Radial engine

This article is about the conventional radial engine with fixed cylinders and a revolving crankshaft. For the otherwise similar engine with a rotating crankcase, see rotary engine.

Radial engine in a biplane

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.

The radial configuration was commonly used for aircraft engines before gas turbine engines became predominant.

Moving parts showing operation of a typical small five-cylinder radial.
Pistons are in gold and valves in pink, master rod in pale purple, slaved connecting rods in blue, crankshaft / counterbalance in gray and timing ring and cams in red.