Wind turbine

A personal-use clone of the Turby would be nice.

If I were to make one, I would fabricate a mold for an airfoil that is, let's say, 250 cm tall and includes 12.5 degrees of rotation along a helix 1 meter in diameter. I would then cast twelve airfoil sections out of polyurethane foam, and assemble them into the three vanes of a Turby-style turbine. I would then cast some kind of FRP around the foam, maybe fiberglass/polyester compressed with electrical tape. Add some galvanized pipe, bearings, a dynamo, and some power electronics, and you have reliable renewable energy.

I don't think I'll do this, but I wanted to share the idea, in case someone else does.

Turby technial brochure:
[www.turby.nl]

We could make a 1:10 scale model of the turbine, but 250cm is HUGE!!!. Nice idea though.

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Jay

Making a mold for a 250 cm airfoil building it by extruding thermoplastic traditional RepRap style would take a very long time.

The two quicker ways to do it would be by CNC-routing the mold out of foam sheets, or by building up foam, and then CNC-routing it, as in:
[forums.reprap.org]

But if we've built a CNC router of that scale, we might as well machine the foam cores directly, maybe.

I personally wonder how to build a large scale CNC router using a RepRap. I'd go along these lines: build up the molds, and then fill the molds with epoxy+granite:
[forums.reprap.org]

Edited 1 time(s). Last edit at 05/26/2008 08:13PM by SebastienBailard.

SebastienBailard Wrote:
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> Making a mold for a 250 cm airfoil building it by
> extruding thermoplastic traditional RepRap style
> would take a very long time.

Not necessarily - All you really need to extrude is the surface, with some very sparse infill beneath to maintain its shape. I don't think it would take an impossibly long time to accomplish that.

Actually, one way you could try to build parts of the a mold would be to RepRap a sort of scaffolding*, and then glue down a sheet of mylar or other material for the top surface.

You now have a mold. Well, half of the mold.

Variation:
Coat the mylar with release agent, then build up a layer of fiberglass or some such. Then pop off the fiberglass and use this for your mold. There's a tricky bit here, where the scaffolding+mylar part would be the positive, and would include the space for the airfoil, so that the fiberglass would have a void. (Need a picture here, really.)

Then repeat for the other fiberglass mold-half.

*perhaps including some steel rods for strength, or some such.

There is a simple airfoil that can be cut from PVC pipe of the correct size.

See: [www.fieldlines.com]

How about a windbelt? [www.ecogeek.org] You could build one similar to how a Darwin's constructed. Use threaded rod for the length, making it adjustable. The only parts you'd need to fab are the end blocks.

Windbelt's been done. Too complicated and the vanes are going the wrong way half the time. To counteract that, you have to add even more complexity and end up will dozens of bearings and hundreds of parts. There was one up on the altamont pass in calfornia till it disintregated. Along with a few other exotic vertical axis windmills that met the same fate. Lasted only a few years and fell into disrepair.

The more traditional horizontal axis ones seem to survive if they are maintained.

KIS IMHO

A Windbelt has 0 bearings.

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Jay

Perfect for RepRap-ability. We need one--or 100--of these to power our repraps! Any takers?

Demented

Maybe I should investigate a windbelt instead of shooting from the hip.

I was assuming a windbelt was something like a conveyer belt on its side, with the belt made up of airfoil segments of some kind.

Built a small vertical axis windmill around '77 about 5' or so in diameter but it just about destroyed itself in a storm.