Gatling gun

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An 1876 Gatling gun preserved at Fort Laramie National Historic Site
An 1876 Gatling gun preserved at Fort Laramie National Historic Site

A Gatling gun is a gun with multiple firing pins and breeches connected to multiple rotating barrels. Each barrel fires a single shot as it reaches a certain point in the cycle after which it ejects the spent cartridge, loads a new round, and in the process, somewhat cools down. This configuration allows higher rates of fire without the problem of an overheating single barrel, though accuracy suffers. The gun was designed by the American inventor Dr. Richard J. Gatling in 1861 and patented in 1862.

The Gatling gun may have been the first "machine gun" because, while it did not automatically reload under its own power, it was capable of firing continuously. The first Gatling gun relied on a hand crank for external power. Some time later, Gatling-type weapons diverted a fraction of gas from the chamber to spin the rotating barrels. Later still, electric motors supplied external power.

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[edit] History

Patent drawing for R.J. Gatling's Battery Gun, 9 May 1865.
Patent drawing for R.J. Gatling's Battery Gun, 9 May 1865.

The original Gatling gun was a black powder field weapon, which used multiple rotating barrels turned by a hand crank, and firing loose (no links or belt) metal cartridge ammunition using a gravity feed system from a hopper. It was first used by the Union Army during the American Civil War. Unlike earlier weapons such as the mitrailleuse which had limited capacity and long reloading times, the Gatling gun was more reliable, easy to load, and had a high firing rate. Gatling guns were used by the US side during the Spanish-American War, most notably during the battle of San Juan Hill.[1]

[edit] Modern Gatling-style guns

After Gatling guns were replaced by lighter, cheaper blowback-style weapons, the approach of using multiple rotating barrels fell into disuse for many decades. However, Gatling gun-style weapons made a return in the 1940–50s, when weapons with very high rate of fire were needed in military aircraft. For these modern rotating-barrel cannons, electric motors were used to rotate the barrel.

One of the main reasons for the resurgence of the Gatling gun-style design is the weapon's tolerance for continuous high rates of fire. For example, if 500 rounds were fired non-stop at high rate from a conventional single-barrel weapon, this would likely result in the barrel overheating (distorting in extreme cases) or a weapon jam. In contrast, a five-barreled Gatling gun-style weapon firing 500 rounds fires 100 per barrel, an acceptable rate of fire. Ultimately the limiting factor is the rate at which loading and extraction can occur. In a single barrel design these tasks must alternate, a multiple barrel design on the other hand lets them occur simultaneously, with different barrels at different points in the cycle. Their high rate of fire also makes them popular for systems that often have little time to engage their targets, such as CIWS which defend against fast-moving anti-ship missiles.

The M61 Vulcan 20 mm cannon is the most commonly-used member of a family of weapons designed by General Electric and currently manufactured by General Dynamics. It is a six-barreled Gatling capable of more than 6,000 rounds per minute, a rate unachievable with a conventional machine gun. Similar systems are available ranging from 5.56 mm to 30 mm (there was even a 37 mm Gatling on the prototype T249 'Vigilante' AA platform); the rate-of-fire being somewhat inversely-proportional to the size and mass of the ammunition (which also determines the size and mass of the barrels).

Another Gatling design well-known among aviation enthusiasts is the GAU-8 Avenger 30 mm cannon, carried on the A-10 Thunderbolt II (Warthog) ground-support aircraft. It is a seven-barreled cannon designed for tank-killing and is the most powerful Gatling weapon currently active in the U.S. arsenal. The A-10 was in fact built around this weapon and purpose.

During the Vietnam War, the 7.62 mm caliber M134 Minigun was created as a helicopter weapon. Able to fire 6,000 rounds a minute from a 4,000-round linked belt, the Minigun proved to be one of the most effective non-explosive projectile weapons ever built and is still used in helicopters today. When used in Vietnam, the Minigun was nicknamed "Puff, the Magic Dragon" because it fired red tracers and the high volume of fire created a continuous muzzle flash that gave the appearance of breathing fire.

They are also used with lethal effectiveness on USAF AC-47, AC-119 and Lockheed AC-130 gunships, their original high-capacity cargo airframes able to house the items needed for sustained operation. With sophisticated navigation and target identification tools, Miniguns can be used effectively even against concealed targets. The crew's ability to concentrate the Gatling's fire very tightly produces the appearance of the 'Red Tornado' [1] from the light of the tracers, as the gun platform circles a target at night.

The GAU-8 Gatling gun of an A-10 Thunderbolt II  at Osan Air Base, Korea.
The GAU-8 Gatling gun of an A-10 Thunderbolt II at Osan Air Base, Korea.

In addition to the benefits mentioned above, many modern systems have the advantage of being externally-driven (as opposed to relying on the energy from fired cartridges). This increases their reliability, as cartridge firing failure will not interrupt the operation cycle. Additionally, certain other stoppages, such as faulty extraction and many feeding-related problems, are eliminated or reduced considerably due to the external power source. It should however be noted that, although complex mechanically and uncommon, modern systems that derive power from the ammunition do exist. The world's fastest Gatling-style weapon, the 10,000 round-per-minute GSh-6-23 uses a gas-operated drive system.

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