Answer:
The world wars. Especially world War II
Step-by-step explanation:
The world wars were the single most notable events that led to the leap in development of the aircraft from a simple apparatus capable of flight to a sophisticated flight machine. Airplane production was at its maximum during these periods (especially world war II) and has never seen that capacity of production again since. Countries focused on research that could add even the slightest enhancements to their aircraft in order to for it to surpass that of other countries.