2,048 mile (3,296km) course – with the aid of a tailwind.

Since then Mustangs have been raced in standard, slightly modified and highly modified forms, the latter exemplified by the famous and ill-fated ‘Red Baron’ in which Steve Hinton set a world speed record for piston-engined aircraft of 499mph (803 km/h) in 1979. The ‘Red Baron’, was powered by a 3,800hp Rolls-Royce Griffon 57 engine driving contra-props!

And it took another Mustang to set a new record. This time it was Frank Taylor, whose Merlin-powered P-51 (with the engine producing over 3,000hp) recorded 517mph (832km/h) in 1983. The use of the Mustang as a two-seat executive aircraft was probably not high on ‘Dutch’ Kindelberger’s list of operational requirements when he designed the original NA-73 in 1940, but that’s exactly the role a company called Trans-Florida Aviation envisaged for it in the late 1950s. Two-seater Mustangs were not a new idea, field modifications of P-51Os first being performed in 1944 by removing the fuselage fuel tank and installing a seat instead. North American Aviation delivered 1 Osuch aircraft in the same year after modifying them on the production line, and in 1951 the Tempco Aircraft Corporation modified 15 more aircraft under the designation TF-51D.

The Tempco conversion was more elaborate than the earlier ones in that a set of controls and instruments were provided for the rear seat and the canopy size and profile were modified.

Trans-Florida Aviation was formed in 1957 by David B Lindsay Jr, who originally had set out to make his company a primary source of spare parts for the many military and civil operators of the Mustang around the world. He purchased large amounts of Mustang spares and Rolls-Royce Merlin engines from the USAF and set up business, and along the way offered a TF-51D for conversion training and pilot check-out. His company also supplied refurbished armed Mustangs to several South American countries.

From there the idea of an executive two-seat Mustang evolved with increased fuel capacity, extensive avionics and a comfortable cockpit with a high standard of soundproofing. The basic P-51· was stripped, rebuilt and ‘zero timed’ and FAA Type Approval was obtained in February 1959.

These Mustangs were dubbed ‘Cavalier’ and five models were eventually offered, the model suffix denoting the aircraft’s no reserve range in statute miles.

The Cavalier 2000 was the basic model with two 110 US gallon external wing tip tanks which brought the total capacity up to 374 US gallons; the 750 lacked the tip tanks; the 1200 had no tip tanks but two 48 US gallon L-shaped bladder tanks in the wings; the 1500 dispensed with the bladder tanks and replaced them with two 63 US gallon rectangular ones and the 2500 was similar to the 2000 but had two additional 60 US gallon integral fuel cells in the wings. Trans-Florida changed its name to Cavalier Aircraft Corporation in 1962, and among its many customers was North American Aviation itself, who purchased one for the legendary Bob Hoover to fly at air shows.

The Vietnam war revived interest in COIN or counter insurgency aircraft and Cavalier developed a Mustang-based aircraft to fill that need in 1967. Called the Cavalier Mustang 11, this latest version of a basic design now more than a quarter of a century old used the P-51D airframe with wings strengthened so as to carry a variety of underwing stores up to a total of 4,000Ib (1,814kg). Although successful in trials; none were ordered.

The next step was a turboprop version of the aircraft, dubbed the Mustang Ill. The first version, flown in October 1968, was powered by a 1,600shp Rolls-Royce Dart 51O turboprop from a retired Capitol Airlines Vickers Viscount, but two others were powered by 2,445shp Lycoming T55-L-9s. Any resemblance to a Mustang was becoming fairly vague – even the familiar ventral scoop had disappeared! Cavalier sold the production rights of the Mustang 111 to Piper in 1970 who redesigned and retooled the aircraft further, renamed it the Enforcer and entered it in the USAF’s PAVE COIN competition, one intended to find a cheap aircraft to supply to smaller air forces under the USA’s Military Assistance Programme. By now there was little connection between the Enforcer and the Mustang with less than ten percent component part commonality and the addition of not only the powerful turboprop engine but also an ejector seat, very large tip tanks and a total of ten underwing hardpoints capable of carrying a load of no less than 5,680Ib (2,576kg).

The Enforcer never achieved production although two more were built under a USAF evaluation contract awarded in 1981, but as late as 1984 Piper was still offering the aircraft to smaller nations.

The Australian Connection

Australia’s involvement with the Mustang was unique in that it was the only source of production of the aircraft outside the United States. However the first locally-built Mustang wasn’t handed over to the RAAF until June 1945, a very short time before the end of World War II. Before that, the RAAF had operated US-built aircraft, and the first squadron to re-equip with the type was No. 3, operating in the Italian campaign alongside Royal Air Force Mustangs and converting to the type (from Kittyhawks) from November 1944.

Flying from their coastal base at Fano, 3 Squadron’s aircraft flew mainly ground support missions across the Adriatic Sea in support of the Yugoslav partisans, usually with two 500lb bombs slung under the wings. The squadron operated a mixture of P-518/C Mustang Ills and P-510/K Mustang IVs using RAF serial numbers.

But to the RAAF, the Mustang was best suited for service in the Pacific where its long range would be an advantage. Two hundred and ninety-eight P-51D and K Mustangs were thus supplied during 1945 and early 1946, these aircraft serving with Nos. 76, 77 and 82 Squadrons in North Borneo plus Nos. 84 and 86 in Queensland and were allocated the RAAF serial numbers A68-500/583, A68-600/699, A68-700/799 and A68-800/813.

