Rotary cannon
Encyclopedia
Autocannon
An autocannon or automatic cannon is a rapid-fire projectile weapon firing a shell as opposed to the bullet fired by a machine gun. Autocannons often have a larger caliber than a machine gun . Usually, autocannons are smaller than a field gun or other artillery, and are mechanically loaded for a...
of equivalent caliber. The loading, firing, and unloading functions are performed simultaneously in different barrels as they rotate, and the rotation also provides the barrels some time to cool. The rotating barrel cluster on most Gatling-type guns is powered by an external force such as an electric motor, although gas operated versions
Gryazev-Shipunov GSh-6-23
The Gryazev-Shipunov GSh-6-23 is a powerful, fast-firing six-barreled 23 mm Gatling gun used by some modern Soviet/Russian military aircraft....
have also been developed.
The cyclic multi-barrel design synchronizes the firing/reloading sequence. Each barrel fires a single shot when it reaches a certain point in the cycle, after which the spent cartridge
Cartridge (firearms)
A cartridge, also called a round, packages the bullet, gunpowder and primer into a single metallic case precisely made to fit the firing chamber of a firearm. The primer is a small charge of impact-sensitive chemical that may be located at the center of the case head or at its rim . Electrically...
is ejected and then a new round loaded, and in the process, the barrel cools down somewhat.
History
The original rotary cannon was the Gatling gunGatling gun
The Gatling gun is one of the best known early rapid-fire weapons and a forerunner of the modern machine gun. It is well known for its use by the Union forces during the American Civil War in the 1860s, which was the first time it was employed in combat...
, designed by the American inventor Dr. Richard J. Gatling
Richard Jordan Gatling
Dr. Richard Jordan Gatling was an American inventor best known for his invention of the Gatling gun, the first successful machine gun.-Life:...
in 1861 and patented in 1862. Hand cranked and hopper fed, it could fire at a rate of 200 rounds per minute.
The Gatling gun was a field weapon, first used in warfare during the American Civil War
American Civil War
The American Civil War was a civil war fought in the United States of America. In response to the election of Abraham Lincoln as President of the United States, 11 southern slave states declared their secession from the United States and formed the Confederate States of America ; the other 25...
and subsequently by European and Russian armies.
The design was steadily improved; by 1876 the Gatling gun had a theoretical rate of fire of 1,200 rounds per minute, although 400 rounds per minute was more readily achievable in combat. By 1893, the M1893 Gatling gun was capable of a maximum rate of fire of some 800–900 rounds per minute.
Ultimately the Gatling's weight and cumbersome artillery carriage hindered its ability to keep up with infantry forces over difficult ground and was superseded by lighter and more mobile machine-guns. All models of Gatling guns were declared obsolete by the U.S. Army in 1911, after 45 years of service.
Development of modern Gatling type guns
After the Gatling gun was replaced in service by newer recoil- or gas-operated non-rotating machine guns, the approach of using multiple rotating barrels fell into disuse for many decades.During World War I, Imperial Germany was working on the Fokker-Leimberger
Fokker-Leimberger
The Fokker-Leimberger was an early example of an externally powered machine gun of Imperial German origin that predated the M134 Minigun. It had 12 barrels and could fire at a rate of 7,200 rounds per minute but it suffered from jamming due to the poor quality of German war time production...
, an externally-powered 12 barrel gatling gun in the 7.92x57mm round capable of firing over 7200 rounds per minute.
The Slostin machine gun
Slostin machine gun
The Slostin was a Soviet-made self-powered Gatling type machine gun, developed directly after World War II but never put into production. It was gas-operated, with stationary breech and movable barrels, intended for 7.62x54mmR ammunition, and it was mounted on PM M1910 wheeled tripods. Each barrel...
was a World War II Russian design, using a gas-operated drive system.
After World War II, the U.S. Army Air Force determined that an automatic cannon of improved design with an extremely high rate of fire was required to achieve a sufficient number of large-caliber hits on fast-moving enemy jet aircraft
Aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...
. Using experience gained from 20mm and 30mm
MK 108 cannon
The MK 108 was a 30 mm caliber autocannon manufactured in Germany during World War II by Rheinmetall-Borsig for use in aircraft.-Development:...
cannon utilized by Luftwaffe
Luftwaffe
Luftwaffe is a generic German term for an air force. It is also the official name for two of the four historic German air forces, the Wehrmacht air arm founded in 1935 and disbanded in 1946; and the current Bundeswehr air arm founded in 1956....
aircraft, a larger caliber cannon shell for the new gun was deemed desirable, as it contained room for an explosive with more destructive force than the .30 and .50 caliber machine gun cartridges previously employed, and thus capable of destroying aircraft with only a few hits on target.
