Sunday's Windgen design - what do you think?
By Matrix1000, Section Wind Posted on Mon Apr 11th, 2005 at 02:14:43 AM MST
Well I've been reading some posts and got inspired...please critique my design.

Well I've been reading some posts and got inspired and came up with this design. It's pretty simple, it uses a 2' O.D. pipe and a 2 1/2in O.D. pipe and some steel disks for the stator mount and magnet mounting plates. A case hardened rod runs the length of it through the center of the pipe. There are bearings on each end and everything is held in place by bar clamps. I'm thinking of using 3 blades up front and either 3 or 6 in back, Im not sure yet but I need to keep the rev's high. I used Aluminum 2024-T4 flatbar standoffs so that the rear blades could flex back in high winds as a way to furl it. The reason for this is because I was reading a couple posts that indicated that the inner third of the blade accounts for only 11% of the energy gathered by the blade. (also noticed that the 'Whisper' mills do this also) Also the standoffs move the blades out of the wind shadow caused by the front blades. The combined power of all those fast blades with more surface area I thought might drive a more powerful generator so I added another stator and mag plate. (let me know if you think it is overkill or would be a good idea) The side mounted tower pipe also allows it to furl a little to the side to give the rear blades a better shot at clear air and with the combination of the rear fin might furl it sideways in high winds.  It kind of works like a dart where the big rear end pulls the thing straight so it faces the wind. The rear fin besides helping direct it into the wind, smoothes out the turbulant air that hits the tower pole before it goes through the blades. I could go on but heres a pic, Let me know what you think, 'before' I build it :) Thanks :) Click on it to get a large detailed view.

Sunday's Windgen design - what do you think? | 12 comments (12 topical, 0 editorial)

Re: Sunday's Windgen design - what do you think? (3.00 / 0) (#1) by Matrix1000 on Sun Apr 10th, 2005 at 08:19:51 PM MST (User Info)

Sorry, Try this link for a larger 'clearer' view Also heres a pic of the aluminum

Re: Sunday's Windgen design - what do you think? (3.00 / 0) (#5) by windyknight on Mon Apr 11th, 2005 at 01:36:50 AM MST (User Info)

If you are going to have two mag plates/stators wouldn't they be better one each side so that flux 'shorting' between plates (instead of going thru copper)is avoided? Weight balance would also be better at centre point yaw bearing Just when you think things can't possibly get any worse- they usually do! [ Parent ]

Re: Sunday's Windgen design - what do you think? (3.00 / 0) (#2) by hiker (hiker.wild[at]yahoo[dot]com) on Sun Apr 10th, 2005 at 09:26:32 PM MST (User Info)

there is a post here somewhere--one was built using microwave mags--dual stator,, from what i remember it put out some good power.......... WILD IN ALASKA

Re: Sunday's Windgen design - what do you think? (3.00 / 0) (#3) by domwild (domwild at hotmail dot com) on Sun Apr 10th, 2005 at 09:46:36 PM MST (User Info)

Interesting idea. The long thin shaft may whip and may need an extra bearing in the middle. What sort of props are you thinking of? Material? Why not have a vertical fin at the top for smoothing in addition to the lower one? No doubt you realize that there is no furling, so you must brake this setup somehow unless your props are inefficient anyway at higher RPM and are not going to run away. dom There is one thing money cannot buy: POVERTY!

