![M2Bradley-M242](https://upload.wikimedia.org/wikipedia/commons/4/47/M2Bradley-M242.jpg)
An autocannon, automatic cannon or machine cannon is a
fully automatic
An automatic firearm is an auto-loading firearm that continuously chambers and fires rounds when the trigger mechanism is actuated. The action of an automatic firearm is capable of harvesting the excess energy released from a previous discharge ...
gun
A gun is a ranged weapon designed to use a shooting tube (gun barrel) to launch projectiles. The projectiles are typically solid, but can also be pressurized liquid (e.g. in water guns/cannons, spray guns for painting or pressure washing, pr ...
that is capable of rapid-firing large-
caliber
In guns, particularly firearms, caliber (or calibre; sometimes abbreviated as "cal") is the specified nominal internal diameter of the gun barrel Gauge (firearms) , bore – regardless of how or where the bore is measured and whether the f ...
( or more)
armour-piercing
Armour-piercing ammunition (AP) is a type of projectile designed to penetrate either body armour or vehicle armour.
From the 1860s to 1950s, a major application of armour-piercing projectiles was to defeat the thick armour carried on many warsh ...
,
explosive
An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An expl ...
or
incendiary shells, as opposed to the smaller-caliber
kinetic projectile
A kinetic energy weapon (also known as kinetic weapon, kinetic energy warhead, kinetic warhead, kinetic projectile, kinetic kill vehicle) is a weapon based solely on a projectile's kinetic energy instead of an explosive or any other kind of payl ...
s (
bullet
A bullet is a kinetic projectile, a component of firearm ammunition that is shot from a gun barrel. Bullets are made of a variety of materials, such as copper, lead, steel, polymer, rubber and even wax. Bullets are made in various shapes and co ...
s) fired by a
machine gun
A machine gun is a fully automatic, rifled autoloading firearm designed for sustained direct fire with rifle cartridges. Other automatic firearms such as automatic shotguns and automatic rifles (including assault rifles and battle rifles) a ...
. Autocannons have a longer
effective range Effective range is a term with several definitions depending upon context.
Distance
Effective range may describe a distance between two points where one point is subject to an energy release at the other point. The source, receiver, and conditions ...
and greater
terminal performance than machine guns, due to the use of larger/heavier
munition
Ammunition (informally ammo) is the material fired, scattered, dropped, or detonated from any weapon or weapon system. Ammunition is both expendable weapons (e.g., bombs, missiles, grenades, land mines) and the component parts of other weapo ...
s (most often in the range of , but bigger calibers also exist), but are usually smaller than
tank gun
A tank gun is the main armament of a tank. Modern tank guns are high-velocity, large-caliber artilleries capable of firing kinetic energy penetrators, high-explosive anti-tank, and cannon-launched guided projectiles. Anti-aircraft guns can also ...
s,
howitzer
A howitzer () is a long- ranged weapon, falling between a cannon (also known as an artillery gun in the United States), which fires shells at flat trajectories, and a mortar, which fires at high angles of ascent and descent. Howitzers, like ot ...
s,
field gun
A field gun is a field artillery piece. Originally the term referred to smaller guns that could accompany a field army on the march, that when in combat could be moved about the battlefield in response to changing circumstances ( field artille ...
s or other
artillery
Artillery is a class of heavy military ranged weapons that launch munitions far beyond the range and power of infantry firearms. Early artillery development focused on the ability to breach defensive walls and fortifications during siege ...
. When used on its own, the word "autocannon" typically indicates a non-rotary weapon with a single
barrel
A barrel or cask is a hollow cylindrical container with a bulging center, longer than it is wide. They are traditionally made of wooden staves and bound by wooden or metal hoops. The word vat is often used for large containers for liquids, ...
. When multiple rotating barrels are involved, such a weapon is referred to as a "rotary autocannon" or occasionally "
rotary cannon
A rotary cannon, rotary autocannon, rotary gun or Gatling cannon, is any large-caliber multiple-barreled automatic firearm that uses a Gatling-type rotating barrel assembly to deliver a sustained saturational direct fire at much greater rate ...
", for short (particularly on aircraft).
