In aeronautics, an aircraft propeller, also called an airscrew, converts rotary motion from an engine or other power source into a swirling slipstream which pushes the propeller forwards or backwards. It comprises a rotating power-driven hub, to which are attached several radial airfoil-section blades such that the whole assembly rotates about a longitudinal axis. The blade pitch may be fixed, manually variable to a few set positions, or of the automatically variable "constant-speed" type.
The propellers of a C-130J Super Hercules military transport aircraft
A decorated Japanese taketombo bamboo-copter
Leonardo's aerial screw
Prototype created by Mikhail Lomonosov, 1754
An aircraft engine, often referred to as an aero engine, is the power component of an aircraft propulsion system. Aircraft using power components are referred to as powered flight. Most aircraft engines are either piston engines or gas turbines, although a few have been rocket powered and in recent years many small UAVs have used electric motors.
A Rolls-Royce Merlin installed in a preserved Avro York
Wright vertical 4-cylinder engine
Ranger L-440 air-cooled, six-cylinder, inverted, in-line engine used in Fairchild PT-19
A Rolls-Royce Merlin V-12 Engine