Author Topic: "Squirrel Cage" VAWT progress !  (Read 18930 times)

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CmeBREW

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"Squirrel Cage" VAWT progress !
« on: October 05, 2007, 01:19:02 AM »
The following are the two "squirrel cage" Vawts I've been working on lately. I think they have alot of promise. Even though they are my own specific design, squirrel cages have obviously been around forever. I have seen one made out of sheet metal, but never 4" PVC "drain/sewer" pipe and 3/4" treated plywood. I quarter saw ripped the 4" PVC pipe with my table saw. So thats 4 pieces per pipe. Each piece is only 3 inches wide. This is 'solid' wall pvc, so it is very 'bendable' and "snaps back" well, which is nice.

The first two pictures are of the small Prototype Vawt-- it has 12 blades and is 18" diam. x 39" high. I really like what i am seeing so far from the testing!







The normal generating rpm range of it is (or;will be) 200-600 rpm. Right now it is attached to a high rpm treadmill motor , so it does not reach 12v cut-in to generate useful power. I may or may not make an alternator for it. It was really only the test prototype. I kept the wires 'shorted' and the rpm looks to be the same as when I allow it to freespin! It just survived what had to be at least a 70mph wind during a terrible thunderstorm last week. It kept perfectly steady and as straight as an arrow and was probably going 1000 rpm with the wires shorted together!! It was AMAZING as I watched the whole thing happen from the window. So it probably has twice the torque of my 4' hawt in the 100-600rpm range. When I short my 4' hawt treadmill motor/generator, it takes over a 40mph wind to turn it!!(or;to break it free from stop and/or stall)







And now... comes the pictures of the 'Real' one. I have named it the "VERTIGO -SC/100".

It better do at least 100 watts! It has very nice torque.





It is mounted to my small trailer hub alternator. (But the Stator is not done yet. Monday, my wire will FINALLY get here, and I will make the stator!!)

It is the same quarter sawed 4" PVC as the prototype. It is 2 feet Diam. x almost 5 feet high. (2" less than 5', because the 10' long pipe has a 'flaired out' 4" part on one end. I cut that off.)

So it is technically 4' 10" high. There is NO center pole in the middle. It is totally supported by the 24 blades. The proto has no center pole either. It is quite strong and actually can bend if it has to. Here is the template. Now I can make more quickly if it performs well!







You can see the angle I chose for the blades. It is my current theory that the wind flows into and around the center and 'swirls' fast and actually EMPOWERS ALL the 24 blades forward, for maximum TORQUE per revolution!! (unlike most if not all other VAWT types) Also, the air resistance is very small on the opposing side of the rotor since the blades are so close together.





The bottom is the one on the left and it has a DOUBLE stack of 3/4" treated plywood glued and screwed together with Waterproof wood glue. Yes, its heavy, but it gives alot of extra support for the blades. This big rotor weighs about 45 lbs. The small prototype rotor only weighed 14 lbs. The small hole in the middle of the top helps with air flow to get more power in higher winds. (I believe)

If the treated plywood don't hold up, I will then weld up all steel centers and no wood. But right now I can see what kind of power I will get out of this rotor.








This is how I 'centered' the whole cylinder shape. I screwed the top on first. Flipped it over and only put one screw in each blade at the bottom. Then kept pushing it 'square' as I put the second screw in each blade. Understand?







These are only ugly (not perfectly straight) testing poles. I will mount them to strong 3 or 4" steel poles painted white real and concreted into the ground real soon. (probably only 8-10 feet high)

I know there is better winds up higher, but I am going primarily for 'looks'.

If the VERTIGO-SC100 does what I think it will, I will make a second one before winter. I am very excited about the speed and torque of these. As soon as I get the Stator done next week and I get the WATT results, I will post more pictures and info!!  Feel free to give Any comments, questions, or suggestions!.

« Last Edit: October 05, 2007, 01:19:02 AM by (unknown) »

electrondady1

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Re: "Squirrel Cage" VAWT progress !
« Reply #1 on: October 04, 2007, 08:17:31 PM »
i think it's perhapse the best looking wind mill i've  seen .

« Last Edit: October 04, 2007, 08:17:31 PM by electrondady1 »

chadking

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Re: "Squirrel Cage" VAWT progress !
« Reply #2 on: October 04, 2007, 10:56:05 PM »
Indeed, this looks very nice. That looks like a straight forward and duplicatable design. I always like to see interesting progress on unconventional VAWTs.  

Keep us informed as you get some results!  
« Last Edit: October 04, 2007, 10:56:05 PM by chadking »

DamonHD

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Re: "Squirrel Cage" VAWT progress !
« Reply #3 on: October 05, 2007, 01:01:10 AM »
Lovely bit of engineering!
« Last Edit: October 05, 2007, 01:01:10 AM by DamonHD »
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oztules

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Re: "Squirrel Cage" VAWT progress !
« Reply #4 on: October 05, 2007, 01:49:01 AM »
Thats a top looking project. Even if they don't end up generating any real power, they will generate real interest.

Nice work there.


Good to see a different design being played with.


........oztules

« Last Edit: October 05, 2007, 01:49:01 AM by oztules »
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thefinis

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Re: "Squirrel Cage" VAWT progress !
« Reply #5 on: October 05, 2007, 03:52:22 AM »
Very nice like the concept. A real clean and slick looking machine.


Remember that as the diameter increases the rpms decrease usually. I think that you are okay for now (from 18"-24") but often what seems to be working great in the smaller versions for desired rpms suddenly takes a lot higher wind speed to reach the same rpm numbers in a bigger model.


Keep up the good work.


Finis

« Last Edit: October 05, 2007, 03:52:22 AM by thefinis »

tecker

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Re: "Squirrel Cage" VAWT progress !
« Reply #6 on: October 05, 2007, 04:06:36 AM »
 This is a good Idea . I can see what you mean about keeping it square . I played around with this on a smaller scale with stacked blades from Squirrel cage fans .Good 1/4 cycle push . It pushed air out 360 though.It made a good center to a three blade darius as the darius has 45 degrees of straight back push to overcome . In short add some darius blades to the some adjustable outriggers to get the most from this setup .The air thrown out makes a good vortex that's elieptical extending to the back and sides . This matches the darius dead zone.  
« Last Edit: October 05, 2007, 04:06:36 AM by tecker »

electrondady1

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Re: "Squirrel Cage" VAWT progress !
« Reply #7 on: October 05, 2007, 06:04:32 AM »
what sort of angle have you set the vanes at ?

it looks to be about 45 degrees to a radius line.
« Last Edit: October 05, 2007, 06:04:32 AM by electrondady1 »

Bruce S

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Re: "Squirrel Cage" VAWT progress !
« Reply #8 on: October 05, 2007, 07:21:39 AM »
Those are things of beauty!!

After reading about the torgue that these ahve even with the treadmill motor shorted, I was thinging that until you get a purposed built gen, you couold attach either a V-grooved or cog belted pulley on the bottom of either one and use pulley sizing to get one up to the RPMs you need to get it into the 12v region. Sure there'll be losses but it can work to give you some idea of the work horses these can turn into.


Maybe Talk to DamonHD to do some graphics to paint on so cool little scenes so up once they start turning? :-D


Very NICE !! Keep up the great work!!

Bruce S

« Last Edit: October 05, 2007, 07:21:39 AM by Bruce S »
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windstuffnow

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Re: "Squirrel Cage" VAWT progress !
« Reply #9 on: October 05, 2007, 08:43:30 AM »
Very nice Cmebrew!  Thats about the nicest looking squirl cage turbine I've ever seen.  When you build your alternator for it you'll want to load it to a TSR of 0.33 for the highest production of power.  Their typically not super efficient but do make good torque.


Keep up the great work!

.

« Last Edit: October 05, 2007, 08:43:30 AM by windstuffnow »
Windstuff Ed

Norm

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Re: "Squirrel Cage" VAWT progress !
« Reply #10 on: October 05, 2007, 01:05:12 PM »
Put some spiral lines on it like a barber pole

and you'll be able to count the number of turns

per minute??

   ( :>) Norm.
« Last Edit: October 05, 2007, 01:05:12 PM by Norm »

vawtman

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Re: "Squirrel Cage" VAWT progress !
« Reply #11 on: October 05, 2007, 02:10:49 PM »
Very Nice Cmebrew

 A design like this may be a candidate for Tom W and the hard to ever forget Zubbly vawt idea.


