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Forum Index : Windmills : blade length

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Eddie
Newbie

Joined: 16/10/2011
Location: United States
Posts: 25

Posted: 11:15pm 06 Feb 2012

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I have a small 125 watt wind generator.I originaly had six 12 inch long pvc blades on it,but it took a pretty strong wind to get it going.
I made three 19 1/2 inch blades for it and it gets going in lower winds,but it doesn't turn quite as fast.
My question is does anyone think if I shortened the 19 1/2 blades a little would they turn faster?

VK4AYQ
Guru

Joined: 02/12/2009
Location: Australia
Posts: 2539

Posted: 11:45pm 06 Feb 2012

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Hi Eddie

Shorter blades will turn faster but they collect less energy from the wind so you need to balance the two effects.

http://www.alton-moore.net/wind_calculations.html

Have a look at the Altons site as it will give you and idea on blade sizing.

All the best

Bob

Foolin Around

Eddie
Newbie

Joined: 16/10/2011
Location: United States
Posts: 25

Posted: 02:41am 07 Feb 2012

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Thanks Bob for the link,had some good info.I guess I'll just to have do some experimenting,I've got plenty pvc.
I,ve got smaller one I built with a 12 volt motor that I put a model airplane prop on,It spins like crazy but it's a high speed motor and will never see 12 volts.I only built it because I had all the parts I needed for it laying around.

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