Today I decided to see if my 3 bladed Savonius was going to work at all, because the winds were a nice 20 mph and relatively constant. So I put the windmill on top of my ladder and hooked up the bridge rectifier and my nicd cells to charge. No load voltage was about 5 volts in a good gust, maybe 25 mph. Amperage came out to a peak 0f 0.58 amps @ ~1.33 volts. Cut in was maybe 15 mph +.
The design seems to be very inefficient in terms of the blades. Granted, my motor has a lot of friction, but even when it got going, there was very little torque. It may be possible that the 3rd blade blocks too much wind.
Design flaw #2 maybe be the idea of using the benesh shape for the blades. I think there is a lot of air resistance coming up wind.
I think I will do much better with a 6ft blade set that starts up in low wind speeds than a VAWT. Plus, the windswept area was fairly small with the VAWT (20" x 24").
So in conclusion, if anyone wants to build a VAWT, don't do what I did
I think it is certainly possibly, but for your time and money, a normal 3 HAWT will be much better.
Here is a picture from last month: