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Forum Index : Windmills : F&P w/Extruded Blades flying
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Steve9R Regular Member  Joined: 24/01/2006 Location: AustraliaPosts: 72 |
Thought I'd finally get around to posting some pics of one of my two mills.. This one is an F&P running as a 7phase 2pole rectification is done on the pole.. the blades are 1.5m PVC (Jabar's ones) that i got ages ago from him.. and they seem to work really well.. the tail is an old road sign that i found.. we've had this mill run up to 8amps and never had an issue.. Yes i know.. there is no furling on this mill, and honestly where we are located there is no reason to, as the wind isnt strong enough to enduce furling anyway!.. heres a couple of pics anyway to enjoy.. Steve 
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Nice looking windmill there Steve. Not having any furling is kind of scary. Furling has been a hot topic recently as these blades tend to behave a little differently than expected under furling conditions. So even if you did have furling, its not guarenteed to help. Maybe a mechanical brake? Its low enough to throw a rope over anyway, I do that to mine if I'm expecting strong winds. Whats the system voltage? Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| Steve9R Regular Member Joined: 24/01/2006 Location: AustraliaPosts: 72 |
Yeah ive been reading all the furling topics for a long time.. my experiences with furling in lower winds though is that once furled it is very difficult to get them to 'unfurl'.. the mill above is on a 15m tower, and is running into 24v batt bank.. We've been thinking about a bicycle disc brake and caliper for braking, as they are very light.. but today its been averaging 2amps all day....peaking to 7amps.. the other mill i have is one of the original chinese 200w ones with the whipper snipper string fibreglassed onto the blades.. today its been averaging about 1.5amps.. so with them both and the solar, the batt bank is full.. Steve |
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GWatPE Senior Member  Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi Steve, Re pt #2, You are talking about the windmill in the pic above? 15m tower? Here is a pic of a 15m tower windmill [whisper200 1kW, 8'rotor], I have measured. 
Here is a pic of a 10m tower windmill [Skystread 3.7, 2.5kW, 3.7m rotor], I have measured. 
I have also put up a pic of a 19m tower. My estimates put your blades at about 5m long. You may choose to confirm the dimensions. Good luck throwing a rope over a windmill up 15m to try and stop it. Here is some video of my own windmills furling. windmill 1 furling windmill 2 furling I think you should get some protection mechanisms in place before you start to rely on the windmill power. Murphy will come along and wreck your windmill, usually when you don't have the protection systems in place. If you are observing the windmill showing a reluctance to come out of furl, it suggests binding in the Yaw area, or problems with the furling angles. Gordon. become more energy aware |
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| Steve9R Regular Member Joined: 24/01/2006 Location: AustraliaPosts: 72 |
yeh sorry.. i mistyped.. i didnt mean to say 15.. it is 5m.. :) Steve |
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| Steve9R Regular Member Joined: 24/01/2006 Location: AustraliaPosts: 72 |
we're planning on pulling the mill down next week, and will be adding the braking mechanism to it.. Steve |
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Downwind Guru  Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
Steve, I will go out on a limb here and say i think you are tackling this backwards with mechanical braking compared to dynamic control with furling. Its a recipe for failure i think. There is close to 1000 mills on the forum here and the ones that are here year after year have good furling and the others come and blow away. The first thing in building a mill should be how you will control it for that 1 day a year freak wind when you are not there. Furling is the only self limiting system that is reliable. We all get high winds at some time regardless of what the average is. Some design facts on furling. (this will go against some designs) If you look at the mill without a tail then it will tend to rotate on the tower in one direction depending on which way the blades are set to rotate.(CW or CCW) If it swings to the left (CW) then the yaw bearing needs to be offset to the right The bigger the blade diameter the greater the offset needed. (2-4 inches should be enough on average) The idea is the tail holds the mill into the wind, and when the tail moves the rotational direction of the blades drives the mill out of the wind. Some mills are set up backwards to this (hence the furling problems) and relies on the tail pushing the mill out of the wind, in high winds this fails as the power of the blades screw the mill headon into the wind and the tail will waggle behind with no effect. This is also partly due to not enough offset on the yaw bearing and the forces causing a straight line effect back onto the yaw bearing as the mill only furls a few degrees and becomes locked into the wind. If the yaw is offset to the correct side of the mill the yaw will work well and will be a very soft action. Set wrongly it will be a much more violent action between kicking into and out of the wind, as you quoted with problems of the mill returning from a furled position. Pete. Sometimes it just works |
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