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dave sainsbury

Member Since 15 Nov 2010
Offline Last Active Oct 07 2011 04:13 PM

#76991 in the air again

Posted by dave sainsbury on 14 January 2011 - 01:49 PM

I worked out the handle angle issue, and why they were bent in the first place.
In fear of describing the obvious
A closed fist is not at right angles to our arm.
It is kiltered away from our thumb.

The maximum change in relative line lengths, on rotating the handle position, occurs when the attachment points are perpendicular to the lines.
Conversely virtually no change in relative line length occurs when one attachment point is directly behind the other.

So, when I hold the handles in my most comfortable, relaxed, and natural position, the top attachment point should be equidistant from the kite as the bottom attachment point.
To minimize the strain in my arm at this time my forearm would also be pointing directly along the axis of the pull in the lines.
So, if I stand with my forearms horizontal, a weight on the top leader should see it hang down in line with the bottom attachment point.

One consequence of this, for the way I hold the handles, is that the angle becomes less acute as the handle gets longer.

This logic assumes you need the most sensitive control in the neutral position.
If you tend to over control in reverse flight you would have straighter handles :-)
(And, of course, you would need to lengthen the bottom leader to compensate)

Simlar issues wil occur at the kite end of the lines.
These will reference the relative angle of the kite surface to the points that the flying lines effectively attach to the bridal.

And finally, the ratio between the length of the handles and the vertical height of these bridal attachment points will determine the amplification (or reduction) of handle movements with repect to change in the inclination of the sail.
On this theory, the same result could be achieved by lengthening the handles or shortening the vertical distance of the points that the lines attach to the bridal. Although having a range of handles is the simpler solution.

extendable handles would be an interesting optiion but probably overcomplicate things.