flettner rotor

A Flettner rotor is a smooth cylinder with disc end plates which is spun along its long axis and, as air passes at right angles across it, the Magnus effect causes an aerodynamic force to be generated in the third dimension.

A rotor ship, or Flettner ship, is a type of ship designed to use the Magnus effect for propulsion. The Magnus effect is a force acting on a spinning body in a moving airstream, which acts perpendicularly to the direction of the airstream. Rotor ships typically use rotor sails powered by a motor to take advantage of the effect. German engineer Anton Flettner was the first to build a ship which attempted to tap this force for propulsion.