windgen.org vawt discussion

That's an interesting build.   Takes advantage of the flex qualities of the sheet.

You might consider finding a suitable glue to assemble the panels tall with the ribs in a "with-the-wind" orientation... IPS Weld-on #3, #16 and #33 come to mind

http://www.craftics.com/products.cfm?Category=80

Make sure it's "hot" enough to bite the PC.

As far as the ribs' vertical orientation "grabbing" the wind... well, the data will be valuable, to say the least.

Self-taught is one of the best ways to learn- the mistakes seem to lodge higher in the cerebral filing system.

Keep at it, mate!

Turtle, learning as well

No, it's just the Polycarbonate Panels at Lowes.  ($30 for a 12 ft. long Piece -- then I cut it in half with tin snips)

I like the stuff myself -- even though I am aware that the Corrugations go the WRONG direction for the Vawt.  But hey, these Savonius Vawts are always going much slower than the wind speed anyway, so I thought why not try-- since it would look really neat. 

Who knows, the vertical corrugations might just 'grip' the wind better and make even MORE power. (dreaming)

Well I'm afraid I didn't get it done and up today. 
I didn't get as much time to work on it as I hoped.  But Boy am I happy I only went with the 90 degree blade turn!

This is my first Helix Vawt, so I am just learning stuff.  But if I had tried a bigger twist angle, it would not have worked the way I'm doing it, and would have set me back a week.

The 90 degree twist just barely made it, with the frame I welded up.  Only a couple inches to spare on Top and bottom.  

Its hard to explain but I did not think the twist itself would 'Raise' the corners (at top and bottom of Polycarb panel) so much.  

It was somewhat difficult to hold the Poly blade in place by myself to mark for where the nuts will were to be welded.  It does not exactly fit like a glove but it is ok.
So I got all the 32 little nuts welded on (which was a bigger job than I thought) and it is almost done and painted.

It really puts ones welding skills to the test.  I'm not pro, just self-taught in my garage.

I will try my best to post some pics and actual wind results in a few days.  

Its been fun though.  Finally found a USE for my welder.   

Thanks. 




 
 

if that's the stuff they use for out door signage, it's very tough.

what are you going to use for blade material?

Thanks Turtle-

Well, I will see tomorrow how easy/difficult things go together.  My 90 degree Helix will be up tomorrow for initial testing!  Getting excited about it.
Few hours ago, I ran out of Welding wire and I was almost done! Bummer.
So tommorow I'll get it and paint it with my fast dry paint and put it up on the post for testing. 
Tommorow is suppose to be 10-20mph wind day-- so not bad.
Here's a photo I just took when I ran out of welding wire and had to stop.  I was on a roll too until that.  It spins super easy on my 3-phase alternator.

I will make a new post real soon (with Video) IF nothing goes terribly wrong.

The difficulty in twisting the blade is more a function of the radius than length, is what I found.  Larger diameters = easier forming

Turtle

Well, I guess I've changed my mind (unless someone sees a problem)  --
I've decided to only twist each blade 90 degrees like the following Vawt video appears to be.  I just saw it onYoutube:

http://www.youtube.com/watch?v=4LQMmbsOyKw&feature=related

It sure looks 90 degrees to me.  The height of my rotor is only 6 feet so I do not believe I can turn each blade anywhere near 180 degrees.  If the rotor blades was 8 feet long I probably could.

I just got the simple tower made and cemented in the ground a couple days ago, so now I am getting ready to weld the blade supports at the appropriate angles to the center steel post.  It should be done soon.

Getting excited about it now!  I will show when done here.

CmeBREW1 wrote:

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I'm not smart enough to make the other type yet. Ha

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Take it from a turtle- that's not necessarily a prerequisite.

Just being willing to try and fail [repeatedly] and having the ability to learn from mistakes (yours and others) is enough to go a long way in this.

As for the complexity of spirals, basic materials knowledge is the starting point.; as in, how to take an otherwise rigid piece of wood and shape it into something it does not want to be shaped into.

Visit the qr5 site and go to their engineering page; download the documents on spiral savonius and vibration.  You'll find it fascinating reading. 


http://www.quietrevolution.co.uk/factsheets.php

And no, I don't understand the calculus either

Turtle, still building

 

Thanks Guys! 
Yes, I think I can do the entire 180 degrees since it is 2 blade.  Of course I am just trying to make the simpler Helix Savonius Vawt.  I'm not smart enough to make the other type yet. Ha

I'm not sure if I know how to attach a photo yet.  I'm still looking over this cool site-- but I will try.  My PVC Squirrel Cage Vawt never did really work very good when I just started a few years ago.  I have learned a lot more now-- 

I think I would not use PVC since the blades are too small and not that great. Plus, I believe there was 'Wobbling' a bit at the top in big winds, and that messes up everything to.  Now, I am happy to be messing with the simple Savonius, since I know I'll at least get something out of it!

-Thanks. Glad to be here.

That's a question I'm hoping to answer through "build-n-try".  The qr5 does indeed appear to fully complete the cylinder in its 3-blade arrangement.

From their engineering prints, the arms are offset 88 degrees from the top to bottom for each blade.   With the blade extension beyond the mounting point, it appears to complete the sweep, as evidenced by the alignment of the bottom of one blade to the top of the next.

I would think that any sweep would serve to mitigate vibration.  In the non-working model I built, "full wrap" aint workin' for me

Turtle, still at it

-- Edited by keithturtle on Thursday 21st of January 2010 09:09:24 PM

-- Edited by keithturtle on Thursday 21st of January 2010 09:10:16 PM

cmebrew , please
don't be too shy to post some picks of your older vertical projects.
i still love the squerrel cage you built.

electrondady1 wrote:

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hey!
welcome aboard cmebrew
i always thought the 180 degree was to eliminate a torque pulse.

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Me too, but to be clear that's 180 degrees if you have 2 blades.  If you have 3 blades it's 120 degrees, 4 blades 90 degrees, etc.  The idea is to have some blade in all locations around the VAWT.

 

Welcome to the site

hey!
welcome aboard cmebrew
i always thought the 180 degree was to eliminate a torque pulse.

Hello,  just joined friends.  Hope I ask this question in the right place.

I am currently making an 18sq.ft. Helical type VAWT. 
I was wondering if the twist angle of each blade HAS to bend around 180degrees?

If I can't twist each blade 180degrees, will 90 degrees be good enough, or would it mess things up badly.

Also, a little side question--- Is it better to have the wind twist upward or downward -- Or does it not matter?

-Appreciate it -- Thanks.