MadModder

Gallery, Projects and General => How do I?? => Topic started by: sbwhart on January 15, 2009, 06:42:58 AM

Title: Adjusting Propelar Pitch
Post by: sbwhart on January 15, 2009, 06:42:58 AM

OK Chaps

This is your starter for ten:-

 :mmr:

This question has come from a friend who's into renewable energy, he's thinking of building a wind turbine (he lives on top of Maucop, only people from Cheshire or Stafordshire will understand the signifcance of this:- its a B***dy windy hill).

And he wants to know how the pitch is adjusted on a propelar, the constraint is he wants something cheep a chearfull that could be made in a home shop.

Crap O Cad answers acceptable. :headbang:

So get your thinking hats on and see what you can come up with.  :coffee:

Cheers

 :wave:
Stew

Title: Re: Adjusting Propelar Pitch
Post by: HS93 on January 15, 2009, 07:25:02 AM

I saw a program recently on tv showing making cheap wind turbines and they used a simple centifical brake that stoped it over reving, I take it thats what you need it for

peter

Title: Re: Adjusting Propelar Pitch
Post by: sbwhart on January 15, 2009, 07:31:46 AM

Hi Peter

That's correct the concern is that the turbine will over rev and cause damage to the generator.

Cheers

Stew

Title: Re: Adjusting Propelar Pitch
Post by: HS93 on January 15, 2009, 07:38:11 AM

yes it was on discovery recently and what it did is it used an AIR brake I think there where two padels on the back and when it got to a certain speed it twisted them to form a brake , ill try and find some info.

Peter

Title: Re: Adjusting Propelar Pitch
Post by: HS93 on January 15, 2009, 08:11:35 AM

Watch this

Peter


http://www.scienceontv.com/2008/11/03/how-its-made-wind-generators/

Title: Re: Adjusting Propelar Pitch
Post by: sbwhart on January 15, 2009, 08:51:03 AM

Thanks Peter

It didn't run but that probably security on the system at work, will watch it tonight at home

Cheers

Stew

Title: Re: Adjusting Propelar Pitch
Post by: Bernd on January 15, 2009, 09:49:25 AM

Quote from: sbwhart on January 15, 2009, 06:42:58 AM

And he wants to know how the pitch is adjusted on a propelar, the constraint is he wants something cheep a chearfull that could be made in a home shop.

If your familar with hit-n-miss engines I'd say use a govenor liked that used on these engines to regulate the speed, but instead use it to regulate the pitch of the blades on the prop. Just an idea if I understand the question correctly.

As the prop turns faster the govenor would turn the blades flat against the wind or parallel to the wind to keep the prop at a close to constant speed.

Only throwing out ideas. I'm sure a search on your favorite search engine will turn up something.

Here's something that may help. I have the book. It's the second one down.
http://www.otherpower.com/otherpower_wind.shtml (http://www.otherpower.com/otherpower_wind.shtml)

Good luck,
Bernd

Title: Re: Adjusting Propelar Pitch
Post by: sbwhart on January 15, 2009, 10:13:12 AM

Thanks Bernd

I've passed the info on

Cheers
 :wave:
Stew

Title: Re: Adjusting Propelar Pitch
Post by: Darren on January 15, 2009, 12:18:03 PM

I can't help thinking that if a brake is used then as the prop turns faster the brake applies more resistance and so on.

Wouldn't this induce some high stresses on the prop shaft etc.
On the other hand, blades turning flat would avoid all these issues and give a comfortable result.
Could the blades not be spring loaded, more wind pressure the more they fold back against the spring?