Autocannons are heavy weapons that are unsuitable for use by
infantry
Infantry is a military specialization which engages in ground combat on foot. Infantry generally consists of light infantry, mountain infantry, motorized infantry & mechanized infantry, airborne infantry, air assault infantry, and marine i ...
. Due to the heavy weight and
recoil
Recoil (often called knockback, kickback or simply kick) is the rearward thrust generated when a gun is being discharged. In technical terms, the recoil is a result of conservation of momentum, as according to Newton's third law the force requ ...
, they are typically installed on
fixed mounts,
wheeled carriages,
combat vehicle
A combat vehicle, also known as a ground combat vehicle, is a self-propelled, weaponized military vehicle used for combat operations in mechanized warfare. Combat vehicles can be wheeled or tracked.
History Ancient
The chariot is a type of ...
s,
aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air. It 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 ...
or
watercraft
Any vehicle used in or on water as well as underwater, including boats, ships, hovercraft and submarines, is a watercraft, also known as a water vessel or waterborne vessel. A watercraft usually has a propulsive capability (whether by sail, ...
, and are almost always
crew-served during operation, or even
remote-operated with
automatic target recognition
Automatic target recognition (ATR) is the ability for an algorithm or device to recognize targets or other objects based on data obtained from sensors.
Target recognition was initially done by using an audible representation of the received signal ...
/
acquisition (e.g.
sentry gun
A sentry gun is a weapon that is automatically aimed and fired at targets that are detected by sensors. The earliest functioning military sentry guns were the close-in weapon systems point-defense weapons, such as the Phalanx CIWS, used for dete ...
s and naval
CIWS
A close-in weapon system (CIWS ) is a point-defense weapon system for detecting and destroying short-range incoming missiles and enemy aircraft which have penetrated the outer defenses, typically mounted on a naval ship. Nearly all classes of la ...
). As such, ammunition is typically fed from a
belt
Belt may refer to:
Apparel
* Belt (clothing), a leather or fabric band worn around the waist
* Championship belt, a type of trophy used primarily in combat sports
* Colored belts, such as a black belt or red belt, worn by martial arts practit ...
system to reduce reloading pauses or for a faster
rate of fire
Rate of fire is the frequency at which a specific weapon can fire or launch its projectiles. This can be influenced by several factors, including operator training level, mechanical limitations, ammunition availability, and weapon condition. In m ...
, but
magazine
A magazine is a periodical publication, generally published on a regular schedule (often weekly or monthly), containing a variety of content. They are generally financed by advertising, purchase price, prepaid subscriptions, or by a combinatio ...
s remain an option. Common types of ammunition, among a wide variety, include
HEIAP,
HEDP and more specialised
armour-piercing
Armour-piercing ammunition (AP) is a type of projectile designed to penetrate either body armour or vehicle armour.
From the 1860s to 1950s, a major application of armour-piercing projectiles was to defeat the thick armour carried on many warsh ...
(AP) munitions, mainly composite rigid (
APCR) and discarding sabot (
APDS) rounds.
Although capable of generating extremely rapid
firepower
Firepower is the military capability to direct force at an enemy. (It is not to be confused with the concept of rate of fire, which describes the cycling of the firing mechanism in a weapon system.) Firepower involves the whole range of potent ...
, autocannons overheat quickly if used for sustained fire, and are limited by the amount of ammunition that can be carried by the weapons systems mounting them. Both the US
25 mm M242 Bushmaster and the British
30 mm RARDEN have relatively slow rates of fire so as not to deplete ammunition too quickly. The
Oerlikon KBA
The Oerlikon KBA is a 25 mm (25×137mm) autocannon, developed as a close range multipurpose weapon for the mechanised battlefield, originally made by Oerlikon (now Rheinmetall AG) and currently produced in Rheinmetall Italia S.p.A. facilities. It ...
25 mm has a relatively mid-high rate of fire 650 rounds per minute but can be electronically programmed to 175-200 rounds per minute. The rate of fire of a modern autocannon ranges from 90
rounds per minute
Round or rounds may refer to:
Mathematics and science
* The contour of a closed curve or surface with no sharp corners, such as an ellipse, circle, rounded rectangle, cant, or sphere
* Rounding, the shortening of a number to reduce the numbe ...
, in the case of the British RARDEN, to 2,500 rounds per minute with the
GIAT 30
The GIAT 30 is a series of 30 mm cannon developed to replace the DEFA 550 series weapons on French military aircraft.
