I've volunteered to help an artist, who wants to place a number of small vertical rotor windmills in a seaside park, on top of picnic sheds. (He has permission!)
The rotors will be about 6 ft diameter, 3 ft high, and free-spinning - won't drive anything. The challenge is how to control the things so they don't spin too fast, but still be able to start in a light breeze.
Of course, cost matters.
Ideas so far:
- Centrifugal-operated "air brake".
- Permanent-magnet motor, with speed-sensing switch to short out for back-emf braking.
- Sails attached with Velcro, to rip out in big wind.
All comments and suggestions welcome.