Rich, I'm going to build a unit that I can attach an alt to for actual testing but till then it's just visual observations and gut feelings(seat of the pants science). I do expect this to perform somewhat better than I would have thought a VAWT would untill I actually tried it.

Ed, I'm going to reproduce this as is for now to establish a benchmark before I fiddle with the design. I was originally concerned about the solidity but the wider wings seemed to work better with the venturi on paper and so far I'm seeing impressive rpm in a stiff wind suggesting it may be ok. The part that impresses me most so far is 50 rpm in no decernable wind at all! I would dance like a school kid on the last day of the year if I could wind tunnel test things with a smoke stream for visualizing airflows. I'll make the test unit so I can swap pieces to do comparisons

ghurd, It's a corrugated cardboard center, heavy posterboard wing skins and plywood ends and wing/center hub forms. I used salvaged skate rolls(not roller skates but material transfer types)for bearings. Total cost not including stuff I had on hand: $7.50 The wings are hollow, the whole thing is held together with the poster board and cardboard.

Underground, I'm very excited about this unit(thanks ed) and will post all test results in the future. I expect this will beat the pico turbine type savonius if that's what your referring to. I think the sandia savonius would have greater start torque but the curves would intersect quickly as the rpm increases as the above unit likely has significantly less drag on the upwind side. I'd also expect much better high wind performance with out the associated failure issues. I have much to learn yet though.

Thanks all,