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.

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.

A rotor/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 — spinning bodies that are essentially vertical cylinders — powered by a motor to take advantage of the effect. These types of propulsion cylinders are now commonly called Flettner rotors. Rotor ships have unique points of sail.

The German engineer Anton Flettner was the first to build a ship which attempted to use the Magnus effect for propulsion.

Assisted by Albert Betz, Jakob Ackeret, and Ludwig Prandtl, Flettner constructed an experimental rotor vessel; October 1924 the Germaniawerft finished construction of a large two-rotor ship named Buckau. The vessel was a refitted schooner which carried two cylinders (or rotors) approximately 15 metres (50 ft) high, and 3 metres (10 ft) in diameter, driven by an electric propulsion system of 50 hp (37 kW) power. In 1926, a larger ship with three rotors, the , was built by the shipyard A.G. Weser in Bremen.

Following completion of its trials, the Buckau set out on her first voyage, from Danzig to Scotland across the North Sea, in February 1925. The rotor ship could tack (sail into the wind) at 20-30 degrees, while a vessel with a typical sail rig, cannot tack closer than 45 degrees to the wind; hence, the rotors did not give cause for concern in stormy weather.

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