The Gatling Gun was a machine gun consisting of multiple barrels revolving around a central axis and firing at a high rate of speed. The Catling principle is used in modern weapons to achieve high rates of fire. The 20 mm Vulcan aircraft gun, arming modern fighters and bombers, is a 6-barreled, rapid-fire weapon that fires a high-velocity, high-explosive projectile at an average rate of 6,000 rounds per minute. It may be powered by an electric, a hydraulic, or a ram-air, turbine-drive motor.
A smaller type of Vulcan, the Minigun, uses small-caliber ammunition (7.62 mm or less) and has a firing rate of up to 7,000 shots per minute. Miniguns are mounted on helicopters.
Artillery versions, the self-propelled and towed types of Vulcan, are air defense weapons with a dual rate of fire - 1,000 or 3,000 shots per minute - using armor-piercing ammunition. The towed version of the weapon can be dropped by parachute.
The original Gatling gun was patented in 1862 by Richard Jordan Gatling (1818-1903). It had six barrels grouped around a central axis and fired .58 caliber rimfire cartridges. This weapon was first used in the Civil War, during the siege of Petersburg, Va., in 1864-1865 by Gen. Benjamin F. Butler. The multibarreled gun was subsequently used in nearly every conflict of the next half century.
Improvements were made until the standard version was a 10-barreled, .30 caliber hand-cranked weapon, fed from a 40-round gravity-fed magazine and firing about 400 rounds per minute. The automatic reciprocating weapon of Hiram Maxim made the Gatling gun obsolete, but when reciprocating firing mechanisms were found to be too slow for supersonic aircraft, the Gatling principle of several barrels revolving about an axis was revived.