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Forum Index : Windmills : how to figure rotor offset

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newbie-from-pa
Newbie

Joined: 20/06/2008
Location: United States
Posts: 8

Posted: 02:28pm 20 Jun 2008

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I would like to know how to calculate the rotor offset. From what I read the diameter of the prop/blades changes the rotor offset. Please advise. Thanks.

Gill

Senior Member

Joined: 11/11/2006
Location: Australia
Posts: 669

Posted: 03:58pm 20 Jun 2008

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G'day n-f-p,
Welcome to the forum.
Regarding your quirey,
Well no, if you select an offset it doesn't change no matter what blades you fit.
What changes is the moment of force due to the changed blade diameter. A moment of force in American speak has the unit foot/pounds. In our case it is the offset distance(in feet) multiplied by the force(in pounds) exerted by the wind onto the blades.

The purpose of the offset is part of the furling geometry. This furling system is balanced with all sections interdependent. Change one thing and it will need to be compensated for by another. There is no formula to calculate every item of a furling system. One needs to select key parameters and work the others out from them. If a suitable balance of the system is not achieved, some adjustment of the selected parameters is needed. There is more of an art than a science/formula to designing windmills. A good start is to look at successful designs and get a feel for the relationships, then coupled with research into the forces and their causes and effects, build on that.

If however you need guaranteed results then build to somebody else's proven design.

was working fine... til the smoke got out.
Cheers Gill _Cairns, FNQ

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