While the work by Paul Gipe is accurate and commendable, that article you reference by Gary Novak titled "Windmill Efficiency" is pure bunk, IMO. Although he claims to be an "independent  scientist", he failed to do the proper research and note the proper documentation on the 'number of blades' and relies on:

"Let me say this in plain English. Anyone can look at an old-fashioned farm windmill, which had about 18 blades, and compare it to an experimental windmill, which had 2 blades, and see that the farm windmill was extremely efficient, and the experimental windmill is extremely inefficient. It is quite visible that unused wind goes between the blades with two and three blade systems. Propagandists use a lot of numbers and jargon to deny the obvious, but their numbers are not fact."

I regret, Mr.Novak, the numbers are fact and have been proven. One only needs to find the proper research paper.

Numbers can be juggled in a lot of ways to prove things one way or the other to the ignorant. It is far easier to ignore reality and just bad-mouth a concept because one does not understand it.