Inside a twin-rotor Wankel

The NSU Ro80 and the more modern Mazda cars with Wankel engines all use twin rotors. The rotors drive an output shaft running through their centre. This shaft is linked to a flywheel to smooth out the power impulses of the engine.

The advantage of twin rotors is that, when set to run 180° out of phase with each other, one rotor cancels out any vibrations produced by the other rotor, making for an exceptionally smooth-running engine.