Flettner rotor ship

Article By:

Neu, Wayne L. Department of Aerospace and Ocean Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia.

Last reviewed:2013

DOI:https://doi.org/10.1036/1097-8542.YB130204

The world has known sailing ships for centuries. The thought, romantic to some, conjures images of canvas and the sea, but you don't need a traditional canvas sail to get a propulsive force from the wind—and it's not a new idea! Anton Flettner (1885–1961), a German aviation engineer and director of the Institute of Aerodynamics at Amsterdam, the Netherlands, filed an application for a German patent in 1922 on a ship propelled by vertical circular cylinders rotating in the wind. Then, in 1924, he purchased an old 2000-ton steel-hulled schooner, the Buckau, and aided by the now-famous aerodynamicist Ludwig Prandtl, among others, he converted it to the first rotor ship at Kiel, Germany (Fig. 1). The ship was 47.5 m (156 ft) long with a beam of 9 m (28.5 ft). Flettner installed two rotating cylinders each 3 m (10 ft) in diameter and 15 m (50 ft) high driven by two 11-kW (15-hp) electric motors with power supplied by a 34-kW (45-hp) diesel generator. The rotors turned at a top speed of 125 revolutions per minute. They were constructed of heavy gauge steel but were still lighter than the masts and rigging they replaced. Performance of the ship was very good. She moved at nearly twice her former speed. She reportedly could tack to 25° to the wind while the original schooner could only tack 45° to the wind. In February 1925, after 62 trial voyages around Kiel loaded with up to 35 metric tons of coal, the ship was put into commercial service hauling lumber from Gdansk, Poland to Leith, Scotland through the North Sea. She handled the stormy weather without trouble. In 1926, the ship was renamed the Baden Baden, sailed to New York, and continued her commercial service for several years, mostly in American waters. Eventually she was converted to conventional engine and propeller propulsion as it was deemed to be more efficient and continued service as a motor freighter. She sank in the Caribbean Sea in 1931.

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