Introduced in the late 1980s, the GIAT 30 is a revolver cannon with electric ignition and automatic recocking. Unlike the DEFA ...
. Rotary systems with multiple barrels can achieve over 10,000 rounds per minute (the Russian
GSh-6-23
The Gryazev-Shipunov GSh-6-23 (russian: Грязев-Шипунов ГШ-6-23) (GRAU designation: 9A-620 for GSh-6-23, 9A-768 for GSh-6-23M modernized variant) is a six-barreled 23 mm rotary cannon used by some modern Soviet/Russian military ...
, for example). Such extremely high rates of fire are effectively employed by aircraft in
aerial dogfight
A dogfight, or dog fight, is an aerial battle between fighter aircraft conducted at close range. Dogfighting first occurred in Mexico in 1913, shortly after the invention of the airplane. Until at least 1992, it was a component in every majo ...
s and
close air support
In military tactics, close air support (CAS) is defined as air action such as air strikes by fixed or rotary-winged aircraft against hostile targets near friendly forces and require detailed integration of each air mission with fire and moveme ...
on ground targets via
strafing
Strafing is the military practice of attacking ground targets from low-flying aircraft using aircraft-mounted automatic weapons.
Less commonly, the term is used by extension to describe high-speed firing runs by any land or naval craft such ...
attacks, where the target dwell time is short and weapons are typically operated in brief bursts.
History
Early developments
![Zu-23-2-belarus cropped](https://upload.wikimedia.org/wikipedia/commons/8/8e/Zu-23-2-belarus_cropped.jpg)
The first modern autocannon was the British
QF 1-pounder, also known as the "pom-pom". This was essentially an enlarged version of the
Maxim gun
The Maxim gun is a recoil-operated machine gun invented in 1884 by Hiram Stevens Maxim. It was the first fully automatic machine gun in the world.
The Maxim gun has been called "the weapon most associated with imperial conquest" by historian M ...
, which was the first successful fully automatic machine gun, requiring no outside stimulus in its firing cycle other than holding the trigger. The pom-pom fired gunpowder-filled explosive shells at a rate of over 200 rounds a minute: much faster than conventional artillery while possessing a much longer range and more firepower than the infantry
rifle
A rifle is a long-barreled firearm designed for accurate shooting, with a barrel that has a helical pattern of grooves ( rifling) cut into the bore wall. In keeping with their focus on accuracy, rifles are typically designed to be held with ...
.
In 1913, Reinhold Becker and his ''Stahlwerke Becker'' firm designed the
20mm Becker cannon, addressing the
German Empire
The German Empire (),Herbert Tuttle wrote in September 1881 that the term "Reich" does not literally connote an empire as has been commonly assumed by English-speaking people. The term literally denotes an empire – particularly a hereditary ...
's perceived need for heavy-calibre aircraft armament. The Imperial Government's
Spandau Arsenal assisted them in perfecting the ordnance. Although only about 500+ examples of the original Becker design were made during World War I, the design's patent was acquired by the Swiss
Oerlikon Contraves
Rheinmetall Air Defence AG is a division of German armament manufacturer Rheinmetall, created when the company's Oerlikon Contraves unit was renamed on 1 January 2009 and integrated with Rheinmetall's other air-defence products. Oerlikon Contr ...
firm in 1924, with the Third Reich's ''Ikaria-Werke'' firm of Berlin using Oerlikon design patents in creating the
MG FF
The MG FF was a drum-fed, blowback-operated, 20 mm aircraft autocannon, developed in 1936 by Ikaria Werke Berlin of Germany. It was a derivative of the Swiss Oerlikon FF F cannon (its ''FF'' suffix indicating ''Flügel Fest'', for a fixed ...
wingmount cannon ordnance. The
Imperial Japanese Navy
The Imperial Japanese Navy (IJN; Kyūjitai: Shinjitai: ' 'Navy of the Greater Japanese Empire', or ''Nippon Kaigun'', 'Japanese Navy') was the navy of the Empire of Japan from 1868 to 1945, when it was dissolved following Japan's surrender ...
's
Type 99 cannon
The Type 99 Mark 1 machine gun and Type 99 Mark 2 machine gun were Japanese versions of the Oerlikon FF and Oerlikon FFL autocannons respectively. They were adopted by the Imperial Japanese Navy (IJN) in 1939 and served as their standard aircraft ...
, adopted and produced in 1939, was also based on the Becker/Oerlikon design's principles.
During the
First World War
World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...
, autocannons were mostly used in the trenches as
anti-aircraft gun
Anti-aircraft warfare, counter-air or air defence forces is the battlespace response to aerial warfare, defined by NATO as "all measures designed to nullify or reduce the effectiveness of hostile air action".AAP-6 It includes surface based, ...
s. The British used pom-pom guns as part of their
air defence
Anti-aircraft warfare, counter-air or air defence forces is the battlespace response to aerial warfare, defined by NATO as "all measures designed to nullify or reduce the effectiveness of hostile air action".AAP-6 It includes surface based, ...
s to counter the German
Zeppelin
A Zeppelin is a type of rigid airship named after the German inventor Count Ferdinand von Zeppelin () who pioneered rigid airship development at the beginning of the 20th century. Zeppelin's notions were first formulated in 1874Eckener 1938, pp ...
airships that made regular bombing raids on
London
London is the capital and largest city of England and the United Kingdom, with a population of just under 9 million. It stands on the River Thames in south-east England at the head of a estuary down to the North Sea, and has been a majo ...
. However, they were of little value, as their shells neither ignited the hydrogen of the Zeppelins nor caused sufficient loss of gas (and hence lift) to bring them down. Attempts to use the guns in aircraft failed, as the weight severely limited both speed and altitude, thus making successful interception impossible. The more effective
QF 2 pounder naval gun
The 2-pounder gun, officially the QF 2-pounder ( QF denoting "quick firing") and universally known as the pom-pom, was a British autocannon, used as an anti-aircraft gun by the Royal Navy.British military of the period traditionally denoted s ...
would be developed during the war to serve as an anti-aircraft and close range defensive weapon for naval vessels.
Second World War
Autocannons would serve to a much greater extent and effect during the
Second World War
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...
. The German
Panzer II
The Panzer II is the common name used for a family of German tanks used in World War II. The official German designation was ''Panzerkampfwagen'' II (abbreviated PzKpfw II).
Although the vehicle had originally been designed as a stopgap while la ...
light tank, which was one of the most numerous in German service during the
invasion of Poland
The invasion of Poland (1 September – 6 October 1939) was a joint attack on the Republic of Poland by Nazi Germany and the Soviet Union which marked the beginning of World War II. The German invasion began on 1 September 1939, one week aft ...
and the
campaign in France, used a 20 mm autocannon as its main armament. Although ineffective against tank armour even during the early years of the war, the cannon was effective against light-skinned vehicles as well as infantry and was also used by
armoured cars
Armored (or armoured) car or vehicle may refer to:
Wheeled armored vehicles
* Armoured fighting vehicle, any armed combat vehicle protected by armor
** Armored car (military), a military wheeled armored vehicle
* Armored car (valuables), an arm ...
. Larger examples, such as the 40 mm
Vickers S
The Vickers 40 mm Class S gun, also known simply as the "S gun", was a 40 mm (1.57 in) airborne autocannon designed by Vickers-Armstrongs for use as aircraft armament.
It was primarily used during World War II by British aircr ...
, were mounted in
ground attack aircraft
An attack aircraft, strike aircraft, or attack bomber is a tactical military aircraft that has a primary role of carrying out airstrikes with greater precision than bombers, and is prepared to encounter strong low-level air defenses while pres ...
to serve as an anti-tank weapon, a role to which they were suited as tank armour is often lightest on top.
The Polish
20 mm 38 Fk auto cannon was expensive to produce, but an exception. Unlike the Oerlikon, it was effective against all the tanks fielded in 1939, largely because it was built as an upgrade to the Oerlikon, Hispano-Suiza, and Madsen. It even proved capable of knocking out early Panzer IIIs and IVs, albeit with great difficulty. Only 55 were produced by the time of the Polish Defensive War. However it was in the air war that these weapons played their most important part in the conflict.
