| Continued from above… was adopted primarily to permit installation of a heavy-caliber gun in the nose. As originally designed, the P-39 (Bell Model 12) had a 37-mm T-9 cannon firing through the propeller hub and two 0.50-in machine-guns in the upper front fuselage firing through the propeller disc. |
The P-39 Air Cobra was the first US Army fighter to be fitted with a retractable tricycle type landing gear. These features were imposed by a desire at the time of the middle and late 1930s to mount heavy armament in the nose.
Generally a very pleasing aircraft to look at, the P-39 design came about at a time when streamlining aircraft shapes were just coming into their own. The P-39 was a vast departure from most aircraft being conceived of at the time and featured several design elements that distinguished the type from her contemporaries. Chief among these was in the internal layout, the Allison series engine mounted in the middle of the fuselage just aft of the cockpit. Engineers ran an extended shaft from the engine through a center bearing underneath the pilots feet to the front fuselage section where the three-blade propeller and reduction gear were mounted. As a result of this engine placement, the engine had to be fed through intakes mounted along the fuselage as opposed to a conventional placement in the nose.
From April 1942, P-39s of the USAAF were in action from bases in Hawaii, Panama, Alaska and New Guinea against Japanese attackers; and from July 1942 against German targets in Europe. The January 1940 decision to delete the turbo-supercharger was soon found to have restricted the P-39's usefulness as a fighter; but late in 1942 the type began operating in a ground-attack role in North Africa with considerable success.
Despite early operational difficulties with the P-39, production continued at high pressure, for an eventual total of 9,558. Of these, 4,773 went to the Russian Air Force under lend-lease arrangements, and a small quantity found their way to the Portuguese Air Force after forced landings in Portugal. Late in the war, the Free French forces received 165 P-39s.
Production variants accounted for a number of different designations with few major changes in design. The P-39F had an Aeroproducts, in place of Curtiss, propeller; the P-39J had a V-1710-59 rather than -35 engine; the P-39K had a V-1710-63 engine and Aeroproducts propeller; the P-39L was similar with a Curtiss propeller; the P-39M had a V-1710-83 engine; the P-39N had a V-1710-85 and was lighter than preceding versions; and the P-39Q introduced two 0.50-in wing guns in external fairings, replacing the four 0.30-in guns.
Although heavily armed and armored and very tough, this plane was a bust in its original design role as an interceptor. However, it was very successful as a ground attack aircraft.
Half of all production of P-39s went to the Soviet Union, which used it with great success as a tank buster. Operational losses of this type in the Southwest Pacific were extremely high because of its unusual engine placement and 37mm armament, which made maintenance difficult. The engine placement also seems to have degraded the maneuverability. About 60% of American P-39 crews were deployed to the Pacific.
The first large order for 369 P-39Ds was placed in September 1940, and the initial deliveries of these began several months later. A total of 675 aircraft ordered by a British purchasing commission were exported to Great Britain arriving in April of 1941. These differed only in armament as the 37-mm cannon was replaces with a 20-mm, and the six-.30-cal. Machine guns were replaced by 0.303-in caliber. In September that year No. 601 squadron exchanged its Hawker Hurricanes for these new aircraft. Immediately they were introduced into service, the full implication of the decision to delete the turbo charger was appreciated for the first time, for the aircraft had an inadequate rate of climb and its high altitude performance was completely unacceptable for deployment in the European theatre.
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Bell P39 Airacobra
American fighter / bomber
The Bell P-39 Airacobra was one of a group of fighters that pioneered the tricycle undercarriage. Another distinctive feature was the position of its engine, which was carried in an unorthodox siting beneath and behind the pilot's seat. The propeller was driven through an extension shaft that was linked to a gearbox in the fighter's nose. Although an American product, Airacobras were first used operationally by the RAF, in October 1941. The prototype had appeared in 1939, but to begin with there were no American orders. The French were interested, however, and after the fall of France their contract was taken over by the British.
The RAF wanted to use the P-39 in a ground-attack role, but after a short proving period the planes were withdrawn from service. Then, as the United States entered the war, the remainder of the Bell factory's initial output was taken up by the USAAF for training duties.
Once it had established itself, the P-39 served throughout the war in various modified states, the model numbers reaching as far as 'Q' by 1944; by July of that year the total production figure had reached 9,558. Of these, 4,773 were supplied to Russia under the Lend-Lease agreement. Following the Torch landings of late-1942, the P-39 made its mark as a ground-attack or recce machine specializing in 'rhubarb' missions that involved strafing or reconnoitring enemy positions at low altitude. When the fighting began in Sicily and Italy, the P-39s' limited range proved something of a problem. Although the official range figure for the Q model is set at 675 miles, in practice it was pegged much lower at 150 miles there and 150 back plus 10 minutes' combat time; these figures also allowed for use of an auxiliary tank. In their favor, however, it could be said that the P-39s were stoutly resistant to AA fire, and the USAAF continued to use them profitably on convoy escort and patrol duties.
P-39 details (Q model)
Length: 30 ft 2 ins. Span: 34 ft 0 ins. Combat weight: 8,300 lb. Crew: 1. Top speed: 385 mph. Ceiling: 35,000 ft. Range: 675 miles. Armament: 1 x 37-mm cannon and 4 MGs: 1 x 500 lb bomb optional.