World War 1 saw the introduction of aircraft to the battlefield. Initially, crude wood framed canvas covered aircraft were deployed in light reconnaissance roles. However the combat potential of aircraft was quickly realized and military aircraft development bureaus were established to oversee the development of planes designed for attack, fighter, bombing, and reconnaissance roles.
In the beginning, pilots were armed with conventional handheld firearms to take potshots at enemy scout planes. However research and development of heavier armed planes soon saw the introduction of light machine guns and many methods were attempted to find a way for pilots and gunners to accurately aim. After much trial and error with different configurations, it became clear that the easiest solution was to affix weapons directly to the fuselage or wing of the plane, rather than attempt to manually aim weapons independent of in-flight movement of the aircraft.
The earliest crude iterations of this setup included the Morane Saulnier N which mounted a machine gun directly on the centerline of the fuselage, directly in front of the pilot for relative ease of aiming. However this presented a problem of the bullets hitting the propeller. Initial crude solutions included mounting reinforced steel armor to the propeller to deflect bullets that struck the propeller.
The introduction of the interrupter gear finally solved this problem by a direct mechanical synchronization between the engine’s rotation and the timing of the gun’s firing. This development meant that more robust armaments could be used without the need for a specialized heavy propeller.
As the war raged on in Europe, the British, French, and the Germans engaged in an air arms race driven by constant experimentation and design fads such as the ‘three winged craze’ which spawned the Sopwith Triplane and Fokker Dr.1. Even the slightest edge in speed, armament, or maneuverability could make the difference in air superiority. Pilots’ skills were also constantly put to the test, attempting to push their wood-framed contraptions to the breaking point, often with tragic results.