In the First World War, rifle-calibre machine guns became the standard weapons of military aircraft. In the Second, several factors brought about their replacement by autocannon. During the inter-war years, aircraft underwent extensive evolution and the all-metal
monoplane
A monoplane is a fixed-wing aircraft configuration with a single mainplane, in contrast to a biplane or other types of multiplanes, which have multiple planes.
A monoplane has inherently the highest efficiency and lowest drag of any wing confi ...
, pioneered as far back as
the end of 1915, almost entirely replaced wood and fabric
biplane
A biplane is a fixed-wing aircraft with two main wings stacked one above the other. The first powered, controlled aeroplane to fly, the Wright Flyer, used a biplane wing arrangement, as did many aircraft in the early years of aviation. While ...
s. At the same time as they began to be made from stronger materials, the machines also increased in speed, streamlining, power and size, and it began to be apparent that correspondingly more powerful weapons would be needed to counter them. Conversely, they were becoming much better able to carry exactly such larger and more powerful guns; the technology of which was in the meantime also developing, providing significantly improved rates of fire and reliability.
When the Second World War did break out, it was swiftly realised that the power of contemporary aircraft allowed armour plate to be fitted to protect the pilot and other vulnerable areas. This innovation proved highly effective against rifle-calibre machine gun rounds, which tended to
ricochet
A ricochet ( ; ) is a rebound, bounce, or skip off a surface, particularly in the case of a projectile. Most ricochets are caused by accident and while the force of the deflection decelerates the projectile, it can still be energetic and almost ...
off harmlessly.
Similarly the introduction of
self sealing fuel tanks provided reliable protection against these small projectiles. These new defenses, synergistically with the general robustness of new aircraft designs and of course their sheer speed, which made simply shooting them accurately in the first place far more difficult, entailed that it took a lot of such bullets and a fair amount of luck to cause them critical damage; but potentially a single cannon shell with a high-explosive payload could instantly sever essential structural elements, penetrate armour or open up a fuel tank beyond the capacity of self-sealing compounds to counter, even from fairly long range. (Instead of explosives, such shells could carry incendiaries, also highly effective at destroying planes, or a combination of explosives and incendiaries.) Thus by the end of the war, the fighter aircraft of almost all the belligerents mounted cannon of some sort, the only exception being the United States which in most cases favoured the
Browning AN/M2 "light-barrel" .50 calibre
heavy machine gun
A heavy machine gun (HMG) is significantly larger than light machine gun, light, medium machine gun, medium or general-purpose machine guns. HMGs are typically too heavy to be man-portable (carried by one person) and require weapon mount, mountin ...
. A fighter equipped with these intermediate weapons in sufficient numbers was adequately armed to fulfill most of the Americans' combat needs aloft,
as they tended to confront enemy fighters and other small planes far more often than large bombers; and as, in the earlier phases of the war, the Japanese aircraft they dealt with were not only unusually lightly built but went without either armour plate or self-sealing tanks in order to reduce their weight. Nevertheless, the U.S. also adopted planes fitted with autocannon, such as the Lockheed P-38 Lightning, despite experiencing technical difficulties with developing and manufacturing these large-calibre automatic guns.
Weapons such as the
Oerlikon 20 mm
The Oerlikon 20 mm cannon is a series of autocannons, based on an original German Becker Type M2 20 mm cannon design that appeared very early in World War I. It was widely produced by Oerlikon Contraves and others, with various models emplo ...
, the
Bofors 40 mm Bofors 40 mm gun is a name or designation given to two models of 40 mm calibre anti-aircraft guns designed and developed by the Swedish company Bofors:
*Bofors 40 mm L/60 gun - developed in the 1930s, widely used in World War II and into the 1990s
...
and various German
Rheinmetall
Rheinmetall AG is a German automotive and arms manufacturer, headquartered in Düsseldorf, Germany. Its shares are traded on the Frankfurt stock exchange.
History
Rheinmetall was founded in 1889. Banker and investor Lorenz Zuckermandel
L ...
autocannons would see widespread use by both sides during the Second World War; not only in an anti-aircraft role, but as a weapon for use against ground targets as well. Heavier anti-aircraft cannon had difficulty tracking fast-moving aircraft and were unable to accurately judge altitude or distance, while machine guns possessed insufficient range and firepower to bring down aircraft consistently. Continued ineffectiveness against aircraft despite the large numbers installed during the second World War led, in the West, to the removal of almost all shipboard anti-aircraft weapons in the early post-war period. This was only reversed with the introduction of computer-controlled systems.
