background image
Numerous applications are given the rotor, some of which are questionable and some more
reasonable.
The author proposes two alternative braking systems, i.e., a brake drum, and "air brakes
consisting of small flaps which open out from the wing surface when a predetermined speed is
exceeded."According to the report, the rotor's performance in water is analogous to that in air,
taking into account the differences in the densities of the two media.The author claims that 1.6
horsepower per square meter of surface area at a water speed of 2 meters per second was
attained.
An interesting and feasible application described is the placement of the rotor with its axis in a
horizontal position so that it is turned by the wave motion.A device of this type was installed in
Monaco around 1930 and pumped water 200 ft up. A power output of 1.8 to
2.7 HP per square meter is claimed at a wave speed of 3 meters per
second.
6.Design, Development and Testing of a Low Head, High Efficiency Kinetic Energy Machine,
by Russel B. MacPherson, U. Mass. School of Engineering, Amherst, Massachusetts.
The paper presents wind tunnel test data on an S-rotor model.Curves are plotted showing
relationships between efficiency, rotor speed and power output.A polar torque diagram is
given.The test curves are of some use to the designer, and indicate a rather low capability of the
S-rotor, except in very high winds.
7.Appendix C. The Savonius Rotor. A Study Conducted for the OFFICE OF PRODUCTION
RESEARCH AND DEVELOPMENT, WAR PRODUCTION BOARD, Washington, DC,
January 31, 1946, by Engineering Research Division, New York University.
The article describes tests on a model in a wind tunnel.The results are tabulated, and power vs
efficiency, power vs rpm of the S-rotor and efficiency vs rpm of the rotor curves are plotted.
Analysis of a hypothetical rotor operating in a 30 mph wind and developing 1000 kw was
made.The rotor would have to be 360 ft tall, mounted on a 50 ft base, and would have a diameter
of 60 ft. The calculated cost of building such a Savonius rotor was much higher than for an axial
flow windmill producing the same power.
8.Wind and Windspinners, by Michael A. Hackleman and David W. House, published by Peace
Press Printing and Publishing, 3 28 Willat Ave., Culver City, California 90230 USA.
Several chapters on such fundamentals as energy concepts and generation of electricity are
included in this book, plus some construction information.The explanations are clear, but over-
simple.The book contains many contradictions and numerical errors. Overall, the authors
overestimate the capabilities of the S-rotor.
In some instances it may be that misprints are responsible for data that is in error by as much as a
factor of 101 (In chapter 7, figures for generated power should be 82.85 watts instead of 828.495
watts, and 37.5 watts instead of 373.5 watts.) In other cases, the errors combine with unsupported
optimism to confuse or mislead the reader.Table 1 on page 96 contains arithmetical errors, and
further, leaves a layman under the impression that the S-rotor is capable of generating several
kilowatts of electricity, which could only be the case in a hurricane which would blow away
the whole structure.
The table starts off with a wind velocity of 32 mph; there are few places in the world where
steady winds are that high.
The "cube law" pertaining to wind energy is simply explained.The section on generators and
alternators is useful for a layman who wants to know something about their application. The