The first airplanes that took to the sky in World War I had only one purpose: scouting enemy positions and movements. Nevertheless, in no time at all, pilots began looking for ways to shoot each other down. Flyers made the first kills by firing pistols and rifles off to the side. Then, backseat observers began operating moveable machine guns. However, what they clearly needed were forward-firing guns that could bring an enemy down from behind. The British were the first to mount forward-firing guns on the upper wing, shooting over the propeller. That, of course, made aiming hard, and it put the guns out of the pilot’s easy reach when they jammed. The French then put metal deflectors on the propeller so the pilot could fire straight through the blades, with a bullet glancing off now and then. That worked until crankshafts deformed under the hammering of their own pilots’ bullets. Then came Anthony Fokker, who was contracted to build 10 airplanes for the Germans. He, of course, was faced with the problem of how to allow the pilots to fire and not damage the planes' propellers. He decided that the way around that was to let the propeller fire the fun. The propeller turns at 1200 rpm and the gun fires 600 times a minute. Putting a cam on the shaft and letting it fire the gun every other turn was the answer. Then, no bullet would ever hit the propellers. Fokker’s synchronized machine gun was then mounted on all German aircraft headed into combat.