The German ''
Luftwaffe
The ''Luftwaffe'' () was the aerial-warfare branch of the German ''Wehrmacht'' before and during World War II. Germany's military air arms during World War I, the ''Luftstreitkräfte'' of the Imperial Army and the '' Marine-Fliegerabtei ...
'' deployed small numbers of the experimental ''Bordkanone'' series of heavy aircraft cannon in 37, 50 and 75 mm calibres, mounted in
gun pod
A gun pod is a detachable pod or pack containing machine guns, autocannons, revolver cannons, or rotary cannons and ancillaries, mounted externally on a vehicle such as a military aircraft which may or may not also have its own guns.
Description ...
s under the fuselage or wings. The 37 mm
BK 3,7
The Bordkanone 3,7 (BK 3,7) ("on-board cannon 3.7") was a German anti-tank/bomber autocannon of World War II and based on the earlier 3.7 cm Flak 18 made by Rheinmetall.
It was mounted on Luftwaffe aircraft such as the Junkers Ju 87 G-1 ...
cannon, based on the German Army's
3.7 cm FlaK 43 anti-aircraft autocannon was mounted in pairs in underwing gun pods on a small number of specialized
Stuka
The Junkers Ju 87 or Stuka (from ''Sturzkampfflugzeug'', "dive bomber") was a German dive bomber and ground-attack aircraft. Designed by Hermann Pohlmann, it first flew in 1935. The Ju 87 made its combat debut in 1937 with the Luftwaffe's Cond ...
''Panzerknacker'' (tank buster) aircraft. The
BK 5 cm cannon, based on the
5 cm KwK 39
5 (five) is a number, numeral and digit. It is the natural number, and cardinal number, following 4 and preceding 6, and is a prime number. It has attained significance throughout history in part because typical humans have five digits on eac ...
cannon of the
Panzer III
The ''Panzerkampfwagen III'', commonly known as the Panzer III, was a medium tank developed in the 1930s by Germany, and was used extensively in World War II. The official German ordnance designation was Sd.Kfz. 141. It was intended to fight oth ...
, was installed in
Ju 88P bomber destroyer
Bomber destroyers were World War II interceptor aircraft intended to destroy enemy bomber aircraft. Bomber destroyers were typically larger and heavier than general interceptors, designed to mount more powerful armament, and often having twin en ...
s, which also used other ''Bordkanone'' models, and in the
Messerschmitt 410 ''Hornisse'' (Hornet) bomber destroyer. 300 examples of the BK 5 cannon were built, more than all other versions. The
PaK 40
The 7.5 cm Pak 40 (''7,5 cm Panzerabwehrkanone 40 -'' "7.5cm armour defence cannon 90") was a German 75 millimetre anti-tank gun of the Second World War.
The gun was developed in 1939–1941 and entered service in 1942. With 23,303 e ...
semi-automatic 7.5 cm calibre anti-tank gun was the basis for the BK 7,5 in the
Junkers Ju 88
The Junkers Ju 88 is a German World War II ''Luftwaffe'' twin-engined multirole combat aircraft. Junkers Aircraft and Motor Works (JFM) designed the plane in the mid-1930s as a so-called ''Schnellbomber'' ("fast bomber") that would be too fast ...
P-1 heavy fighter and
Henschel Hs 129
The Henschel Hs 129 was a World War II ground-attack aircraft fielded by the German ''Luftwaffe''. The aircraft saw combat in Tunisia and on the Eastern Front.
A key requirement of the original specification was that the aircraft be powered by ...
B-3 twin engined ground attack aircraft.
The German
Mauser MK 213
The Mauser MG 213 was a 20 mm aircraft-mounted revolver cannon developed for the ''Luftwaffe'' during World War II. It was never put into service, but the principles formed the basis for several post-war developments by the Allies. A 30 mm vers ...
was developed at the end of the Second World War and is regarded as the archetypal modern
revolver cannon
A revolver cannon is a type of autocannon, commonly used as an aircraft gun. It uses a cylinder with multiple chambers, like those of a revolver handgun, to speed up the loading-firing-ejection cycle. Some examples are also power-driven, to fur ...
