Bigger-box VAWT on real PM gen failed so far...

[DamonHD]

Well, I visited various local DIY/tool shops today, and now have nearly a grown-up haul of G-clamps, mallets, roofing bolts, etc.

The first thing I did was make a bearing for my PM gen so that I could build the rotor on top for a VAWT configuration.  Cunning use of a plank of wood, 2 G-clamps, and two angle brackets to grasp the flat on the PM gen shaft, etc.  It may not last but it is reasonably sturdy for experimental purposes and government work... B^>

This also for the first time allowed me to test when I might get cut-in to charge a 12V battery, using my analogue multimeter on 'AC Volts' across one pair of the delta-wired outputs.  My guess is at about 120rpm, which is probably just about do-able.

Then I attached my biggest-available box (from my scanner) to the PM gen, and cut the slots as for my smaller cereal-box rotor.

Then we put it out to face the wind, but so far, nada!

I'll put a little write-up with pics on my site later, if anyone is interested.

Rgds

Damon

[feral air]

I liked your trash can squirrel cage idea better, this benesh-box thing is kind of silly. It's not that hard to cut a pipe in half lengthwise and put it back together in an S shape. You're havin' fun though so don't let me rain on it...it's good to experiment. :-)

[DamonHD]

Fun, yes!

It certainly seems like this big box ain't working right now!  I'm going to try some alternatives (and a more windy day) to rescue it, but the small cogging is killing me at the moment I think.  I'm sure that it is ultimately usable.

I only remembered one comment about the squirrel cage idea of mine (negative), but if you think it is plausible then I'll happily revisit it.

For a few quid/dollars it is worth a punt.  Might even be quite pretty yard art.

Note that the Benesh box design was chosen for its extreme simplicity, because of my extreme ham-fistedness!

I'm not sure how best to do the dustbin transformation to tree-rat jail: is there a good general paper/URL on the design of these cages?  I am of course inspired by the PVC pipe version, and might try that at some point.

Rgds

Damon

[DamonHD]

Hi,

I'm doing a small write-up on today's (non-functional) fun with a few pictures (no videos, since this turbine remained stationary!) here:

http://www.earth.org.uk/VAWT-experiment3-scanner-box-and-real-PM.html

I'm still working on it now, so don't all rush in...  B^>

Rgds

Damon

[Norm]

Damon,

   To give you an idea of what you are up against

http://www.fieldlines.com/comments/2005/11/10/191155/99/2#2

as an example...I did a similar weight thing with

a stepper motor which took a 1.5 pound weight

traveling about 12 ft. in 10 seconds to light

this 2 led light at full normal brilliance.

 Now this light will shine with 4 AA batteries

for about 24 hrs. by that time the voltage has

dropped to about 5 volts.

  I built a VAWT this size:

http://www.picoturbine.com/PTDELUXE-cover.jpg

 It was 8 inches x 3ft. high it turned the stepper motor in a 10mph. just barely fast enough

to light the lamp about 2/3 normal.

  I think your turbine is just about big enough

to overcome the friction in your generator

bearings.   IMHO.

                 ( :>|) Norm

[feral air]

It might spin but you'll have to use a huge box to get anything out of it is what I'm thinking. I really do like the trash can idea but there may be a few things to watch out for (there always is)...

I would push on the side of the trash can to test its rigidity before committing, you don't want it too rigid or too flexible. If there's a taper on the can that could make it more difficult and I don't know how you would keep the flaps bent in. Oh, and water might want to collect in the bottom but that's easily fixed and it'll get pushed to the outer edge and spill out when the thing spins up anyway.

I wasn't (and I'm not) trying to be negative, just imagining pitfalls so you can avoid 'em if you decide to go ahead. :-)

CmeBREW's squirrel cage design isn't exactly easy to build. I made a little 8" diameter one with 8 blades (2.88sqft) and it works ok but none of the blades are quite the same size and it wobbles a bit. I had to scrap a couple of the "almost rounds" that I screwed up and I was cutting straight lines instead of 'humps'. I could spend several hours rearranging the blades to get rid of some of the wobble but..no. For people with our (lack of) skills this design is hard....just being honest here.

I still think you should try making a 'quick vawt'. The only thing you can really screw up is the pipe cutting, the rest is nuts and bolts. If you start by cutting it in half and it doesn't come out quite right you can always trim/file some material off - it actually seems to work better if the halves aren't really halves anyway. And even if it wobbles a bit it's going to spin like crazy compared to a box.

I've actually been tempted to get your mailing address so I could send you the pieces to one of my quick vawts but the shipping always gets me...not worried about the cost but the energy wasted to get it there - over the continent and across the pond, to Damon's house we go..heh..

