http://www.energy.ca.gov/2005publications/CEC-500-2005-084/CEC-500-2005-084.PDF

I am planning on building one in a few weeks.  As I work two jobs, one of them teaching, I do not have time to do it now.  By the time I build it the wind season will be dead, except for hurricanes.  Florida is my home.

Right now I am trying to ferret out the optimization of a PM alternator before I start building.  A friend of mine is heads up the electrical failure analysis lab at Kennedy Space Center.  He is on board to help design a PIC unit to control alternator switching between star and delta.

Right now he thinks we should skip PM and use voltage regulated a stator.  However I am not convinced.

Has anyone done a hybrid PM voltage controlled stator.

I am just dreaming for the moment, but I expect to have at least one unit build by the end of the summer with plenty of data logging for further optimization.

so my gap ratio = (gap,s - diameter of beam) / diameter of turbine

??

as what I knw, gap ratio shd be around 0.1 - 0.15

If you need a bit of reading material before heading out to the shop...

There's a bit of interesting reading at the Sandia Labs site on Savonius rotors, here's the link:

http://www.sandia.gov/Renewable_Energy/wind_energy/topical.htm

Scroll down to near the very end of the page, and you'll find the VAWT Archives. In there there's a link to Wind Tunnel Performance Data for Two and Three Bucket Savonius Rotors.

Another link:

go here: http://patft.uspto.gov/netahtml/srchnum.htm

and tap in 5,494,407 it's a link to the Benesh Savonius with drawings and proportions etc.

I actually built one (a small one!) according to that patent which works quite well. There's some info and pics in previous posts I put up last fall. I think the pics are still in my files on this board. That's the same one Picoturbine's site is loosely based on.

Hope that helps a bit anyway!