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Forum Index : Windmills : 65mph/29 ms winds, mill down

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Tinker

Guru

Joined: 07/11/2007
Location: Australia
Posts: 1904
Posted: 02:45pm 16 Dec 2010
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Thanks Pete for clearing that one up. I see from Gordon's Utube that the tail swings to the same side as the offset only.
Has the direction of rotation of the blades any influence on which side one fits the offset offset or does it not matter?

Klaus

  Downwind said   The tail dont swing either side of centre only one way, and as it swings the boom of the tail elevates upwards as it rotates through the 90 degree arc.

This is because the tail pivot pin is not vertical and has a lay back angle on it, causing the boom to elevate as it swings.

The bottom stop is there to stop the tail going past centre as it returns back down to its resting position, being directly back behind the mill.

Pete.

Klaus
 
Downwind

Guru

Joined: 09/09/2009
Location: Australia
Posts: 2333
Posted: 02:57pm 16 Dec 2010
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Hi Tinker,

Funny you should ask that, as it is something i feel is a important factor, but have not said a lot about it as it would imply almost everyone has their furling backwards.

With clockwise rotation of the blades i feel the yaw bearing should be on the right hand side and not the left hand as is usually done.

All mills i have seen with the yaw on the right furl very softly, as the tail holds the mill into the wind and the blade pitch is always tring to drive the mill out of the wind, resulting in any movement in the tail and the mill will drive itself out of the wind.

Where as with CW rotation and left hand furling the blades pull the mill into the wind and the tail pushes the mill out of the wind.

I feel this is part of the reason the alumiumn blades have trouble furling in high winds. (as they bite in very well and hold the mill into the wind.)

In saying this i expect to open a can of worms and it may cause some arguments, which at this point i have no real proof except observation of soft furling mills.

I do intend to test the theory when i get my mill completed as the narcell design will allow for either left or right mounting of the alternator to the yaw bearing.

Another way of looking at it would be if the yaw is on the left then the blades should spin CCW, and for a right hand yaw CW.

I am sure others will disagree with this theory.

Pete.Edited by Downwind 2010-12-18
Sometimes it just works
 
JimBo911

Senior Member

Joined: 26/03/2009
Location: United States
Posts: 262
Posted: 11:24pm 16 Dec 2010
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Pete

It will be interesting to see your testing
(theory)results as far as which side to furl toward versus blade rotation.

At present my blades turn CW and the mill is mounted to the left (viewing front the front)

If the Alum blades do in fact PULL into the wind I am not sure if yawing to the left or right would make a difference? I for one do not know. I do believe I am getting closer to the sweet spot with my mill. I will be keeping a close eye as the winds pick up.

I do know that in Hugh Piggotts book (A Wind Turbine Recipe Book)shows his alternators mounted to the left with the blade rotation CW. The blades are carved of wood and do incorporate twisting in them.
Jim
 
KarlJ

Guru

Joined: 19/05/2008
Location: Australia
Posts: 1178
Posted: 06:42am 31 Dec 2010
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wow just checked out the brakes on gordon's mill
that is awesome 500rpm to zero in two seconds

Luck favours the well prepared
 
Downwind

Guru

Joined: 09/09/2009
Location: Australia
Posts: 2333
Posted: 07:49am 31 Dec 2010
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Gordon's mills are a pleasure to watch in operation and should be a base line for how a mill should operate, there appears to be many designs that verg on the point of runaways, where as Gordon's mills float on the edge of the wind whist still producing good power.

The secret is not to be greedy and expect the maximum from the mill.
With a well designed alternator and furling early to what the alternator can achieve in high winds, you have a excellent preforming mill that is always in control.

To have a design that allows you to hit the brakes is always a good thing as Gordon has shown.

Happy flying to all for 2011.

Pete.
Sometimes it just works
 
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