GAU-8 Avenger
The GAU-8/A Avenger is a 30 mm, seven-barrel Gatling gun that is mounted on the United States Air Force's A-10 Thunderbolt II. It is the largest (it is the size and weight of a family saloon car), heaviest and most powerful aircraft gun in the United States military. Specifically designed for the anti-armor (tank-busting) role, the gun delivers a very powerful shell at a high rate of fire.
The GAU-8 was created as a parallel program with the A-X competition that produced the A-10. The specification for the cannon was laid out in 1970, with General Electric and Philco-Ford offering competing designs. The A-X protoytpes (both the A-10 and the Northrop YA-9) were both designed to incorporate the massive weapon, although it was not available during the initial competition and the M61 Vulcan was used as an interim weapon. On the resultant A-10, the GAU-8 fills half of the aircraft fuselage and represents one third of its unloaded weight. The gun is placed in the centre of the plane with the front landing gear positioned to the side.
The GAU-8 itself weighs 281 kg (620 lb), but the complete weapon, with feed system and drum, weighs 4,029 lb (1,830 kg) with a maximum ammunition load. The entire system is 19 ft 10.5 in (5.05 m) long. The magazine can hold 1,350 rounds, although 1,174 is the more normal load-out. Muzzle velocity with armor-piercing incendiary (API) ammunition is 3,250 ft/s (988 m/s), almost the same as the substantially lighter M61 Vulcan.
The standard ammunition mixture for anti-armor use is a four-to-one mix of PGU-13/B High Explosive Incendiary (HEI) rounds, with a projecticle weight of about 12.7 oz (360 grams) and PGU-14/B Armor-Piercing Incendiary (API), with a projectile weight of about 15.0 oz (430 grams. The PGU-14/B round incorporates a depleted uranium penetrator. Just six rounds are sufficient to destroy most current Russian main battle tanks. The use of the depleted-uranium round is controversial, with some reports linking its use to health problems among both survivors of DUP attacks and servicemen involved in the loading and handling of the rounds.
The Avenger's maximum rate of fire is 4,200 rounds per minute. In practice, the cannon is limited to one and two-second bursts, both to avoid overheating and to deal with the substantial deceleration that results from firing--the GAU-8's peak recoil force is roughly equal to the thrust of the A-10's two engines.
Both the A-10 and and the GAU-8/A gun entered service in 1977. The gun is no longer in production. It was produced by General Electric, though Martin Marietta is now responsible for support.
The GAU-8/A is also used on naval ships in the Goalkeeper CIWS.
A four-barrel version of the Avenger, the GAU-13, was developed for gun pod use. The GAU-12 Equalizer, a five-barrel 25mm cannon, is also an Avenger derivative.
