Hi
Here is the address of a page that has an unusual savonius rotor that may be more efficient than cylindrical rotors.
http://www.sierratimes.com/archive/files/jun/05/arwh02-060501.htm
It is a very slow loading page, so slow that even my infinite patience was stretched to the breaking point. So, I will be glad to send a copy to you if you e-mail me your address, if you are too impatient to wait. My E-mail is cphilips@lefca.org.
The bottom third of the article is about the "Windshredder" design and I can send this as a Word document zipped.
Cam