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Forum Index : Windmills : Wind mill help
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| Gary Newbie  Joined: 02/04/2010 Location: United StatesPosts: 14 |
I have a question i was hoping that maybe someone would have an answer to. I bought some blades from WindMax they run great when they arent under a load as soon as i hook up my PMA motor they won't turn at all under winds up to 20MPH. there isnt a whole alot of drag maybe a oz at most. I am using a 40 HP treadmill motor 90vdc @5.4 amps, and also using the pulley system with a belt that was on the treadmill I thought that may be there was too much drag with pulley and belt, my ratio is good I thought 1:4 the blades turn 1 revolution to the motor 4 revolutions. I would really be interested in somebodys ideas Thanks Gary Gary2010 |
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| windlight Guru  Joined: 03/03/2007 Location: AustraliaPosts: 331 |
Stall from overload! Gary tell us the blade length, the battery or load voltage,motor rated RPM and 40HP? allan "I like this place and willingly could waste my time in it" - (Act II, Scene IV). |
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niall1 Senior Member  Joined: 20/11/2008 Location: IrelandPosts: 331 |
hi Gary i also bought some of the windmax blades a while back...mine had a very unusual airfoil ...curved on both sides of the blade which seemed to suggest a low start up torque....adding this (if similar to yours) to a geared set up might be problematic they may perform better in a direct drive setup.... i:4 step up needs a lot of extra torque ...ie bigger blades the ideal ratio is 1:1 ....pullys , gears can be a big drain on the prop what size blades were they ? ps....thinkng a lot more about it ...i erm... kind of like Garys gearing up idea .....not wanting to open a can of worms or anything like that ...  niall |
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| Gary Newbie Joined: 02/04/2010 Location: United StatesPosts: 14 |
I do believe that the motor runs at 4200 rpm, the blades are 6' 8" span or 3' 4" a piece. Niall, my reasoning behind not using direct drive is because the shaft of the motor is only 1/4" and running that big of blades would bend the shaft or the drive. Yeah it does have a unusual airfoil. Thanks alot of your guys input. Gary Gary2010 |
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GreenD88 Senior Member Joined: 19/05/2009 Location: United StatesPosts: 104 |
hmmm How I have a similar setup except I use real Crappy PVC blades pretty close to the same diameter as what you got. Using a 1:4 ratio too mine spins great and starts up at around 11mph. And I have a 115VDC 9 amp ~5600rpm Treadmill motor on it using the original Belt too. You have the blades on the right way right? Only a couple things I could think of that would cause a problem, either you have your belt way to tight, wires shorted out, bearings to tight(How do you have the blade shaft and bearings setup?). Be nice if you could post some pictures. And that motor is less than 1HP Licensed Master Plumber / EPA 608 Universal License / 410a Safety Certified / Medical Gas Brazer/Installer |
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| Gary Newbie Joined: 02/04/2010 Location: United StatesPosts: 14 |
Greend88, My setup is a 2 1/4 pipe with 2-ecentric bearings on each end.The bearings are a little tighter than I would like.According to the distribtor that's the way they are. Next I'll use a regular roller bearing.The belt isn't tight at all,and as far as the wire shorting out I haven't hooked any wires up yet, just a run test to see if it works right.I'm hoping that tomorrow I'll be able to post some pics for you. Thanks again, Gary P.S Does anyone know of any suppliers that has pulleys? Gary2010 |
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MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
[Quote=Gary]P.S Does anyone know of any suppliers that has pulleys? Try Here . . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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| GreenD88 Senior Member Joined: 19/05/2009 Location: United StatesPosts: 104 |
With those kind of bearings if you don't have them perfectly square and straight or if your mounting system can twist any it would bind up pretty bad I think. With it on the ground how much effort does it take you to spin the blades by hand? Licensed Master Plumber / EPA 608 Universal License / 410a Safety Certified / Medical Gas Brazer/Installer |
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| Gary Newbie Joined: 02/04/2010 Location: United StatesPosts: 14 |
Not much at all,I did make sure that they were exactly square to each other so there wasn't any binding that way. The bearings are just tight according to the supplier.Like I said I'm gonna change those bearings out for something else.I will have to lower my system down...it is only 10ft up in the air. I have to get someone to help me lower it. Yeah talking about doing this,it is always nice to have someone helping me...the other day I got my thumb pinched between 2 pipes that were telescoping. Needless to say it took quite a bit of meat off my thumb! Thanks, Gary Gary2010 |
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| Gary Newbie Joined: 02/04/2010 Location: United StatesPosts: 14 |
GreenD88- I guess I misread the motor as you can see...it is a .40 not a 40..... here are some pics of it... Thanks, Gary 
Gary2010 |
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Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
Its not an over large motor for the blade set you have and with a 1:4 step up ratio it will take 4 times the wind speed to start it compared to a 1:1 ratio. Any cogging effect or drag will 4 x greater to overcome. Looking at the photos it dont look like a 1:4 ratio. Pete. Sometimes it just works |
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| niall1 Senior Member Joined: 20/11/2008 Location: IrelandPosts: 331 |
hi Gary... those blades do seem very similar to the ones i had....if their the same batch they probably have a fairly high tsr and minimal twist ...unfortunately this isnt going to help their start up much even with just hub bearing drag higher tsr blades can take a couple secs to get going...not much grunt in there till their up to their ideal speed maybe try 1:2 as an experiment ? ...feel her out a bit niall |
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| GreenD88 Senior Member Joined: 19/05/2009 Location: United StatesPosts: 104 |
Just curious have you tried it without the belt on? Start up easy? Without a belt on it, it should start up with the slightest breeze. With my blades I started out without anything hooked up to them and they would start spinning in 3mph wind. Maybe you could cut out some PVC blades and compare the performance of the two? Try more blades it will lower the overall speed but trade it for more torque. Licensed Master Plumber / EPA 608 Universal License / 410a Safety Certified / Medical Gas Brazer/Installer |
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DTV004 Regular Member  Joined: 30/04/2009 Location: United StatesPosts: 65 |
i have the same blades the don't work. you have to have hi wind all the time ..ps:try from pvc pipe |
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ChrisOlson Regular Member Joined: 19/01/2010 Location: United StatesPosts: 60 |
Those WindMax blades are a knockoff clone of these: http://www.magnet4sale.com/Wind-Generator-Blades/ The PowerMax blades use an S809 airfoil and I have three sets of them flying - an 8 and two 10's. They have excellent startup (<6 mph), reach max torque around 18 mph wind, and run in stall at 24+ mph. They run at a 6 TSR starting at ~10 mph wind and hold that up thru 18 mph with the appropriate generator, then drop off to about 5 TSR by the time they get to 24+ mph. My 8 foot with these blades will make 600 watts @ 20 mph without even breathing hard. The 10's will make about 1 kW at that same wind. All three machines running dual rotor axial generators. Assuming they (WindMax) copied the S809 airfoil correctly, the shorter version (6.8 ft) should run at a 6 TSR well below 20 mph. Since yours won't run I can only assume you have them too heavily loaded - the 6.8's should be running at 175 rpm before the generator cuts in. Hope this helps -- Chris off-grid in Northern Wisconsin, USA |
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