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The ShVAK ( ru , ШВАК: Шпитальный-Владимиров Авиационный Крупнокалиберный, Shpitalnyi-Vladimirov Aviatsionnyi Krupnokalibernyi, "Shpitalny-Vladimirov Aviation Large-calibre") was a
20 mm 20 mm caliber is a specific size of popular autocannon ammunition. It is typically used to distinguish smaller-caliber weapons, commonly called "guns", from larger-caliber "cannons" (e.g. machine gun vs. autocannon). All 20 mm cartridges ha ...
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 (bulle ...
used by the
Soviet Union The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, ...
during
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 World War II by country, vast majority of the world's countries—including all of the great power ...
. It was designed by Boris Shpitalniy and Semyon Vladimirov and entered production in 1936. ShVAK were installed in many models of Soviet aircraft. The TNSh was a version of the gun produced for light tanks ( ru , ТНШ: Tankovyi Nudel’man-Shpitalnyi). ShVAK shares the name with its 12.7 mm
heavy machine gun A heavy machine gun (HMG) is significantly larger than light, medium or general-purpose machine guns. HMGs are typically too heavy to be man-portable (carried by one person) and require mounting onto a weapons platform to be operably stable o ...
predecessor.


Development and production


12.7x108mm ShVAK

The development of the 12.7 mm ShVAK was in response to a Soviet government decree passed on 9 February 1931, directing domestic manufacturers to produce an aircraft machine gun for the
12.7×108mm The 12.7×108mm cartridge is a 12.7 mm heavy machine gun and anti-materiel rifle Cartridge (firearms), cartridge used by the former Soviet Union, the former Warsaw Pact countries, modern Russia, China and other countries. It was invented in 1934 ...
cartridge that had been introduced a couple of years prior for the DK machine gun. Tula designer S.V. Vladimirov answered the call by producing basically an enlarged version of the
ShKAS The ShKAS (Shpitalny-Komaritski Aviatsionny Skorostrelny, Shpitalny-Komaritski rapid fire for aircraft; Russian: ШКАС - Шпитального-Комарицкого Авиационный Скорострельный) is a 7.62 mm calibre ...
, with a 1246 mm long barrel and a total length of 1726 mm. The first prototype was ready for trials on May 28, 1932. The testing process was fairly drawn out, but the 12.7 mm ShVAK was nominally adopted into service in 1934.Shirokorad, pp. 74-75 Series production officially started in 1935 at the INZ-2 factory in Kovrov, but production soon fell well behind schedule because the ShVAK receiver was fairly complex to manufacture. According to Soviet records, out of the 410 12.7 mm ShVAKs planned for aircraft in 1935, only 86 were completed; for the tank version, 40 had been planned but only 6 were delivered that same year. A 1952 Western intelligence report indicates that only "a few" ShVAKs were produced in the 12.7 mm caliber. A further problem complicating the adoption of the gun was that the 12.7 mm ShVAK ended up not using the 12.7×108mm rimless cartridge used by the DK machine gun, but rather—because it was an adaptation of the ShKAS mechanism—it required its own rimmed 12.7 mm cases.Борцов А.Ю. "Пятилинейный", ''Мастер-ружье'
issue 110, May 2006
pp. 56-62
Production of the rimmed 12.7 mm ammunition ceased in 1939, when it was decided that the Berezin UB was preferable because it could share ammunition with the DShK.


20×99mmR ShVAK

The 20 mm ShVAK was designed sometime between 1935 and 1936 and series production began in 1936. A few months later, production of the 12.7 mm version ceased.Shirokorad, p. 75 Similarly to its predecessors, the 20 mm ShVAK was a gas-operated gun, belt-fed by disintegrating link ammunition. Depending on the intended mount, the ShVAKs were marked with "MP" for the tank version (total gun length 2122 mm; weight 44.5 kg), "KP" for the wing-mounted version (1679 mm total length; 40 kg), "TP" for flexible mounts (1726  mm length; 42 kg), and "SP" for synchronized installations. The "bird-cage" feed system in the 20 mm ShVAK was an improved version of the ShKAS. It could hold 11 rounds and had an even smoother operation. As with the ShKAS, the purpose of the feed cage was to gradually delink the rounds, avoiding any belt lurch. The Berthier-type gas regulator had four holes (of 3.5, 4, 4.5, and 6 mm) allowing for different rates of fire to be selected. The most significant design difference from the ShKAS was that the gas cylinder was moved under the barrel in the ShVAK, giving it a more compact assembly.Chinn, p. 85 The end of the barrel was threaded, and this thread was used to screw on a blast-reduction tube of a length that depended on the installation requirements:Chinn, p. 82 The 1952 Western intelligence report said of the 20 mm ShVAK: "in relation to its power, the gun is very light and extremely compact" and that it "has a range comparable to our M3 cannon, although their short barrel version is 16 pounds lighter". It was however considered "relatively difficult to produce" in American factories, because it was constructed from relatively soft parts (not heat-treated) that were then filed down. This choice of materials was assumed to be motivated by the desire to allow parts to "deform and bend well in advance of fracture" enabling a safer operation at a high rate of fire, but having the tradeoff of shorter overall lifespan of the gun. Soviet archives indicate the 20-mm ShVAK was produced in large numbers during World War II:Shirokorad, p. 77 * 1942 — 34,601 produced * 1943 — 26,499 * 1944 — 25,633 * 1945 — 13,433 * 1946 — 754 After the war, the ShVAK was supplanted by the Berezin B-20, which offered similar performance but weighed significantly less.


