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nweeks

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Joined: 22/01/2007
Location: Australia
Posts: 36

Posted: 12:38am 22 Jan 2007

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Hi All,

I'm in a windy part of Tassie, where speeds gust over 130km/h every few days (viva the west coast).

I'm interested in building a simple Lenz2 VAWT, but I'd like to keep it from flying to bits.

Would increasing the diameter of the turbine when the speed picks up work, or would the increased centrifugal force make it fly to pieces faster?

I was thinking, instead of a fixed arm from the center axle to the outside, have four arms with a spring in between. The spring keeps the vanes in against some stops, but when speed picks up, the spring is overcome, and the vanes move outward, increasing diameter, and hopefully, decreasing speed.

Alternatively, I could put two of the coggless F&P on the top and bottom, and use one primarily as an EM brake dumping juice into the hot-tub...

Ideas?Edited by nweeks 2007-01-23

Nigel Weeks
nweeks at karbonit dot com

nweeks

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Joined: 22/01/2007
Location: Australia
Posts: 36

Posted: 03:05am 22 Jan 2007

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I've roughly drawn up an alternative to the four-link design I originally thought of.

Large Version
Original Scan

Nigel Weeks
nweeks at karbonit dot com

Gizmo

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Joined: 05/06/2004
Location: Australia
Posts: 5116

Posted: 05:56am 22 Jan 2007

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Yeah it could work, a sort of govenor system.
As a rule, VAWT's dont tend to overspeed as much as HAWT's, once the VAWT starts to run too fast they create a lot of turbulance that keeps them in check, but I could be wrong.

Glenn

The best time to plant a tree was twenty years ago, the second best time is right now.
JAQ

vawtman

Senior Member

Joined: 14/09/2006
Location: United States
Posts: 146

Posted: 10:58pm 23 Jan 2007

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nweeks said Hi All,

I'm in a windy part of Tassie, where speeds gust over 130km/h every few days (viva the west coast).

I'm interested in building a simple Lenz2 VAWT, but I'd like to keep it from flying to bits.

Would increasing the diameter of the turbine when the speed picks up work, or would the increased centrifugal force make it fly to pieces faster?

I was thinking, instead of a fixed arm from the center axle to the outside, have four arms with a spring in between. The spring keeps the vanes in against some stops, but when speed picks up, the spring is overcome, and the vanes move outward, increasing diameter, and hopefully, decreasing speed.

Alternatively, I could put two of the coggless F&P on the top and bottom, and use one primarily as an EM brake dumping juice into the hot-tub...

Ideas?

vawtman

Senior Member

Joined: 14/09/2006
Location: United States
Posts: 146

Posted: 11:20pm 23 Jan 2007

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Increase the number of blades and it will self furl.However tower loading will be high.Might try to fly.Im thinkin of a solidity around .5 for a darrius.
Still Thinkin But have witnessed my test turbine.In 60mph winds with max rpm around 180 in 30mph winds and held at that rpm in the gusts from there to 60mph, not sure how that windspeed converts to your figure.

wind-pirate

Senior Member

Joined: 01/02/2007
Location: Canada
Posts: 101

Posted: 03:25am 07 Feb 2007

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Hi Nweeks.

You might want to check with Ed Lenz "Windstuff now"
He has a RPM formula for his lenz2 VAWT. I had a problem
trying to get more speed and power from mine. I emailed Ed and he told me
not to go wider to to get more speed.
highter for more power for our turbulant winds. I live in a valley where the winds are not friendly.

THE Pirate.
stealing wind & solar energy is fun

vawtman

Senior Member

Joined: 14/09/2006
Location: United States
Posts: 146

Posted: 11:16pm 07 Feb 2007

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Eds right on with that(has always

.Build your tower stronger if you go higher.

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