 The idea is to have an alt at the base and and alt on top.Just twin towers with a crossbrace to support the bottom and top motor and its bearings.


 2 alts on 1 turbine.


 Carry on with the vawt.

« Last Edit: October 05, 2007, 02:10:49 PM by vawtman »

CmeBREW

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Re: "Squirrel Cage" VAWT progress !
« Reply #12 on: October 05, 2007, 02:15:50 PM »
Thanks guys. Appreciate the comments. After I paint the hub and alternator white and mount it to the 10' high white (steel) pole it will really look nice close to my off-white house. It looks really neat when it spins. Everyone thinks so including the mailman, UPS driver, and my one neighbor, and many,many others. They have never seen anything like it. First they ask WHAT it is, and then ask if it makes electricity. If I wanted, I could fib and tell them it is a 'Doppler Sonar' that attracks bats to eat mosquitoes or something. They would WANT one then! But I quess I'll tell the truth.(for now that is)

That soft 'drain pipe' PVC cuts REALLY easy with a tablesaw. I just had my normal 24 tooth rip blade on there and 'free hand' ripped the pvc, simply using the fence as a guide. Those 10' sections of 4" PVC drain pipe are only $7 at Lowes. Make sure they are straight. I had to make the guy go and get me some 'staight n' fresh' ones at the back of the store. When I told him why, he was AMAZED and got the manager and they both want me to bring photos of the windmill next time!


That soft PVC cuts like butter! Not even one screw up! One could also use a 'Orbital' jigsaw with a plywood blade to cut them also but it would take longer. Of course you have to make lines down the pvc with a black marker. Never try to cut the PVC up in the air on the tablesaw though--always keep it DOWN on the table as you're ripping it. Also, I crosscut the pipe with a manual wood handsaw.


I really believe this will do some OK power. There is one company that sells one like mine, but it is SMALLER than mine is (almost a foot less high), and they claim they get 670 Watts from it in a 35mph!!  But they "rate" it at like 430 watts at 30mph. Of course, I dont believe their claims myself, but if mine would do just 100 watts in a 20mph, I would be happy! It may even do more, I simply have no idea at this time. I should know next week.  

I forgot to mention that these Vawts make absolutely ZERO noise. I let my ear actually hit the rotor when its spinning over 400rpm! It is also the only mill I would call "safe"

enough to have at ground level. It don't hurt at all when you tough it with your fingers, ears, nose, head or anything else!  Obviously, Its because the blades are so close together and the soft plastic blades bend.  However, it will look and perform alittle better 8 or 10 feet up than down on the ground level.


It looks like the blades are at about a 45 degree angle.

Sorry, I just noticed I'm going on and on like its story time!

I will also make a nice VIDEO of it going and producing some WATTS, if my brother will let me borrow his camera.

I will see what happens next week and keep you posted on the results!  

-Thanks for the comments and the Ideas. I will keep them in mind.

« Last Edit: October 05, 2007, 02:15:50 PM by CmeBREW »

TomW

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Re: "Squirrel Cage" VAWT progress !
« Reply #13 on: October 05, 2007, 02:32:54 PM »
vawtman;


I was gonna say that, but was worried I might be misunderstood or say something unkind trying to crack wise.


Either way, I think its gonna need a top bearing of some sort as there will be a bunch of stresses on the single one as is.


It looks very nice. I kept wondering if you could paint numbers or colors on it somehow so as it rotated the RPM would be obvious.


Cheers.


TomW

« Last Edit: October 05, 2007, 02:32:54 PM by TomW »

Off grid in Tonopah

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Re: "Squirrel Cage" VAWT progress !
« Reply #14 on: October 05, 2007, 05:16:23 PM »
So here's a crazy question. Other than the aspect of wind from any direction being usable. Is there any reason that one couldn't run a mill like that horizontal? Some place like the sea coast were the wind is always onshore or off shore comes to mind. Any disadvantages? Seems bearing issues and generator issues would be easier to deal with.


