2 stage Savonius?

[Norm]

   A lot of us are in a location much like

Rotornuts...and have come to the conclusion that

small VAWTs in turbulent areas are the answer:

http://www.fieldlines.com/poll/1118937724_adntvKuh

   I've also noticed that stepper motors would

work pretty good if they would spin faster

than a wind turbine will spin in a 5 or 6mph wind.

   I've posted this concept of a two stage VAWT

a couple of times ...and it's either slipped by

everyones attention or they just don't understand

....or whatever....

   Anyhow a reply from a few friends would be

appreciated...

               Thanks Guys!

                 ( :>) Norm

[ghurd]

Hi Morm!

Not sure they would need geared up,

or even very complex.

Sometimes the simplest PVC type go

fast enough to blow themselves up.

Probably depends on the stepper,

and I'm still having no luck

with 12V 0.1A out of any stepper.

G-

[ghurd]

Sorry- NORM.

I can't really type.

Or spell.

G-

[Norm]

 How fast do any of your steppers have to spin

to get 12 volts?

  I seem to recall that you have better luck with

6. volts ? and you get you get closer to 1 amp at
   
6. volts?
   
   

  1 stepper at bottom and 1 at top then hooked in

series? The motors don't support the VAWT you use a couple of roller blade bearings.

        A small diameter VAWT but long blades!

should spin very rapidly even in a 5mph. breeze!

   An air brake like in the Winchargers? had?

to limit the speed...in case we happened to get an 8mph wind? LOL!

   BTW lot of times I think we are getting a good

wind ...take out the good ole windguage and get like 7-9 on it!

  Also BTW  That little fan I gave you just happens to

turn about 1 rev. per ft.

                 Have Fun!

               ( :>) Norm.

[Norm]

  Yeah....Norman the Morman  eh? LOL!

[Ungrounded Lightning Rod]

Tip speed is proportional to wind speed (though a bit below it).  So the smaller the faster.  Narrow ones get up to hysterical speeds.  (As ghurd points out, if you make it narrow enough you can get all the shaft speed you want.  Then make it tall for power.)

But for a given wind speed / tip speed the smaller the radius the higher the centripital forces on the mill.  VAWTs tend to have long unsupported spans so a small one has to be STRONG - or have extra cross-bracing - to avoid tear-apart.  (Fortunately the square-cube law is on the other side of the battle.)

If your site has wind from a prevailing general direction and you have a lot of stepper motors you could make a row of narrow VAWTs and combine their outputs.

[finnsawyer]

Mount a steel ring or flange around the base (say 5 feet in diameter).  Engage a 10 inch diameter tire against it and use the tire to drive your alternator.  Voila, a 6 times increase in rpm with not much loss.  I've been suggesting the tire transmission for some time, but no one seems to want to try it.  The beauty of the thing is that the tire can be tensioned by its own air pressure.  If the tire is mounted inboard of the ring, the contact area is increased and the distortion of the tire is decreased for the same foot print.  Hence less flexing and lower losses.

[ghurd]

Well, The best stepper I have for 12V is a 8.6V 25ohm, 99 cents.

It gets like 150 or 200ma at 6V, about 60ma at 12V if its really spinning.

I have a little tiny stepper with a 1" wheel on the shaft.

It gets past 50VAC running it down the table edge.

It would be great for a 3 or 6V Nimh pack, about 100ma to either.

It puts almost 20ma into a 12V battery.

Most of the maybe 30~40 different kinds here make 12V open,

but only 3 to 25ma into a 12V battery.

Yes, I bought them all for wind power.

Nameplate ratings have nothing to do with what they will make.

In the last 3 days, I got 2 types of 24V 3A steppers.

BIG dollar stuff. Maybe 3 pounds each.

One makes 0.09VAC open (NOT a typo).

A 5 wire.

Connected it every which way too,

not just like it should.

The other makes 4.1VDC rectified open,

and 4A short. Only 3 wires.

Didn't connect it to a 2 AA Nimh pack,

seemed a little extreme on the amps.

BTW, it is 3 phase star (wye) wired.

G-

[Norm]

  Replys acknowledged answer all later....

  gotta go for now....thanks for your replys

               ( :>) Norm.

[ghurd]

Guy getting 12V half amp with any old stepper

out of any old printer are doing better than me.

G-

[Norm]

Finsawyer,

I've been suggesting the tire transmission for some time, but no one seems to want to try it. ....

   Just haven't got around to it yet. But plan on

trying it as soon as I get the savonius flying.

