Editing Cannon (section)

====Aircraft use====
{{main|Aircraft artillery}}

The first documented installation of a cannon firing [[explosive shell]]s on an aircraft was on the Voisin Canon in 1911, displayed at the Paris Exposition that year. By World War I, all of the major powers were experimenting with aircraft-mounted cannons; however, their low rate of fire and great size and weight precluded any of them from being anything other than experimental. The most successful (or least unsuccessful) was the SPAD 12 Ca.1 with a single 37&nbsp;mm Puteaux mounted to fire between the cylinder banks and through the propeller boss of the aircraft's Hispano-Suiza 8C. The pilot (by necessity an ace) had to manually reload each round.<ref name="Early Aircraft Armament">{{cite book | last = Woodman | first = Harry | author-link = Harry Woodman | title = Early Aircraft Armament – The Aircraft and the Gun up to 1918 | publisher = [[Arms and Armour Press]] | year = 1989 | isbn = 978-0-85368-990-4}}</ref>

The first autocannon were developed during World War I as anti-aircraft guns, and one of these, the [[Coventry Ordnance Works]] "[[COW 37 mm gun]]", was installed in an aircraft. However, the war ended before it could be given a field trial, and it never became standard equipment in a production aircraft. Later trials had it fixed at a steep angle upwards in both the [[Vickers Type 161]] and the [[Westland C.O.W. Gun Fighter]], an idea that would return later.

During this period autocannons became available and several fighters of the German {{lang|de|[[Luftwaffe]]}} and the [[Imperial Japanese Navy Air Service]] were fitted with 20&nbsp;mm cannons. They continued to be installed as an adjunct to machine guns rather than as a replacement, as the rate of fire was still too low and the complete installation too heavy. There was a some debate in the RAF as to whether the greater number of possible rounds being fired from a machine gun, or a smaller number of explosive rounds from a cannon was preferable. Improvements during the war in regards to rate of fire allowed the cannon to displace the machine gun almost entirely.<ref name="Aircraft Cannon"/> The cannon was more effective against armour so they were increasingly used during the course of World War II, and newer fighters such as the [[Hawker Tempest]] usually carried two or four instead of the six [[M2 Browning|.50 Browning machine guns]] for US aircraft or eight to twelve [[M1919 Browning machine gun]]s on earlier British aircraft. The [[Hispano-Suiza HS.404]], [[Oerlikon 20 mm cannon|Oerlikon 20&nbsp;mm cannon]], [[MG FF cannon|MG FF]], and their numerous variants became among the most widely used autocannon in the war. Cannons, as with machine guns, were either fixed to fire forwards (mounted in the wings, in the nose or fuselage, or in a [[pannier]] under either), or mounted in [[gun turret]]s on heavier aircraft. Both the Germans and Japanese mounted cannons to fire upwards and forwards for use against heavy bombers, with the Germans calling guns so-installed {{lang|de|[[Schräge Musik]]}}, derived from a German colloquialism for jazz music—{{lang|de|schräg}} means "off-key".

Preceding the [[Vietnam War]] the high speeds aircraft were attaining and availability of missiles led to a move to omit cannon due to the belief that they would be useless in a [[dogfight]], but combat experience during the Vietnam War showed conclusively that, despite advances in missiles, there was still a need for cannon. Nearly all modern [[fighter aircraft]] are armed with an autocannon, and they are also commonly found on [[ground-attack aircraft]]. One of the most powerful examples is the 30mm GAU-8/A Avenger Gatling-type rotary cannon mounted on the [[Fairchild Republic A-10 Thunderbolt II]].<ref name="Aircraft Cannon" /><ref>{{cite web|url= https://www.442fw.afrc.af.mil/News/story/id/123055695/ |title=GAU-8/A |publisher=442nd Fighter Wing |access-date=26 May 2008 |url-status=live |archive-url= https://web.archive.org/web/20110719063934/http://www.442fw.afrc.af.mil/news/story.asp?id=123055695 |archive-date=19 July 2011 }}</ref> The [[Lockheed AC-130]] gunship (a converted transport) can carry a 105&nbsp;mm howitzer as well as a variety of autocannons ranging up to 40&nbsp;mm.<ref>{{cite web|url= http://www.123exp-warfare.com/t/03804237449/|title=Information on the GAU-8/A| work =The Language of Weaponry|access-date=26 May 2008|archive-url= https://web.archive.org/web/20090619223736/http://www.123exp-warfare.com/t/03804237449/ |archive-date=19 June 2009|url-status=usurped}}</ref> Both are used in the [[close air support]] role.

<gallery>
File:Westland C.O.W. Gun Fighter.jpg | [[Westland C.O.W. Gun Fighter]] with 37&nbsp;mm C.O.W. gun mounted to fire upwards
File:Supermarine Spitfire Mk XVI.jpg| [[Supermarine Spitfire]] with 20&nbsp;mm cannon protruding from the leading edge of the wing
File:GSh-23 on MiG-23.jpg | [[GSh-23]] autocannon mounted on the underside of a [[Mikoyan-Gurevich MiG-23]]
File:GAU-8 in A-10.jpg | The [[GAU-8/A Avenger]] rotary cannon, mounted in a [[Fairchild A-10 Thunderbolt II]]
</gallery>