Autocannon

Source: Wikipedia, the free encyclopedia.

US M242 Bushmaster 25 mm autocannon mounted on an M2 Bradley armoured fighting vehicle
Part of a series on
Cannons
History
Operation
By country
By type

An autocannon, automatic cannon or machine cannon is a

munitions (most often in the range of 20–60 mm (0.79–2.36 in), but bigger calibers also exist), but are usually smaller than tank guns, howitzers, field guns, or other artillery. When used on its own, the word "autocannon" typically indicates a non-rotary weapon with a single barrel. When multiple rotating barrels are involved, such a weapon is referred to as a "rotary autocannon" or occasionally "rotary cannon
", for short (particularly on aircraft).

Autocannons are heavy weapons that are unsuitable for use by

armour-piercing (AP) munitions, mainly composite rigid (APCR) and discarding sabot (APDS
) rounds.

Although capable of generating extremely rapid

aerial dogfights and close air support on ground targets via strafing
attacks, where the target dwell time is short and weapons are typically operated in brief bursts.

History

QF 1-pounder Mk II "pom-pom" of 1903

Early developments

ZU-23-2, a twin barrel 23×152 mm anti-aircraft autocannon from the 1960s still in service with some former members of the Warsaw Pact

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, 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 1 pound (0.45 kg) 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
.

In 1913, Reinhold Becker and his Stahlwerke Becker firm designed the

Oerlikon Contraves firm in 1924, with the Third Reich's Ikaria-Werke firm of Berlin using Oerlikon design patents in creating the MG FF wingmount cannon ordnance. The Imperial Japanese Navy's Type 99 cannon
, adopted and produced in 1939, was also based on the Becker/Oerlikon design's principles.

During the

QF 2 pounder naval gun
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

ground attack aircraft
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.

During 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, pioneered as far back as the end of 1915, almost entirely replaced wood and fabric biplanes. 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

Browning AN/M2 "light-barrel" .50 calibre heavy machine gun. A fighter equipped with these intermediate weapons in sufficient numbers was adequately armed to fulfill most of the Americans' combat needs aloft,[3] 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.[5] 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.[6]

Weapons such as the

Bofors 40 mm and various German Rheinmetall
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

PaK 40 semi-automatic 7.5 cm calibre anti-tank gun was the basis for the BK 7,5 in the Junkers Ju 88P-1 heavy fighter and Henschel Hs 129
B-3 twin engined ground attack aircraft.

The German

Mauser MK 213 was developed at the end of the Second World War and is regarded as the archetypal modern revolver cannon
. 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.

Modern era

Oerlikon KBA automatic cannon turret on a IFV Freccia.

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 aircraft kept their guns.[7] During the Vietnam War, however, the United States Air Force 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 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.

RCWS-30 automatic cannon turret on a Czech Pandur II

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

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 systems on naval vessels, which are used to destroy anti-ship missiles
and low flying aircraft.

See also

References

  1. ^ "Oerlikon KBA Description". WeaponSystems.net. Archived from the original on 2020-12-04.
  2. ^ The GSh-6-30K, a six-barreled Russian rotary autocannon, has a ROF of 6,000 rounds per minute. Williams, p. 241.
  3. ^ a b "Cannon or Machine Gun". Archived from the original on 2020-01-27. Retrieved 2020-05-12.
  4. ^ "World War 2 Fighter Gun Effectiveness". Archived from the original on 2017-10-30. Retrieved 2020-05-12.
  5. ^ The Encyclopedia of Aircraft of WWII. Editor Paul Eden.
  6. ^ The Machine Gun. George M. Chinn.
  7. ISBN 0-517-41265-9
  8. ^ "Freccia IFV (2006)". www.tanks-encyclopedia.com. Retrieved 2021-02-28.

Further reading

External links

Wikimedia Commons has media related to Automatic cannons.
Retrieved from "https://en.wikipedia.org/w/index.php?title=Autocannon&oldid=1169653183"