. With multiple chambers and a single barrel, autocannons using the revolver principle can combine a very high rate of fire and high acceleration to its maximum firing rate with low weight, at cost of a reduced sustained rate of fire compared to rotary cannon. They are therefore used mainly in aircraft for AA purposes, in which a target is visible for a short period of time.
File:50mm BK5.jpg, German BK 5
The Rheinmetall ''Bordkanone'' 5, or BK-5, was a WWII-era German 50 mm autocannon primarily intended for use against Allied heavy bombers, such as the United States Army Air Forces's (USAAF) Boeing B-17 Flying Fortress. The shells had a hig ...
50 mm aircraft autocannon displayed in front of the Me 262A jet, a design once tested with it
File:XM307-01.jpg, XM307
The XM307 Advanced Crew Served Weapon (ACSW) was a developmental 25 mm belt-fed automatic grenade launcher with programmable airburst capability. It is the result of the ''OCSW'' or ''Objective Crew Served Weapon'' project. It is lightweight and ...
25 mm caliber man portable Automatic Grenade Launcher An automatic grenade launcher (AGL) or grenade machine gun is a grenade launcher that is capable of fully automatic fire, and is typically loaded with either an ammunition belt or magazine.
These weapons are often mounted on vehicles or helicopte ...
, part of the cancelled OCSW The OCSW (''Objective Crew Served Weapon'') was a U.S. Military arms program started in the 1980s that led to a hybrid smaller prototype automatic autocannon developed by General Dynamics Armament Systems. It led to the XM312 and XM307 designs.
As ...
program
File:Autocannon MLG27.jpg, An MLG 27
The BK 27 (also BK27 or BK-27) (German abbreviation for ''Bordkanone'', "on-board cannon") is a caliber revolver cannon manufactured by Mauser (now part of Rheinmetall) of Germany. It was developed in the late 1960s for the MRCA (Multi Role Comba ...
remote controlled autocannon of the German Navy
The German Navy (, ) is the navy of Germany and part of the unified ''Bundeswehr'' (Federal Defense), the German Armed Forces. The German Navy was originally known as the ''Bundesmarine'' (Federal Navy) from 1956 to 1995, when ''Deutsche Mari ...
File:Oerlikon-20mm-batey-haosef-2-1.jpg, The 20 mm Oerlikon, an early autocannon
File:30 mm.jpg, 30mm × 113 mm rounds being loaded into a M230 chain gun
The M230 Cannon is a 30 mm (30×113 mm), single-barrel electrically-driven autocannon, using external electrical power (as opposed to recoil or expanding gas generated by the firing cartridge) to cycle the weapon between shots. It was desi ...
Modern era
![Italian Army - Mechanized Brigade](https://upload.wikimedia.org/wikipedia/commons/7/7c/Italian_Army_-_Mechanized_Brigade_%22Pinerolo%22_Freccia_IFV.jpg)
The development of guided missiles was thought to render cannons unnecessary and a full generation of western fighter aircraft was built without them. In contrast, all
Eastern Bloc
The Eastern Bloc, also known as the Communist Bloc and the Soviet Bloc, was the group of socialist states of Central and Eastern Europe, East Asia, Southeast Asia, Africa, and Latin America under the influence of the Soviet Union that existed du ...
aircraft kept their guns.
[Gunston, Bill and Mike Spick. ''Modern Air Combat''. New York: Crescent Books, 1983. ] During the
Vietnam War
The Vietnam War (also known by #Names, other names) was a conflict in Vietnam, Laos, and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. It was the second of the Indochina Wars and was officially fought between North Vie ...
, however, the
United States Air Force
The United States Air Force (USAF) is the air service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part of the United States Army Signal ...
realized that cannons were useful for firing warning shots and for attacking targets that did not warrant the expenditure of a (much more expensive) missile, and, more importantly, as an additional weapon if the aircraft had expended all its missiles or enemy aircraft were inside of the missiles' minimum
target acquisition
Target acquisition is the detection and identification of the location of a target in sufficient detail to permit the effective employment of lethal and non-lethal means. The term is used for a broad area of applications.
