Introduction and Specifications
The 27mm BK27 revolver cannon was developed by Mauser in early 1971. Its automatic mechanism operates using the energy from diverted gases. The gun’s drum holds 5 rounds, and ammunition feeding can be configured for either the left or right side.
The cannon has an overall length of 2310 mm and a barrel length of 1700 mm, weighing 100 kg. When engaging ground targets, it fires at a rate of 1000 rounds/min, increasing to 1700 rounds/min for aerial targets. It reaches its maximum rate of fire in just 20 milliseconds.
Ammunition and Performance
The BK27 uses “27 x 145B” cartridges, each weighing 516 g with a 260 g projectile. High-explosive rounds contain 22 g of explosive. Projectiles achieve an initial velocity of 1050 m/s and feature plastic driving bands.
The cannon’s ammunition range includes armor-piercing (AP), armor-piercing high-explosive (APHE), APHE with self-destruct fuze, high-explosive (HE), and HE with self-destruct fuze projectiles. All projectiles share a consistent weight and contain an identical 84 g propellant charge.
Armor-piercing rounds also possess a potent incendiary effect, achieved by zirconium located in the projectile’s nose and around the base of the penetrator. Upon impact, the zirconium fragments, heated to white-hot temperatures, maintain high heat for several seconds, creating ignition points and ensuring the incendiary action.
Aircraft Integration and Future Development
Two 27mm BK27 cannons are installed on Tornado fighter-bombers, each supplied with 125 rounds per gun. The initial order for the BK27 was placed in 1976. By late 1985, Mauser and its partners RO (UK) and Breda (Italy) had supplied over 2000 cannons for Tornado aircraft in service with the air forces of these nations.
In the fighter-bomber variant of the Tornado, two cannons are positioned internally in the lower fuselage, each with 180 rounds. The interceptor variant uses a single cannon located in the lower front fuselage. For the German Alpha Jet, a single BK27 cannon is housed in an external gun pod mounted under the fuselage.
Since the early 1990s, Mauser has been developing a linkless ammunition feed system for the BK27 cannon, intended for the prospective EFA (Eurofighter) fighter. This system aims to reduce the volume and overall weight of the aircraft gun installation (or allow for increased ammunition capacity), enhance operational reliability, and facilitate faster reloading.