how did propellor warplanes shoot their machine guns through the propellor?
In: 2413
Oh this is actually very cool.
They would time the gun to a cam on the propellor axle, there was a little bump on the axle that would push the mechanism to fire the gun, but it was placed on the axle in a place that it would only push when the propellor was out of the way of the gun. This technique is used very often still in modern engines to time things properly.
This also kinda meant firing rate was dependent on the speed of the propellor turning.
The machine gun and propeller were connected by a [special gear](https://en.wikipedia.org/wiki/Synchronization_gear). The gear would only let the gun fire so that the bullets would pass between the propeller blades.
This became possible after the invention and implementation of the interruptor gear, also called a sync gear. It timed the machine gun rate of fire with the propeller so that it did not fire bullets when the propeller blade was directly in front of the barrel of the gun.
The very first ones with fixed guns didn’t. They just added armour to the propeller, and any rounds that hit it just bounced away. It wasn’t remotely perfect, it added weight, and it wasn’t unknown for a pilot to effectively shoot their own propeller off.
In 1915 that changed, when Fokker came up with an “interrupter gear” mechanism to briefly prevent the guns firing whenever the propshaft was in certain positions (basically just a cam and a lever linkage, I believe). Every time the cam hit the linkage, it briefly blocked the gun from firing. Then all you had to do was set the cam in the right position. (Edit sp.)
Edit 2: Nope, that was the first, pre-war design. See below.
[deleted]
The trigger inside the cockpit was not directly pulling the trigger on the machine guns, instead it allowed the machine guns to fire by allowing the trigger mechanism to operate through a synchronisation mechanism that was not much unlike the camshafts which operate valves in engines. Camshafts with cam lobes that were timed to the engine rpm would only allow the machine guns to fire when the propeller blades were not directly in front of the barrels. This timed when the machine guns fired, and their overall fire rate, so that they could shoot through the propeller. I know propellers are moving very fast, but so are bullets so it was possible.
[removed]
ELI5: Imagine that they took a propeller shaft with two propeller blades. Then they put a bumps on the shaft a 90 degrees to the blades. So imagine you are looking at a clock that is set to 6 0’clock, so that there was a blade at 6 and a blade at twelve. Then you put a bump at 3 O’clock and 9 O’clock. Imagine that the bump pushes the trigger of the gun. So you spin the shaft and the gun’s trigger only fires when the bump touches it, but the bumps are out of the way of the blades because the bump are physically aligned where there are no blades.
So now the gun is timed to fire between the blades.
See here :
For a video of the mechanism
[https://youtu.be/faZiS1CYZs0](https://youtu.be/faZiS1CYZs0)
See here for a much more interesting video [https://youtu.be/zUS6dB5Ro2w](https://youtu.be/zUS6dB5Ro2w)
As others have already mentioned the timing mechanism in the engine I wanna throw another solve some engineers realized between the wars
Since the drive in the inline engines, used more by 1930’s, didn’t need to be a solid axel to turn the propeller designer found that through a little engineering they could make an empty cylinder wide enough to fit a canon through the engine itself
This was used extensively be the Germans during WW2 most prevalent on the famous BF-109 (not ME-109 you dirty yanks!!)
The gun was harder to maintain but it gave a big cannon a solid centerline aim without sorting to using an engine on each side
Engineers(or other people in the know) can correct if my description of the internals are off
It was called a fokker interrupter gear and it synchronized the firing of the gun with the passing of the propellor blade. When the trigger was squeezed, bullets would only be fired when they would pass between the blades.
Latest Answers