an internal-combustion engine in which power is transmitted directly to rotating components

an internal-combustion engine having cylinders arranged radially around a central crankcase

a good second choice, though not without a few drawbacks The upper left engine mount was rebuilt with a slightly different design to Rotary Mount Design

an internal combustion engine, but it's not like the one in most cars

an internal combustion engine, combustion and exhaust

See 'Wankel engine'. Rotor arm - A rotating arm in the distributor, which distributes the HT spark voltage to the correct spark plug.

An internal combustion engine which is not of a reciprocating (piston) engine design. There is no true crankshaft, although the power-take-off shaft is sometimes called the crankshaft. It is stationary or fixed in that it simply spins in place. The central rotor turns in one direction only and yet produces the required intake, compression, firing and exhaust strokes. Because it uses rotary motion instead of reciprocating motion, the rotary engine has better balance and less vibration than piston engines. Two common rotary engines are the gas turbine and the Wankel engine.

The rotary engine was an early type of internal combustion aircraft engine, used mostly in the years shortly before and during World War I. It was also used in a few motorcycles and cars.