The FF were a series of 20mm

autocannon An autocannon, automatic cannon or machine cannon is a fully automatic gun that is capable of rapid-firing large-caliber ( or more) armour-piercing, explosive or incendiary shells, as opposed to the smaller-caliber kinetic projectiles (bull ...

introduced by Oerlikon in the late 1920s. The name comes from the German term ''Flügel Fest'', meaning ''wing mounted, fixed'', being one of the first 20mm guns to be small and light enough to fit into a

fighter aircraft Fighter aircraft are fixed-wing military aircraft designed primarily for air-to-air combat. In military conflict, the role of fighter aircraft is to establish air superiority of the battlespace. Domination of the airspace above a battlefield ...

's wing. The FF series inspired many 20mm cannon used in

World War II 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 ...

, including the

Hispano-Suiza HS.404 The HS.404 is an autocannon originally designed and produced by Spanish/French company Hispano-Suiza in the mid-1930s. It was widely used as an aircraft, naval and land-based weapon by French, British, American and other military services, par ...

(adopted by the French, British and U.S. forces), the German

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 ...

, and the Japanese

IJNAS The was the air arm of the Imperial Japanese Navy (IJN). The organization was responsible for the operation of naval aircraft and the conduct of aerial warfare in the Pacific War. The Japanese military acquired their first aircraft in 1910 a ...

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 ...

Design

The basic design was based on the original

Oerlikon 20 mm cannon 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 ...

, in turn based on 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 Becker 20 mm cannon of

World War I 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 ...

. In the post-war period, Oerlikon had developed the original design to produce three autocannons with increasingly powerful rounds; the original model, later known as the "F", used the Becker 20x70mm round, the newer "L" model used a 20x100 round, and finally the "S" model used a 20x110. All of these weapons used the

API blowback Blowback is a system of operation for self-loading firearms that obtains energy from the motion of the cartridge case as it is pushed to the rear by expanding gas created by the ignition of the propellant charge. Several blowback systems exist wi ...

operational principle. In 1935 Oerlikon started development of versions suitable for use as wing-mounted guns. In addition to various changes needed for remote firing and cartidge ejection, the new series focused primarily on rate-of-fire. The original "FF" used a slightly upgraded 128 gram 20x72mm round with a muzzle velocity of at a cyclic rate of 520 rounds per minute, almost double that of the original F and AF models. The gun weighed only . Similar improvements led to the FF L using a longer 20x101mm round which gave , and the FF S firing a 20x110mm round at at a slightly slower 470 rounds per minute. The original guns became known as the FF F from this point on. The FF F was licensed by the Japanese and produced as the Type 99-1, along with the FF L as the Type 99-2.

Hispano-Suiza Hispano-Suiza () is a Spanish automotive–engineering company. It was founded in 1904 by Marc Birkigt and Damian Mateu as an automobile manufacturer and eventually had several factories in Spain and France that produced luxury cars, aircraft en ...

built the FF S as the HS.7, and slightly improved HS.9. This design was later abandoned by Hispano-Suiza. In the 1930s,

Marc Birkigt Marc Birkigt (8 March 1878, Geneva – 15 March 1953, Versoix) was a Swiss engineer, automotive and aviation pioneer, and co-founder of Hispano-Suiza in 1904. He lived in Barcelona, Spain when he was hired by Emilio de la Cuadra in 1898 to wor ...

designed an entirely new

gas-operated Gas-operation is a system of operation used to provide energy to operate locked breech, autoloading firearms. In gas-operation, a portion of high-pressure gas from the cartridge being fired is used to power a mechanism to dispose of the spent ...

cannon with a locked bolt, the HS.404, which became one of the best 20 mm weapons of the war.

Ikaria Werke Icaria, also spelled Ikaria ( el, Ικαρία), is a Greek island in the Aegean Sea, 10 nautical miles (19 km) southwest of Samos. According to tradition, it derives its name from Icarus, the son of Daedalus in Greek mythology, who was b ...

in Germany started production of the FF F with a slightly more powerful 20x80mm round as the

, but later introduced a new

mine shell A mine shell (from the German term ''Minengeschoß'', "mine shot"), also known as High-Explosive, High-Capacity (HEHC) in British military nomenclature, is a military explosive shell type characterized by thin (usually steel) shell walls and a cor ...

round which was lighter and improved velocity. The resulting MG FF/M was a common weapon until about 1944. Starting in late 1940 these were replaced by the very different Mauser MG 151/15 and Mauser MG 151/20 autocannon, respectively of 15mm (early) and 20mm calibre (primary production).

References

Bibliography

*Heller, Daniel. ''Zwischen Unternehmertum, Politik und Überleben. Emil G. Bührle und die Werkzeugmaschinenfabrik Oerlikon, Bührle & Co 1924–1945.'' Verlag Huber: Frauenfeld 2002. *
The Machine Gun, History, Evolution, and Development of Manual, Automatic, and Airborne Repeating Weapons
'' 1951 by George M. Chinn, Lieutenant Colonel USMC. Prepared for the Bureau of Ordnance Department of the Navy. {{DEFAULTSORT:Oerlikon Ff Oerlikon-Contraves Aircraft guns Autocannon World War II weapons 20 mm artillery