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Forum Index : Windmills : Vawt...going in a big way
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Rastus Guru  Joined: 29/10/2010 Location: AustraliaPosts: 301 |
Hi Mac46, I have a habit of miss understanding things,but I thought Greenbelts figures showed you are virtually on the money as far as your test run went.23-24 rpm from the wind you had,and at guestimate of 30 it was showing signs of maintaining speed.I might be looking at the half full glass not half empty but I think you must be close!Cheers Rastus see Rastus graduate advise generously |
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mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412 |
Rastus, and Everyone, Hello, and thanks for the comment...I think that it is like you say, "close"....... I have'nt had time to experiment with it today, But I agree, "it" was trying to go. VK4AYQ suggests takeing the load off while starting it and Thats what I need to do to see what happens. Other posibilities would be to spin it up to speed with a electric motor. There is some drag on it from the belts and gearbox, by eliminating this it just might spin up on its own. When I first put the wings on and did a quick test it was trying to start on its own, but that was before all the rest of the belts and pulleys, bearinging, alternator, ect. were hooked up. I'm pretty busy with other things right now, so it might be a few days yet. ....Mac46 I'm just a farmer |
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| Air Bender Senior Member  Joined: 25/01/2011 Location: AustraliaPosts: 206 |
Hi Mac46 Im just wondering how hard it would be to remount the wings around the other way the same as Smithy is running his with the front angled out. Iooking at your wings i thing that your leeward wing is powering while your windward wing is stalling, which will happen on any vawt with wings that arnt symetrical, but this is not a problem if the powering is stronger than the stalling. Looking at your mill you have quite a bit of structure in the centre so the leeward wing is getting a bit of dirty wind while the windward wing is in clean wind so i thought it might be better to have the windward wing powering, this will proberly become more relevent if you add more wings to it. All the best Dean |
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| mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412 |
Air Bender, Everyone, ...I did go out last night after my last post, took along a stop watch and a red piece of tape. Spinning it up by hand as fast as before yielded only 13 RPM, not 30 as previously stated. So that was a major malfunction on my part.(Sorry). Last nights winds were approx. 5 MPH, WSW with a few higher gusts and also a few lulls to near zero MPH. I then removed the first drive belt...as soon as I had the belt off it started to spin on its own. I then fiddled with different angle settings of the wings and concluded that the 3 degree setting, (inward at the nose), was indeed the optimum setting for self starting. I then hand spun it to 13 RPM and it continued to spin at this speed for approx. 8 to 9 minunets, (did'nt have a timer on it), and then finely stopped. It stopped because of deminishing winds...0 to 3 MPH. Dean, as far as turning the wings outboard...I can't because of the mounting groove is built into the wings under side. I could flip them end over end and spin the other direction, but I can't turn them crown in, not without doing major surgery on them. A good suggestion and one worth studying. So there is a glimmer of excitement and hope, winds are still deminished this morning so I won't be able to do any testing. ....Mac46 I'm just a farmer |
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rissole Newbie  Joined: 10/05/2011 Location: AustraliaPosts: 15 |
Hey Mac, don't get down hearted, you have achieved a fabulous thing here and inspired many of us all around the world. you will look back on this time now as a minor hicup and just a bit more learning. I dips me lid to you! (there is a chance that my project will see its first wind this week-end thanks in part to guys like you) well done mate! Rusty |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi mac On the larger mills I found that the 5 blades started better than four blades, I tried 6 but no significant improvement. With the high efficiency blades like you are using they need to be at or above TSR of three to work, below that they are virtually stalled, you could improve the starting a bit by fitting vortex generators on the leading curve of the blades, this allows another 8 degrees of rotation in an unstalled state, so it goes from 16 degrees to 24 degrees. I found a SV rotor on the top was the simplest way to go as it is a drag type rotor it worked from 0 rpm up, the mill still needs to be unloaded to wind up and fly. I did try a air conditioning clutch of a 2 cyl compressor to disengage drive at lower speeds it worked OK but was too small for heavy loads. All the best Bob Foolin Around |
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shawn Senior Member Joined: 30/03/2010 Location: New ZealandPosts: 210 |
Still following your build its a machine I would like spinning outside my shed, if it spins ok without all those horable belts I think a direct drive huge air gap alternator might be the go, no resistance untill she gets a good spin up were all the power is anyway, keep the chin up its just teething problems we all get them. shawn |
