The Aircraft
The Bell P-39 Airacobra was a beautiful design. It had an innovative layout for the fuselage, with the engine mounted in the center fuselage, behind the pilot. The P-39 was also the first US Fighter with a tricycle undercarriage.
With these advantages came one large disadvantage. The engine did not have a turbo supercharger, which prevented the aircraft from performing well at high altitude, above 12,000 feet. Because of this, the RAF rejected the P-39. The Soviet Air Force did accept the Airacobra, as most of their combat took place at low to medium altitudes.
The P-39 also had a solid weapons system. The central mounted engine allowed the mounting of the T9 37mm cannon in the nose. This weapon could penetrate 8 inches of armor at 500 yards.