In June 1946, the General Electric Company was awarded a U.S. military defense contract to develop an aircraft gun with a high rate of fire which GE termed Project Vulcan. While researching prior work, ordnance engineers recalled the experimental electrically-driven Gatling weapons of the turn of the century. In 1946, a Model 1903 Gatling gun borrowed from a museum was set up with an electric motor drive and test-fired by General Electric engineers. The 40-year old design briefly managed a rate of fire of 5,000 rounds per minute.
In 1949 General Electric began testing the first model of its modified Gatling design, now called the Vulcan Gun. The first prototype was designated the T45 (Model A). It fired 0.6 in (15.2 mm) ammunition at about 2,500 rounds per minute, from six barrels driven by an electric motor
Electric motor
An electric motor converts electrical energy into mechanical energy.Most electric motors operate through the interaction of magnetic fields and current-carrying conductors to generate force...
. In 1950, GE delivered ten initial model A .60 cal. T45 guns for evaluation. Thirty-three model C T45 guns were delivered in 1952 in three calibers: .60 cal., 20mm, and 27mm, for additional testing. After extensive testing, the T171 20mm gun was selected for further development. In 1956, the T171 20mm gun was standardized by the U.S. Army and U.S. Air Force as the M61 20mm Vulcan aircraft gun.
While electric motors were used to rotate the Vulcan barrels, a few examples of self-operated Gatling-derived weapons use the recoil or gas impulse from their ammunition, such as the GShG-7.62 machine gun
GShG-7.62 machine gun
The Shipunov GShG-7.62 is a four-barreled rotary machine gun, similar to firearms such as the M134 "Minigun". It is a gas operated, self-powered weapon which is in contrast with most other rotary guns , and has been used only in gun pods and flexible mounts on Kamov Ka-29 prototypes.-See...
and GSh-6-23
Gryazev-Shipunov GSh-6-23
The Gryazev-Shipunov GSh-6-23 is a powerful, fast-firing six-barreled 23 mm Gatling gun used by some modern Soviet/Russian military aircraft....
.
Rate of fire
Rate of fire is the frequency at which a specific weapon can fire or launch its projectiles. It is usually measured in rounds per minute , or per second .-Overview:...
. For example, 1000 rounds per minute of continuous fire from a conventional single-barrel weapon ordinarily results in rapid barrel heating followed by stoppages caused by overheating. In contrast, a five-barreled machine gun firing 1000 rounds per minute fires only 200 rounds per barrel per minute, an acceptable rate of fire for continuous use. The only 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 allows them to occur simultaneously, using different barrels at different points in the cycle. The design also solves the problem of defective ammunition, which can cause a normal machinegun to malfunction when a cartridge fails to load, fire, or eject from the weapon. As it is powered by an independent source, the gun simply ejects the defective round along with the rest of the cartridges while continuing to operate.
M61 Vulcan and other designs
The M61 VulcanM61 Vulcan
The M61 Vulcan is a hydraulically or pneumatically driven, six-barreled, air-cooled, electrically fired Gatling-style rotary cannon which fires 20 mm rounds at an extremely high rate. The M61 and its derivatives have been the principal cannon armament of United States military fixed-wing aircraft...
20 mm cannon
Autocannon
An autocannon or automatic cannon is a rapid-fire projectile weapon firing a shell as opposed to the bullet fired by a machine gun. Autocannons often have a larger caliber than a machine gun . Usually, autocannons are smaller than a field gun or other artillery, and are mechanically loaded for a...
is the most prolific member of a family of weapons designed by General Electric
General Electric
General Electric Company , or GE, is an American multinational conglomerate corporation incorporated in Schenectady, New York and headquartered in Fairfield, Connecticut, United States...
and currently manufactured by General Dynamics
General Dynamics
General Dynamics Corporation is a U.S. defense conglomerate formed by mergers and divestitures, and as of 2008 it is the fifth largest defense contractor in the world. Its headquarters are in West Falls Church , unincorporated Fairfax County, Virginia, in the Falls Church area.The company has...
. The M61 is a six-barreled 20mm rotary cannon, which fires at up to 6,600 rounds per minute. Similar systems are available in calibers ranging from 5.56 mm to 30 mm (the prototype T249 Vigilante
T249 Vigilante
The T249 Vigilante was a prototype 37 mm self-propelled anti-aircraft gun designed as a replacement for the Bofors 40 mm gun and M42 Duster in US Army service. The system consisted of a 37 mm T250 six-barrel Gatling gun mounted on a lengthened M113 armored personnel carrier platform...
