Bell P-39 'Airacobra'

P-39 'AIRACOBRA'

Bell P-39 'Airacobra', Duxford 2007 ©Nigel Key

ROLE
Fighter.

FIRST FLIGHT
6 April 1938.

The P-39 Airacobra was designed by Bell Aircraft and was in service when the United States entered World War II.

The P-39 was designed to accommodate the 37mm T9 cannon, which had to be rigidly mounted, fire parallel and be close to the centreline of the fighter.

As it was not possible to fire the cannon ‘through’ the engine and spinner due to the size, the cannon was mounted in the front of the fuselage and the engine was mounted in the centre of the fuselage behind the pilots seat.

A 10ft (3.0m) drive shaft (in two sections) connected from the engine to a gearbox in the nose which in turn drove the propeller by a further shorter shaft.

The fuselage had a central ‘keel’ on which engine and gearboxes were mounted. A strong arched bulkhead provided the main attachment point for the wing spar.

There is an armour plate between the engine and the cockpit and bullet-resistant glass behind the pilots head.

Due to the unconventional design, there was no space in the fuselage for a fuel tank so the standard fuel load was carried in the wings, with the result that the P-39 was limited to short-range tactical strikes.

PRODUCTION
The Bell P-39 was produced from 1940 to 1944, with 9,558 built.

ENGINE
Allison v-1710-83, producing 1200 hp.

ARMAMENT
1 x AAC T9 37mm cannon through spinner
2 x Browning 0.5” machine gun in nose
2 or 4 Browning 0.3” machine gun in wings
1 x 500lb bomb on centre rack.

The P-39 Airacobra saw combat throughout the world, particularly in the Southwest Pacific, Mediterranean and Soviet theatres.

Because its engine was equipped with only a single-stage, single-speed supercharger, the P-39 performed poorly above 17,000 feet (5,200 m) altitude. In both Western Europe and the Pacific, the Airacobra found itself outclassed as an interceptor and was gradually relegated to other duties. It was often used at lower altitudes for ground strafing.

No. 601 Squadron RAF was the only British unit to use the Airacobra operationally, receiving their first two examples on 6 August 1941. On 9 October, four Airacobra attacked enemy barges near Dunkirk, in the only operational action with the RAF.

The squadron continued to train with the Airacobra during the winter, but a combination of poor serviceability and deep distrust of this unfamiliar fighter resulted in the RAF rejecting it after only one combat mission. In March 1942, the unit re-equipped with Spitfires.