I dunno, it'll be interesting to see how this box thing works out anyway. It does seem pretty easy to cut some holes out of a box and there ya go. take it easy

[DamonHD]

Remember that I made the toy S-VAWT which does spin.  The problem with the current 'big box' is not enough surface, too thick a shape, and a bit too much cogging, IMHO...

This is what prototypes are for of course.  B^>

If you have a link to plans/pics of the 'quick' design that you have in mind, it may inspire me.

And since I've now got everything set up, all I have to make to test new things is the rotor...

Thanks again for the thoughts!

Rgds

Damon

[feral air]

Not plans exactly but here's a post about it with pics...in my diary if it has 'quick' in the title, that's it. I can go into more detail if you'd like and get a pic of all the pieces before they go together...etc.

You've seen that post before but if you open up the second image in a new window you can see the bracket assembly more clearly...that might help.

[Norm]

Damon,

    Try something like this...but with 2 trash

cans instead of these buckets.( the rims are

bolted together).

 



   This bucket savonius is about 20 inches high

and 16 inches in diameter, it spins about 200rpm

or better in a 10mph wind (no load) and probably

has at least 5 times the torque of your box...

but I doubt if it could overcome the cogging of

your generator....but bigger like a trash can

will





    ( :>)Norm

[DamonHD]

That looks do-able if I don't run out of garden...  B^>

Rgds

Damon

[disaray1]

 Norm...you give great advice, I appreciate your posts. Thanks!

  Damon...ck this out

http://www.google.com/patents?id=7J0rAAAAEBAJ&printsec=abstract&zoom=4#PPA9,M1

 Looks alot like your box Sav with a few mods...who knows how well it does, but I found it interesting. A bunch of others here

http://www.google.com/patents?id=aN54AAAAEBAJ&dq=savonius

 Links compliments of Ed Lenz, Thanks Ed!

 David

[DamonHD]

Thanks for those!

Well, I shall try peeling back the main flats to approximate the deisgn in the first link, and may use the cut-outs or a bottle to make the inner rotor!

Rgds

Damon

[feral air]

Norm, I built a Sav. just like that not all that long ago but a bit smaller. I used a pair of those really thin black plastic containers plants come in...it was really flimsy (thicker planters would fix that) and came apart in a big storm but they sure do spin up quick since they don't weigh anything. It was pretty cool watching it destroy itself..that was half the fun.

..it should only take about 10 minutes to make the rotor...good idea.

[Norm]

Ah yes! Then these,





Look pretty spinning...I imagine 3 or 4 stack

would run an alternator like Ed Lenz's education kit.

 Then of course there is the coffee can one...it

looked like it would work, was easy to build

just coffee cans screwed to a square wood polebut it was a dismal

failure....no overlap.





         ( :>) Norm

[disaray1]

 Thats alot of coffee Norm. Here's my modified wing coffee sav...

 I keep changing it's profile to see what happens. Fun!

 David

[Norm]

Interesting....do you realize that connected

to an alternator like Pico Turbine (except with

magnets like Ed uses instead of ceramics) you

could be lighting maybe a White led?

   How would 4 or 5 stacked on top of each other

work?

 You've right that is a lot of coffee about 1

can a month...they keep piling up they come in handy...

   Is that 2 or 3 blades on yours? You just bend

the flaps away from the rest of the cans right?

   Guess I'll try that with a plastic Folgers

can!

   Thanks for the idea and inspiration.

             ( :>) Norm

[disaray1]

 I get a can about every three months...Doc said 2 cups a day max.

 Two blades on this one and a three winger on the bench. The latest profile, "M" shaped..

 kinda looks odd but works very well. The next two blade can will have the blades supported in the middle, instead of the trailing edge. Looking for lift.

 Still having good, cheap, wholesome and caffeinated fun.

 David

[Norm]

Yes supported in the middle would be sturdier

and slightly smaller diameter it might go faster

Have you tried the threaded rod and nut method

to see how fast it spins?

Once you get a good design and stack enough of

them on top of each other you would get enough

torque and speed to drive a small stepper motor

....really !

            Have Fun !

             ( :>) Norm.

[DamonHD]

I've tried pulling flaps inwards, and we have a little wind here today, but still no rotation of the big box even though everything else in sight has spun!

Rgds

Damon

[DamonHD]

Sample pic here:

http://gallery.hd.org/_c/mechanoids/_more2007/_more10/turbine-wind-small-VAWT-Benesh-squared-off-pro
totype-made-from-large-cardboard-box-on-real-Permanent-Magnet-PM-generator-11-DHD.jpg.html

Rgds

Damon

[Norm]

I've built your box type and I've built lots of

Savonius type out of buckets, plastic cups,and such....

I've come to the conclusion that they

work better and are easier to make than boxes....

no need to be good at making curves

 when they are already there.

  as in #8

          ( :>) Norm

[DamonHD]

Yes, well, I'm definitely up for trying out the dustbin version ASAP: thanks for the pic!

Rgds

Damon