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Minigun

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Image:HH-3-minigun-vietnam-crop.GIF
A helicopter-mounted minigun
A minigun is a multibarreled machine gun with a high rate of fire (several thousand rounds per minute), employing Gatling-style rotating barrels. More technically, a minigun is an externally powered Gatling gun of rifle caliber, though the term is sometimes used more generally to refer to guns of similar rates of fire and configuration regardless of power source. The name was originally adopted for the M134 Minigun, but has since been applied to a number of other weapons, many of which were derived from that design. The "mini" of the name is in comparison to designs that use a similar firing mechanism but 20 mm or larger shells, such as the M61 Vulcan.


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[edit] Overview and history

The ancestor to the modern minigun was made in the late 19th-century, when Richard J. Gatling replaced the hand crank mechanism of a rifle caliber Gatling gun with one of the relatively new electric motors. Even after Gatling deliberately slowed down the mechanism, the new electric-powered Gatling gun was credited with a cyclic rate of 3,000 rpm--roughly three times the rate of a typical modern, single-barreled machine gun. This design received US Patent #502,185 on July 25, 1893.

When the U.S. entered the Vietnam War during early 1960s, it found it needed to arm its helicopters to provide additional firepower against enemy infantry. Those applications also required a high rate of fire delivered in short bursts, so General Electric designers simply scaled down the 20 mm M61 Vulcan for 7.62 x 51 mm NATO ammunition. The resulting weapon, known as the Minigun, could fire up to 4,000 rounds per minute and was soon adapted to the various helicopter mounts. It was mounted on OH-6 Cayuse and OH-58 Kiowa side pods, in the turret and wing pods on AH-1 Cobra attack helicopters, on door, pylon and pod mounts on UH-1 "Huey" Iroquois transport helicopters, and on many other helicopters and aircraft.

Image:HH-3-minigun-vietnam-19681710.gif

The minigun's multibarrel design helps prevent overheating, but also serves other functions. Multiple barrels allow for a greater capacity for a high firing rate through the parallel processes of firing/extraction/loading taking place in all barrels simultaneously (for example, as one barrel fires, two others are in different stages of shell extraction and another three are being loaded, though the actual process scheme may be different from what is described here). The minigun is composed of multiple closed-bolt rifle barrels arranged in a circular housing. The gun is not actuated by the gas pressure or recoil energy of fired cartridges. Instead, an external power source must be supplied, usually electric, pneumatic, or hydraulic.

Several larger aircraft were outfitted with miniguns, specifically for close air support, including famous gunship airplanes like the Douglas AC-47 ("Spooky" a.k.a. "Puff the Magic Dragon", converted Douglas DC-3s), AC-119 Gunship ("Shadow" and "Stinger", converted Fairchild "Flying Boxcars"), and the original AC-130 "Spectre" Gunship (converted C-130 Hercules cargo planes), the H-53 (MH-53 Pave Low), and the common H-60 family of helicopters (UH-60 Black Hawk/HH-60 Pave Hawk) transport helicopters - a replacement for the aformentioned UH-1 Iroquois.

[edit] Variants

US Army Designation US Air Force Designation US Navy Designation Description
XM134/M134 GAU-2/A N/A 7.62x51 mm NATO GE “Minigun” 6-barreled machine gun
N/A GAU-2A/A N/A GAU-2/A variant; unknown differences
N/A GAU-2B/A Mk 25 Mod 0 GAU-2A/A variant;
N/A GAU-17/A N/A GAU-2B/A variant; optimized for flexible use with an integrated motor and drive assembly and a MAU-201/A or MAU-56 delinking feeder,
XM196 N/A N/A M134/GAU-2B/A variant; housing modified by addition of an ejection sprocket; for use in the XM53 armament subsystem on the AH-56 helicopter

[edit] Designations

The term Minigun actually originated in the 1960s, when General Electric scaled down a larger caliber weapon to a 7.62 mm rifle caliber. The resulting weapon, dubbed a minigun, was adopted by the U.S. military and other armed services for various roles, with one of the more common being a helicopter door-gun. Miniguns have been used in most major U.S. military operations since then, and been adopted by several other countries. In fact, G.E.'s minigun is in use in all major branches of the US military, under a number of designations. The basic fixed armament version was given the designation M134 by the U.S. Army, while the exact same weapon was designated GAU-2B/A by the U.S. Air Force. A variant was further developed by the U.S. Air Force specifically for flexible installations, at the time primarily for the UH-1N helicopter, as the GAU-17/A. The primary end users of the GAU-17/A have been the U.S. Navy and the U.S. Marine Corps, who mount them on as defensive armament on a number of helicopters and surface ships.

[edit] Gun pods and mounts

Image:Gatling Minigun.jpg

The GE 7.62x51 mm Minigun has been used in gun pod applications by the United States and with purpose-built mounting hardware used on the aforementioned fixed wing gunship aircraft. In fact, before the purpose-built mounts were created, those aircraft used mounts simply designed to hold the gun pods that had already been developed.

US Army Designation US Air Force Designation US Navy Designation Description
N/A SUU-11/A N/A Gun pod fitted with the GAU-2/A 7.62 mm machine gun
XM18/M18 SUU-11A/A N/A SUU-11/A variant; differences unknown
M18E1/A1 SUU-11B/A N/A SUU-11A/A variant; differences unknown
N/A MXU-470/A N/A Emerson Electric module for mounting a GAU-2B/A minigun; used in AC-47, AC-119G/K, and C-130A/E/H aircraft
N/A N/A Mk 77 Mod 0 Machine gun mount for the GAU-2/Mk 25 Mod 0/GAU-17 series of machine guns; deck mount applications

Various iterations of the minigun have also been used in a number of armament subsystems for helicopters, with most of these subsystems being created by the United States. For more information, check out the page on US Helicopter Armament Subsystems.

[edit] Non-aircraft applications

This article contains speculation and may try to argue its points.</br>Information must be verifiable and based on reliable published sources.
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Image:Xm706m1.jpg

While the minigun is primarily associated with fixed wing airplanes and helicopters it has an interesting if often overlooked history on the ground. Since its creation members of the US military from the upper echelons to the soldiers on the ground have looked for a practical way to use the weapon on vehicles and as a heavy infantry weapon. The XM214, described later in this article, is a direct product of this thinking.

A pamphlet from the early sixties advertising the Cadillac Gage V100 or (XM706 as it was designated by the US Army) talks of "Firepower for Today's Army" showing a vehicle with the "XM-134/GAU-2B/A Minigun." The rate of fire is advertised as selectable from "500 to 6000 shots/minute."

While an airplane or a helicopter can quickly evacuate an area when their ammunition supply is depleted, a vehicle caught in an ambush or during an assault would need to make up for the weapon's high rate of fire with a large supply of ready ammunition, something not easily done. This would be a good explanation of why miniguns have continued to be used sparingly in vehicles, from Vietnam Era gun trucks to the HMMWVs recently in Fallujah, Iraq. Similar projects have been attempted using the GAU-19/A, a rotary barreled .50 caliber weapon also produced by GE, with similar results.

Assault boats in use by US Navy special boat units and also by riverine forces in Vietnam also used the Minigun on their watercraft, again sparing for roughly the same reasons that has limited its ground usage.

[edit] See also

[edit] References

[edit] External links

fr:Minigun ja:M134 (機関銃) pl:M134 Minigun ru:M134 Minigun sv:Minigun zh:M143六管航空机枪

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