quick vawt

[feral air]

Here's a couple snapshots of a small vawt I made a few weeks ago. Total build time was less than an hour and it consists entirely of scavanged/on-hand materials. You could probably build a dozen of these for around $50 if you bought the parts retail, assuming some part-substitutions.

I had intended to hook a small dc motor to it but got distracted and abandoned the idea - it's fine as an ornamental. It could use a roof piece though so that the bearings don't rust more than they have already.

The vanes are made from 6" PVC pipe, and are about 18inches long. Someone had drilled holes down the length (homemade perf-pipe? I dunno) of the pipe so the vanes aren't exactly semicirclular. The bearings are from an old pair of inline skates. A couple hose clamps, some old cantilever breaks for the support arms...yada, yada..

Pretty rough but it spins like crazy...

[gotwind2]

Looks remarkably similar to mine I made a couple of months ago, and did actually conect directly to an ametek 30v dc motor.

http://www.fieldlines.com/story/2007/8/27/122329/221

I agree, great as an ornemantal spinning 'thing' but very little power could be made at such small dimensions in my experience.

Got to go big with VAWT's or live in a coastal (v.windy)location I think.

Ben.

[feral air]

I dunno, it sure looks like there's a lot of potential there. At least a watt or two, probably more if you spent some time coiling, casting and all that jazz. I'm no good with that kind of stuff though, unfortunately.

I think your vawt failed because of the shaft and the direct connection more than anything (sorry!). If you had an unobstructed air gap like mine does and geared it up to a smaller motor you would've had a hit. It also helps to have bearings on either end so it can deal with high winds. Also, the lighter the better - that plywood on yours didn't help matters.

I agree though that at these sizes they aren't big producers. But they're cheap and easy to make. If you had some surplus motors of the right size...I could see being able to make a 50+ over a weekend if you were set up for it.

I think you could easily go to 3ft long vanes using the same design. An unobstructed air gap makes a huge difference but making it too tall would make it flimsy. A larger diameter would be better too, maybe a 10" pipe instead.

I guess I need to revist the idea of mating a motor to it. I've got one about the right size but the pulley on it is too small...hmm..

[gotwind2]

Hi feral air.

There is an air flow gap at the axle of the blades, as suggested by a few guys here.

I can imagine a well made axial flux alternator mounted horizontally would produce some power in the right location, A cutin at maybe 100 rpm.

There is plenty of room to mount the coils on the 10" diameter base plate - this would have to be made of steel obviously, and maybe settle for a single rotor setup.

This would be a great DIY solution if it could be made a reality.

Ben.

[feral air]

A reality like this one?

He says at some point, either there or in his alternator instructable, that he got 78volts out of it once but (as I only skimmed) I didn't see if he gave a watt value or the volts&amps. 78volts at .1 amps wouldn't be impressive, afterall...that'd be just 7.8watts for the math-challenged...but apparently he's charging a pair of 12v deep-cycle batteries.

The wood adds some heft that I don't like and his looks a tad flimsy to me but that's what inspired me to build mine.

[DamonHD]

Just a thought: where wind direction is fairly constant (eg alongside a long wall, etc), why not put a drag-style VAWT horizontally at 90 degrees to the flow like a carpet beater.  Would that work?

Rgds

Damon

[feral air]

Excellent question...

It does work but balance is more important and you can miss out on a lot of wind that way. S-hawts can spin a bit faster than S-vawts though too because you can easily block the side that shouldn't be catching the wind.

There's a building in Chicago(?), I think it is, that has a huge "vawt" (a drag+lift combo) mounted horizontally on the roof. IIRC, the building was actually designed to channel the prevailing wind through it. I heard about/saw it on a tv show here a few weeks ago.

Darn fading memory, I wish I could remember for sure what city it was in or the building's name.

[feral air]

Sorry GW, I was just re-reading that instructable's comments and it looks like you already knew about that one it seems. In a reply to you(?) he gave up numbers for his first 9 coil alt design; 13v at 0.7amps, or 9.1watts.

That's not too bad right there and no doubt he improved it with his second alt. I may have to tryr making an alt for mine, that's too freakin' awesome.

His pipes were only 3ft tall and the weight, who knows. A 2 footer without the heft could probably put out 10watts then. WAG, of course...but even 5watts would be neat because a well designed and built 2 footer would be pretty darn portable.

A little 2ft vawt for camp lighting or accessory charging...that'd be too cool.

[DamonHD]

Dead right it would be kewl!  And it would be half my base load...

Rgds

Damon

[feral air]

I put it back up on the fence post last night and got treated to a blur (which isn't unusual, really). It was spinning so fast I couldn't count out the rpm with any kind of accuracy but it was easily more than 300, though probably closer to 400.

Since the vanes aren't half circles I wonder if that's making a difference. I also wonder if how they're mounted is better or worse...look carefully at the vanes where they attach to the "U" bracket in the first pic...

Most s-vawts I've seen don't overlap quite like that. If you pulled a string through a typical (cylinder-based) s-vawt the string wouldn't have to bend much, it'd basically be a straight line. If I pulled a string through mine the string would bend a lot more noticeably, both in the center and at the outer edges.

It rained last night and is misting this morning. As soon as it clears up I'm gonna see if I can't get a video of it running. I don't have an anemometer but I've got a piece of ribbon that's "calibrated" to show when the wind hits 8mph...I'll see if I can get that in the vid too.