In early 1946, 76, 77 and 82 Squadrons moved to Japan to serve with the British Commonwealth Occupation Forces. The former two squadrons served there until 1949 but the latter went to Korea in 1951. Back in Australia, Mustangs then flew with the Citizen Air Force (a part-time volunteer reserve) until as late as 1960, having formed the initial equipment of Squadron Nos. 21 (City of Melbourne), 22 (City of Sydney), 23 (City of Brisbane), 24 (City of Adelaide) and 25 (City of Perth). Other ‘regular’ RAAF Squadrons to fly the Mustang were Nos. 75 and 78, both of whom converted to the type in August 1946 after returning to Australia from operations in Borneo.

As early as the latter stages of 1942, the Australian Government had decided to find a replacement for the then front-line Curtiss P-40 and an aircraft which could be manufactured locally. The Mustang, Spitfire VIII and P-47 Thunderbolt were all evaluated, the North American Aviation product finally getting the nod after it was decided their aircraft not only met the operational requirements but also exhibited qualities which made it an easier aircraft to manufacture than its opponents.

Additionally, Australian industry already had a close liaison with NAA, due to the Commonwealth Aircraft Corporation’s licence building of the NA-16 advanced trainer/general purpose aircraft as the Wirraway.

The final recommendation of the evaluation committee was that 690 Packard Merlin powered Mustangs be built by CAC. The first contract covered 80 complete aircraft made up from 100 sets of imported P-51D components. These aircraft were designated CA-17 Mustang 20.

A P-510 Mustang, serial number A69-1001 (ex-USAAF 44- 13293) had arrived in Australia in 1944 as a development and ‘pattern’ aircraft prior to the rolling out of the first locally-built example. This Mustang was also re-engined with a Rolls-Royce Merlin 70 engine to test its suitability and as such served as the prototype for the later Australian-built Mustang 23.

The end of the war meant wholesale cancellations of many military contracts all over the world, Australia being no exception. As a result procurement of Australian-built Mustangs ended at exactly 200 aircraft, with deliveries spread between 1945 and 1951.

Four distinct versions were built by CAC. The first 80 were CA-17 Mustang 20s (A68-1 to A68-80) with 1,520hp Packard Merlin V-1650-3 engines, the first of which was handed over to the RAAF on June 4, 1945 and the last in July 1946. A68-1’s first flight had been on April 29, 1945. A second contract was awarded to CAC later in 1946 covering a further 170 aircraft of which 120 were ultimately built, almost exclusively from local resources.

The 80 Mustang 20s were followed by 40 CA-18 Mustang 21s with Packard Merlin V-1650-7 engines. The first fourteen of these aircraft (A68-81/94) were fitted with an F. 24 oblique camera in the fuselage and redesignated Mustang 22. The remainder of the batch were numbered A68-95/120 and deliveries began in July 1947.

The next batch of CAC-built Mustangs received by the AMF was 66 CA-18 Mustang 23s (A68-121/186) with British-built 1,650hp Merlin 70 engines, while the final batch was of 14 camera-equipped Mustang 22s (A68-187/200) with Packard Merlin V-1650-7 engines. The last example was taken on charge by the RAAF on August 3, 1951, while a further contract (CA-21) for 250 aircraft was cancelled when the decision was taken to replace the RAAF’s piston-engined fighters with jets.

The Australian-built Mustangs were too late to see service in World War II and most were issued to home squadrons. However they did see active service with 77 Squadron in Korea.

Apart from fighter and reconnaissance duties, Australia’s Mustangs were put to other uses such as target towing (a special flight for this purpose was formed at Richmond, NSW in 1946), gunnery training at the East Sale Air Armament School, experimental and development work at the Australian Research and Development Unit, pilot medical research at the Flight Personnel Research Unit and of course the most famous ‘special use’ of all, testing the effects of an atomic blast.

This exercise was carried out at Maralinga, South Australia, in October 1953 and six Mustangs (including the first Australian built example, A68-1) were parked on a simulated airstrip close to the British atomic bomb’s blast tower and left to ‘weather the storm’. They survived, but remained in the desert for 14 years before an attempt to remove them was made. Only one (A68-1) was able to be flown out after overhaul on site, the others having suffered more by the effects of souvenir hunters, vandals and to a lesser extent the weather, than the atomic blast!

It would require a hefty volume to fully tell the tale of the North American Mustang. But even through this necessarily abbreviated account, it is obvious that when North American Aviation rejected the idea of building Curtiss P-40s under licence for the Royal Air Force in 1940, they were very serious when they claimed they could do better. The result was a classic fighter aircraft designed and built in an astoundingly rapid time which was – along with the Spitfire and Focke-Wulf 190 – one of the three best of its era and by far the longest-lasting in terms of its operational career.

Various sources quote different production figures for the $2. 75? Mustang, but a ‘line of best fit’ indicates the following quantities: one NA-73X prototype; 1,583 Allison-engined Mustang I, IA, P-51, P-51A and A-36 (etc) variants; 3,740 P-51B and C models; 7,956 P-51D, 1,500 P-51K, 555 P-51H and a handful of P-51F/G/ JIM prototypes. That brings North American Aviation production to approximately 15,343 aircraft to which must be added the 200 built in Australia