Wankel rotary combustion engine was invented by Felix Wankel in 1957, it has a three-lobe rotor which moves in a circular path, while rotating about its own axis, within a housing having an epitrochoidal bore - i.e. a wide-waisted figure-of eight shape. Planetary rotation is controlled by an eccentric shaft, an internally-toothed gear and a fixed pinion mounted centrally on the rear cover plate. The tips of the rotor are in continuous contact with the housing, forming three chambers, reach of which changes in volume, with rotation, to effect suction, compression, expansion and exhaust phases, as in a four-stroke reciprocating engine. Spring-loaded tip seals on the rotor prevent gases from passing from one chamber to the adjoining one and the rotor uncovers ports, as in a two-stroke engine, to control intake and exhaust timing.