Wankel rotary engine, 1965.
© Science Museum / Science & Society Picture Library
The Wankel rotary engine was invented by the German engineer Felix Wankel (1902-1988). This example powered the NSU 'Spider' motor car of 1965. The engine generates rotary motion directly, rather than converting reciprocating motion via a crankshaft as in conventional car engines. The main advantages of rotary engines are the small number of moving parts and the lack of vibration, as well as compactnes and light weight. However, problems including sealing at the tips of the rotor lobes, higher fuel consumption, and pollutants in the exhaust have limited their practical use.