Fieldlines.com || Blade thickness

Front Page - [Homebrewed Electricity-- (wind) (solar) (hydro) (steam) (controls) (storage) (mechanical)] - Classifieds - Site News
Everything - Newbies - [Remote Living-- (housing) (heat) (light) (water)] - Reviews - Diaries - Our Products

Blade thickness
By Them, Section Wind Posted on Sun Oct 03, 2004 at 06:13:46 PM MST
Blade thickness

I am carving my first set of baldes. my concern is the instructions on mr Piggotts web page called for a piece of wood 50mm thick with a 50mm drop at station 1. But a 2x6 is only 40mm.Thats a difference of 20%. so I redused the values at each station by 20%. Will it still work?
Thanks charlie

Blade thickness | 7 comments (7 topical)

Re: Blade thickness (3.00 / 0) (#1)
by Ungrounded Lightning Rod on Sun Oct 03, 2004 at 07:10:03 PM MST

I think it will work but you raised your tip speed ratio by 20% If I'm correct this will make it start at a higher wind speed, spin faster, and have less torque on the shaft. That means higher voltage and lower current for a given wind of the genny. Your cutin speed will go down unless the startup went above it.

Not sure what it will do to the power produced.

Re: Blade thickness (3.00 / 0) (#2)
by Them on Sun Oct 03, 2004 at 08:11:14 PM MST

Thanks for the fast reply. I thought I would include the numbers, for anyone who knows how to calculate them.
I hope you folks will excuse my temporary lack of knowladge on this subject, im very new but im studying hard. I know I need to buy the book, and I will soon.
Five stations 23 cm apart.
Station 1 Width 14 cm Drop 4 cm Thickness 2 cm
Station 2 Width 13.1cm Drop 2.64cm Thickness 1.6 cm
Station 3 Width 11.7cm Drop 1.36cm Thickness 1.44 cm
Station 4 Width 10.4cm Drop .8 cm Thickness 1.2 cm
Station 5 Width 9 cm Drop .4 cm Thickness .9 cm
Again thanks to all...

Re: Blade thickness (3.00 / 0) (#4)
by Flux on Mon Oct 04, 2004 at 12:58:55 AM MST

It would have been better if you had kept the dimensions the same as far as possible and just blended the thing into your timber near the centre.

I am not sure whether you have just changed the thickness values or whether you have also changed the drops and reduced the pitch, but either way it's not going to be a disaster.

If you have reduced the pitch and raised the tip speed ratio and you still have the option you could reduce the turns in the coils about 10%.

If you have made the alternator, try it and if it stalls you can increase the gap between the magnets a few millimeters.

Flux

[ Parent ]

Blade thickness Calculators (3.00 / 0) (#3)
by DanOpto on Sun Oct 03, 2004 at 08:27:20 PM MST

It is well worth purchasing the Blade designer program for $5 from
http://www.windstuffnow.com/main/formulas.htm
(I bought it too - I have no connection to the program writer)

You can adjust the angles and twist on your computer before you put your knife to the wood.

The U of Mass Wind Engineering Mini Codes are free
They can be complicated but can give you great information.

http://www.ecs.umass.edu/mie/labs/rerl/Software/MiniCodeOverview.html

I suggest that you not worry about the angles in the first third of the blade.
It is more important that you built the inner sections thick and strong.
There is only a small contribution from the inner slow moving section.
If you need more power, add a little more length to the outer blade.

Re: Blade thickness (3.00 / 0) (#5)
by scoraigwind on Mon Oct 04, 2004 at 01:04:07 AM MST

Generally speaking it doesnt matter what you do near to the root of the blade although you can get some advantage in using the optimum shape. But just because your wood is a little thin that is no reason to play around with the drop in the outer part.

If you make the drop smaller and the chord width narrower then you are optimum for higher tip speed ratio but watch out for noise and strength issues.
Hugh Piggott http://www.scoraigwind.co.uk

Re: Blade thickness (3.00 / 0) (#6)
by cevonk on Mon Oct 04, 2004 at 10:37:51 AM MST

Or you could glue a 1"x6" to the board and end up with a 3"x6".

Re: Blade thickness (3.00 / 0) (#7)
by Them on Mon Oct 04, 2004 at 06:23:40 PM MST

Wow,
Thanks for the fast responce.
I have not started on the alt yet. Let me say, I know nothing about this stuf. Im very impressed by what ive seen on this site. Much thanks to Mr Piggott and any on else how has ever done an experiment. My hats off to you all.
Im getin off the grid baby!
Ungrounded Lightning Rod, Thanks for your imput. I dont understand everything you said, but im workin on it.
Flux, Hi, I dont fully understand how to build the alt yet. Any help or advice is very welcome.
DanOpto, Thanks for the site. Iv not had time to download it yet.
Mr Piggott, Thanks for stoping by. Will, I have two of the three blades carved, so I guess ill try them. I can allways build more.
cevonk, Hey thats a good idea. Why didnt I think of it. Is there any strength problems with glueing the boards together?
Thanks to you all...Charlie

Blade thickness | 7 comments (7 topical)

Menu

� create account
� How to use the board
� FAQs
� search the board
� Google search the board

Login

Make a new account

Username:

Password:

Total Views

��87 Scoop users have viewed this posting.

Related Links

� Also by Them

You must be a registered user to post here. It's easy and free, and the link is on the upper right side of your page.
All trademarks and copyrights on this page are owned by their respective companies. Postings are owned by the poster, but may be deleted or moved at the ADMIN's sole discretion. The Rest � 2009 Forcefield.
You can Email the board ADMIN here. PLEASE include the username you signed up with!