Mini 200

[windstuffnow]

  This one started as thoughts of a small, reasonably powered, lightweight wind turbine.  I also wanted to combine the prop hub, magnet disc and bearing hub into one unit to keep it simple.  I also wanted to keep it simple enough to change stators and try different magnet layouts.   Then I decided it should have adjustable wing mounts for different blades. I also wanted to incorporate a built in assembly jig where all the parts will jig each other to make the assembly super simple. So one thing lead to another and this is the end result...

  It weighs in at 15 lbs as mounted on the tower, complete with furling system.  I'm using Jerry's blades uncut and the little unit does a modest 200 watts.   Below is a picture of the unit assembled...

 

  The small but quite sturdy head assembly...

  All the parts cut and ready to assemble the unit...

  This unit doesn't have the adjustable wing angle installed.  The parts are cut just not assembled as yet...

  Lots of fun!   Another of the dozen or so projects out of a million idea's...

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[Jerry]

Great work Ed.

Could you list the specs of the unit in the picture? What was the wind speed at 200 watts?

How about a photo of the genny from farther back. Like to see the complete genny to get a feel for the size.

Thanks Ed.

                         JK TAS Jerry

[windstuffnow]

  I'm not sure of the rpm it was running but my wind speed indicator was reading 24-28 mph making 200 watts.   The alternator is simply another 8 inch, single rotor air core.  

  It starts charging in fairly low winds, I could drop a few turns per coil and get some better performance out of it.  I wasn't really looking for efficiency in this unit, simply a base to experiment with, somewhat "universal" and simple to change.  

  There's no doubt it could produce considerably more power by changing the windings.   I'm using #18 wire in this one, 16 would boost the output considerably.  Just a fun simple project that's easy to modify.  

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[nothing to lose]

Well that is certainly a very nice looking unit/kit there.

And I like the barn with the big fan. Is that for summer cooling or your wind tunnel

Great work!

[hvirtane]

How big Lenz turbine would you need to get the same power?

- Hannu

[wayne]

Nice job Ed and looks like a nice turbine. Are you selling these as kits or just one of. What is the cutin speed if you know.

Thks

Wayne

[windstuffnow]

Hi Hannu, A 3ft x 4ft would match the output of the mini200

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[hvirtane]

A 3ft x 4ft would match the output of the mini200

So I think that with a little development a vertical axis machine could beat that horizontal axis in price?

- Hannu

[windstuffnow]

  Well I'm not sure about that Hannu, There are a few more components needed in a Vertical than in a Horizontal but I'd bet you could get pretty close...  I'll be working on a small Lenz2 by the end of the month and one of my goals is to reduce the amount of materials to make a safe vertical machine... we'll see how much I can take away from it...

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[hvirtane]

Have you tried to make a Lenz turbine of a drum?

You might do without rods to hold the vanes, just leaving a part of the drum uncut.

You also might try making it with skewed vanes...

- Hannu

[windstuffnow]

  I've seen your cute little can turbine before Hannu, I would imagine it screams in the wind.  I've played with various set ups including skewed or offset rotors.   I found that you don't gain anything by doing so and sometimes you actually loose.  As an example I tested 4 sections of a Savinous which formed an 8ft tall by 2ft diameter turbine.  If they were all in line the torque was significant with a very noticable torque pulse but tended to run a bit slower.  With the 4 sections offset slightly where only one section lined up in the wind at a given time the torque pulse went away.. but .. the torque was equal to the one section and more continuous.  It didn't run any faster and the overall output was pretty much the same in the same wind.  

One of my tests included 3 Lenz wings.   As they are mounted normally on one turbine they follow the same path.  The turbine wing was 2ft tall on a 2ft diameter.  I wondered if you separated the wings, alowing them to fly in their own space but increasing the area they flew in if that would actually increase the output in proportion to the added area.  So instead of a 4 sq ft turbine it would fly in a 12sq ft area but your only using 3 wings ( less materials ).  In theory, you would think if you tripple the area you should tripple the output.  Any thoughts on how this one came out?....

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[hvirtane]

I've played with various set ups including skewed or offset rotors. I found that you don't gain anything by doing so and sometimes you actually loose.

You are probably right that you don't gain much in power. At least much experimenting is needed to find out the right shape. But I think that the structure is much easier to make strong this way. If the blades are curved there is some structural strength in their form to resist them flexing? That seems to be one of the main ideas, why Gorlov water turbines are made a similar way.

I made one model about 1 m tall and 30 cm wide of a PVC pipe. I used screws to fix some of cut off materials to make J- curves for the blades and an angle grinder to smooth the shapes. Unfortunately the pipe was made of quite thick material and really heavy. It would need quite a storm to move...

- Hannu

[bug bit]

"In theory, you would think if you tripple the area you should tripple the output.  Any thoughts on how this one came out?...."

I think it would have no power and run very slow?

How did it come out?

Brian

[windstuffnow]

   As far as starting and running it did great, I was disappointed to see only 1.5 times that of the original 3 blade configuration..  So although it actually did a bit better the efficiency dropped considerably.  It would be much easier to construct a normal turbine with slightly larger diameter to get the same power.  

   My thoughts were, at the time, comparing it to a HAWT with one blade.   If you built 3 of them each would run in it's own wind (area) you would achieve 3 times the output.  

   I've built a couple single wing Lenz2 turbines that do very well with the exception there are a couple spots where it simply won't start.  So putting the two together simply seem'd logical at the time.  Yes, it was an odd looking thing, it was simply someting that was stuck in my head and I had to get it out.  I did it, learned something and moved on...

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[hvirtane]

I think that vertical axis wind machines are quite difficult to understand theoretically. Probably much experimenting is needed to get them working well.

I don't think that we still understand even hawts correctly, so with vertical axis wind machines... we'll have lots of problems. But in the final end they'll maybe work very well...

I'm looking for something symmetrical with that skewed blade rotor. From every angle the wind will see it the same way. On the other hand from every angle the wind will push it turning. The next step is to get the wind pushing it as well as possible...

- Hannu

[Ungrounded Lightning Rod]

As far as starting and running it did great, I was disappointed to see only 1.5 times that of the original 3 blade configuration..

You have to scale up the blades when you expand the sweep to get it to scale with the swept area.  Just moving them apart lets slugs of air slip through without being decelerated - and loses any interaction between the inner surfaces of the blades.

[windstuffnow]

  That was my conclusion as well,ULR, by using the same blades the solidity dropped considerably allowing a large portion of the energy to slip through.  It was an interesting experiment and I learned a bunch from it.  However, I wasn't compelled to build one that might work better.  I might build another single wing VAWT though... it's such an odd duck that it's simply comical to watch it run.  

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[Spdlmt150]

After seeing 60 watts max in very strong winds from my motor conversion (part of the problem is myself limiting to a 6 ft rotor to keep from scaring the neighbors - stalling bad - maybe a raca candidate? plastic stator & rewind?), I am thinking the axial design is the way to go for wind power. Any more details available on this "mini"?

I am curious as to what mags, coils, laminates (or lack of) were used on it. If you care to share details, I would be quite interested in the workings of the mini 200.

I am working on a mini 12/9 dual rotor with half inch square mags, half inch gap, probably 4 ft rotor. No idea yet what I'll get from it (I can cad model the assembly, but not the performance), but it's fun building it. My ideal setup is 2-3 smaller mills. I figure something will fail eventually, & I'd prefer it to be a percentage of what I have running. Where I live, I have to keep things smallish, otherwise I'd be working on a 20 footer.