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Forum Index : Windmills : Vawt...going in a big way
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mac46 Guru  Joined: 07/02/2008 Location: United StatesPosts: 412 |
Hey everyone, My daughter and grand daughter visited yesterday...first time they had seen the wings for the project. They were asking what I would name the thing? Honestly, I had'nt given it a thought. But this was inspired "from the land down under" and so I was thinking maybe I should let you guys come up with a proper name. I'd like to reserve the right to make the final decision, but you'r free to give it a go. This picture was taken yesterday morning just after sunrise, notice the blue skys...I think they were sent in from California, not sure. .....Mac46 I'm just a farmer |
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| mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412 |
And here is the wing after final sanding and shapeing...ready for the next step, "Fiber glass". .....Mac46 I'm just a farmer |
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Oscar4u Regular Member  Joined: 23/02/2011 Location: New ZealandPosts: 42 |
Hello Mac 46 looks like a giant eggbeater. Name it after your wife, a safe bet. What rpm do you think this will turn at and what are you going to power with it? Maybe I have not read your posts correctly but am very curios. What is the tower size? Would never have dreamt of making it like that, partially because pipe that size is hard to find. Cheers Oscar Oscar4u - for all your rotary cowshed repairs |
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| mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412 |
I used the woven fibberglass cloth, heavey guage, with the 12 min. epoxie. That means that you have 12 min.s to get it layed and satisfied after you mix in the hardener catilist."less in warmer conditions" I solved this problem by glassing 1/3 of one side of the wing at a time and proceeding on to the next 1/3 and right on to the last 1/3rd. You can see I have a few folds that did'nt lay down, no problem, just take you'r sissors and cut the top of the fold and it should lay right down for you. You'll need to clean the sissors right away or else you won't be useing them again. This was my first experiance with fibberglass and it turned out pretty well. Hint, make sure you have disposeable gloves on, and don't rub you'r nose. The stuff sets up rock hard and is sandable in a few hours. I was worried that it might warp the wing when it cured, but did'nt seem to shrink any. .....Mac46 I'm just a farmer |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
I hate fibreglass. Just thinking about it makes me itchy! 
To help answer your questions about blade numbers, look up vawt solidity in google. Its to do with the number of blades, and their chord width, and how it affects speed and power. The high speed Darrius and H wings use 2 or 3 very narrow blades, lots of speed and power, but hard to start and very little low speed torque. The Darrius needed to be driven up to speed before it would work. Something like a Ropatec uses very wide blades, starts easily and lots of low speed power. 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 |
Hi Oscar4u, The size is 24 feet from the floor surfice of the foundation to the top of the upper frame. The tube its self is approx. 5 feet 8 inches dia. x 13 feet 4 inches in height. It has 1/4 inch side wall thickness, and was salvaged from a steam boiler refit...was part of the old exaust stack. I don't know what rpm it will run for a given wind speed, I could tell you what the mathmatics says it should run at, but at this point it would be just a guess. I'm hopeing for 200 rpm with 10 mph wind, but would be satisfied with half that. It may surprise everyone and do better or it may do worse too. But you'r right it should have lots of torque. I'm think along the lines of 12 volt DC to charge storage batteries and also an air compressor to charge a 500 gallon tk. for the shop, but have'nt made final plans yet. The wings themselves are approx. 9 feet 6 inches tip to tip and 2 feet wide,(cord). .....Mac46 I'm just a farmer |
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| mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412 |
Hello Gizmo, Yes you are correct about the itchy itchy part, and the fumes can drive out a stabble full of horses, you want to have all the doors and windows open. vawt solidity...never would of "thunk", my serch skills are not so good, but thank you for that. I'll check it out. Thank you for the info. .....Mac46 I'm just a farmer |
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| Oscar4u Regular Member Joined: 23/02/2011 Location: New ZealandPosts: 42 |
Hello mac 46 could you cap the tower and use that as air storage? That would be 3500 galons or so? Suppose you want to house compressor and genie in there. Just a mad thought. Best wishes Oscar Oscar4u - for all your rotary cowshed repairs |
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| mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412 |
Hello Oscar4u, I suppose a person could do that but without the domed ends it would'nt be good or safe for handleing much pressure. I already have a 500 gallon pressure tank, so no need to go that route. 
