How did the machine gun on a biplane fire through the propeller arc?

Question

I've seen WWI-era biplanes where the machine gun was mounted on the nose and fired through the propeller arc. It would seem like there would be a chance that a bullet would hit a propeller blade.

How did the machine gun on a biplane fire through the propeller arc without hitting the blade?

Answer 1

There was a mechanical interupter that would not allow the gun to fire as the prop crossed the muzzle of the gun. It would fire a number of rounds, stop as the blade passed, fire a few more, stop as the blade passed and so on.

Answer 2

Biplane Propeller

Answer 3

French Pilot Roland Garros first solved this problem by attaching metal deflectors to the propeller of his plane, this solution worked but was dangerous because bullets could be deflected back at the pilot, and this solution didn't work at all on german planes because they used steel jacketed bullets which would shred the deflectors and propeller, another solution that was used was mounting the gun on the wing, which eventually became the way guns were mounted from WWII to until the propeller driven fightercraft were replaced by jet powered fighters, another solution was mounting the engine and propeller at the rear of the plane, commonly known as a pusher prop, however this solution was uncommon because pusher planes were not mauverable enough to dogfight making them easy prey for other fighters
Then fokker introduced the synchronizer gear on their planes which used a cam mounted on the propeller shaft to fire the gun which allowed the plane to fire through the propeller arc without hitting the propeller blades, this temporarily gave germany the advantage in the air, however it didn't take too long for the allies to use this technology, and germany was also facing problems importing resources after the allies cut off their supply lines and turned the tide of the war.

Answer 4

the germans invented the interupter gear. everytime the propeller spun in front of the gun, the gear would push up on the trigger system, causing the gun to stop firing everytime a blade was in front of gun. the delay was so fast its not even noticable. also some propellers were reinforced with steel but bullets would richochet and hit pilot. the interupter gear was on connected to the cam shaft so it was timed with the propeller. i could really get into details about the entire system but thats it in a nutshell. this is alway why alot of ww2 fighters had guns in the wings.

Answer 5

They had the gun timed to fire so that it would not hit the prop through a mechanical gearbox. Some of the early planes did not have the syncronization system, and shot their props off. They also tried metal shielding on the props, but that was not effective either.

Answer 6

Mechanical interrupter that wouldn't allow the gun to shoot with a blade in line with it, invented by the Germans. For a thread discussing this, see http://www.ww2aircraft.net/forum/old-threads/firing-through-propeller-arc-181.html

Answer 7

At first the Metal on the Back was tried, did not work well, then an Synchronization or interrupter gearing was used to allow fire and retard fire as the prop crossed the the bullets path.

Answer 8

The crank had a timing mark that which would only allow the gun to fire in between the props

Answer 9

NO No No The speed or the velocity was calculated to determine what degree to fire the firing mechanism was run of of the engined crank shaft, And the propeller was in a fixed degrees fixed position thus for the firing always stays constant while varying rpm's.

Answer 10

thers a mechanical system that stops the machine gun firing when the prop gets in the way , then releases when the props gotten out of the way kinda like a car engine timing belt. its so fast u cant even se it happening