Mauser BK-27

The BK 27 (also BK27 or BK-27) (German abbreviation for Bordkanone, "on-board cannon") is a 27 mm caliber revolver cannon manufactured by Mauser (now part of Rheinmetall) of Germany. It was developed in the late 1960s for the MRCA (Multi Role Combat Aircraft) program that ultimately became the Panavia Tornado.

The BK 27 is a gas-operated cannon firing a series of 27×145 mm cartridges with a typical projectile weight of 260 g (9.2 oz), and a total weight for the complete round of 516 g (1.14 lb). Most models use a linked feed system for the ammunition; however, the Eurofighter Typhoon makes use of a specially developed variant of the BK 27 that uses a linkless feed system instead, which is intended to improve reliability.

Design
The Mauser BK 27 is used in the Panavia Tornado, the Alpha Jet, the JAS 39 Gripen, and the Eurofighter Typhoon. At one time Lockheed Martin was considering a licensed-built version for the F-35 Lightning II.

Rheinmetall has also developed remote-controlled naval versions, the MN 27 GS and the MLG 27 fully automatic naval guns, which are installed on many ships of the German Navy. Ninety-nine MLG 27s have been ordered by the German Navy so far. The cannon is a single-barrel, high-performance, breech-cylinder gun operated by a fully automatic, electrically fired, gas-operated system at a selective rate of 1000 or 1700 rounds per minute(+/− 100 rpm). The Mauser BK 27 utilizes pyrotechnic cocking charges to cycle the action.

The gun mainly fires mine shells as these have the best effect against aircraft, there are also several types of armor piercing shells like the frangible armour piercing shell named Fap 27 mm x 145 mm ammunition/peb327 (DM103).

Operational history
In his book Typhoon, former RAF pilot Mike Sutton reported his 27 mm cannon jamming during a strafing run in Syria, against ISIS targets, while supporting Allied ground units. According to his book, the Typhoon was to be built, originally, without an internal gun, like the F-4 Phantom and the Harrier jump jet. However while a decision was made to install an internal gun but this led to "manufacturing issues". Sutton claimed that during his strafing run the gun jammed after "twenty-six rounds", the HUD showing "GUN FAIL". During the debrief this problem was well known to both the pilots and ground crews. One pilot told Sutton: "They said that issue had been fixed", to which Sutton replied "Exactly. We've been here before."

Current operators

 * Algerian Navy
 * Austrian Air Force: Eurofighter
 * Brazilian Air Force: Gripen
 * Royal Brunei Navy
 * Cameroon Air Force: Alpha Jet
 * Discovery Air Defence Services: Alpha Jet
 * Czech Air Force: Gripen
 * German Air Force: Panavia Tornado, Eurofighter
 * German Navy: MLG 27 remote-controlled mount
 * Hungarian Air Force: Gripen
 * Italian Air Force: Panavia Tornado, Eurofighter
 * Royal Saudi Air Force: Panavia Tornado, Eurofighter
 * South African Air Force: Gripen
 * Spanish Air Force: Eurofighter
 * Swedish Air Force (under the designation 27 mm automatkanon m/85, 27 mm akan m/85): Gripen
 * Royal Thai Air Force: Alpha Jet, Gripen
 * United Arab Emirates Navy
 * Royal Air Force: Eurofighter
 * Hungarian Air Force: Gripen
 * Italian Air Force: Panavia Tornado, Eurofighter
 * Royal Saudi Air Force: Panavia Tornado, Eurofighter
 * South African Air Force: Gripen
 * Spanish Air Force: Eurofighter
 * Swedish Air Force (under the designation 27 mm automatkanon m/85, 27 mm akan m/85): Gripen
 * Royal Thai Air Force: Alpha Jet, Gripen
 * United Arab Emirates Navy
 * Royal Air Force: Eurofighter
 * Swedish Air Force (under the designation 27 mm automatkanon m/85, 27 mm akan m/85): Gripen
 * Royal Thai Air Force: Alpha Jet, Gripen
 * United Arab Emirates Navy
 * Royal Air Force: Eurofighter
 * United Arab Emirates Navy
 * Royal Air Force: Eurofighter
 * Royal Air Force: Eurofighter
 * Royal Air Force: Eurofighter

Former operators

 * Portuguese Air Force: Alpha Jet
 * Royal Air Force: Panavia Tornado
 * QinetiQ: Alpha Jet
 * Royal Air Force: Panavia Tornado
 * QinetiQ: Alpha Jet

Specifications


Data from Jane's Information Group
 * Type: single-barrel, five chamber revolver cannon
 * Caliber: 27 mm × 145 (1.063 in)
 * Operation: revolver
 * Length: 2.31 m (7 ft 7 in)
 * Weight (complete): 100 kg (220 lb)
 * Rate of fire: 1,000-1,700 rpm selectable (+/− 100 rpm)
 * Muzzle velocity: 1,100 m/s (3,600 ft/s)
 * Muzzle energy: ≈157,300 Joules
 * Projectile weight: 260 g (9.2 oz)