                                                         Bob

« Last Edit: October 05, 2007, 05:16:23 PM by Off grid in Tonopah »

CmeBREW

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Re: "Squirrel Cage" VAWT progress !
« Reply #15 on: October 05, 2007, 05:47:50 PM »
Hi Bob. Yes, they now have (or, soon will have) those. They are very interesting for roof tops. You might want to look at the following link:


http://www.youtube.com/watch?v=iPuWSBYMWqg


I don't know if its been showed here before. Can't remember. But I think it is cool.

« Last Edit: October 05, 2007, 05:47:50 PM by CmeBREW »

FishbonzWV

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Re: "Squirrel Cage" VAWT progress !
« Reply #16 on: October 05, 2007, 06:31:47 PM »
Well done CmeBREW!

Hope it makes good power. I laughed at the 'what is it' comment...had a guy stop in front of my house and asked where I got my 'fans', (two 6 foot mills on test poles).


Okay, here's your get rich quick scheme.

Build these things strong enough to mount on skyscrapers. Every floor gets one on all four corners. Floors are 12 feet, so they would be about 10' tall. Maybe get 1KW out of each one? So depending on the wind direction possibly 3 out of 4 producing power at a time. Lets say 50 or 60 floors. Hmmmmmmm  

Let me know if you are going to sell stock!  :-)


Good job

Bonz

« Last Edit: October 05, 2007, 06:31:47 PM by FishbonzWV »
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CmeBREW

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Re: "Squirrel Cage" VAWT progress !
« Reply #17 on: October 05, 2007, 06:33:35 PM »
Since this is just my Diary thing, you should also see this HALARIOUS video about the 'Global Warmings' ,by this kid imitating president Bush. His voice sounds just like him! Its the funnest thing I've seen in a long time! I don't know if its been on TV or something. I don't watch much. I thought you could use a good laugh!!!


http://www.stupidvideos.us/video.aspx/IDp~1572/George%20W.%20Bush%20imitation/Funny%20videos/

« Last Edit: October 05, 2007, 06:33:35 PM by CmeBREW »

feral air

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Re: "Squirrel Cage" VAWT progress !
« Reply #18 on: October 05, 2007, 10:13:01 PM »
That's just slick! You're the vawt god, you win.


The only thing I don't get is the holes in the top and bottom. It seems to me that without those holes the air would have to exit out the sides and would give it a bit more oomph. It would be interesting to see for sure if there's a difference either way.


I want one, I'm sold!

« Last Edit: October 05, 2007, 10:13:01 PM by feral air »

wooferhound

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Re: "Squirrel Cage" VAWT progress !
« Reply #19 on: October 06, 2007, 01:38:30 AM »
to get RPM

paint a single pipe piece

Then it would be real obvious
« Last Edit: October 06, 2007, 01:38:30 AM by wooferhound »

electrondady1

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Re: "Squirrel Cage" VAWT progress !
« Reply #20 on: October 06, 2007, 07:07:46 AM »
like i said before i think you mill looks great.

i asked about the angle you set the blades to as that would probably qualify as  the angle of incidence and is very important.


i would avoid any sort of top bearing or secondary generator at the top .

that would require a support structure which would ruin the visual impact.


if you find that there is a tendency for the mill to get "tippy"

then try this ,

 move the base support disk(the one that ties into the alternator) from the bottom up into the middle to keep it hidden and equalize the loading.


it would require building another end disk  for the bottom but that would be a small price to pay for a stable machine.

you might need a larger center hole in it so it can easily straddle the support pipe.


i havent put a new geni up in three years .


ive just been studying step by step and experimenting with  alternators  

but your mill design has real curb appeal.

i think something  like it may appear in my front yard .

thanks for posting.

« Last Edit: October 06, 2007, 07:07:46 AM by electrondady1 »

CmeBREW

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Re: "Squirrel Cage" VAWT progress !
« Reply #21 on: October 06, 2007, 08:15:03 AM »
Feral Air,


   Thanks Feral. I appreciate and benefit from EVERYONE'S ideas and experiments including yours. Thats the great thing about this site!


You bring up a good point. I thought about that too,,,concerning the hole(s).

I will tell you what I have observed so far. You are right, the cylinder APPEARS to turn alittle faster in the BREEZES (under 10mph) WITHOUT any holes in the top or bottom. Thats the way I had my Prototype in the beginning tests. I was always aware that most or all of the commericial models had holes in the top and bottom. But I wanted to see the difference.

