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Forum Index : Windmills : wing shapes available?????
| Author | Message | ||||
| itsandbits1 Regular Member  Joined: 13/08/2010 Location: CanadaPosts: 81 |
------------------------------------------------------------ -------------------- I developed these wings after looking unsuccessfully for a suitable shape and posted in the classified a request for information anyone had on any blades/wings that are available on the open market as opposed to proprietry, so that any one looking for a ready made unit could pick and choose the location and type of wing/blade they were interested in trying out if they did not want to make it themselves. The reason I am posting here is that I am sure there are more than two types available; and I would like to document them so that anyone wanting can easily find one. it would give people a choice of a tried and true profiles to bolt on to various types of machine; whether it run in air or water or some other medium as we leave this planet. I have found 2 so far, 1 in Germany, 1 in Australia, any other listings? These are my wings flying on a test vawt 45" dia x 42" long My test vawt 1 |
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Big Al Newbie  Joined: 06/10/2010 Location: United KingdomPosts: 38 |
I analysed my first months wind logging this w/e -disappointing and I don't understand how they can be as low as recorded altho October was n't a typically windy month. Well the leaves are off the trees now and we'll see what November brings. I'm certainly going to build something having got the bug. I will post the results however disappointing but will wait until I have November's figures partly because I'm pretty busy trying to fix a shaper 1000 miles away by email (not as crazy as it sounds -I got spares I can ship). To get to the point I'm probably going to need a good wing (for good read miracle ) and reading so far has lead me to thinking around an S2027 profile (which is non-symmetrical ). Two questions--- what led you to a symmetrical profile ? I can see if the wind blew straight thro to the downwind side symmetry would be good but as the wind is modified by the windward side before acting on the downwind side is symmetry a good thing ? Second question is how tough are those wings ? They look a bit fragile.Is the secret that they bend with the wind instead of fighting it ? This mill seems to start in next to nothing winds (just what I got for October ). I guess by now you must have had a really strong wind hitting the mill and it seems to be still in one piece . Rgds. Big Al Every Day is a school day (even at 67) |
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| itsandbits1 Regular Member Joined: 13/08/2010 Location: CanadaPosts: 81 |
a lot of good questions Big Al, the reason I picked the symetrical is because of the pole stresses, the sims Steve at [http:www.vawt.net] did on a lot of different profiles showed the real power of the syms. The asymetrical only have it on one side and if you watch the sims you can see the way the vawts actually get lift all the way round if they are sym. thats why I say with the right blade you need to count 360 degrees in the power calculation.I know the speed is not there but the torque is in the 120-350 rpm range. the wings are made of foam with a 30thou skin of aluminum sheet and they are tough but I would use something more durable for long term. I think some light cedar or pine or a extrusion of aluminum. The mounts are what really take the strain. The wings have survived 100km wind gusts and this is because they are so sensitive to the wind that most of the wind gets turned into rotationand then harvested again at the back side. You can see it quite clearly in the simulations. I really can't judge a blade by the look because some of them just won't start and others just barely do, and some start well in sims but in real life they do nothing so its a matter of doing what I did if you want to make your own and make them simpl out of foam and aluminum or something easy to form so you can try a few. Vawts are a tough breed to get started and once you get them going you might not get much out. I'm hooked on them though |
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| VK4AYQ Guru  Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Itsandbits I have a set of coordinates for a airfoil I used in the past with success on a large VAWT it is a symmetrical airfoil of the non critical laminar design it was designed by my engineer, who was an aeronautical engineer, it is not self starting as most foils that are high efficiency are lift force foils not drag force airfoils, that start reasonably easily but do not produce as much power. The efficiency can be increased by around 10% by adding vortex generators, not practical on cord width of less than 12 inches. I used a SV rotor on the top of the main turbine to spin it up. Let me know if you can work from coordinates and if you would like to use it. All the best Bob Foolin Around |
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| itsandbits1 Regular Member Joined: 13/08/2010 Location: CanadaPosts: 81 |
thanks Bob for the offer but what I was wanting to list here was units that are up and runniung and a person can buy, I don't care if they are made privately or commercially but some place a guy can get a good start. If you pm me the coordinates though I'd be happy to look at them and if you want to post a picture here or; scale drawing, telling a little about the blade;like chord length, thickness,mount angle from the chord to the mounting arm, 90 degrees being 0, in your post along with how it performed, that would be great because as you may know there are a million airfoil shapes and most of them are designed to be pushed with power,not to get it. Lloyd |
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| itsandbits1 Regular Member Joined: 13/08/2010 Location: CanadaPosts: 81 |
here are a couple of listings that I came up with wing shapewindkraft ecokraft the back shed homegrown power technik chrome (fixed the links. Glenn) |
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| itsandbits1 Regular Member Joined: 13/08/2010 Location: CanadaPosts: 81 |
thanks again Glenn |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi This is the airfoil we used with good success blades 20 ft long by 24 inch cord. Station %cord :- upper lower 0.000:- 0.000 - 0.000 0.250:- 1.090 - 1.090 0.500:- 1.527 - 1.527 0.750:- 1.856 - 1.856 1.250:- 2.367 - 2.367 2.500:- 3.268 - 3.268 5.000:- 4.443 - 4.443 7.500:- 5.250 - 5.250 10.00:- 5.853 - 5.853 15.00:- 6.681 - 6.681 20.00:- 7.172 - 7.172 25.00:- 7.427 - 7.427 30.00:- 7.502 - 7.502 Main Spar at this point. 35.00:- 7.440 - 7.440 40.00:- 7.265 - 7.265 45.00:- 7.000 - 7.000 50.00:- 6.655 - 6.655 55.00:- 6.240 - 6.240 60.00:- 5.775 - 5.775 65.00:- 5.190 - 5.190 70.00:- 4.540 - 4.540 75.00:- 3.817 - 3.817 Rear spar at this point 80.00:- 3.053 - 3.053 85.00:- 2.290 - 2.290 90.00:- 1.537 - 1.537 95.00:- 0.760 - 0.760 100.0:- 0.000 - 0.000 The blade wasn't self starting it used a small SV rotor on the top to get it moving the blades where set at 8 degrees helix angle to make it run quieter and the second improvement was fitting vortex generators at 5% cord station spaced every 3 inches along the blade, this gave about 20 percent extra torque. We used 6 blades on a 10 foot diameter mill, it ran best at 120 to 135 rpm. All the best Bob Foolin Around |
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