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Rahai vawt anyone?
By john j, Section Wind Posted on Thu Mar 13th, 2008 at 01:11:10 PM MST
Rahai vawt anyone?

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.

Rahai vawt anyone? | 23 comments (23 topical, 0 editorial)

Re: Rahai vawt anyone? (3.00 / 0) (#1)
by fcfcfc on Thu Mar 13th, 2008 at 08:38:58 AM MST
(User Info)

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

Re: Rahai vawt anyone? (3.00 / 0) (#2)
by feral air on Thu Mar 13th, 2008 at 09:11:00 AM MST
(User Info)

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

Re: Rahai vawt anyone? (3.00 / 0) (#3)
by vawtman (vawtman(at)charter(dot)net) on Thu Mar 13th, 2008 at 04:00:57 PM MST
(User Info)

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

Re: Rahai vawt anyone? (3.00 / 0) (#4)
by Lumberjack on Thu Mar 13th, 2008 at 05:50:02 PM MST
(User Info)

I think he means radial....

Re: Rahai vawt anyone? (3.00 / 0) (#5)
by obelix on Fri Mar 14th, 2008 at 02:41:12 AM MST
(User Info)

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!!!

[ Parent ]

Re: Rahai vawt anyone? (3.00 / 0) (#6)
by vawtman (vawtman(at)charter(dot)net) on Fri Mar 14th, 2008 at 03:03:09 PM MST
(User Info)

Thanks obelix
Feel like the poster here since he abandoned us apparantly.

Me need to get a grant.Hmmm

[ Parent ]

Re: Rahai vawt anyone? (3.00 / 0) (#7)
by john j on Fri Mar 14th, 2008 at 03:25:17 PM MST
(User Info)

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

Cheers, john j
[ Parent ]

Re: Rahai vawt anyone? (3.00 / 0) (#8)
by vawtman (vawtman(at)charter(dot)net) on Fri Mar 14th, 2008 at 04:46:12 PM MST
(User Info)

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.

[ Parent ]

Re: Rahai vawt anyone? (3.00 / 0) (#10)
by elvin1949 (elvin1949@yahoo.com) on Sat Mar 15th, 2008 at 12:03:12 AM MST
(User Info)

I would direct drive it myself.
later
Elvin

[ Parent ]

Re: Rahai vawt anyone? (3.00 / 0) (#9)
by tecker on Fri Mar 14th, 2008 at 08:07:23 PM MST
(User Info)

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

Re: Rahai vawt anyone? (3.00 / 0) (#11)
by john j on Sat Mar 15th, 2008 at 02:10:57 AM MST
(User Info)

Thanks for comments. Nice profile this Rahai isnt it?
Pictures have been sent. Wonder if anyone can find them........
Cheers, john j
[ Parent ]

Re: Rahai vawt anyone? (3.00 / 0) (#13)
by fungus (info@reenergy.co.uk) on Sat Mar 15th, 2008 at 06:13:21 PM MST
(User Info) http://www.reenergy.co.uk/

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

'Two things are infinite: the universe and human stupidity; and I'm not sure about the universe.'-Albert Einstein
Fungus - www.reenergy.co.uk

Re: Rahai vawt anyone? (3.00 / 0) (#14)
by TomW on Sat Mar 15th, 2008 at 08:03:46 PM MST
(User Info)

Fungal;

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

TomW

Light Travels Faster Than Sound, Which Is Why Some People Appear Bright Until You Hear Them Speak.

[ Parent ]

Re: Rahai vawt anyone? (3.00 / 0) (#15)
by electrondady1 on Sun Mar 16th, 2008 at 07:49:48 AM MST
(User Info)

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 !

[ Parent ]

Re: Rahai vawt anyone? (3.00 / 0) (#17)
by john j on Sun Mar 16th, 2008 at 01:46:37 PM MST
(User Info)

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.

Cheers, john j
[ Parent ]

Re: Rahai vawt anyone? (3.00 / 0) (#20)
by feral air on Sun Mar 16th, 2008 at 02:48:39 PM MST
(User Info)

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

[ Parent ]

Re: Rahai vawt anyone? (3.00 / 0) (#16)
by john j on Sun Mar 16th, 2008 at 01:37:51 PM MST
(User Info)

"considering they are 700K each" and "human stupidity" could you be a little more clear? Think Im missing the point.....
Cheers, john j
[ Parent ]

Re: Rahai vawt anyone? (3.00 / 0) (#18)
by TomW on Sun Mar 16th, 2008 at 01:49:03 PM MST
(User Info)

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

[ Parent ]

Re: Rahai vawt anyone? (3.00 / 0) (#19)
by john j on Sun Mar 16th, 2008 at 01:52:32 PM MST
(User Info)

Thanks Tom, Ill try and reduce
Cheers, john j
[ Parent ]

test rig turning, pics (3.00 / 0) (#22)
by john j on Fri Apr 4th, 2008 at 02:53:42 AM MST
(User Info)

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$
Cheers, john j
[ Parent ]

Re: test rig turning, pics (3.00 / 0) (#23)
by ghurd on Fri Apr 4th, 2008 at 07:43:19 AM MST
(User Info)

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-

[ Parent ]

Re: test rig turning, pics (3.00 / 0) (#24)
by john j on Sat Apr 5th, 2008 at 05:21:33 AM MST
(User Info)

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.
Cheers, john j
[ Parent ]

Re: Rahai vawt anyone? (3.00 / 0) (#21)
by pyong on Mon Mar 24th, 2008 at 02:06:42 AM MST
(User Info)

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?

Rahai vawt anyone? | 23 comments (23 topical, 0 editorial)

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