Rotor ship

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. In addition to the familiar principle of backspin imparted to increase range in ball sports, the Magnus effect was also employed in the bouncing bombs developed by Barnes Wallis.