In WWI, Fighter Planes and Machine Guns Were the Perfect Team

Innovative design ensured the two worked together seamlessly.

AVIATOR SEATED IN HIS PLANE BEHIND HIS MACHINE GUN, WHICH IS OPERATED IN HARMONY WITH THE MOVEMENT OF THE PROPELLER SO THAT THE LATTER AVOIDS THE BULLETS
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  • Photo Credit: Library of Congress

There was a lot of new technology brought to the battlefield during World War I. Two of those were used in tandem—and somehow managed to perfectly complement each other. It was the fighter plane and the machine gun, mounted perfectly for the pilot's use, without shooting up the propeller that kept the bird aloft.

Was the gun designed to fire through the propeller, or the propeller designed to be used with the machine gun? Yes.

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The system worked because of its synchronization gear, which kept the gun from firing when the propeller would be hit by the bullet. While airborne the propeller would actually be spinning five times as fast as the weapon could fire, so there was little margin of error. The problem was solved by the addition of a gear-like disc on the propeller, which only allowed the gun to fire in between the blades' rotation.

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Often called an "interrupter," the disc did not actually interrupt the firing of the weapon. It merely allowed it to fire semiautomatically instead of at an even pace. When the propller spun around to a certain position, it would allow the weapon's firing mechanism to fully cycle and fire a round. Usually, when the round was supposed to be interrupted, the weapon was actually just in the process of cycling.

Put another way, pulling the trigger would essentially connect the weapon to the propeller, and the propeller would actually be firing the gun. Letting the trigger go would disconnect the weapon from the propeller.

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Later versions, such as the Kauper interrupter used on the Sopwith Camel, allowed for multiple machine guns at different rates of fire. The interrupter was a welcome change from the early days of combat aviation, where propellers were sometimes metal plated just in case mechanically uncoordinated rounds hit the propeller, causing the bullet to ricochet.