Mac46..... I'm just a farmer |
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| mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412 |
Continueing with the wing assembly aspect of the post... Here is a real good picture of the GEO222 wing profile that I used. It is important to dry fit and check all the joints for binding and tightness, take the effort and make everything fit "just snug" and not tight, because later you'll be glueing lots of pieces together in a short time span. Believe me...you don't want to have to stop to make a proper fit on a few joints while the glue is drying on several other pieces next in line. Also, the glue will swell the wood slightly and make things fit even tighter than when dry fitted. You can also see the differance in thickness in the ribs I've set out in front for you to see, the thin ones are for the main wing, while the thick ones are for the attachment areas. Notice the grain direction, some books say to lay it at a 45*-while others say 90* for strength, depends on what the rib is made of and how the material reacts during compression tests, but basicly speaking its stronger when the grain is vertical to the cord of the wing. 
Mac46..... I'm just a farmer |
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| smithy Regular Member Joined: 30/01/2011 Location: AustraliaPosts: 52 |
I've used the GOE-222 wings that I purchased from Phil to make the following. http://www.youtube.com/watch?v=Dx3KtMqqLaA I called mine the AirBlenda, similar theme to the eggbeater concept. Mine is made from all aluminium including the blades. With a decent wind it really fly's around, some more mods to do on it before I grid tie it into the house but its not far from being finished. Mods are more to strengthen it and also the grid tie portion. I live in the city so could never even contemplate making it as large as your one. Also my blades look like they are angled in the video, but they aren't and are vertical, so its just a visual illusion. 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 |
Hello Smithy, I'm interested in how you't getting along with the vawt, I have'nt visited you'r link yet but I intend to. "AirBlenda", pretty cool name. I was interested to know about permormance of your's in a 10mph wind as this is what my average wind speed is. I've been logged off for awhile because I'm reserching info about vawt air foils and stress loading ect. But hey, thankyou for responding and thanks for the link. Some reserch I've done suggests that not much wattage can be obtained under 10 mph, while other studies say different. Mac46..... I'm just a farmer |
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fillm Guru Joined: 10/02/2007 Location: AustraliaPosts: 730 |
Hi Smithy, I fixed the link up for you , good to see you put your work up as well as it is a well built smaller VWAT http://www.youtube.com/watch?v=Dx3KtMqqLaA seeing what you have done with the ALU GOE222 is inspiring me to have a go one of these days. You said it is very silent , is the noise from the wind in the mic ? PhillM ...Oz Wind Engineering..Wind Turbine Kits 500W - 5000W ~ F&P Dual Kits ~ GOE222Blades- Voltage Control Parts ------- Tower kits |
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| mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412 |
Hello again Smithy, I just had a veiw of you'r link...Very impressive, does it have 3 wings? Spinning right along there, should be produceing some good steady power. Do you have it coupled to batteries, and if so what voltage? I'm going to have a second look at that vid. Thanks for posting. .....Mac46 I'm just a farmer |
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| smithy Regular Member Joined: 30/01/2011 Location: AustraliaPosts: 52 |
Yes it is a 3 blade unit, I did some experimenting with lift side facing inwards and outwards. I found that self starting (common problem with vawts) was better for this foil with lift side in, and toe in head out. It does however take a reasonable breeze (about 5m/s) to start the unit turning around. I suspect that with more foils (maybe 5) it will start better in lower wind speeds. I have fixed up a few glitches in the design since that video was put on youtube, and I'm now working on a Grid tie version. A bit trickier again, but what does one do in thebackshed over winter. And yes the unit is really quiet, the noise in the microphone was wind noise on the Mic. The VAWT is mounted right above my bedroom and I don't hear a thing at night time. The one in the video was hooked up to a 2*12 Volt batteries in series (i.e 24V). I wasn't measuring full output, but I know the PMA that I was using didnt put out more than 24V until it was going > 220-240 RPM. This VAWT was designed to only really go upto 350-400 RPM, more testing is required before I really let it loose in any serious way. Smithy "The answer my friend is blowing in the wind, the answer is blowing in the wind" Bob Dylan |
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KarlJ Guru Joined: 19/05/2008 Location: AustraliaPosts: 1178 |
