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Forum Index : Windmills : Coroflute Blades
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| Xmaswiz Regular Member  Joined: 14/04/2011 Location: United StatesPosts: 69 |
Mac, in the VAWT wings use the abrupt end as the leading edge when it is being forced in to the wind. The folded over bend is the trailing edge on the vawt. So I am asking how you would close the corrugated ends? Noel Santa Maria, CA. Noel |
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MacGyver Guru  Joined: 12/05/2009 Location: United StatesPosts: 1329 |
Xmaswiz I'm pretty sure that's not the way it works. The wings or blades "fly" in either a HAWT or a VAWT. I never heard of them going backwards. Are we both on the same page here? There are two basic types of VAWT machines; drag and lift type. The drag type just immerses a blade arrangement in the flow of the wind and things turn much the same as a paddle wheel. Those 55-gallon drum (Savonius) rigs do it that way. The "lift" type actually present an airfoil to the oncoming wind. Some of these have to be started with a mechanical means while others are self starting, depending on how the blades are arranged in relation to the wind front. When it is in "lift" mode, the blades or wings actually "fly" and create more lift than would be present were the blades just sitting in the soup (wind flow) twisting about an axis. This is due in part to their aerodynamic shape as well as what is called "apparent wind" which as I've explained somewhere else around here and is a result of the blades' momentum reacting to the oncoming air and creating lift. Does that make any sense? . . . . . 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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| Jarbar Senior Member  Joined: 03/02/2008 Location: AustraliaPosts: 224 |
Mac, I think Noel is meaning when the the blades go upwind the opposite blade is going downwind and the trailing edge is exposed to this airflow.But as as blades are theoretically going faster than the down wind speed they are leaving the wind behind not being pushed by it. 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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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
Jarbar Oh, of course. I'm a little slow sometimes. But you're absolutely right; unless the thing is a drag-type machine, the blades will be traveling in excess of the wind speed and that trailing edge won't matter. Thanks for the nudge! 
. . . . . 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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Poss Newbie  Joined: 27/09/2009 Location: AustraliaPosts: 30 |
Norcold, Bunnings sell Coroflute A brave man may not live for long, but a careful man does not live at all. |
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| Xmaswiz Regular Member Joined: 14/04/2011 Location: United StatesPosts: 69 |
Jarbar got what I was trying to say. I want a way to close off the rib opeings in the corflute. it would be a lift style - 3 blade VAWT. by the way did you have to drill extra holes in the mole-chaser hub to fit the plades on to it? Santa Maria, CA. Noel |
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norcold Guru Joined: 06/02/2011 Location: AustraliaPosts: 670 |
Poss, Next time I`m near a Bunnings will grab some Coroflute. Actually found a sheet 2400*1200(only 1/8 thick)amongst my junk, believe it came as protective packing on pallet of aluminium sheeting. Many thanks Poss. Vic We come from the land downunder. Vic |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
[Quote=Xmaswiz]I want a way to close off the rib opeings in the corflute. I can't imagine why you'd want to go to the trouble, but you could fill them with glue, if you wanted. 
. . . . . . 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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| Xmaswiz Regular Member Joined: 14/04/2011 Location: United StatesPosts: 69 |
Mac, what is the smallest blades you have ever made with corflute? what would the ratio of length to width be for a blade that is only 1 foot long? as you can tell I know almost nothing about airfoil information. Santa Maria, CA. Noel |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
Xmaswiz Marcello Jacobs was a wind-power pioneer and he always used a "tapered" blade. To that end, that's how I now build my blades too and the smallest ratio I've used on a 4-foot blade is 3" @ the root and 2" at the tip. I suppose a 1-foot section could be cut out at the tip end that would serve your purposes. I hope you intend mounting that small a blade on what is termed a "stand-off". A stand-off is a little post that couples the blade to the hub, but the actual "blade" part is mounted on the post several inches from the center of the hub. The amount of power that can be derived from the wind is directly proportional to the "swept area" therefore, the farther from center the blades are, the greater the swept area and the more power there is available. Make sense? To answer the other part of your question, the smallest blades I've used to date are about two feet long. Here's a Hot Link to my Youtube page and you can see some small (not tapered!) Coroflute blades in action. . . . . . 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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| Xmaswiz Regular Member Joined: 14/04/2011 Location: United StatesPosts: 69 |
