So, in late 1966, then Air Force Chief of Staff General John McConnell ordered the design of a specialized CAS aircraft that would be low-cost, highly survivable, and with lots of firepower. In 1970, the request was modified to include the requirement for a 30mm cannon. 

Six companies, including Northrop and Fairchild, submitted proposals to the Air Force for the first A- designated aircraft to fill the ground attack role. Separately, the Air Force announced a contest for a 30 mm cannon with high muzzle velocity and rate of fire. The purpose was to identify the best cannon to build a jet around. General Electric (that’s right, the same GE that makes lightbulbs) and Philco-Ford (yep, electronics producer Philco) submitted designs, and the GE cannon won out. 

The GAU-8 Avenger 30mm Rotary Cannon

The gun itself, minus ammo drum and hydraulically-driven feed system, weighs in at 620 lbs. GAU-8 is the designation for the cannon itself. Once the drum and feed system are in place, the correct designation is the A/A 49E-6 gun system, and the weight goes up to over 4,000 lbs.

Round Size

Standard rounds for the GAU-8 are 30 x 173mm, armor-piercing, depleted uranium core. Rather than steel or brass cases, the GAU-8 rounds have an aluminum shell, which allows for more rounds for the same weight. At 11.4 inches long, and weighing about 1.5 lbs each, it would be pretty frightening to see one coming at you.

If you did see one coming at you, chances are there are anywhere from 60 to 120 right behind it. The GAU-8 has a fixed rate of 3,900 rounds per minute, but limits have been put in place to fire in one- or two-second bursts. Conservation, conservation, conservation.

Accuracy

This thing is as accurate as it gets. When you’re at the range, you want tight groupings with your 9mm or 45mm (or BB, if that’s your thing). That equates to inches or millimeters at 15, 25, or 50 meters. When the GAU-8 goes BRRRRRRTTTTT, its range is a bit longer. At 4,000ft, the GAU-8 Avenger will put 80 percent of its rounds into a 20 feet radius. When the target is a tank, armored vehicle, or bunker, a 20 feet spread is a pretty tight grouping. 

Operation of the GAU-8

The GAU-8 is an aircraft-mounted Gatling gun. The same basic type you may have seen on the History Channel, with one guy feeding rounds in while the other turns the crank. Rather than tasking a couple of Airmen to do the job, the GAU-8 uses aircraft hydraulics to rotate the seven barrels and feed ammunition. 

The ammunition drum is located just forward of the wings to more effectively distribute weight and maintain weight and balance when rounds are spent. The spent casings are collected back in the drum to compensate for some of the weight differential and maintain center-of-gravity. The gun system is 19.5ft from the muzzle to the “stock” and only the tip of the muzzle protrudes from the nose.

I’ll Have the Gun and Aircraft Combo, Please

Because of the power contained in the GAU-8 Avenger, the A-10 is set up differently than most aircraft. The muzzle of the gun is located just below the aircraft’s center of gravity to compensate for pitch problems when the gun is fired. The gun is also mounted at the centerline of the jet to overcome yaw when fired. Considering that the muzzle velocity of the cannon is about the same as one engine’s thrust, pitch, and yaw considerations are important. 

The recoil force from the GAU-8 is around 10klbs. Each of the A-10’s two engines produces around 9,500lbs of thrust. So, when the gun fires in the air, the rough equivalent of another jet engine is now working against the aircraft. Nevertheless, because the bursts are short, airspeed is not really affected by the gun’s recoil. Lt. Col Matthew Shelly told Business Insider that firing the cannon “[F]eels like driving over railroad tracks… You’re sitting right on top of the gun, so it shakes the whole airplane.” Pilots had to wear double hearing protection due to the extra noise.

Gee Whiz!

Since the GAU-8 Avenger is mounted at centerline, the A-10’s nose wheels are offset slightly to allow for the barrel. Because of this, the A-10 has a tighter turn-radius to the right. That may not sound like a big deal, and it’s not, but does make following the marshaler’s instructions and taxi lines a little more exciting. 

While the U.S. Army makes good use of the A-10 in its CAS role, it does not own any. The USAF is the only operator of the A-10 in the world.

With a price tag of roughly nine million dollars in today’s money, these are expensive for the common man but downright economical in the defense world. The U.S. military does not sell these to private citizens, so you have to join the Air Force if you want to fly an A-10.