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Because it rotates on a vertical shaft, the rotor can turn in wind coming from any direction and
will start turning in very low winds.
A survey of available litreature shows that the rotor is very suitable for manufacture in village
and home situations and that it is not difficult to construct. However, the author feels the
potential user should be aware of the fact that the Savonius rotor, when compared to other wind
machines, may be less efficient and/or require higher wind speeds to achieve a power output
more easily achieved by another type of wind machine.
The text on the following pages provides data compiled by various investigators on the amount
of energy available from S-rotors at various wind speeds. The author feels the potential rotor
builder should use these data carefully to see if an S-rotor can meet his needs--before he begins
the construction process.
The following graphs provide specific figures on the power available from Savonius rotors.
Different rotors--reduced to the same size--are compared in graphs 1 and 2 and the
accompanying tabulation. Graphs 3 and 4 show rotor output for a two-stage rotor and a rotor of
1m projected area respectively.
Here "input" figures measure energy available directly from the rotor.