Flettner rotors

Manchester University found a few years ago that a rotor could give eight times more power than a normal windmill

When I was in college, way back in 1953, studying hydraulics we were shown details of the ship fitted up in the early 1920s with two large Flettner rotors instead of a sailing rig.

The boat sailed across the Atlantic at an average speed of 10 knots. Now in those days that was as fast as a tramp steamer. Wartime convoys seldom sailed above a speed of 8 knots.

Out of curiosity I looked on Google and found that there is a Flettner ventilator for sale but also a great deal of information on Flettner rotors. When I asked young engineers if they knew anything about Flettner rotors they all shook their heads in the negative.

Years ago Tomorrow's World showed a large helium balloon that could be rotated in the wind stream and lift a load of 10 tons. They never mentioned what happened when the wind dropped.

Manchester University found a few years ago that a rotor could give eight times more power than a normal windmill. Why has there been no information about these facts if they are true? Surely this is the sort of equipment that Britain should be producing.

What concerns me from the information that can be gleaned from the internet is that there appears to be no input from British firms.

B H Poulten, Baughurst, Hampshire

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