Installations

Three
Polikarpov I-16 The Polikarpov I-16 (russian: Поликарпов И-16) is a Soviet single-engine single-seat fighter aircraft of revolutionary design; it was the world's first low-wing cantilever monoplane fighter with retractable landing gear to attain o ...
aircraft, all produced in January 1939, were armed with the propeller-synchronized version of the 12.7 mm ShVAK; this short series was given the I-16 Type 16 designation. The three fighter planes successfully passed the factory trials and were delivered to the VVS for military trials. The cancelled Yatsenko I-28 was also planned to use the 12.7 mm ShVAK in a synchronized pair, but the few prototypes which flew in the summer of 1939 did so without armament because a synchronizer for their engine had not been developed. The 20 mm ShVAK was installed in the wings, in the nose, or in a synchronized mounting in the following fighters:
Polikarpov I-153 The Polikarpov I-153 ''Chaika'' (Russian ''Чайка'', "Seagull") was a late 1930s Soviet biplane fighter. Developed as an advanced version of the I-15 with a retractable undercarriage, the I-153 fought in the Soviet-Japanese combats in Mon ...
P and
I-16 I16 may refer to: * Interstate 16, an interstate highway in the U.S. state of Georgia * Polikarpov I-16, a Soviet fighter aircraft introduced in the 1930s * Halland Regiment * , a Japanese Type C submarine * i16, a name for the 16-bit signed integ ...
,
Mikoyan-Gurevich MiG-3 The Mikoyan-Gurevich MiG-3 (russian: Микоян и Гуревич МиГ-3) was a Soviet fighter-interceptor used during World War II. It was a development of the MiG-1 by the OKO (opytno-konstruktorskij otdel — Experimental Design Departme ...
, Yakovlev Yak-1, Yak-3, Yak-7, and Yak-9, LaGG-3, Lavochkin La-5 and La-7, the Petlyakov Pe-3 night fighter and on Soviet-modified
Hawker Hurricane The Hawker Hurricane is a British single-seat fighter aircraft of the 1930s–40s which was designed and predominantly built by Hawker Aircraft Ltd. for service with the Royal Air Force (RAF). It was overshadowed in the public consciousness b ...
aircraft. It was also installed on the wings of the Tupolev Tu-2 bomber and some ground attack versions of the
Petlyakov Pe-2 The Petlyakov Pe-2 (russian: Петляков Пе-2) was a Soviet twin-engine dive bomber used during World War II. One of the outstanding tactical attack aircraft of the war,Ethell 1996, p. 152. it also proved successful as a heavy fighter, as ...
bomber also had it installed in a fixed mounting. Some early versions of the
Ilyushin Il-2 The Ilyushin Il-2 ( Russian: Илью́шин Ил-2) is a ground-attack plane that was produced by the Soviet Union in large numbers during the Second World War. The word ''shturmovík'' ( Cyrillic: штурмовик), the generic Russian ter ...
ground attack aircraft also carried it, but superseded in that aircraft by the 23 mm Volkov-Yartsev VYa-23. The flexible-mount ShVAK was used in the Petlyakov Pe-8 and Yermolayev Yer-2 bombers. The tank version was installed on the T-38 and T-60 light tanks.


Ammunition

ShVAK ammunition consisted of a mix of fragmentation-incendiary and armor-piercing-incendiary rounds. There were problems with ammunition development as well. There were cases of premature cook-off of the ammunition in the barrel. The problem was first addressed in 1936 by changing the fuse from the MG-3 model to the MG-201 model, but the problem was not eliminated until the introduction of the K-6 fuse in 1938, which reliably prevented projectiles from arming until they were 30 to 50 cm out of the barrel.Shirokorad, pp. 76-77


See also

* Berezin B-20 * Volkov-Yartsev VYa-23 * Revolver cannon *
List of firearms This is an extensive list of small arms—including pistols, revolvers, submachine guns, shotguns, battle rifles, assault rifles, sniper rifles, machine guns, personal defense weapons, carbines, designated marksman rifles, flamethrowe ...
*
List of Russian weaponry The following is a list of modern Russian small arms and light weapons which were in service in 2016: Handguns Revolvers Pistols Special purpose Submachine guns Special purpose Shotguns Rifles Bolt-action Semi-a ...
* List of common World War II weapons


References

* Широкорад А.Б. (2001) ''История авиационного вооружения'' Харвест (Shirokorad A.B. (2001) ''Istorya aviatsionnogo vooruzhenia'' Harvest. ) (''History of aircraft armament'') * * Chinn, George M. The Machine Gun, Vol II, Part VII. US Department of the Navy, 1952


External links


20mm TNSh Tank Gun
at battlefield.ru

* http://www.municion.org/20mm/20x99R.htm {{DEFAULTSORT:Shvak Cannon Autocannons of the Soviet Union Aircraft guns of the Soviet Union 20 mm artillery KBP Instrument Design Bureau products Military equipment introduced in the 1930s