Re: Sunday's Windgen design - what do you think? (3.00 / 0) (#4) by TERRYWGIPE (GIPEFAMILY@CS.COM) on Sun Apr 10th, 2005 at 11:24:45 PM MST (User Info)

It looks like a cool design, if you could figure out a furling system,also why not a second gen on the other side?              Terry

Re: Sunday's Windgen design - what do you think? (3.00 / 0) (#6) by wooferhound (tim((NoSpamAt))wooferhound.com) on Mon Apr 11th, 2005 at 06:58:56 AM MST (User Info) http://wooferhound.com

I don't understand why ther are 2 props ? W o o f -={(

Re: Sunday's Windgen design - what do you think? (3.00 / 0) (#7) by kitno455 on Mon Apr 11th, 2005 at 07:10:42 AM MST (User Info)

dont bother with the second prop. the first prop is going to chew up the air near the root especially, and unless you have a masters or better in aerodynamics, you are not going to be able to figure out how to size and shape the rear blade so that it turns at the same speed as the front one. basically, one blade will be trying to turn faster than the other, and the slow one will be acting as an airbrake, not a windmill. put your force into your alternator, not spinning another fan. put six inch longer blades on front prop, and it will work better. i did see a big one that worked this way, but all blades were the same, and they had a huge space between them. also, it has no furling system at all. allan

Re: Sunday's Windgen design - what do you think? (3.00 / 0) (#8) by PHinker on Mon Apr 11th, 2005 at 07:37:31 AM MST (User Info)

Actually, ballparking this would be pretty easy.  Let's say you set up the front blades with a TSR of 4.  Benz says that the most you can take out of the wind is 60% (I know, it's 59.3 but we're ballparking here).  If the wind's blowing 10 mph and your front blades are good but not great (slow the wind 50%) then the downwind blades should see a windspeed of 5 mph or so.  So, front blades TSR 4, downwind blades TSR 8 should give you a good place to start at least.  Also, if you set the downwind blades up to 'cone' you can get some decent furling for free. Paul [ Parent ]

Re: Sunday's Windgen design - what do you think? (3.00 / 0) (#9) by kitno455 on Mon Apr 11th, 2005 at 07:49:05 AM MST (User Info)

nah. the betz equations assume smooth air. turbulence and screw caused be the font blades throws this completely off. no point in even trying. also, how is flexing the rear blades going to cause furling if the front blades are fixed? the fronts will overspeed, and the centrifugal psuedoforce will keep the rear blades out. the best you can do there is that the rear blades will act as a drag on the fronts, but i doubt that will stop overspeeding. again, this thing has no furling. long thin shaft like that between your flapping airbrake and your over-speeding blades? fatigue and broken shaft within the first couple gusty storms. allan [ Parent ]

Re: Sunday's Windgen design - what do you think? (3.00 / 0) (#10) by K3CZ on Mon Apr 11th, 2005 at 09:05:15 AM MST (User Info)

MATRIX: As a long-time practicing engineer (now retired) I thrived on a basic principle of KISS (KeepItSimpleStupid).  Given that philosophy, is all the complexity going to really gain you anything??  Seems to me a basic Pigott machine extended to the size range of the latest Dan's machine would be a lot less work, and deal with parts readily available off the shelf (ie: hub, bearings, etc.)  It would seem to me a route to the power level you a looking for with a lot less risk of some feature not working well enuf over the long run.   Just some of my thots.                                      Van      K3CZ

Re: Sunday's Windgen design - what do you think? (3.00 / 0) (#11) by PowerShower on Tue Apr 12th, 2005 at 04:45:33 PM MST (User Info)

What about these guys idea. They claim they can produce the same power for less cost. Maybe there is something to the multiple rotor thing but I think it may be difficult to scale up to large commercial units. Ray

Re: Sunday's Windgen design - what do you think? (3.00 / 0) (#12) by jimjjnn (jimjjnn at yahoo dot com) on Tue Apr 12th, 2005 at 05:15:42 PM MST (User Info)

The way I look at it. Nothing ventured, Nothing gained. I say "GO FOR IT". Have fun doing it and learning at the same time , what works and what doesn't. You have a group here that can help. I like the diagram except for the extra set of blades. Have to set your 2nd set too far back to get out of the turbulence the front set is creating. Lengthening it will be more complex and make it too heavy. I like the quad mag plates and dual stator idea. Could give you a lot of power. Jim Denver,CO

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