Oerlikon 20 mm cannon

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The Oerlikon 20 mm cannon is an autocannon designed by Reinhold Becker in 1914. It is still in use today, after having been used extensively during the Second World War.

Contents 1 History 2 Description 3 References 4 See also

[edit] History

The German Army was the first user, mounting it on its aircraft during the First World War. In 1919, the patent was transferred to Switzerland, and production assumed by Semag, later bought by Werkzeug Maschinenfabrik Oerlikon. Most of the main parties of the Second World War bought licenses to manufacture the cannon themselves.

In 1935, the cannon was adapted by Britain to be used in the Royal Navy for the short-range anti-aircraft role. It was fielded in United States Navy ships starting in 1942, replacing the M2 Machine Gun, which lacked range and firepower. It came to be famous in the naval antiaircraft role, notably against Japanese kamikaze attacks during the Pacific War. The gun was eventually abandoned as a major anti-air weapon due to its lack of stopping power against heavy aircraft, largely superseded by the Bofors 40 mm gun.

It is still in use today on some naval units, theoretically as a last-recourse anti-air weapon, but mainly used for police shots (warning shots or incapaciting shots).

The Polsten gun was based on the Oerlikon.

[edit] Description

The Oerlikon 20 mm cannon is a monotube cannon with a large coil surrounding the barrel. Ammunition feed is by a 60-round drum magazine on the top of the gun. A feature of this weapon was that it requires greased ammunition. A trigger in the right-hand grip controls fire. Used cartridges are ejected from below the breech.

Different nations and services operated a number of mounting types for the same basic gun. In a typical single-barrell naval version, it is free-swinging on a fixed pedestal mounting with a flat armored shield affording some protection for the crew. The cannon is aimed and fired by a gunner using, in its simplest form, a ring-and-bead sight. The gunner is attached to the weapon by a waist-belt and shoulder supports. For this reason, some mountings existed with a height-adjustment feature to compensate for different sized gunners . A "piece chief" designates targets and the feeder changes exhausted magazines. During sustained firing, the magazine must be frequently changed, reducing the effective rate of fire.

[edit] References

• Campbell, John. Naval Weapons of World War Two. Annapolis: Naval Institute Press, 1985.

[edit] See also

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