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| mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412 |
Hello Everyone, Another busy day on the farm so nothing new about the mill except I let it spin freely all day. Winds were below 10 mph, I thought that it might be good for it to exercise the main bearings, "sort of start the breakin process," and limber things up a little. It looks kinda nice from out in the field, I was within 1/4 mile of it , never did get over 30 rpm but did spin most of the day, winds dropped off by late afternoon. Lots of good info from you guys...thank you for that, and the incouragement too. I'm looking for a electric motor, and I'm also thinking about going back into wing- building, thinking about building 3 more wings...only smaller with a 16 inch cord. I have'nt tested enough yet to determine what would be best. (Lighter wings would be the ticket I think). ...Have a good day, Thank You all for posting, ...Mac46 I'm just a farmer |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Hi Mac Have you tried it without any belts, just the brake in place so you can pull it up? This type of machine should spin like crazy, even in light winds, but it needs to get up to speed, where lift starts to act on the blades. I remember seeing a Junkyard Wars build once on TV, a VAWT like yours. To get it started, they wound a length of rope around a pulley at the bottom of the turbine, and then a few of them pulled on the rope has hard as they could to spin it up/ Once going, it sped up faster and started making power, grinding coffee I think. Also, ever seen the movie Water World. The trimiran had a Darrius turbine built into the mast. To get it started, the sailer ( old Kevin Costner ) connected up a battery to a motor, which started the turbine spinning. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412 |
Hello Gizmo, I currently have all of the drive belts disconnected, It spins much better but fails to speed up much, but I have'nt had any wind to speek of lately. I think you'r correct, it needs to be spun up to the point where it starts flying. I was really hopeing the wings would come out lighter than they did, and I think this may be part of the problem. 51.3 pounds each x 3 with the mounting hardware...thats alot of mass to spin up. I missed the tv shows you'r refering to. Thanks for posting. ...Mac46 I'm just a farmer |
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| mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412 |
VK4AYQ, Interesting that 5 blades would start better than 4, but the 6th. blade did'nt make a significant inprovement...stands to reason that 5 blades would also be better than 3 blades. The way my rotor is set up I'll need a total of 6 blades enorder to keep everything in balance. I was thinking perhaps 3 SV blades, one inbetween each existing wing might be worth trying. I also thought about makeing up some shot wings...about 1/2 the height of the 3 I have now, and with less cord and very light weight. I also have been thinking of a electric motor to spin start it, or a air starter motor off of a semi even. I do have a spare starter motor for the bulldozer. rissole, Best of luck with you'r project, I'll be looking for it here on the forum. Thanks for the "well done mate", makes me feel welcome, like I'm one of the guys. shawn, Thanks for the suggestion on the direct drive alternator, I've been thinking about that very same thing. It would be a huge improvement over the belts and pulleys that I have now. Everyone, Raining again here...need I say more. Thanks for you'r interest. ...Mac46 I'm just a farmer |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Mac There is an ideal density ratio for blades that comes into play along with the Reynolds number of the blades, this from memory was more critical at low speeds and starting, unfortunately I have lost the information I had on the combinations so am not a lot of help on the efficiency side of things. Six blades worked good but wasn't significantly a better starter than a five blade so you will be OK there, the critical part is to get the blades up to flying speed, the wide cord blade is OK better starting, due to higher Reynolds number. The SV rotor is a better proposition as it works all the time if you are with it not. As long as you can fit it without to much trouble. I like the idea of the axle flux because of no applied load at start up so no need for clutch starting, a dream for one day in the future. All the best bob Foolin Around |
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| mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412 |
VK4AYQ, Thank you for that information Bob. Right now, before I do anything else, I need to hook an electric motor up to it and get it up to speed,...see what happens, do some testing, it might just be ok the way it is. ...Mac46 I'm just a farmer |
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| mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412 |
