Author Topic: Rahai vawt anyone? (Read 6477 times)

john j · « **on:** March 13, 2008, 01:11:10 PM »

I am new here, live in Denmark, Europe. My plan is to build a Rahai type vawt. 1.1 meter diameter, 1.1 meter high. Has anybody plans like this? Could be nice to learn from eachother. I will share plans and thoughts. Dont expect to get patents or rich. Best wishes, John Jorgensen.

fcfcfc · « **Reply #1 on:** March 13, 2008, 08:38:58 AM »

Hi: I am in the process of designing a 144 sqft (4' wide, 36' high) high efficiency VAWT that utilizes both drag and lift. With it I am also designing a high efficiency axial air based gen.. (allot of posts on that already). Allot more info will come over the next year...

.....Bill

feral air · « **Reply #2 on:** March 13, 2008, 09:11:00 AM »

I'm not familiar with the Rahai type vawt, do you have any links or anything? I guess I better ask google too.

I think the consensus around here is that the Lenz2 is the best homebrew vawt design. It's well worth your time to Google search the board for that. take it easy

vawtman · « **Reply #3 on:** March 13, 2008, 04:00:57 PM »

Hi John

I tried to search for pic of the vawt you describe and found nothing.If you have plans it would be cool see them.

Mark

Lumberjack · « **Reply #4 on:** March 13, 2008, 05:50:02 PM »

I think he means radial....

obelix · « **Reply #5 on:** March 14, 2008, 02:41:12 AM »

Hello,

No, it's a novel type of blades for savonius type VAWT.

Take a look at:

http://www.energy.ca.gov/research/innovations/eisg_final_reports/index.html

and then:

DEVELOPMENT OF OPTIMUM DESIGN CONFIGURATION AND PERFORMANCE FOR VERTICAL AXIS WIND TURBINE.

It was very interesting, because it encompass the double mode of vawt:

Drag + Lift and study the implementation of the lift side !!

Hope this helps!!!

vawtman · « **Reply #6 on:** March 14, 2008, 03:03:09 PM »

Thanks obelix

Feel like the poster here since he abandoned us apparantly.

Me need to get a grant.Hmmm

john j · « **Reply #7 on:** March 14, 2008, 03:25:17 PM »

Thanks so far, I dont have plans really, Im just building. http://www.energy.ca.gov/2005publications/CEC-500-2005-084/CEC-500-2005-084.PDF

My plans are stoneage-simple: Mount hub, with rim and part of axle from agriculture-type trailer. (Can handle about 1000 kgs of weight/each wheel). Weld rotor to rim. Use rim as v-belt pulley (bottom-(flat) of v-belt is used on the rim) Generator is from a car.

Remember this is just for testing rotor setup. This heavy hub has too much resistance to be super, but should give me an idea of the forces that is working my vawt.

And these are parts I have lying around.Ill buy only 3 sq meters of steel plate.

My plan is to carefully balance rotor before welding it to rim, and also I plan to put a small support bearing on top of rotor. Pictures will follow soon. Cheers, John

vawtman · « **Reply #8 on:** March 14, 2008, 04:46:12 PM »

Thanks for the info John and welcome aboard(not sure if i'm qualified has welcome lady)

You may be able to do better without the vbelt and car alt but get her spinnin and HAVE FUN!

Can't wait to see the pics.

tecker · « **Reply #9 on:** March 14, 2008, 08:07:23 PM »

That parabola has some history that design was in the John Prenis book I wore the cover off of .

elvin1949 · « **Reply #10 on:** March 15, 2008, 12:03:12 AM »

I would direct drive it myself.

later

Elvin

john j · « **Reply #11 on:** March 15, 2008, 02:10:57 AM »

Thanks for comments. Nice profile this Rahai isnt it?

Pictures have been sent. Wonder if anyone can find them........

fungus · « **Reply #12 on:** March 15, 2008, 06:13:21 PM »

"I hope you don't mind" .. considering they're 700K each I'm assuming quite a few peopl e will.

TomW · « **Reply #13 on:** March 15, 2008, 08:03:46 PM »

Fungal;

I killed the comment, 2 megs in one comment is a blatant size violation.

TomW

electrondady1 · « **Reply #14 on:** March 16, 2008, 07:49:48 AM »

hello john,

your farm machine hub looks very strong.

it should be able to support a large vawt.

clean it up and paint it to look nice .

find a farm or auto parts place and get some new bearings for only a little money

i have seen the rahi profile before.

is it considered to be superior?

what is the total swept area of your device?.

remember automotive alternators are designed to turn at more than 1,000 rpm.

there are bettor ones to use .

don't give up when things get difficult.

good luck !

john j · « **Reply #15 on:** March 16, 2008, 01:37:51 PM »

"considering they are 700K each" and "human stupidity" could you be a little more clear? Think Im missing the point.....

john j · « **Reply #16 on:** March 16, 2008, 01:46:37 PM »

Thanks Dady, In my motorcycle days, the saying was: If it doesnt run, chrome it (-; Paint will come later. Bearings in hub are mint condition, after what, 25 years?

I dont know how to calculate swept area, its 1.1 metres high and 1.1 metres in diameter. As I plan to run the car alt off the base of the rim, I guess Ill have a 15:1 increase in rpm. Should be OK, I hope. If things work as I hope, Ill come back to better alternator design.

TomW · « **Reply #17 on:** March 16, 2008, 01:49:03 PM »

jj;

Well, there are size limits on photos. Any one of those broke that rule and 3 at once fractured it.

Clear now?

The stupidity thing is his .sig line not necessarily a comment on this post.

Not sure why folks don't "get" .sig lines. They are apopended to all comments from the individual.

You are welcome.

T

john j · « **Reply #18 on:** March 16, 2008, 01:52:32 PM »

Thanks Tom, Ill try and reduce

feral air · « **Reply #19 on:** March 16, 2008, 02:48:39 PM »

Sorry, I didn't notice the size...my bad. We just recently got a satellite connection after having dialup for forever...I know how bad it can suck at dialup speeds. I'll be more careful in the future. take it easy

pyong · « **Reply #20 on:** March 24, 2008, 02:06:42 AM »

the rahai data is flawed as he does not accommodate tunnel blockage in his calculations.

the lenz2 is a more interesting profile, however I've yet to replicate the cp's posted.

- has anyone?

john j · « **Reply #21 on:** April 04, 2008, 02:53:42 AM »

Just got the stoneage vawt up. There will be more sets of wings to come. Just wanted to see how it reacts. It starts turning with very little wind. I tried to measure resistance in the very heavy bearing. If I measure correctly, turning of the hub and bearing takes 29 volts and 0.05 amps. Cost so far: about 100 US$

ghurd · « **Reply #22 on:** April 04, 2008, 07:43:19 AM »

Probably work a lot better if the top is covered.

Just for a quick test, maybe slap a piece of 3/8" plywood on top with tarp straps?

G-

john j · « **Reply #23 on:** April 05, 2008, 05:21:33 AM »

Yes I think youre right. Only its hard to know any difference, as I dont have an alternator yet. And even then, how would you measure output? Thanks anyway.

News:

Author Topic: Rahai vawt anyone? (Read 6477 times)