March 11, 1974: A-10 Stubborn Gun Gas GAU-8 Rotary Gun Testing

  • Published
  • Air Force Flight Test Center

An A-10 pilot fired a long burst from his rotary cannon that ignited a large fireball of gun gasses just forward of the aircraft’s nose. A second test later that day resulted in airflow disturbances and mild compressor stalls in the A-10’s engines. This was the first indication of a stubborn gun gas problem associated with the high rate of fire from the GAU-8 weapon.

The A-10 Warthog’s massive 30mm cannon, the GAU-8/A Avenger, is one of the most iconic weapons ever designed and is as famous as the plane that carries it into battle. But as undeniably badass as it is, a closer look at its history reveals that early on, the gun seemed to spend almost as much time trying to kill the aircraft’s pilot as the enemy, producing potentially blinding smoke and fire, fumes that threaten to choke out its engines, and violent vibrations. The Air Force had to find creative solutions to all of these issues in order to make sure the weapon and its flying carriage functioned properly.

The Avenger's story really gets started in 1971 when the U.S. Air Force hired General Electric and Philco-Ford to build competing prototype cannons for a future close air support aircraft then only known as A-X. The two companies would be responsible for building the weapons and ammunition, as well as installing them, along with a linkless feed system and fire control equipment, onto the two A-X prototypes, the Northrop YA-9A and Fairchild Republic YA-10A.

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