Testing titanic A-10 cannon

  • Published
  • By Airman Anthony Jennings
  • Team Eglin Public Affairs
EGLIN AIR FORCE BASE, Fla. --  What may be mistaken as a fog horn frequently blasting throughout the base is actually one of the largest, heaviest and most powerful aircraft cannon in the U.S. military--the GAU-8/A. 

The GAU 8/A is mounted in the A-10 Thunderbolt II and is capable of firing 4,000 rounds per minute with a muzzle velocity of 3,500 feet per second. At nearly 20 feet in length and weighing in at about two tons, it represents approximately 16 percent of the aircraft's weight. 

The gun automatic unit and its ammunition are rigorously tested by a team of engineers at the Gun and Ammunition test facility on Range A-22 here. 

"The A-10 was pretty much built around this gun," said Phillip Estrem, 780th Test Squadron test engineer. "If the GAU-8 was taken out of the aircraft, weights would need to be added to counteract the weight deficit." 

The percussion produced from the weapon is so thunderous that two sets of ear protection must be worn during testing. The cannon violently rattles the doors of the facility and the vibration can be felt through the floor. 

"Imagine the loudest concert you have ever been to. Now imagine that times 10," said Mr. Estrem. "When that gun goes off, it is a life-altering event." 

The Air Force buys the GAU-8's 30 mm ammunition from two vendors, which bid competitively for each year's order. Before a purchase is made, however, a 500-round batch of the ammunition must be tested to ensure there are no flaws with the lot. 

"We're pretty much the only facility in the Air Force, and probably the largest, with the capability to test both gun and ammunition," said Robert Dupont, 780th TS. 

Behind the safety of closed doors, a team of engineers fire the weapon in controlled bursts of 2.3 seconds, pumping out more than 150 rounds. 

"Three of these rounds can destroy a tank," said Mr. Estrem. 

The team checks for fragmentation of the rounds with high-speed cameras that capture the muzzle fire as the round exits the barrel. Bullet velocity and dispersion is another aspect of testing analyzed by technicians with the use of piezoelectric transducers, an instrument that measures the bullet's impact into a piece of cardboard and converts the energy released into an electrical signal that can be plotted by computers. 

Once all the data is collected, the team sends the information to analysts at Hill Air Force Base, Utah. Upon approval, the ammunition is then introduced to the supply system where it is made available for the warfighter in the field around the world. 

To watch the GAU-8/A in action click the link below
GAU-8