The DEFA cannon (Direction des Études et Fabrications d'Armement) is a family of widely used French-made aircraft revolver cannon firing 30 mm caliber NATO standard rounds.
Design history
The initial DEFA 551 was developed in the late 1940s. It is based on the German Mauser MG 213C, an experimental revolver cannon developed for the Luftwaffe. The MG 213 never reached production, but inspired the DEFA, the very similar British ADEN cannon, and the smaller American M39 cannon. As the DEFA 552 it entered production in 1954. In 1968 an upgraded version, Canon 550-F3, was developed, entering production in 1971 as the DEFA 553. The new version provided a new feed system, nichrome plated steel barrel, forged drum casing, and improved electrical reliability.
Overview
The DEFA 553 is a gas-operated five-chamber revolver cannon using pyrotechnic cocking and electrical ignition. It fires a range of 30 mm ammunition of various types, and is capable of continuous fire or 0.5-second or 1-second bursts.
The 553 was superseded by the DEFA 554, which incorporates a number of detail improvements. The DEFA 554 uses three, rather than two, of the chambers for reloading, increasing the rate of fire. Barrel life and mechanical reliability are improved, and an electrical control unit allows the pilot to select two rates of fire: 1,800 rounds per minute for air-to-air use or 1,200 rounds per minute for air-to-ground attacks.