In two days the Dutch engineer had improved on Garros' innovation considerably. 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. Way of the Eagle , Major Charles J. Biddle, a leading World War I ace, described the principle of the synchronized machine gun.
T here 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.