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Tom Potts wrote: >> So if the wings drive the windward side of the conveyor in a given >> direction, what happens with the wings on the leeward side? Do you >> have to have some mechanism to have the wing turn around so it >> drives the leeward side in the other direction? > the blade turns 180 degrees round the end which is just what you need! > >> There's also the >> possible problem that the leeward blades would always be running in >> "spoilt" air and causing drag. > You may get a throbbing/woosh woosh noise - but the displaced air would be > assisting the drive of the following blade - or if it truly is a problem then > the blades on one side could be made to feather. So you'd need some sort of control mechanism for feathering the leeward side, which does make the system rather more complicated. > but we're talking a much cheaper device here I'm not sure we're comparing like with like, tbh. It *is* possible to build workable propeller turbines quite cheaply. They're just not *sold* cheaply. >> which would be far less >> problematic to mount, I'd have thought. > A windmill on the edge of a house roof suffers enormously from turbulence > problems due to the roof. Not just because of the roof, but surrounding buildings, trees etc. etc. In the wind-power world, it's fairly commonly accepted general rule that it's actually fairly pointless mounting any kind of wind turbine on a house roof because aerofoils are dramatically less efficient in dirty air. > To me it looks like its worth a try and I grant there are a lot of things to > iron out. I think it's an interesting idea, but what I've researched about wind power over the last few years just suggests it's not going to work well. Of course, that doesn't mean everyone else is right. Build a scale model and demonstrate that it works :) (FWIW, I have plan to build a number of wind turbines from scratch for various applications, hence the research.) What you're suggesting looks similar to a giromill on steroids and my gut feeling is that the same design constraints would apply, otherwise people would have made the giromill work better. If you have a look half to two-thirds of the way down this page: http://www.otherpower.com/windbasics2.html there are a couple of pictures of giromills together with a list of reasons why they consider vertical axis wind turbines to be less desirable than horizontal ones. Still, they did once tell people that the world was flat, too :) James -- The Mailing List for the Devon & Cornwall LUG http://mailman.dclug.org.uk/listinfo/list FAQ: http://www.dcglug.org.uk/linux_adm/list-faq.html