In the early days of military airplanes, attacks were limited to dropping bricks or shooting pistols out of the cockpit, since you couldn’t exactly risk tearing up your propellors by mounting guns in their way. But as a solution, this 11.8-liter WWI-era Hispano-Suiza engine has a 37mm cannon mounted directly between its cylinder banks.
The flaw of the setup was that the Puteaux cannon was only semi-automatic, with the pilot having to close and lock the breech with his fingers after ever shot. While the “motor-cannon” did see combat, it was never very popular.
But what really killed this Hispano-Suiza engine was that it was fast becoming obsolete. In 1917, the Allies began to use something called a synchronization gear. Connecting an independent machine gun to the engine’s crankshaft using either gears or hydraulics, the synchronization gear, well, synchronized, the timing of the machine gun fire with the arc of the propeller. A synchronized machine gun fired between the propeller blades, completely superseding the Hispano-Suiza’s motor-cannon. Though Hispano-Suiza had been working on a prototype motor-canon fitted with a fully-automatic machine gun, the whole concept of a gun mounted inside an engine was history.
Submitted by Delsyd