One thing more. It appears that your reason for adding the extra blades is to cause the air flow over the original blades to be laminar. Well, if memory serves me right, I believe that in wind tunnel tests involving model air foils it was found that the air flow was laminar, whereas in larger air plane wings it is laminar only over the leading few inches. You may, in fact, be trying to solve a non existent problem when it comes to windmill blades. GeoM[ Parent ]