This article is about the conventional radial engine with fixed cylinders and a revolving crankshaft. For the otherwise superficially similar engine with a rotating cylinder block, see Rotary engine.
Radial engine timing and cam mechanism. Click here for full resolution animation.
Radial engine of a biplane
Master rod (upright), slaves and balances from a two-row, fourteen-cylinder Pratt & Whitney Twin Wasp
Mounting of a Wright R-2600 Twin Cyclone engine on a North American B-25 Mitchell bomber, 1942
The radial engine is a reciprocating type internal combustion engine configuration in which the cylinders "radiate" outward from a central crankcase like the spokes of a wheel. It resembles a stylized star when viewed from the front, and is called a "star engine" (German Sternmotor, French moteur en étoile, Japanese hoshigata enjin) in some languages. The radial configuration was very commonly used for aircraft engines before gas turbine engines became predominant.