Smithy nice one, I cant help but notice it air blending the obviously turbulent air. Any chance it can go up another 6m? In my experience higher = better wind less turbulence and hence longer life. I appreciate that the VAWT will handle turbulent winds better but nothing beats clean wind Luck favours the well prepared |
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| smithy Regular Member Joined: 30/01/2011 Location: AustraliaPosts: 52 |
KarlJ, Unfortunately being in the suburbs I am at the beck and call of the local councils. Is it designed to handle high winds yes!. One of the difficult parts was getting strong airfoils. Phil from this website provided some great airfoils that made my task a lot easier. Could I put it up another 3-4m.... yeh I could. Would the council then tell me to take it down. you bet ya. Right now I would like to fly under the radar of the local govt types. Locals walking the dogs, think its great and want more info, and would like to get one. But it does suffer from wind shadows in certain directions from other buildings, and also my solar panels certainly act as a deflector for NE winds (lucky I don't get many of them). Its the olde story keep your head down and it wont get chopped off. Phil's airfoils link http://www.thebackshed.com/windmill/Trade/AlBladeOrders.asp "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 |
Hello Smithy, 
I think you have a real working machine there,"without a dought". Like you say, a few minor adjustments here and there...grid tie, ect. and you'r set. (High marks) You may want to keep a note book of you'r adjustments, findings, thoughts, for later referance...lots of pictures seem to help too.(I have several) There's a engineering problem with scaleing up airfoils and the like, well accually several), Things don't always follow the same charicistis and have the same tendencies once their enlarged from small size to a large size. In fact they almost always don't, at least "exactly" anyway. What I'm trying to say is Thanks, you'r turbine is a big leap up off the drawing board, and into a real functioning machine, not an easy thing to achive. I would imagine some serious thinking was involved. "Thumbs up." .....Mac46 I'm just a farmer |
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| mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412 |
Alright...getting back to building the wing, For one thing, you know you will nodought be building more than a single wing, and ofcourse you'll want these wings to be the same size and shape in all respects. So, You need a "jig"... This way you can repeatidly make as many as needed, and be assured that they will be the same. Sometimes the jig is harder to make than the wing, certainly it must be as accurate as it can be with in reason. So take some time and plan this thing out, this is where you'r creativity comes in. Take you'r skills and talent and alittle imagination and put them to work. Its sorta like makeing a reverse mold for a casting. Keep it simple and durable. The jig in the picture took only took a short time to construct, but much longer to plan out ahead of time. So give it some thought. Also you can see the vertical spar stiffeners...connects the upper and lower spars into a "I beam", extreamly strong, and variations of this are used in wings worldwide. .....Mac46 I'm just a farmer |
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| mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412 |
Picture in you'r mind a very large and very heavy ship, a supper tanker or other large ship, moveing along in the ocean at cruseing speed. Ok, if I still have you...now picture you'r self looking down on this ship from high above, you can see the wake trailing the ship, spreading out as it becomes left behind. This is called "a ships wake", a series of waves if you will. Now think about wings on an aircraft and the air going over and under the wing as the aircraft flys through the air. There is also a "wake" or wave generated. This is what the geese fly on as they fly through the sky, and the wake propagates outward, hence the "V" formation. A differance in "pressure",and speed of the air..."turbulance". The first goose in the "V" formation is working harder because it must do the work that produces this pressure wave that the rest take advantage off. This differance is called "pressure drag", the physics people call this the dominate force of all the forces associated with drag created by a wing in flight. There is also "friction drag", "induced drag", and boundary layer, all to be considered. But, wings can and do generate forward thrust during certain and specific conditions. This is what is called "the wing is starting to fly", or move faster than the surounding air and wind. Its this force that spins our hawt's and vawt's fast enough and powerful enough to generate the electricy we use. Ok...class dismissed, quiz tommorrow. .....Mac46 I'm just a farmer |
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