The design was developed and tested by Ed Lenz of Windstuffnow.com:
The Lenz2 VAWT (Vertical Axix Wind Turbine) is 4 foot tall and 3 feet in diameter. It is a basically a Savonius style turbine but with the refinement that the three wings are shaped to provide lift as well because or their teardrop configuration. In the above link Lenz describes how he placed an ananometer inside the stational turbine and showed that the windspeed picked up passing past the solid portion of the wings. This turbine is more efficient than a pure Savonius in that it provided both drag and lift.
In my design I scaled down the diameter to approximately 18 inches and the height to 21 inches. (In hindsight, I should have made the height 18 inches so that there would be more of the center axis free on both ends for flexibility in mounting.)
I was able to use materials I had on hand to build the turbine. When I tested it in a 15 mph wind, it worked so well that I was afraid to stop it for fear of getting injured. The only downside of what I produced is that it seemed to produce very little electricity. This is not due to the design of the turbine but to the nature of the DC motor that I had it attached to. The emphasis in this tutorial will be on how to construct the turbine itself. Full credit for the design and some of the instructions goes to Ed Lenz.
[Note: Since this instructable was published, I learned more about how the wings should be shaped. The construction details for the lenz2 provided in this instructable still hold but the dimensions of the wing in Step 2 should be substituted for those given in the newly inserted Step 3.]