The Rheinmetall ''Bordkanone'' 5, or BK-5, was a WWII-era German 50 mm

autocannon An autocannon, automatic cannon or machine cannon is a automatic firearm, fully automatic gun that is capable of rapid-firing large-caliber ( or more) armour-piercing, explosive or incendiary ammunition, incendiary shell (projectile), shells, ...

primarily intended for use against Allied

heavy bombers Heavy bombers are bomber aircraft capable of delivering the largest payload of air-to-ground weaponry (usually bombs) and longest range (takeoff to landing) of their era. Archetypal heavy bombers have therefore usually been among the largest ...

, such as the

United States Army Air Forces The United States Army Air Forces (USAAF or AAF) was the major land-based aerial warfare service component of the United States Army and ''de facto'' aerial warfare service branch of the United States during and immediately after World War II ...

's (USAAF)

Boeing B-17 Flying Fortress The Boeing B-17 Flying Fortress is an American four-engined heavy bomber aircraft developed in the 1930s for the United States Army Air Corps (USAAC). A fast and high-flying bomber, the B-17 dropped more bombs than any other aircraft during ...

. The shells had a high

muzzle velocity Muzzle velocity is the speed of a projectile (bullet, pellet, slug, ball/ shots or shell) with respect to the muzzle at the moment it leaves the end of a gun's barrel (i.e. the muzzle). Firearm muzzle velocities range from approximately t ...

and significant

kinetic energy In physics, the kinetic energy of an object is the form of energy that it possesses due to its motion. In classical mechanics, the kinetic energy of a non-rotating object of mass ''m'' traveling at a speed ''v'' is \fracmv^2.Resnick, Rober ...

, allowing them to be fired from distances outside the range of the bombers' defensive guns. The large

explosive An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An ex ...

content of each shell almost ensured the destruction of any bomber that was hit. Rheinmetall was given a contract in 1943 to adapt the 50 mm 5 cm ''KwK'' 39 tank gun, from the

Panzer III The ''Panzerkampfwagen III (Pz.Kpfw. III)'', commonly known as the Panzer III, was a medium tank developed in the 1930s by Nazi Germany, Germany, and was used extensively in World War II. The official German ordnance designation was List of Sd.K ...

tank, for aerial use in the twin-engined Messerschmitt Me 410 ''Hornisse''

bomber destroyer Bomber destroyers were World War II interceptor aircraft intended to destroy enemy bomber aircraft. Bomber destroyers were typically larger and heavier than general interceptors, designed to mount more powerful armament, and often having twin en ...

. They were installed as ''Umrüst-Bausätze'' ("factory modification") 4 in the Me 410 A-1/U4, and, experimentally, in two

Messerschmitt Me 262 The Messerschmitt Me 262, nicknamed (German for "Swallow") in fighter versions, or ("Storm Bird") in fighter-bomber versions, is a fighter aircraft and fighter-bomber that was designed and produced by the German aircraft manufacturer Messers ...

A-1a/U4 jet fighter prototypes (though these were not used operationally),Ziegler, Mano, "Me 262: Hitler's Jet Plane", Greenhill Books, London, Stackpole Books, Pennsylvania, 2004, , pages 175-182. as the MK 214A cannon of similar caliber was not yet available. An experimental fitment of the BK 5 in an undernose '' Bola'' (or "dustbin") mount on a small number of

Heinkel He 177 The Heinkel He 177 ''Greif'' (Griffin) was a long-range heavy bomber flown by the ''Luftwaffe'' during World War II. The introduction of the He 177 to combat operations was significantly delayed by problems both with the development of its ...

A-3 heavy bombers was part of a small force of the bombers that was given the task of suppressing ''Flak'' on the Eastern Front near

Stalingrad Volgograd,. geographical renaming, formerly Tsaritsyn. (1589–1925) and Stalingrad. (1925–1961), is the largest city and the administrative centre of Volgograd Oblast, Russia. The city lies on the western bank of the Volga, covering an area o ...

early in the winter of 1942–1943 as the A-3/'' Rüstsatz'' 5 version, allegedly nicknamed the ''Stalingradtyp''. The semi-circular magazine of the BK-5 weapon system held 21 rounds. Approximately 300 were produced but saw only limited action, most notably in the Me 410 A-1/U4 aircraft that served with the ''II. Gruppe'' of ''Zerstörergeschwader'' 26 (ZG 26). It was also mounted on the

Junkers Ju 88 The Junkers Ju 88 is a twin-engined multirole combat aircraft designed and produced by the German aircraft manufacturer Junkers Aircraft and Motor Works. It was used extensively during the Second World War by the ''Luftwaffe'' and became one o ...

. Intended for long-range shots, the cannon was given a telescopic sight in addition to the Me 410's standard Revi C12C gunsight, in order to make it easier to take long-range shots from outside a bomber's defensive perimeter, as a "stand-off" weapon system. This proved to be more of a hindrance than a help in the turning fights in which the Me 410s often found themselves when engaged by enemy fighters, as the manoeuvring targets easily escaped from the telescopic sight's small field of view, forcing them to use to normal sights instead. Since the BK 5 was almost useless against such small, nimble targets, the use of the telescopic sight was unnecessary in these situations anyway. As installed in the Me 262, with the muzzle protruding well beyond the nose of the fighter, the cannon was found to be prone to jamming, and if fired at night the

muzzle flash Muzzle flash is the light — both visible and infrared — created by a muzzle blast, which is caused by the sudden release and expansion of high-temperature, high-pressure gases from the muzzle of a firearm during shooting. Both the blast ...

tended to temporarily blind the pilot's night vision. According to the account of the engagements against the USAAF by II./ZG 26 from late February through mid-April 1944, the 53 Me 410 ''Hornisse'' of that ''Zerstörergruppe'' equipped with the BK 5 claimed a total of 129 B-17 Flying Fortress and four

Consolidated B-24 Liberator The Consolidated B-24 Liberator is an American heavy bomber, designed by Consolidated Aircraft of San Diego, California. It was known within the company as the Model 32, and some initial production aircraft were laid down as export models desi ...

heavy bombers, destroyed over five or six interceptions while losing nine of their own Me 410s.

Notes

References

* . {{DEFAULTSORT:Bk 5 Cannon Aircraft artillery Autocannon 50 mm artillery Weapons and ammunition introduced in 1943

See also

Notes

References