Today in Technology History
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May 9
Last November, we wrote about Anton Flettner (1885-1961), a German-born aviation engineer who made important contributions to airplane and helicopter design. We promised to write more someday about a strange boat that Flettner built in the 1920s. Here's the thing that's unusual about Flettner's ship: it appeared to have two big smokestacks -- but they were actually rotating cylinders.
According to his memoirs, Flettner became very interested in the Magnus Effect, a phenomenon discovered by German scientist Heinrich Gustav Magnus (1802-1870), an expert in aerodynamics. When you aim an air current perpendicular to an upright cylinder, Magnus had noted, the air current splits on both sides of the cylinder. But if the cylinder is rotating, the air current on one side gets helped along by the cylinder's rotation; the air current on the other side is slowed. This creates a pressure differential, which results in a force pushing in one direction.
Flettner's idea, then, was to harness the power of the Magnus Effect to make a ship move. He bought a schooner called Bruckau and mounted two 50-foot cylinders onto it. The cylinders were powered by electricity, and when they started to rotate, they pushed the ship forward like powerful sails.
After several tests in Europe in various kinds of weather, Flettner's rotor-ship, now renamed Baden-Baden, made a successful voyage across the Atlantic, arriving in New York on May 9, 1926. The ship was greeted warmly, and many curious people came aboard to examine it.
Although Flettner proved that the Magnus Effect could move a ship, his cylinders were still less efficient than conventional engines. After a while, Flettner moved on to other projects and the cylinders were dismantled. In 1931, Baden-Baden was destroyed in a storm in the Caribbean.
The rotor-ship idea was reborn in the 1980s under a new name -- "turbosail" -- as part of a propulsion system designed by Jacques Cousteau and his colleagues to save fuel and cut pollution. It was never widely adopted.
Related links:
This page explains the Magnus Effect in greater detail.
Click here to read a little more about Flettner's rotor-ship.
Click here for an encyclopedia article about H.G. Magnus.
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