WW1 planes - firing through a propeller

[Chris]

I talked to some classmates today and we were wondering how they managed to fire through the propeller on old WW1 and maybe WW2 planes. I once heared something about a chain connected to the engine and regulating the ROF or whatever.

I guess this board is the right place to ask this ;)

http://www.nhmgs.org/gallery/gallery_images/dogfight.jpg

Edit:
found something, I just used the wrong words before, damn ;)

There is no mystery about a machine gun firing through a propeller without hitting the blades. Nearly everyone understands the principle by which the valves of a gasoline motor are timed so as to open and close at a given point in the revolution of the engine. In the same way a machine hgun may be timed to shoot. On the end of the cam shaft of the motor is plaved an additional cam. Next to this is a rod connected with the breech block of the gun. When the gun is not being fired the rod is held away from the cam by a spring. pressing the trigger brings the two in contact , and each time the cam revolves it strikes the rod which in turn trips the hammer of the gun and causes it to fire. The cam is regulated so that it comes in contact with the rod just as each blade has passed the muzzle of the gun which can therefore fire at this time only. The engine revolves at least 1,000 turns per minute and as there are two chances for the gun to fire for each revolution, this would allow the gun to fire 2,000 shots per minute. The rate of fire of a machine gun varies from about 400 to 1,000 shots per minute according to the type of gun and the way in which it is rigged. The gun therefore has many more oppurtunities to fire between the blades of the propeller than its rate of fire will permit it to make use of. Consequently, the gun can work at full speed regardless of ordinary variations in the number of revolutions of the engine.

[Heinzi]

On the planes the guns was synchronized with the engine.

Other, older planes had fixed mgs on the upper wing. Of course it was not so easy to aim with that setup.

[Freibier]

Germans had it first

[Hydro]

Some earlier designs even had the gun shooting straight through the propeller without the "Interrupter gear" to sync the gun and the engine, and the propellor was fitted with deflectors to deflect the rounds that did hit.

[CoRe]

Some earlier designs even had the gun shooting straight through the propeller without the "Interrupter gear" to sync the gun and the engine, and the propellor was fitted with deflectors to deflect the rounds that did hit.

You sure about that? Most of the early props were made of wood so I think a bullet would cause the fast rotating device to crack...not to mention deflected bullets flaying all around.

[LazyLob]

You sure about that? Most of the early props were made of wood so I think a bullet would cause the fast rotating device to crack...not to mention deflected bullets flaying all around.

He's quite correct.

[LazyLob]

Germans had it first

Fokker off.

[Nansouty]

You sure about that? Most of the early props were made of wood so I think a bullet would cause the fast rotating device to crack...not to mention deflected bullets flaying all around.

The Morane Saulnier L used this system. It was flown by Roland Garros. But this was for a very short time, before synchronized MGs were invented.

http://en.wikipedia.org/wiki/Morane_Saulnier

BTW, Chris, beautiful minis and terrain! Are they yours?

[mas36]

The Morane Saulnier L used this system. It was flown by Roland Garros. But this was for a very short time, before synchronized MGs were invented.

http://en.wikipedia.org/wiki/Morane_Saulnier

BTW, Chris, beautiful minis and terrain! Are they yours?


If I'm not mistaken, French ace Roland Garros used deflector blades on the props at the point where the bullets would have hit. Extremely crude, but apparently it worked ok and he managed to shoot down several German aircraft. Problem was those bullets which could potentially be deflected back towards the pilot.

[Chris]

BTW, Chris, beautiful minis and terrain! Are they yours?

thats where I plan how to take over the world ;)
no its not mine, found it online and thought it would look nice in here, I am a fan of all kind of models;cars, planes, tanks, ships, lingerine, trains

[CoRe]

The Morane Saulnier L used this system. It was flown by Roland Garros. But this was for a very short time, before synchronized MGs were invented.

http://en.wikipedia.org/wiki/Morane_Saulnier

BTW, Chris, beautiful minis and terrain! Are they yours?

Ok, thanks. Freaky idea at all :D

[Ordie]

The Soviets were able to sychonize 4 MG through the propeller. Gen. Chennault was able to "aquire" the device from the Soviet military mission in China and send details and specs back to the US. Needless to say the folks back in stateside didn't know what to do with it and left it on some bookcase collecting dust.

[mi35d]

Maybe because there was no need to fire through the props when they were better mounted in the wings - larger guns, larger magazines, etc.

[Oneto15]

Her's a sketch of a later version of an interupter gear. I hope this helps.

[big_les]

I've seen a propeller full of .303 bullet holes where the interrupter gear had apparently failed. It stayed intact long enough to get the pilot (A Sub Lt Graham) home.

[Grumpy Bastard]

Maybe because there was no need to fire through the props when they were better mounted in the wings - larger guns, larger magazines, etc.

Difficult to aim & something of a **** for the pilot change the 40-70rd drum mag & sort out (frequent) stoppages. It involved holding the controls steady with your legs whilst hanging out of the cockpit........

Needless to say the synro-gear was an improvement. I believe that some aircraft had an MG firing through a hollow cam shaft straight out the centre of the prop. Am I imagining this?

[Breakfast in Vegas]

Needless to say the synro-gear was an improvement. I believe that some aircraft had an MG firing through a hollow cam shaft straight out the centre of the prop. Am I imagining this?

The ME-109 did in WW2... a 20mm cannon.

http://www.adlertag.de/mainindex.htm

[Grumpy Bastard]

Yeah. I thought I'd seen it do on a biplane in an old copy of Jane's or something. It doesn't bother me enough to do a detailed search thought.

[loganinkosovo]

Before the interupter gear they were shooting at each other with pistols, rifles and fouling pieces or throwing large darts or homemade grenade. The begining of the first war was a time of expiedency and innovation at the troop level.

http://en.wikipedia.org/wiki/Interrupter_gear

[Nansouty]

Indeed. Other solutions were explored as well, such as pulser engines.
http://www.greatwarflyingmuseum.com/aircraft/commonwealth/dehavilland_dh2.html

http://en.wikipedia.org/wiki/Pusher_configuration

and even a video

http://www.raindesert.com/great_war/202_dh2.htm

[Engine Mech]

Special batches of ammunition were made for synchronized guns as the speed of the bullet has to be more consistant. Guns timed using plywood disc attached to propellor. Also guns timed at specific engine RPM to allow for flight time of bullet between gun muzzle and prop.