As is known, fighter aviation was born during the First World War. The option to install a machine gun at that time was only one – in front of the top of the fuselage just in front of the pilot so that he could aim. The main problem encountered by the designers of the first combat aircraft – how to avoid hit bullets in the propeller rotating in front of the barrel of the machine gun.
The way out was soon found. In March 1915, the German aircraft designer Anthony Fokker created a synchronizer and installed it on his Fokker EI fighter. The principle of the mechanism was as follows.
On the rotating part of the engine was installed a cam with a ledge. When rotating, he moved the thrust associated with the machine gun trigger. Another shot was made immediately after passing the blade before the barrel of the machine gun. Thus, two problems were solved at once: a high rate of fire and safety of the screw was ensured.
Synchronizer work can be seen in this video:
But what would have happened in the absence of a synchronizer: