How did they syncronize machineguns on WWI biplanes?

Question

I have this report to do on WWI biplanes but i forgot how they syncronized the machine guns! I know it had something to do with a lever between the propeller shaft & the gun's firing pin, & the process was too expensive so most pilots like Roland Garros took their chances with the propeller being hit. But what the heck did the lever do to the gun to do tht?

Answer 1

Anthony Fokker improves Garros' Innovation
The problem of perfecting a machine gun that would synchronize its firing with the rotation of the propellers was the assignment given to Anthony Fokker. In two days the Dutch engineer had improved on Garros' innovation considerably. Fokker Eindekkers were armed with synchronized Spandau machine guns and roamed the skies virtually unopposed for a while. German aces such as Immelman and Boelcke led a reign of terror in the skies, known as the Fokker Scourge. But, as things went in that war for control of the air, the Allies weren't too far behind in making an answer to the Fokker Scourge. A little while later the Allies came up with a synchronized gun designed by Georges Constantinesco
Garros' Innovation
During the month before the outbreak of the war, Raymond Saulnier had been working on an interupter gear that would allow a machine gun to be fired through the propeller arc. He had grown impatient with hang-fire failures so he attached steel deflection plates on the propeller where the bullets passed through the arc. The military lost interest in his idea once the war started and made Saulnier return the machine gun he had borrowed. After a few months into the war, all the pilots were unanimous in their desire for fixed machine guns facing forward that they could shoot in the direction they were flying. Lieutenant Roland Garros, who had been a famous stunt pilot before the war, came to Saulnier and had steel deflector plates attached to his propeller blades and a fixed machine gun mounted in front of the cockpit. The interrupter gear was not installed, Garros relying on the steel plates to ward off the bullets that hit the airscrew. At the end of March Garros took to the air, and in just over a fortnight he had shot down five German planes. On April 19, though, he was brought down by enemy ground fire while strafing an infantry unit near Coutrai. His attempts to set fire to his plane (as all pilots did when they crashed landed in enemy territory, so the enemy could not get their hands on their technology) were unsuccessful and his modified airscrew was quickly in the workshop of Anthony Fokker.

Fighting Airman -The Way of the Eagle
Major Charles J. Biddle, described the principle of the synchronized machine gun.

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

Answer 2

The lever actually prohibited the firing pin from hitting the shell cartridge which would cause the explosion of the shell to send the bullet down the length of the barrel when the propeller was in direct line with the barrel of the machine guns.

There was only a very small window of time that the bullet could be fired and come out of the barrel either just after the propeller went past the barrel or just before the other part of the propeller would again.come in front of the barrel.

This was made much more difficult since the propeller was spinning at a much, much greater speed than what the bullets could be fired out of the barrel of the machine gun.

And this is why you see some pictures of WW! planes having a machine gun on top of its upper wing which was above the propeller.

Answer 3

Actually it was a gear and chain system from the shaft of the propeller to the gun, when the gear hit a certain spot it disabled the gun. Then there was the metal plate that would be wrapped around the propeller at the area where the machine gun to cause a bullet to be bounced off and not going through the propeller.

Answer 4

Basically, that lever would prevent the trigger from being pulled if the propeller was in a certain position. Otherwise, you've got everything right. Take a look at howstuffworks.com, they might have something about it in there.

Answer 5

If memory serves correctly, it was called an "interrupter gear" and worked on a "cam" system to allow bullets to fire through the propeller without hitting it.

Answer 6

A mechanical link between the firing pin of the weapon and the crankshaft of the engine (much the same as the distributor in modern automobiles.)

Answer 7

It was called an interrupter, it waited until the prop had gone by then it would allow a bullet to be fired from the gun, go here to learn more
http://www.thirteen.org/warplane/special2.html

good luck with your report.!!!!

Answer 8

Here is an interesting and accurate story of the development of effective synchronized machine guns for aviation.

Answer 9

They covered the propellers in metal sheet so the bullets bounced off.

Answer 10

they had a cam on the prop that when a blade from the prop passed in frount of the gun it would not allow the gun to fire.