The holes (I believe) are to ALLOW more air circulation thru the cylinder during higher winds , which allows getting much more power in the bigger winds. If you don't have holes, then, at some point as the winds increase, the 'swirreling' air and pressure inside the cylinder cannot leave fast enough, and a percentage of the wind would simply flow AROUND the outside of the rotor. (at least thats my belief at this time)


On the other hand, if the hole(s) are TOO big, you could send too much of your low wind pressure out the hole(s) and miss out on some CONSISTENT low power potential. (As you said)

So I actually believe now, that the hole in the top of my Prototype is much too large. I would only make a 3" hole now and NO holes in the bottom.  The big VERTIGO rotor has only the one 3" hole in the top.  

I am glad you brought up that point, because I have noticed a difference. I will keep doing different test to see which is best. Also, having less 'air flow' MIGHT help regulate or 'air brake' the rotor in extreme wind conditions. Which MAY be good!(IF it don't sacrifice power below that point)

 I did not have the holes on the Proto when that 70mph+ Hurricane like wind hit it last week. So I must keep doing testing.  Thanks  

« Last Edit: October 06, 2007, 08:15:03 AM by CmeBREW »

CmeBREW

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Re: "Squirrel Cage" VAWT progress !
« Reply #22 on: October 06, 2007, 08:33:52 AM »
Thanks Electrondady1,


Yes, the blades are about 45 degrees. But I have the curve of each blade BARELY pointing forward of the center axis.(or;each line that goes to the center axis)

 I thought it would be better to have them pointing forward a bit to aid in the swirling air flow circulation.

Yes, your idea of dropping the blades down like that is one of my back-up designs if the other proves unreliable in high winds. But I thought I would 'push the envelope' first, and try this method. I was also concerned about having the cylinder's air flow cut in half by the middle board. So I just wanted to try this method first and see the power it will produce.

I agree with you, that if this design proves reliable, it looks better than the 'cage' look.  Yes, we all know it would be more 'stable' with a bearing supporting it at the top. Thats the first thing we all think about! But as you said, I am going for the best 'looks' according to my own opinion. My whole family are a bunch of artists, and if I made something that looks ugly , they would probably disown me! So I am pushing the envelope and it is fun and exciting to say the least!! I have been experiment like crazy all summer long and this design is my favorite by far. I intend to make many of them. I am going with it!   -Thanks friend.

« Last Edit: October 06, 2007, 08:33:52 AM by CmeBREW »

ghurd

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Re: "Squirrel Cage" VAWT progress !
« Reply #23 on: October 06, 2007, 09:42:23 AM »
You don't have a real plan for the small one?

Maybe a small conversion, like 150W, 110V, 1750 RPM, 4 magnets, no rewinding.  I can tell you it doesn't take many RPMs to get past 12V!  Not many amps though.


How do you think it would work in a water fall?


G-

« Last Edit: October 06, 2007, 09:42:23 AM by ghurd »
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CmeBREW

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Re: "Squirrel Cage" VAWT progress !
« Reply #24 on: October 06, 2007, 11:49:01 AM »
Sorry, I was incorrect about the angle. I'm not too good at Geometry. Heres a picture to show the angle. Each blade is actually 58 degrees:



Yes, thats a line from the outer point of the blade to the inner point of the blade. Be the way, the rotor obviously turns CLOCKWISE.

Today, I'm getting better breeze (so-called 5-10mph) , and it is REALLY going nice!
« Last Edit: October 06, 2007, 11:49:01 AM by CmeBREW »

jmk

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Re: "Squirrel Cage" VAWT progress !
« Reply #25 on: October 06, 2007, 01:06:15 PM »
 Looks great! This is very interesting. Do you have a way to figure out the torque so you can match an alternator?  I'm interested in what it can do. Great engineering! It looks easy to build. I always thought it would be cool to put them stacked on a tilt up tower. They could go  between the guy wires with the tower pole being the center axis. Of course the HAWT would be at the top still. If they work really good maybe the HAWT could be replaced. It would be neat if they were painted in a way that they could show rpm. Then you could see how the winds very  at different heights. You got me wanting to build one. What are you using for a bearing?
« Last Edit: October 06, 2007, 01:06:15 PM by jmk »

jmk

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Re: "Squirrel Cage" VAWT progress !
« Reply #26 on: October 06, 2007, 01:22:55 PM »
 I noticed on the smaller one that you can see through it and on the larger one you can't. I'm just wondering if that will make a difference? The pipe is the same diameter on both. With the bigger dia and more blades it closed the gaps up. I wonder what would be the difference if the pipe was scaled up to make the gap the same. It has something to do with the holes in it too I would guess.  
« Last Edit: October 06, 2007, 01:22:55 PM by jmk »

