Definition
An aircraft that uses an unpowered, freely rotating rotor to generate lift and a separate engine-driven propeller for forward thrust. The rotor is not powered in flight; it spins because air flows up through it as the aircraft moves forward, a process called autorotation.
Plain English
A small aircraft with an overhead rotor that spins on its own from the airflow, while a propeller pushes or pulls it forward. The spinning rotor provides the lift, and the propeller provides the speed.
Context Anchor
Seen in discussions of rotorcraft design, aircraft classification, and maintenance differences between gyroplanes and helicopters.
Derivation
From Greek 'auto' (self) and 'gyro' (turning or rotation). The name reflects the key feature: the rotor turns by itself from the passing airflow, without engine power driving it.
Why Pilots Care
An autogyro behaves differently from both helicopters and fixed-wing aircraft. It cannot hover like a helicopter because its rotor is unpowered, but it can fly very slowly and land in short distances. Knowing the difference matters when identifying aircraft, understanding rotorcraft regulations, and discussing maintenance categories.
Intuition Check
Do not assume an autogyro is just another name for a helicopter. A helicopter powers its main rotor for lift; an autogyro normally uses an unpowered main rotor and a separate propeller for forward motion.
Example Sentence 1
The autogyro lifted off after a short ground roll, its rotor already spinning fast enough to carry the aircraft into the air.
Example Sentence 2
During preflight the pilot confirmed the autogyro's rotor blades were free to spin before starting the engine.