This article relies largely or entirely on a single source .(November 2017) |
HS.820 | |
---|---|
Type | Autocannon |
Place of origin | Swiss |
Specifications | |
Mass | 66 kg (146 lb) (without ammunition) |
Length | 2,489 mm (98.0 in) |
Barrel length | 1,727 mm (68.0 in) |
Caliber | 20×139mm |
Action | Gas unlocked, delayed blowback |
Rate of fire | 1000 round/min |
Muzzle velocity | 1,050 m/s (3,400 ft/s) |
Effective firing range | 1,500 m (4,900 ft) against aerial targets |
The HS.820 was a 20 mm caliber autocannon developed by Hispano-Suiza primarily for aircraft use, but more widely used in a series of ground-based anti-aircraft guns. After Oerlikon purchased Hispano's armaments division in 1970, the HS.820 became the Oerlikon KAD, supplanting Oerlikon's own KAA and KAB weapons in the process. [1] A US-built model, the M139, saw some use on vehicles.
Developed in the post-World War II era, the HS.820 fired a 20×139 mm round developed from the Swiss 20×139 FMK (and FK 38) as a replacement for their earlier 20×110 mm design of the widely used HS.404. The new round was one of two post-WWII European 20 mm designs, the other being the 20×128 developed by Oerlikon for a similar role. [2] The HS.820's high 1100 m/s muzzle velocity and equally high 1000 round per minute firing rate made it a formidable weapon. Nevertheless, the rapid introduction of even higher performance revolver cannons meant the HS.820 was never as popular in aircraft role as the HS.404 had been.
The weapon was more widely used in a variety of mounts for the anti-aircraft role, especially in naval use. Hispano introduced a number of mountings with a variety of sighting systems, feeds and power traverse. The HS.639-B3 (later known as the GAI-CO1) was a single-gun mounting fed from a 75-round drum, a fairly serious limitation for a gun with such a high rate of fire. Variants included the HS.639-B4 (GAI-CO3) with a 50-round drum mounted on top of the weapon, and the HS.639-B5 (GAI-CO6) that used dual 75-round magazines for longer firing times. The HS 665 was a triple-mount variety using the same drum feeds. The HS.666A (GAI-DO1), developed in the mid-70s, featured two HS.820 with new 120-round box magazines mounted on a shared hydraulically powered platform which could be tied into an associated radar-guided fire-control system. [3]
After Oerlikon purchased Hispano-Suiza, they undertook a renaming exercise for all of their weapons. The HS.820 was then known as the KAD, meaning Kanone, A for 20 mm [lower-alpha 1] and D as the fourth model. Oerlikon's own 20×128 mm became the KAA in the electrically-fired version, and the KAB in the gas-operated version.
The United States produced a slightly modified version of the HS.820 as the M139. It saw use on a number of vehicles, including the US Army's M114 and the Marine Corps Amphibious Assault Vehicle and the ill-fated MICV-65 series of armored vehicles, including on a palletised mount in the cabin of a Bell UH-1 helicopter. [4]
The 20×139 mm round was also widely used in a variety of other weapons, including the Rheinmetall MK 20 Rh 202 and 20 mm modèle F2 gun.
An autocannon, automatic cannon or machine cannon is a fully automatic gun that is capable of rapid-firing large-caliber armour-piercing, explosive or incendiary shells, as opposed to the smaller-caliber kinetic projectiles (bullets) fired by a machine gun. Autocannons have a longer effective range and greater terminal performance than machine guns, due to the use of larger/heavier munitions, 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.
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 engines, trucks and weapons. In 1923, its French luxury car arm became a semi-autonomous partnership with the Spanish parent company. In 1946, the Spanish parent company sold all of its Spanish automotive assets to Enasa, a Spanish state-owned vehicle manufacturer, and the French arm continued as an independent aviation engine and components manufacturer under the Hispano-Suiza name. In 1968, Hispano-Suiza was taken over by the aerospace company Snecma, which is now part of the French Safran Group. An attempt to relaunch the marque was made by the company Hispano Suiza Cars associated with the Peralada Group in 2019 with a fully-electric car.
A revolver cannon is a type of autocannon, commonly used as an aircraft gun. It uses a cylinder with multiple chambers, like those of a revolver handgun, to speed up the loading-firing-ejection cycle. Some examples are also power-driven, to further speed the loading process. Unlike a rotary cannon, a revolver cannon only has a single barrel, so its spun weight is lower. Automatic revolver cannons have been produced by many different manufacturers.
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, particularly during World War II. The cannon is also referred to as Birkigt type 404, after its designer Marc Birkigt and later versions based on British development are known as 20 mm Hispano.
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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 employed by both Allied and Axis forces during World War II. Many versions of the cannon are still used today.
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