ORIGINAL: da Rock
You've also got the problems caused by the outside shape of your big old scoops. The load on your tower also includes the drag caused by what the tower supports. There will be the sudden loads that'd happen with a shifting wind direction during storms and such. None of those considerations exist with the present designs that are basically just blades on a relatively small generator.
Yea, pretty much what I was thinking...
Years ago I had given this idea some though and at that time the obstacles involve in the structure alone was an engineering nightmare.
When I sized the fan to work with winds of 5 mph up, I figured even for a 10-20 Kw unit, that they would have to be at least 6 meters in diameter.
Now enclose this within a scoop or shroud to boost the efficiency (not all that much of a gain) sticking that whole thing 120-200 feet up in the air was a nightmare.
Could it be made to work possibly in a commercial application, if you had real deep pocket for the R/D and construction, but still i think it is a case of very quickly diminishing return...
This is a case where you have to use Archimedes principals (he is still right after all these years) and not reinvent the wheel.
Oh, by the way...
At 30 mph and I got the DF to spin, if you had a hurricane you might be able to get 2-3 volts out of it...
For me, I am going to go with the blades attached to a generator, so much easier and cheaper, not to mention off the shelf technology.