Posted on February 15, 2009
How Guns Fire Through Propellors
I always wondered how this worked. So I finally looked it up. Interesting. Makes sense.
Well, they did shoot off their propellors on the first experiments. The first French aircraft designer to try this simply installed a deflector plate on the propellor blade. The logic was that if the blade and the plate was angled enough, the bullet would hit the plate and glance off. This worked—-most of the time.
The Germans inspected a downed French plane and decided to solve the problem. They designed what is called an interrupter gear. This was a gear that was driven off of the aircraft engine. It was rigged so that it would prevent the gun from firing (or interrupt the firing sequence) when the propellor was in front of the gun. This would not allow the gun to fire when the propellor was in its line of fire.
This interrupter gear was a shaft that was geared off of the engine and used a bell crank to convert the input to the machine guns mounted on top of the engine cowl.