The M61 Vulcan is a Gatling Gun on Steroids

The M61 Vulcan is a Gatling gun on steroids. It isn't possible with the human eye to see a bullet as it leaves the muzzle of a gun. But in the case of the General Dynamics M61 20mm Rotary Cannon, it isn't just a single bullet that can't be seen, but literally hundreds each second. With a rate of fire that exceeds 6,600 rounds per minute, that's more than 100 rounds leaving the barrels each and every second. The key to this is the barrels, six of them, which are electrically driven, allowing for both the lightning-fast cyclic rate and in helping keep the barrels from overheating. This also increases multi-hit probabilities when compared to a single barrel. The Vulcan War Born While this might seem like cutting-edge 21st century technology, the original M61 was developed after World War II by General Electric and first introduced in 1956. But the concept to utilize multiple barrels dates back a century earlier. It's based on the Gatling principle, which permits a high rate of fire while also reducing heat and barrel erosion. The M61 Vulcan is the deadly weapon of the Civil War era Gatling gun, developed by inventor John Gatling, who wasn't looking for a more effective killing machine. Rather, he developed his rapid-fire gun as a response to the carnage he witnessed during the American Civil War. Gatling saw how many more soldiers died of disease than from gunshots and sought to develop a weapon that could supersede the need for large armies and believed that deaths from the disease would be diminished. General Electric took up Project Vulcan in 1946 to develop the 20mm rotary cannon that could be capable of firing 7,200 rounds per minute. The use of multiple barrels minimized barrel erosion and heat generation, which prolonged the weapon's life. In modern aircraft, the M61 was designed to be hydraulically driven and electrically primed. It was also developed to utilize a linkless ammunition feed system. A NEW GATLING GUN? With the development of jet aircraft, engineers with the United States Army Air Force determined that a higher rate of fire would be necessary and determined that single-barrel revolver cannons would not be up to the task. Instead, designers of the Armament Division of General Electric considered the 19th century concept of utilizing multi-barrels instead. General Dynamics, which acquired the Armament Division of General Electric, currently produces the M61A1 and M61A2 improved versions, with the latter being 20% lighter and is meant for applications where weapon system weight reduction is critical. Most aircraft versions of the M61 are hydraulically driven and electrically primed. The gun rotor, barrel assembly and ammunition feed system are rotated by a hydraulic drive motor through a system of flexible drive shafts. The round is fired by an electric priming system where an electric current from a firing lead passes through the firing pin to the primer as each round is rotated into the firing position. A lighter version of the Vulcan developed for use on the F-22 Raptor, designated M61A2, is mechanically the same as the M61A1, but with thinner barrels to reduce overall weight to 202 pounds. The rotor and housing have also been modified to remove any piece of metal not absolutely needed for operation and replaces some metal components with lighter weight materials. The F-A-18E-F Super Hornet also uses this version. The Vulcan's rate of fire is typically 6,000 rounds per minute, although some versions, such as the F-106 Delta Dart, are limited to a lower rate, and others, A-7 Corsair, have a selectable rate of fire of either 4,000 or 6,000 rounds per minute. The M61A2's lighter barrel allows a somewhat higher rate of fire, up to 6,600 rounds per minute. Applications and First Combat Use The Vulcan first entered aerial combat on 4 April 1965, when four North Vietnamese Air Force MiG-17s attacked a force of 10 escorting North American F-100 Super Sabres and 48 Vulcan-armed and bomb-laden F-105 Thunderchiefs, shooting down two of the latter. The first confirmed Vulcan gunkill occurred on 29 June 1966, when Major Fred Tracy, flying his F-105 Thunderchief with the 421st Fighter Squadron, fired 200 rounds of 20mm into a MiG-17 that had just fired a 23mm shell through one side of his cockpit and which exited out the other side. When the MiG-17 flew in front of him after making his pass, Major Tracy opened fire on him. The Vulcan was later fitted into the weapons bay of some Convair F-106 Delta Dart and General Dynamics F-111 Aardvark models. It was also adopted as a standard in the Teen Series air superiority fighters F-14 Tomcat, F-15 Eagle, F-16 Fighting Falcon and F-A-18 Hornet. Other aircraft include the AMX ground attack aircraft and the F-22 Raptor. It was fitted in a side-firing installation on the Fairchild AC-119 and some marks of the Lockheed AC-130 gunships and was used in the tail turrets of both the Convair B-58 Hustler and Boeing B-52H Stratofortress bombers. The M61 is also the basis of the US Navy Mark 15 Phalanx close-in weapon system