CmeBREW

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Re: "Squirrel Cage" VAWT progress !
« Reply #27 on: October 06, 2007, 04:17:40 PM »
Thanks JMK,,

      I have to just quess with the making of the stator. The stator will be thin, only 3/16" thick for maximum flux strength to try and raise AMPS  quickly since the rpm range is usually limited to only about 50-400rpm on VERTIGO-SC100 and about 100-600rpm on Lil'Vertigo-Jr.  I am using 20ga. wire. My quess is probably around 100 turns. I would like cut-in to be around 50rpm on the big rotor. I may have to remake the stator again to get in better. This will be only my second stator. And my first one was small. I can see the rpm easy upto 120rpm simply by putting a piece of duct tape on the bottom of the rotor and laying in the grass beneath it with my stop watch. The prototype small one has holes in the blades because that pvc is from another project that didn't become fully realized. (translation: That project FAILED and crashed and burned!) So the holes in the pvc blades mean nothing.


The blade spacing is something you'll simply have to experiment with yourself. I do not know much at this early point. I just figured that more blades (upto a point) could mean more torque per revolution in the lower wind ranges--which is what I want.

The Prototype rotor probably goes TWICE the rpm of the bigger one. But the bigger one will probably do 4 times the over-all watts. The bearing in a small trailer hub. It has the two roller bearings in it. It is strong enough for this. 1000lb capacity.

Not a drip of rain will ever get into the bearings.

Yes, I hope many begin making these, because I have alot more ideas myself I want to try. And there is absolutely NO REASON these type mills shouldn't go ANYWHERE including down town, in the city, on one's roof, in one's yard, on the corner of the house, on buildings, or anywhere else for that matter!! Personally, I'm for ALL type mills EVERYWHERE. But I hope enough people get together to finally over-turn all those baseless, unreasonable, worthless codes and ordinances once and for ALL!!

(except perhaps for the few mills that make ALOT of noise)    -Thanks JMK.

« Last Edit: October 06, 2007, 04:17:40 PM by CmeBREW »

CmeBREW

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Re: "Squirrel Cage" VAWT progress !
« Reply #28 on: October 06, 2007, 06:30:30 PM »
Thanks Ghurd,


Thats a very good idea! I would like to try that with the small prototype rotor. That would be a good project for my first ever little motor conversion to begin learning that. The speed of that small Vawt rotor is only about HALF the rpm range of a 4' Hawt though. YOu never have to worry about cogging for start-ups though with these type vawts. Thats a big plus. Ghurd, sounds like you have alot of experience with those little motor conversions, so can you tell me, if the cut-in is at about 100rpm, and the rotor can go up to 600 or 700rpm under load, how many WATTS (or;amps) could one get with one of those small motor conversions? 20,30,40 watts?


Those small diameter rotors like the one on my prototype are VERY easy and cheap to make, are virtually unnoticable, and you can probably make 6 or 7 of them from only one sheet of treated plywood and 4 or 5 /10' pipe sections! I am beginning to like the sound of that. I believe, Treadmill motors and Ameteks are alittle out of the rpm range to reach a good power potential. Then again, they may actually reach 20-40 watts--I'm not sure yet)  I have a nice treadmill motor that does about 25 watts at 550rpm. I think I will try a smaller diameter "squirrel cage" rotor than my Prototype. I really believe it may work. I was thinking of 14" diameter by almost 5 feet high. That would be quick and easy to make. Painting is what takes the longest!

I do also have a 1/4hp 1725 rpm / 120vac motor with ball bearing ready for my first conversion!  Sure is ALOT of fun projects ahead.  -Thanks for the idea.

