Oerlikon FF
The FF were a series of 20 mm autocannon 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 20 mm guns to be small and light enough to fit into a fighter aircraft's wing. The FF series served as the inspiration for many 20 mm cannon that would be used in World War II , including the French Hispano-Suiza HS.404 (adopted by the British and US), the German MG FF, and the Japanese Type 99 cannon.
The original design, introduced as the FF, fired a 128 gram 20 mm x 72 mm round with a muzzle velocity of 600 m/s at a cyclic rate of 520 rounds per minute. The gun weighed only 24 kg. The low muzzle velocity was of some concern, so additional developments led to the 30 kg FF L using a longer 20 mm x 101 mm round which gave 750 m/s, and the 39 kg FF S firing a 20 mm x 110 mm round at 830 m/s at a slightly slower 470 rounds per minute. The original guns became known as the FF F from this point on.
The MG FF, like all pre-World War II Oerlikon guns, was an API blowback recoil-operated weapon and embodies certain features which are not found in other automatic cannons. The most important of these are: 1) a barrel which does not recoil; 2) a heavy breechblock which is never locked against the breech and actually moves forward when the gun is fired.
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 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 designed an entirely new gas-operated cannon with a locked bolt, the HS.404, which became one of the best 20 mm weapons of the war. Ikaria in Germany started production of the FF F with a slightly more powerful 20 mm x 80 mm round as the MG FF, but later introduced a new Minengeschoss round made from pressed instead of milled brass that had considerably thinner walls and therefore carried more explosive. The resulting MG FF/M was a common weapon until about 1941. Starting in late 1940 these were replaced by the Mauser MG 151/20, a very different weapon.
References
- 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 Departement of the Navy.
See also
- Oerlikon 20 mm cannon - a widely used 20 mm calibre Oerlikon autocannon
