More On... The Savonius Super Rotor!

July/August 1974

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MOTHER has received several letters indicating that the amount of power reported available with the Savonius Super Rotor ( MOTHER NO. 26, pp. 78-80; NO. 27, pg. 39) was much higher than is actually possible with this type of unit.

With the kind assistance of William Vance, Advanced Concepts Division of Science Applications, Inc., La Jolla, California, and with the aid of Mark's Mechanical Engineer's Handbook, we have calculated values for the amount of power produced by the S-rotor. The following is the method used and the results.

S- Rotor design and operation is still an experimental field. But these power equations are as close as possible to the expecte output... enough to act as a guide for design. For instance, if one desired a 1,000-watt output in a 15 mph wind (requiring a Stuart of 7.7-ft radius), the S-rotor dimensions would be:

In general, the S-rotor appears convenient for situations with smaller power requirements where its size is manageable... Elektro GmbH of Switzerland produces a 250-watt and a 500-watt model, but uses the familiar three-bladed Stuart for higher-powered models, 1,000 watts and up. But any situation is unique in its wind characteristics, power requirements, topography and available materials and skills, and each factor should be considered in deciding the best windplant to erect

John Boll
Director of Research and Development