A "target" here is an e ...
range in a high-G close range engagement. This was particularly important with the lower reliability of early air-to-air missile technology, such as that employed during the Vietnam War. As a consequence, fighters at the time had cannons added back in external "gun pods", and virtually all fighter aircraft retain autocannons in integral internal mounts to this day.
![Pandur2 1457](https://upload.wikimedia.org/wikipedia/commons/2/2d/Pandur2_1457.JPG)
After the Second World War, autocannons continued to serve as a versatile weapon in land, sea, and air applications. Examples of modern autocannons include the 25 mm
Oerlikon KBA
The Oerlikon KBA is a 25 mm (25×137mm) autocannon, developed as a close range multipurpose weapon for the mechanised battlefield, originally made by Oerlikon (now Rheinmetall AG) and currently produced in Rheinmetall Italia S.p.A. facilities. It ...
mounted on the
IFV Freccia,
the
M242
The M242 Bushmaster chain gun is a 25 mm (25×137mm) single-barrel chain-driven autocannon. It is used extensively by the U.S. military, such as in the Bradley fighting vehicle, as well as by other NATO members and some other nations in ground ...
Bushmaster mounted on the
M2/M3 Bradley, updated versions of the
Bofors 40 mm gun, and the
Mauser BK-27
The BK 27 (also BK27 or BK-27) (German abbreviation for ''Bordkanone'', "on-board cannon") is a caliber revolver cannon manufactured by Mauser (now part of Rheinmetall) of Germany. It was developed in the late 1960s for the MRCA (Multi Role Com ...
. The 20 mm
M61A1 is an example of an electrically powered rotary autocannon. Another role that has come into association with autocannons are that of
close-in weapon system
A close-in weapon system (CIWS ) is a point-defense weapon system for detecting and destroying short-range incoming missiles and enemy aircraft which have penetrated the outer defenses, typically mounted on a naval ship. Nearly all classes of ...
s on naval vessels, which are used to destroy
anti-ship missile
An anti-ship missile (AShM) is a guided missile that is designed for use against ships and large boats. Most anti-ship missiles are of the sea skimming variety, and many use a combination of inertial guidance and active radar homing. A good ...
s and low flying aircraft.
See also
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Chain gun
A chain gun is a type of autocannon or machine gun that uses an external source of power to cycle the weapon's action, rather than diverting excess energy from the cartridges' propellant as in a typical automatic firearm, and does so via a conti ...
*
Gast gun
The Gast gun was a German twin barrelled machine gun that was developed by Karl Gast of Vorwerk und Companie of Barmen and used during the First World War. Its unique operating system produced a very high rate of fire of 1,600 rounds per minut ...
*
Infantry support gun
Infantry support guns or battalion guns are artillery weapons designed and used to increase the firepower of the infantry units they are intrinsic to, offering immediate tactical response to the needs of the unit's commanding officer. They typicall ...
*
List of autocannon
Autocannons are automatic guns with calibers of 20mm to 57mm. There are many types including chain guns, gast guns, revolver cannons, and rotary cannons. They are being used as military aircraft main guns, naval guns, anti-aircraft weapons, infan ...
*
Recoil operation
Recoil operation is an operating mechanism used to implement locked breech, autoloading firearms. Recoil operated firearms use the energy of recoil to cycle the action, as opposed to gas operation or blowback operation using the pressure of the p ...
*
Revolver cannon
A revolver cannon is a type of autocannon, commonly used as an aircraft gun. It uses a cylinder with multiple chambers, like those of a revolver handgun, to speed up the loading-firing-ejection cycle. Some examples are also power-driven, to fur ...
*
Rotary cannon
A rotary cannon, rotary autocannon, rotary gun or Gatling cannon, is any large-caliber multiple-barreled automatic firearm that uses a Gatling-type rotating barrel assembly to deliver a sustained saturational direct fire at much greater rate ...
References
Further reading
* Department of the Army. ''Ballistic Data Performance of Ammunition'', TM 9-1907. Washington, D.C.: Government Printing Office, 1948. .
* Williams, Anthony G. ''The Development of Automatic Cannon, Heavy Machine Guns and Their Ammunition for Armies, Navies and Air Forces''. Shrewsbury, Eng.: Airlife Publishing Ltd., 2000. . .
External links
Extensive documentation of Luftwaffe autocannons
{{Authority control
Close-in weapon systems