Mac46...just checking in, I'm still here, I'm sure there are more than just a few members and guests waiting for an up date. I still have no progress to report, very little time has been devoted to the mill lately, lifes been getting in the way. I want to fabricate some new mounting brackets which will allow the wings to be adjusted to the "outward direction" at the nose- or leading edge. I found that 3 degrees is the sweet spot, but I have'nt been able to adjust the wings any further past that direction because of the brackets. I'll need a full range of adjustment anyway for complete testing. Thanks for stopping by. ...Mac46 I'm just a farmer |
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| smithy Regular Member  Joined: 30/01/2011 Location: AustraliaPosts: 52 |
Hi Mac46 As you know I also use GOE-222 air foil (just not as big as yours), and I am looking at 5 blades instead of the current 3 to assist in the self starting. The 5 blades will increase the lower wind speed torque of the unit but decrease the upper end RPM (its a trade off). Also I have found that sometimes just straight upscaling from a small VAWT to a large VAWT is not as simple as straight multiplying of the dimensions, so the adjustable blade angle mounts will assist in defining the sweet spot for your VAWT. I certainly found with my AirBlenda (refer to my AirBlenda thread) that nothing was happening until I moved the blades into the sweet spot, and then she kept tugging and just wanted to spin. Smithy "The answer my friend is blowing in the wind, the answer is blowing in the wind" Bob Dylan |
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| mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412 |
Smithy, Thank you for joining in with you'r comments. Yes this is very true...simply makeing something bigger in phisical size does change the preformance, ...mass to size ratio changes for one, and areodynamics change due to the larger wing surfaces to wind speed ratios for another. A 2 foot scale model in a 10 mph wind will be completely different to the same model scaled to 10 foot, in the same 10 mph wind. I am certainly thankful for takeing the time to fabricate and install the "storm clamp locks", and finely, "the breaking system." I have had frequent strong storms this spring and early summer, I don't think the mill would have survived without them. Its like Grandad told me along time ago...you can go down a hill to slow for ever, (refering to driveing a loaded truck), but you only go down to fast, "once". Grandad did'nt pass along any wisdom about wind turbines, although he did have a Wind Charger and batteries many many years ago. Haveing a home based power system is something that is returning to many rural areas once again. Thanks for you'r comments. ...Mac46 I'm just a farmer |
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| mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412 |
Up date, I have fabricated and installed the new wing brackets. I tested the wings at various angles, but the wind was out of the SSE 5 to 10 mph so I'm in a dead zone again. I did get just enough wind now and then to be able to tell where the mill likes them set. I took a 4 foot "T" square out with me and a measureing tape, I did'nt have any of the three wings set the same...they are now. I did'nt have much time to play today. ...Mac46 I'm just a farmer |
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Greenbelt Guru Joined: 11/01/2009 Location: United StatesPosts: 566 |
mac46, Thanks for the Update. Understand no time to play, This year doesn't seem the best when trying to get the crop in.-----Cheers, Roe Time has proven that I am blind to the Obvious, some of the above may be True? |
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| mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412 |
A quick up date... For a min. or two I had the thing "flying"...........So, It does work after all. I was to excited and happy to be frightend by the wings wizzing right by my head, The wop, wop, wop, wop, wop, of the wings going just inches from my head. It finely sunk in that it was acually starting to fly, and I climbed down off the ladder. I don't know what rpm it reached before the wind changed direction and the show was over. But what a show!!! This is how it happened. The wind was out of the SSE as it has been for the last 4 days but every now and then I'd get a wind change out of the SW and with it was a fairly hard sustained gust of wind about 20 to 25 mph. I went up the ladder and hand spun the mill to around 13 to 14 rpm and kept it there spinning - waiting for that SW gust of wind to come back again, and when it did I gave it all I had and spun that thing up as fast as I could. It was like putting you'r nose right up to the mixing bowel and haveing the mixer switched to high speed. Now mind you, I did'nt have the belts on the drive line, so it was'nt pulling against anything or produceing any power, just the main rotor shaft and bearing. I also cut the hole through the side wall and installed the 2" conduit, or at least the part that goes through the wall anyway, and set the batteries on the shelves...nothing is wired up yet. ....Mac46 I'm just a farmer |
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| Jarbar Senior Member Joined: 03/02/2008 Location: AustraliaPosts: 224 |
Encouraging news mac46, been following with interest.Great to see some results from all your hard work,keep it up. Anthony.  "Creativity is detirmined by the way you hold your tounge".My Father "Your generation will have to correct the problems made by mine".My Grandfather. |
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