« Last Edit: October 06, 2007, 06:30:30 PM by CmeBREW »

ghurd

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Re: "Squirrel Cage" VAWT progress !
« Reply #29 on: October 07, 2007, 09:38:08 AM »
Power out for a given RPM?  No idea!  No fancy tools except a mini-lathe.  Cheap fun.


A 1/4HP is probably too powerful and might have a cut in too high.

The smaller motors have lots of turns of tiny wire, making high volts at low RPMs, but all those turns of tiny wire have high resistance, so not many amps come out.  I'm happy when I get an amp or 2.  Tiny motor = high volts at low RPMs, and low amps.


I was thinking something on the lines of fungus' latest little conversion in his diary, just a tad bigger.  I figured you'll leave it flying anyway, might as well try to get a 1/2A?

G-

« Last Edit: October 07, 2007, 09:38:08 AM by ghurd »
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feral air

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Re: "Squirrel Cage" VAWT progress !
« Reply #30 on: October 07, 2007, 10:46:58 AM »
That makes sense.


Can you do me a favor? Take a few of those blades and (if you think they'll survive) throw them from your roof. That sounds kind of stupid but I'm curious..


If they float down like leaves or wouldn't do any damage to anything then that really is the holy grail. All you'd need to do is change out the top plate with something lighter/safer and if it explodes in 120mph wind, oh well...if you get what I'm sayin'.


The only thing I'd worry about is if the blades fly like an arrow. That could impart a fair amount of energy on a small edge surface. But then if it exploded they probably wouldn't be coming down like that..I dunno though.


Another thing that would be cool for testing purposes is to drive one with a treadmill motor. Not my time/money/life on the line, I know, but if it can survive 5000rpm it should be plenty safe. That's not the same as being powered by the wind (obviously) but it might be useful to know the upper rpm limit. If you do this, be safe...run. ;-)


What a cool design, I'm still stunned!

« Last Edit: October 07, 2007, 10:46:58 AM by feral air »

RP

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Re: "Squirrel Cage" VAWT progress !
« Reply #31 on: October 07, 2007, 02:24:21 PM »
Actually I think they will flutter down like a leaf as long as they're balanced end to end.  That's the difference between a stick and an arrow.  


If the center of mass is not at the center of air resistance it will align itself and become an arrow.  This is why a typical windmill blade is a problem if it breaks off.  The taper in width and thickness will always tend to make it (or pieces of it) into an arrow.


Of course there is still the problem of a broken squirrel cage blade.  The center of mass will move toward the unbroken end with jagged edge following behind.

« Last Edit: October 07, 2007, 02:24:21 PM by RP »

CmeBREW

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Re: "Squirrel Cage" VAWT progress !
« Reply #32 on: October 07, 2007, 03:39:02 PM »
Each blade is less than one pound. In fact, all 24 blades on VERTIGO weigh 19 lbs. total. If a blade were to ever hit the air it would slow up sorta like 'a feather'. A light pine blade would probably do the same.  As you asked, I threw a pvc blade high up in the air like a spear, and sometimes it comes down slowly sideways spinning horizonally, and sometimes more straight. Of course there is not a breath of breeze today! I believe it is about as "safe" as you can get. The rpm is only half that of a small Hawt. That 'solid' PVC will not snap in two--it is very flexible. If you stand on a piece it will bend, but not break-- unlike that 'plummers' type PVC. That stuff is more brittle and it will 'snap' in two.


I admit though, the heavier blades of something like a Darrius Vawt spinning fast, makes me nervous. In fact, I am disassembling the big heavy plywood Vawt (41" diam) I made the video of on Youtube.

The blades are WAY too heavy and a big wind would easily tear them off without some kind  of an rpm control or auto-braking system. It is too much trouble to mess with. It was an IMPRACTICAL design, but I learned ALOT from it. This new design is far better, and even though it is hard to believe, it seems to actually 'self-regulate' in high winds AND actually 'BALANCE' ITSELF in high winds when spinning fast!!

The prototype is mounted to a treadmill motor as you seen in the photo. The shaft on it actually bent alittle bit bent. So the rotor is off about a half an inch at the top when it is spinning in normal winds. But when a big wind hits it (above about 20mph) it straightens up perfectly when it is spinning fast! That was unexpected!

« Last Edit: October 07, 2007, 03:39:02 PM by CmeBREW »