by Greystoke on Mon May 18, 2009 2:20 pm
Can't tell. That info is not given, but I understand your reservations.
My problem with the theoretical formula is the fact that it is based on the kinetic energy of a moving body, ie: ½mv², in which m = the mass of the moving air, and v = the speed of the air.
But the only way in which this energy is tranferred to electrical energy is if the air stops moving AFTER the turbine, having expended ALL its energy. Of course that is not the case, but we'll never know the true story as to what really happened.
50 Watt @ 3m/s (and nothing before that) is indeed strange, particularly if the unit generates only 300 Watt @ 7m/s. It doesn't gell. But then, . . . I've seen a number of these curves, and most leave some questions. I also think a lot depends on the shape of the vanes.
Regards
Cor