AA
Anti-aircraft warfare
NATO defines air defence as "all measures designed to nullify or reduce the effectiveness of hostile air action." They include ground and air based weapon systems, associated sensor systems, command and control arrangements and passive measures. It may be to protect naval, ground and air forces...
platform featured a 37 mm chambering).
Another multi-barrel design well-known among aviation enthusiasts is the hydraulically-driven GAU-8 Avenger
GAU-8 Avenger
The General Electric GAU-8/A Avenger is a 30 mm, hydraulically-driven seven-barrel Gatling-type rotary cannon that is mounted on the United States Air Force's Fairchild Republic A-10 Thunderbolt II. It is among the largest, heaviest and most powerful aircraft cannons in the United States military...
30 mm cannon, carried on the A-10 Thunderbolt II
A-10 Thunderbolt II
The Fairchild Republic A-10 Thunderbolt II is an American single-seat, twin-engine, straight-wing jet aircraft developed by Fairchild-Republic in the early 1970s. The A-10 was designed for a United States Air Force requirement to provide close air support for ground forces by attacking tanks,...
(Warthog) attack aircraft, a heavily-armored close air-support aircraft. It is a seven-barreled cannon designed for tank-killing and is currently the largest bore multi-barrel weapon active in the U.S. arsenal, and heaviest autocannon ever mounted into an aircraft, outweighing the WW II German Bordkanone BK 7,5 75mm aircraft-mount, tank-killing single barrel autocannon by some 630 kg (1,389 lb), with ammunition.
The Gryazev-Shipunov GSh-6-23
Gryazev-Shipunov GSh-6-23
The Gryazev-Shipunov GSh-6-23 is a powerful, fast-firing six-barreled 23 mm Gatling gun used by some modern Soviet/Russian military aircraft....
and GSh-6-30
Gryazev-Shipunov GSh-6-30
The Gryazev-Shipunov GSh-6-30 is a Russian 30 mm cannon used by Soviet and later CIS military aircraft.The GSh-6-30, designed in the early 1970s and entering service in 1975, is a six-barreled Gatling gun similar in design to the Gryazev-Shipunov GSh-6-23. It was based on the naval AO-18 used in...
are Russian gas-powered rotary cannons with maximum cyclic rates of 9,000 to 10,000 rounds per minute.
Minigun
Technically not a "cannon", the Minigun is more correctly classified as a Gatling type gun.During the Vietnam War
Vietnam War
The Vietnam War was a Cold War-era military conflict that occurred in Vietnam, Laos, and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. This war followed the First Indochina War and was fought between North Vietnam, supported by its communist allies, and the government of...
, the 7.62 mm caliber M134 Minigun
Minigun
The Minigun is a 7.62 mm, multi-barrel heavy machine gun with a high rate of fire , employing Gatling-style rotating barrels with an external power source...
was originally created to arm rotary-wing aircraft, and could be fitted to various helicopters as either a crew-served or a remotely-operated weapon. With a rate of fire from 2,000 - 6,000 rounds per minute from a 4,000-round linked belt
Belt (firearm)
A belt or ammunition belt is a device used to retain and feed cartridges into a firearm. Belts and the associated feed systems are typically employed to feed machine guns or other automatic weapons...
, the Minigun proved to be one of the most effective non-explosive projectile weapons ever built and is still used in helicopters today. As the GAU-2B/A, the Minigun was also used on the U.S. Air Force AC-47, AC-119 and Lockheed AC-130
Lockheed AC-130
The Lockheed AC-130 gunship is a heavily-armed ground-attack aircraft variant of the C-130 Hercules transport plane. The basic airframe is manufactured by Lockheed, while Boeing is responsible for the conversion into a gunship and for aircraft support...
gunships. The AC-47 was known during the Vietnam War as "Puff the Magic Dragon" and was said to be "the only thing that scared the VC". This weapon was also used on selected USAF helicopters. 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' from the light of the tracer
Tracer ammunition
Tracer ammunition are bullets that are built with a small pyrotechnic charge in their base. Ignited by the burning powder, the phosphorus tail burns very brightly, making the projectile visible to the naked eye...
s, as the gun platform circles a target at night.
The most recent development of the M134 (GAU-2B/A) Minigun concept is the Dillon Aero M134D Gatling Gun, a six-barrelled, 7.62mm electrically-driven machine gun firing at a fixed rate of 3,000 rounds per minute, fed from a 3,000 or 4,400 round magazine. The Dillon M134D has been optimized for operational reliability and has an average time between stoppages of 30,000 rounds. It is currently in service with U.S. military and NATO forces.