The beauty of the thing is that the tire can be tensioned by its own air pressure

  One more thing that I have been suggesting

is automatic tensioning, if you have the tire so

it is on the end of an arm ...so that the tire

will pivot into the ring and the tire just barely

makes contact...the faster it is turning the more

load to the generator or alternator the more tension is applied auto matically so there would

be just enough tension to prevent it from slipping at any speed.

   Every little bit helps when it comes to using wind power in areas like here!

               Thanks again for the suggestion.            

                   ( :>) Norm.

[Norm]

Cross-bracing Like an AOL disk?

(You'd be optimizing your high-speed VAWT?)

....they gotta be good for something?

If your site has wind from a prevailing general direction and you have a lot of stepper motors you could make a row of narrow VAWTs and combine their outputs.



....or stacking them if the wind blows ever which way?

  I've seen the wind blow in 4 different directions in as many seconds!

                Thanks for the comments

and suggestions ULR !

                  ( :>) Norm.

 

[electrondady1]

i've been paying attention fin and i think the idea is sound . how about this , use four or six small motors beneath the circumference of your big disk  the idea is to eliminate guy wires or upper support bearings . use the multiple motors as support bearings

[RobD]

Here's the VAWT I built awhile back from my own magnets. It's easier starting then the steppers.

I held it out my car window at 65+ mph (Not highly recommended, by the way!)

<BR><img src="http://www.otherpower.com/images/scimages/28/Sav_10.jpg" width=80%><BR><BR><img src="http://www.otherpower.com/images/scimages/28/alt_1.jpg" width=80%><BR><BR><img src="http://www.otherpower.com/images/scimages/28/alt_2.jpg" width=80%><BR><BR><img src="http://www.otherpower.com/images/scimages/28/alt_3.jpg" width=80%><BR>

[RobD]

Wooopppps!!

Try this with a little HTML added!

[RobD]

Here's the core before I encased it in auto body filler. when I was done I removed the aluminum locater disc

[Norm]

RobD,

    What kind of performance did you get at

65mph or was that just to determine the safety

factor?  (that would be a 6.5 for around here)

  Nice little machine

    Well actually what is the rpm in a 10 mph.

wind?

              ( :>) Norm

[RobD]

I wanted to see if it would blow apart. It didn't! The picture is the first prototype of the structure the final came nicer and it was the one that held up in the wind.

I don't remember now what the power was but I just spun it in my hand attached to a peak reading volt/amp meter and it showed 5.05 volts peak and in the current mode 760ma. Not bad for a one lb.(15.8 ounces actually) machine.

I'm doing something on the scale of 1 foot diameter with three 120 degree offset mills on the same stack that should be fun.

The thing is I can knock these off quite fast even with a well built alternator especially since I'm not running a furling system. I did develop a partial furling system that blocked the mill at high speed but my high speed tests were so favorable I skipped using it.

I think the trick is to make an alternator with a diameter almost equal to the blades. Not necessarily a high power alt. but a high speed one to make up for the slow VAWT. Using a lot of magnets and small coils to keep the resistance down.

I do like playing with the VAWTs they allow so much more experimentation then the HAWTs. I guess if you just want a standard design that works go with the HAWTs. But I think I can make more mills cheaper without the furling and sleeve bearings to keep the HAWT from getting hung up. Less parts less problems.

I've always thought you could put up several mills and get good power instead of one big one. When you have one big mill and it fails you're out of luck when you have five small ones you still have 80% of your power with one down.

Just my two cents. I know lot's of people like big mills but for experimentation small mills are better. Less materials, less time to make, easier to mount, test and modify too. I think a three or four hundred watt mill is a nice size.

[Norm]

    RobD,

      I'm with your line of thinking 100%...

it's so quick and easy to make little models

with old free cd's and plastic cups the three

stack at 120 degrees was one of my favorites with

half overlap...stacked about 9 cups high...think

I'll go back to experimenting with those again..

trying to make one that'll spin these little

hobby motors...stepper motors...car blower motors

...which was where I was going with the two stage

deal...but now I'm convinced that a simple

VAWT will work just as well....

         Thanks for all the input!

                   ( :>) Norm.

[finnsawyer]

This certainly would work and the rig needs to be supported.  The problem is you now have the cost of six motors or alternators vesus one.  On the other hand you now have a highly redundant system.  The tires could be running between two disks or rings and allowed to carry all the weight as they track reducing the need for expensive bearings.  The motors could be mounted at the hub with shafts out to the tires.  The motors would turn with the hub as the mill turns.  Slip rings would be needed to bring the current down.  For a large unit this might be the way to go.  Interesting.