Mac, thanks for the info. I actually plan on using them in a very small disk drive motor in a VAWT fashion. 2' seemed very long for the small motor. Santa Maria, CA. Noel |
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mac46 Guru Joined: 07/02/2008 Location: United StatesPosts: 412 |
Mac, I've looked over you'r post and I must say it brings back memories of long ago. I never had cloralite, but I enjoyed the model planes as well. Nice,informative, and well documented post. Happy belated birthday. I was wondering who or where you send payment for the blue skys...been raining and cold here for 3 days. .....Mac46 I'm just a farmer |
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| Xmaswiz Regular Member Joined: 14/04/2011 Location: United StatesPosts: 69 |
Mac, one thing I din't see in the 1st page was how thick the spar was you used for your blade. It looks like it's 1" wide, but I couldn't really get the depth from the pics. Have you considered making a small PDF file to link to for the basic creation of your wing? thanks Santa Maria, CA. Noel |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
Xmaswiz The spar I used was just a piece of "clear" (no knots) pine molding about 1/4" thick by 1/2" wide. I chose that, because I wanted to incorporate it in a small airplane wing and I wanted it to be able to withstand many "Gs". I chose wood because CA (cyanoacrylate) glue sticks to it and the plastic bonding both pieces almost instantaniously. The spar can be any dimension you want. Ideally, it should be thick enough to allow bonding between itself and both upper and lower sections of the wing or blade your are building. Since the entire wing or blade is so light, the thickness of the spar doesn't add much to the overall weight of things. I've never built any blads or wings longer than 4 feet, because that's how wide the sheets of Coroflute are when I buy them. The corrugations in the sheets run the length of the 4' by 8' sheets and since you fold the wing or blade against these, the widest it can be is 4 feet. I suppose you could use multiple blade sectionss all glued to a single spar if you wanted to build a ginormous blade, but all my builds are tiny, so for me it is not an issue. . . . . . . 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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Perry Senior Member Joined: 19/11/2009 Location: Posts: 190 |
Hey MacGyver, Nice post. I think that you are losing some performance due to the doubled up coroflute at the TE. You can get a lot of vortices here which will create drag. You really want that TE to be a knife edge. Crazy thought but I wonder if you could use an iron and thermally deform the TE after gluing. Just find the right temp and iron it to a knife edge. At least a free experiment and I know you like to tinker. Perry |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
Perry Welcome back! As you know, all I build really are toys, so I was never much concerned about the trailing edge (TE). I'll try the iron thing; if it helps, maybe we could call it "Perrying" the trailing edge, eh? I have an iron somewhere that I used to use to apply "monocoat" fabric to glider wings. It's Teflon coated and only gets just hot enough to burn the hell out of your arm when you forget it's on and lean against it! I've got the bug again to go back to building air-pumping windmills. My grndson is 4 1/2 and has taken to my little steam and air engines, so I said I'd build him some more. I'm going to use an "oscillating" engine as both an air pump and an end-use engine; should be fun. Nice thing about a "wobbler" is the valving surface is ginormous and holds lots of lubricant, unlike most other valves that are used on air and steam engines. Right now, I'm finishing up a pumper that uses a swash plate to drive a double-acting air pump up the tower. I'll post the build when it's flying. Thanks for the reply. . . . . . 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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| Xmaswiz Regular Member Joined: 14/04/2011 Location: United StatesPosts: 69 |
These three I just made today will be going on a (very) small axial-flux generator. The magnet wheels are only 4 1/2 inches in diameter, using 6 pairs of 1" N52 neo magnets and a new stator design I cooked up (details when it works!). I expect this little windmill to turn around 500 rpm no load! . . . . . Mac Mac Have you made the little axial-flux genny yet? interested to know if it worked? Santa Maria, CA. Noel |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
Xmaswiz Yes and no. Yes, it's done, but now I've got the bug to make it into a single-phase, skein-wound alternator that will merely drive a light; something to fly over my land yacht and give the neighbors something to talk about. I'll post pictures when I get around to making up my mind. . . . . . 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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| norcold Guru Joined: 06/02/2011 Location: AustraliaPosts: 670 |
Given this UK web address- mugi.com.uk. Looks like coroflute or very similar. We come from the land downunder. Vic |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
norcold It's the same stuff. In the States, we call it coroplast, which is an abbreviation for corrugated plastic. In Australia, it's called coroflute and that's what I call it, since most of the folks I share with here are down under. . . . . . . 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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