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P-51 Mustang

"P-51D Mustang".....illustration by Lance Russwurm

P-51D MUSTANG......Illustration by Lance Russwurm Labusch Skywear

    The P-51 Mustang is usually considered to be the best American fighter aircraft of the Second World War. It had previously undreamed-of range, excellent flying characteristics, adequate cockpit room and heat for the pilot. It was easily the equal or better of any enemy airplane.

    The genesis of this machine goes back to 1938 when the British realized that, in the impending war, their industrial capacity would not be enough to meet their needs. A delegation was sent to the US to establish a means of augmenting British production. Orders were placed with LOCKHEED for 200 Hudson bombers and with NORTH AMERICAN AVIATION for 200 HARVARD advanced trainers. Thus began a co-operative relationship between the US and England for wartime production.

    In 1939, with the invasion of Poland and the actual declaration of war, the British again approached the Americans....this time looking for a fighter aircraft. The first choice of the Brits was the Curtiss P-40, but Curtiss could not deliver anything until the end of 1940, because of American needs. Pleased with the previous dealings with North American, the commission approached them about building P-40's under license. Dutch Kindelberger, the head of the company,  suggested that, instead, they could build a new improved design with increased performance, firepower and range,  using the Allison V-1710-39 powerplant from the P-40. Working overnight, Kindelberger's design team came up with a sleek new fighter plan by morning. The British gave the go-ahead to proceed with detailed drawings. On May 29, 1940, an order was placed for 320 of the new aircraft, now designated the NA-73. The contract required the prototype to be ready within eight months. North American decided to try for 120 days!

    The new design was very innovative in streamlining techniques....the aircraft was tightly cowled with only a very small carburetor intake on the topside. The radiator intake was mounted far back below the wings and was designed for extreme efficiency regarding drag. The NA-73's armament consisted of a pair of 50 caliber Brownings in the lower cowling and two 30 caliber Brownings in each wing. The most important innovation was the decision to use a laminar flow wing design, which had it's widest part further back than normal....keeping the airflow unbroken until later,  causing much less drag, therefore improving performance, fuel economy and range.

    The prototype was wheeled out with three days to spare, on August 30, 1940. It wasn't to receive an engine, however, until October, but the design was seen to be sound and a further 300 machines were ordered. There were the usual teething setbacks but they were solved and production commenced. The British decided to name the aircraft "Mustang", to give it an American flavour.

    The second production machine was delivered to England by October 24, 1941.

    In tests, the Allison engine, being unsupercharged, was found to be inadequate at high altitudes. At low altitudes, it was responsive, stable and was fast in a dive. In light of this it was decided to use it for close support for the army and for low level photo reconnaissance. Fighter command, at this time, was developing the Spitfire for high altitude work.

    The Mustang did indeed prove to be admirably suited to this type of work. The Americans ordered 358 aircraft. They changed the armament to four 50 caliber Brownings in each wing, dispensing with the nose guns. They also used a more powerful 1200 horsepower version of the Allison.

    There was also a dive bomber variant, the A-36A, with dive brakes and other modifications.500 of these were ordered, but they had problems in action. Ultimately they were replaced by P-47 Thunderbolts.

    The Merlin

    The Mustang was seen to be a good airplane, in need of more power. A British test pilot, impressed by the aircraft, suggested to Rolls-Royce that a Merlin 61 with a two stage supercharger would greatly enhance the performance. The aerodynamic engineer at Rolls Royce estimated that 441 miles per hour would be possible at 25,000 feet.

    The installation changed the carburetor intake opening from the top of the cowling to the bottom. By the second prototype, the speed reached was 433 miles per hour at 22,000 feet. The improved performance did come at the expense of handling, however, over the docile Allison versions.

    In US versions, the engine became the Packard built Merlin XX, which attained 453 mph at 28,000 feet, using war emergency boost....a dramatic improvement over Allison versions. Armament consisted of either four or six 50 caliber Brownings in the wings.  Two 1000 pound bombs or two drop tanks could be carried.

    Finally, the allies had a superb fighter with the range to reach Berlin, so this airplane was used extensively for bomber escort missions.

    The Mustang in all its versions went on to serve in every theatre of war with distinction. The most successful of all was the P-51D with its bubble canopy.

    After World War 2, the Mustang soldiered on. A version with two fuselages, the F-82 was used in Korea, along with regular versions. Many other countries used them for first line defense well into the fifties, some banana republics continuing on even beyond this. 

To this day, they are favourites in air racing and warbird gatherings everywhere.

article by Lance Russwurm




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