Has anyone had any experience with small windmills / wind
turbines for power generation.

There are numerous websites with details of all the normal
players and then some. I'm investigating devices which are
small and relatively indestructible. Aim is a power
generation capability in the 100's of milliWatts to few
Watts range with an emphasis on longevity and leanings
toward operation in a wide wind speed range,simplicity, low
cost and audible impact. Minimisation of size is not overly
important as they are liable to be small enough that one
several times larger than an optimum output model is liable
to not be overly large.

The much derided Savonius design may have some advantages
given the above focus on priorities.

For interest I offer the following empirical and so far
untrammelled by reduction to practical test formula for the
upper speed of a Savonius windmill.

    RPM <= 15 x V /d

        V = windspeed in metres per second
        d = diameter in metres.

This says that eg a Savonius built with wheelbarrow buckets
(as they do it on Oz) and a 2 metre diameter would not spin
over 150 RPM in a bracing 20 m/s 'breeze'. (70 kph / 50
mph). Just as well! For a given power this 'explains' their
large torque (also arrived at by other obvious means).



        Russell





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