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Forum Index : Windmills : new mill with f/g blades
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| brucedownunder2 Guru  Joined: 14/09/2005 Location: AustraliaPosts: 1548 |
I finally raised my new 7 foot f/g blades on a single F&P complete with narcelle and nose cone -spiffy- ,Yesterday 120kph winds , today , not a breeze . Anyhow , it looks like a goer , but we'll have to wait .
Bruce Bushboy |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5019 |
Hey Bruce Looks good mate. Any wind yet? Would be good to see how those blades perform. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| brucedownunder2 Guru Joined: 14/09/2005 Location: AustraliaPosts: 1548 |
Well, yesterday we had a nice breeze for 4 hours or so , but the new blades just quivered a bit and refused to turn the neo magnetic rotor-too much magnetic pull and cogging for these slender blades,I think . It did spin up for a short while -30 seconds or so - , so from that I gather nothing is wrong with the mechanics. I'll back off the rotor a bit today and see if that makes a difference, if so it points to a larger blade set . Bruce. Bushboy |
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| RossW Guru Joined: 25/02/2006 Location: AustraliaPosts: 495 |
Just wondering..... would it be possible (or practical) to kick-start it? Ie, treat it like a motor, whack DC across one phase, then the next, just to start the thing off in the right direction? A controller to do that wouldn't be too much more difficult if the concept works in practice :) |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5019 |
The idea of kick starting has been raised before. It is worth looking into, but I dont think anyone has tried it yet. I thought about mounting a modified cooling fan from a PC power supply on the windmill, and use this to charge a capacitor ( say 100,000uF ). When the cap reaches 30 odd volts, dump this via a SCR into one of the phases. A kick in either direction works, if its kicked the wrong way it quickly changes direction. The circuit could be simple. 30 volt zenner diode on the gate of the SCR, and a diode to stop the mill feeding AC back into the capacitor.
Dont know if this would work. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| RossW Guru Joined: 25/02/2006 Location: AustraliaPosts: 495 |
Hmmmm.... I might have a play this weekend, wind permitting :) Most of the cooling fans I've seen don't seem very practical to modify, but I'm sure there will be some that are. You'd get very little power out of one though - so I don't know how long it'd take to store enough energy to bump a decent mill! That's worth knowing. I thought it'd have to go the "right" way to be any real use since it would have to go through "stop" to reverse, and be right back where it started. Still, it makes the design a whole lot easier! My thought was substantially more complex. I was going to use the anemometer output (we all have at least one, don't we?) back through the controller and let the controller do it. It also means that it has access to the (substantially higher) energy reserves of the battery bank to borrow from. When the anemometer output was > some preset limit for some time, and still no output from the turbine, give it a bump. Repeat periodically if required. I still think you'd need to do it across *two* phases because you have a fair chance the turbine will be stopped right over that coil and won't actually move anywhere when you dump something into it. The second phase would at least get it moving in that case. Question is: is it worth all the effort? Almost certainly is if there is a mppt converter there to make use of the (relatively) low output. |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5019 |
Hi Ross. The cooling fans have to be pulled apart and the little circuit board modified, basically just ripping out the switching transistors and connecting the windings to the output leads. They make a lot of volts ( stick it out the window of your car at 60kmh and your get 300+ volts ! ), but little current. Thats the idea in my circuit, the cap charges slowly, over a few minutes even, then is dumped in one hit across the a F&P phase. The kick on one phase is like giving the tower a shake, a bit of a wobble and the windmill will start up. Like you say, though, is it worth the effort, for only low power in low winds. But if every amp counts, then yes it would be. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| KiwiJohn Guru Joined: 01/12/2005 Location: New ZealandPosts: 691 |
I have seen suggestions for a mechanical system to overcome starting inertia. Arrange the prop loose on the shaft with a pin or stopper for the prop to drive against. Fit a spring over the shaft so that when the wind dies the spring pushes the prop back for 3/4 of a turn or so. When the wind rises it only has to overcome this light spring to get started, once the prop has made the 3/4 turn or so the pin contacts and the inertia of the prop bumps the alternator off its resting state.
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| adelaide Regular Member  Joined: 24/03/2006 Location: AustraliaPosts: 46 |
h  help to make progres or radio and vitamin b |
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| adelaide Regular Member Joined: 24/03/2006 Location: AustraliaPosts: 46 |
hi bruce is sort of thing i use to fix the problem befor it is 1 ,ok for 2 years now , use altons cal for angles and mont curved tin bits on front cos thicker wood their and glu/ screw . still powers a 80 p at 12 v easy so no wories about rpm if angls corect masive start talk, made 10 now .befor i did that ,cos in lo wind zone f/p were anoying not starting easy enuf ,hope that helps on non de coged f/p s help to make progres or radio and vitamin b |
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well, u guessed it --no wind.
