Hi all, I'm new here and am about to possibly buy new 80" blade set for my debunked, cracked, carbon-fiber two blade set. My 2 blade set is 108" dia. and seems to seep water in bolt holes into the blades to throw it off balance. Will I lose any power with the shorter blades and will it auto-furl at the same speed? It furls now at approx. 28mph. Also, I'm slightly worried about the metal fatigue on the new aluminum blades at the bolt holes. Any response would be great. Thanks, Barry
Barry, I do not think you will be at risk of metal fatigue any more so than all the other people who use these blades. We have sold several thousand blades with no metal fatigue problems to date. If you generator furls before 35 mph, the blades should last at least 10 ten years with no issues and I would not be surprised if they went 20 to 30 years. If you keep the blades straight into the wind at wind speeds above 35 mph, then the blades will undergo fatigue much faster, especially if your turbine commonly sees 65+ mph wind. But since your turbine furls, you should not have a problem. The turbine will definitely furl at a different wind speed with different blades. They difference should not be that much ... +/- 5 mph is my educated guess. Shorter blades will furl in higher winds speeds. More blades will usually furl in lower wind speeds if you are dealing with identical blades. It is hard to make a direct comparsion since the blade have different shapes and different weights. The turbine will make less power with shorter blades but, again, the difference should not be too bad. If you want to make as much power as before, you should get the same diameter blades.
I think that the power generated by the Blades is proportional to the SQUARE of the size. 80" ^ 2 = 6,400 108" ^ 2 = 11,664 This shows that an 80" Blade set generates less than 55% the power of an 108" Blade set. This of course assumes the air foils are identical - which they probably are not. But this does give us an estimate of the lost power. I would consider this a huge drop in generated power. I realize this was an old post. This just may convince others not to downsize from 108" Blades to 80" Blades. I know I would not.
Well Neoh, do you think it's possible to add 14" extensions to the three blade windgrabber's hub? I'm a little concerned about the wide shape of the blades and if the turbulence would be greater at higher speeds. I'm sure the weight would increase also. I've mentioned in an older post that I'm getting maximum 750 watts on my 1000 watt Whisper with the 80" windgrabbers. Another question is could the speed also increase using only TWO of the THREE blades from the windgrabbers?
