A rotary engine is a type of internal combustion piston engine used in some early aircraft, motorcycles, and cars. Almost the entire engine rotates about a fixed crankshaft.

Rotary engine may also refer to:

• Pistonless rotary engine, a type of pistonless internal combustion engine
• Turbine, a rotary engine that extracts energy from a fluid flow
• Wankel engine, a common type of pistonless rotary engine used in some NSU Motorenwerke AG (NSU) and Mazda cars
• Windmill, a rotary engine that extracts energy from wind
• Waterwheel, a rotary engine that extracts energy from water

• Radial engine, an internal combustion piston engines with a fixed engine block of radially-mounted cylinders driving a rotating crankshaft

This disambiguation page lists articles associated with the title Rotary engine.
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