How many gears do propeller airplanes have?

Propeller airplanes typically have a fixed-pitch propeller, which means that the blades of the propeller are fixed in place and cannot be adjusted during flight. As a result, propeller airplanes do not have gears in the same way that cars do. Instead, the pilot controls the speed of the propeller by varying the throttle, which controls the amount of fuel that is supplied to the engine.