A Motorkanone (German: Motor Cannon) was the German designation for an engine-mounted automatic weapon, commonly an auto-cannon, that fired through a hole in the propeller's nose cone on an aircraft, usually a fighter.
This weapon system was not unique to the Luftwaffe. In the Soviet VVS they were referred to as Моторныйпушка (Pronounced: Motornaya Pushka), meaning Motor Canon. The US Army Air Force operated a few fighters with engine-mounted cannons as well, but only in small numbers. The Yugoslav IK-3 fighter featured a motor-canon, but it was rarely used in combat.
Early examples of Motorkanones were shown to have been detrimental to the engine itself. The over-heating of the weapon often damaged the internal workings of the fighter to a point where it became unoperatable. Later examples were more refined and worked well.