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Gill

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

Posted: 11:20am 19 Oct 2007

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"OOOooohh NNooo!" as he tears his hair out.
"Blades a little longer" musing potential missed.

Sorry John, have a different view in that regard. But I suppose it depends on the objective.

________________________________________________________

Just an added thought before you put that mechanical vane idea away for safe keeping and a rainy day.

When the wind picks up, the relative wind changes, and the vane follows adjusting the pitch. But there is nothing wrong with the pitch. It's just that the prop has not yet picked up speed. The response time may be 2 to 5 seconds for the prop to wind up its flywheel to match the wind increase. In gusty conditions the pitch will be up and down, up and down like a yo-yo chasing the wind where in reality the pitch is perfectly matched to the load and no adjustment would be preferred.

At least with electronic control a pause then recheck can be done before pitch changes there by allowing for mill response time. This then puts the focus more on load changes rather than wind changes.
I don't see a way to do this in a mechanical system.

Well you started it!!!!

Sonic anemometer sounds interesting, post to a new thread when you dig it up. please.Edited by Gill 2007-10-20

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

KiwiJohn
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Joined: 01/12/2005
Location: New Zealand
Posts: 691

Posted: 11:15pm 19 Oct 2007

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Gill said

Just an added thought before you put that mechanical vane idea away for safe keeping and a rainy day.

When the wind picks up, the relative wind changes, and the vane follows adjusting the pitch. But there is nothing wrong with the pitch. It's just that the prop has not yet picked up speed.[/quote] the very instant the relative wind changes is the time time start changing the pitch, the prop will pick up speed faster if it is aligned to optimum use of the new wind conditions.

[quote] The response time may be 2 to 5 seconds for the prop to wind up its flywheel to match the wind increase. In gusty conditions the pitch will be up and down, up and down like a yo-yo chasing the wind where in reality the pitch is perfectly matched to the load and no adjustment would be preferred. [/quote] Ummm, maybe, dont really know but somehow the same considerations are not a big problem when addressing the changes of wind direction.

BTW, I am not advocating any particular method of changing the pitch. Just drawing attention to benefits that might be had by paying heed to the relative wind angle and how this information might be used.
Edited by KiwiJohn 2007-10-21

Gill

Senior Member

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

Posted: 01:34am 20 Oct 2007

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Well you've certainly succeeded there. At least I'm more aware of it than before and would be not so against incorporating such a feature into a design.

Thanks mate.

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

KiwiJohn
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Joined: 01/12/2005
Location: New Zealand
Posts: 691

Posted: 01:48am 20 Oct 2007

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Thanks to you too for helping me to develop the thinking process.

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