[QUOTE=bobmcgov;227081]The twist does incidentally reduce noise caused by stalling at the tips -- on many smaller turbines, the blade tips actually have a negative angle of attack, because their apparent wind is essentially in the plane of the blades, the tips are moving so fast. Some of those machines have tip-speed ratios of eleven or higher (tips moving eleven times actual wind speed).
I was at a sailing club meeting last night and we somehow afterwards got on the subject of onboard wind generators. A friend told me about being up in the North Channel and visiting aboard with a guy who had a wind generator mounted at the stern. The guy was proudly telling him about how many amps the thing could put back into his battery bank, and my friend could barely make himself heard over the noise of what sounded like a small Cessna bolted to the boat.
I too have heard that the sound from the big generators is fairly benign, more like gentle ocean surf. Setting standards for acceptable noise levels and residential setbacks is a really sticky issue. The wind farm industry in Ontario argues that there's no one-size solution, that each installation has to be judged individually for setbacks. But they also argue that background levels of 40-50 dB should be expected at the setback perimeter. I guess the objections up on Georgian Bay from the cottagers (above and beyond their NIMBY predilections) is that when you live somewhere that you can normally hear a pin drop, suddenly introducing a steady 40-50 dB of whooshing noise is going to be noticeable. (That would also apply to cruising anchorages.) But I bet the wind in the pines cranks out something at that level. It always sounds windier along the bay's coast than it usually is because of the way the pines generate sound.
I'm with you on the aesthetics. I generally like the look of them.
C&C 27 Mk 1
Midland Bay Sailing Club
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It is better to be vaguely correct than specifically wrong.
Last edited by Diva27; 11-23-2007 at 03:48 PM.