Rotorcraft

An aircraft that derives lift from one or more rotating wings. Helicopters and gyroplanes are its principal types.

Rotor: A rotating assembly of blades that produces aerodynamic force. Rotorcraft depend on rotating blades to generate lift or control forces.
Lift (force): The aerodynamic force perpendicular to an object’s motion through air. A rotorcraft’s rotating blades must generate enough lift to support its weight.
Fixed-wing aircraft: An aircraft whose lift comes primarily from wings that remain fixed relative to the fuselage. Rotorcraft can hover; fixed-wing aircraft generally need forward speed for lift.
Search and rescue: The coordinated locating and recovery of people in danger or distress. Hovering and landing in confined places make rotorcraft useful in difficult rescues.
Helicopter flight controls: The systems that control a helicopter’s lift, direction, and attitude. Collective and cyclic pitch changes let helicopter rotors control flight.
Airfoil: A shaped surface designed to produce aerodynamic forces as air flows around it. Each rotor blade acts as an airfoil while moving through the air.
Helicopter: A rotorcraft whose engine powers a rotor to provide lift and usually propulsion. Helicopters are the best-known rotorcraft and can hover without forward motion.
Air ambulance: An aircraft equipped to transport patients and provide medical care in flight. Rotorcraft can reach isolated patients and deliver them quickly to hospitals.
Autorotation: A rotor’s continued rotation driven by upward airflow rather than engine power. A helicopter can descend safely after engine failure by maintaining rotor speed in autorotation.
Blade element theory: A method that estimates rotor forces by analyzing small sections of each blade. It connects blade shape and local airflow to total rotor thrust.

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