An engine gun, or engine cannon (from German : Motorkanone, "motor cannon"), is an aircraft gun mounted behind and through the cylinder block of an inline aircraft engine (most often a V engine) with a reduction drive that displaces the propeller axle to be in line with the gun so that gunfire is allowed through the propeller hub. This allows for nose-mounted weaponry on aircraft without the need for synchronization gear while also permitting higher calibers for nose-mounted weaponry, which otherwise would be hard to adapt for synchronization gear. [1]
The first time this was done was during World War I when the French modified the Hispano-Suiza 8 engine to be able to install a 37 mm autocannon. [2] The concept was used widely before the Jet Age.
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