The P-39 Airacobra was a fighter aircraft made by Bell Aircraft. It first flew in 1939, and was introduced in 1941. While it had good weapons, it was known for being very unstable and could lose control easily. It was fast but not very good above 5000 m (15,000 feet) as it lacked turbocharger. The Soviet Union used it during World War II as a fighter interceptor as most air battles at the Eastern front were fought at low heights. Very near the ground the Airacobra became extremely maneuverable and could out-turn any German airplane. The Russians liked the plane, and they often removed the wing guns to make it even more maneuvreable. Several Soviet pilots became fighter aces on P-39. The main weapon of P-39, a 37 mm cannon, was so powerful that it could destroy almost any airplane on a single hit.