Machine Gun Monday – GAU-8 Avenger
The A-10 Warthog Combined with the GAU-8 Avenger Has Been Providing Effective Close Air Support Since 1977.
The Fairchild Republic A-10 Thunderbolt II (Warthog) combined with the GAU-8 Avenger is arguably the most versatile and deadly close air support aircraft ever built.
The GAU-8 was created as a parallel program with the A-X (or Attack Experimental) 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. Both of the A-X prototypes, the YA-10 and the Northrop YA-9, were designed to incorporate the weapon, although it was not available during the initial competition; the M61 Vulcan was used as a temporary replacement. Once completed, the entire GAU-8 assembly (correctly referred to as the A/A 49E-6 Gun System) represents about 16% of the A-10 aircraft’s unladen weight. Because the gun plays a significant role in maintaining the A-10’s balance and center of gravity, a jack must be installed beneath the tail of the plane whenever the gun is removed for inspection in order to prevent the aircraft from tipping rearwards.
Specifications
- Weight: 619.5lbs
- Length: 19ft 10.5in
- Width: 17.2in
- Barrel Length: 90.5in
- Cartridge: 30x173mm
- Caliber: 30mm
- Barrels: 7 barrel, progressive RH twist
- Action: Electrically controlled, hydraulically driven
- Rate of Fire: 4200 rounds per minute
- Muzzle Velocity: 3500 ft/sec
- Effective Firing Range: 4000 ft
- Maximum Firing Range: More Than 12000 ft
- Feed System: Linkless Feed System
The gun is placed slightly off center in the nose of the plane with the front landing gear positioned to the right of the center line, so that the actively firing cannon barrel is directly on the aircraft’s center line. The Russian Gryazev-Shipunov GSh-6-30 is a similar class of weapon, although it is lighter with a higher fire rate, but has a lower muzzle velocity and overheats faster.
The A-10 and its GAU-8/A gun entered service in 1977. It was produced by General Electric, though General Dynamics Armament and Technical Products has been responsible for production and support since 1997 when the division was sold by Lockheed Martin to General Dynamics.
Accuracy and Recoil
The muzzle velocity of the GAU-8/A is about the same as that of the M61 Vulcan cannon, but the GAU-8/A uses heavier ammunition and has superior ballistics. The time of flight of its projectile to 4,000 feet (1,200 m) is 30 percent less than that of an M61 round; the GAU-8/A projectile decelerates much less rapidly after leaving the barrel, and it drops a negligible amount, about 10 feet (3.0 m) over the distance. The GAU-8/A accuracy when installed in the A-10 is rated at “5 mil, 80 percent”, meaning that 80 percent of rounds fired will hit within a cone with an angle of five-milliradians. This equates to a 40 feet (12 m) diameter circle at the weapon’s design range of 4,000 feet (1,200 m)
Size and Weight
The GAU-8 itself weighs 620 pounds (280 kg), but the complete weapon, with feed system and drum, weighs 4,029 pounds (1,828 kg) with a maximum ammunition load. It measures 19 ft 5 1?2 in (5.931 m) from the muzzle to the rearmost point of the ammunition system, and the ammunition drum alone is 34.5 inches (88 cm) in diameter and 71.5 inches (1.82 m) long. Power for operating the gun is provided by twin hydraulic motors pressurized from two independent hydraulic systems. The magazine can hold 1,174 rounds, although 1,150 is the typical load-out. Muzzle velocity when firing Armor-Piercing Incendiary rounds is 3,250 feet per second (990 m/s), almost the same as the substantially lighter M61 Vulcan’s 20 mm round.
