February 26, 1974: Live Firing Tests of a 30mm GAU-8 Cannon Mounted in A-10

  • Published
  • Air Force Flight Test Center

A test team began the first live firing tests of a 30mm GAU-8 cannon mounted in an A-10. The objective was to determine the compatibility of gun and aircraft. The seven-barrel Gatling-type weapon was 20 ft long and, with its high volume ammunition drum and 1,350 rounds of ammunition, weighed nearly two tons.

The General Electric GAU-8/A Avenger is a 30 mm hydraulically driven seven-barrel Gatling-style autocannon that is typically mounted in the United States Air Force's Fairchild Republic A-10 Thunderbolt II. Designed specifically for the anti-tank role, the Avenger delivers very powerful rounds at a high rate of fire.  The GAU-8/A is extremely accurate and can fire up to 3,900 rounds per minute without complications. The 30-mm shell has twice the range, half the time to target, and three times the mass of projectiles fired by guns mounted in comparable close air support aircraft.  The GAU-8/A Avenger Gatling gun next to a Volkswagen Beetle. Removing an installed GAU-8 from an A-10 requires first installing a jack under the aircraft's tail to prevent it from tipping, as the cannon makes up most of the aircraft's forward weight.  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 is 30 percent less than that of an M61 round; the GAU-8/A projectile decelerates much less after leaving the barrel, and it drops a negligible amount, about 10 feet  over the distance.   The GAU-8/A accuracy when installed in the A-10 is rated at 5 miliradans 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-foot diameter circle at the weapon's design range of 4,000 feet.  By comparison, the M61 has an 8-milliradian dispersion.

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