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How to determine the pull of a kite

In article <27sf2r$d5n@irisa.irisa.fr> engel@irisa.fr writes:
>Nevertheless, I found your comments very constructive and encouraging, and
>I decided to incorporate them at ounce in a new theoretical aerodynamic model
>that I'm going to send to NASA. Of course, I won't forget to give you due
>credit for all your helpful remarks ...

Ok, Ok, I asked for that, however let me look further into your question:
You are looking to work out the pull.  Why?  Let me take some guesses:

1) You want to ensure that your line is strong enough.

Important factors include:

Line length, apparent wind during launch and method of launch.
If you long-line launch the kite, it will build up apparent wind, increasing
pull dramatically, perhaps ripping the kite or bridle apart (Ask Patrick),
pulling anchors out of the ground or breaking lines.

Drag.  Watch Martin Lester's Legs or most of Peter Lynn's big toys.  Much
of the pull on the line is due to drag, not lift.

Flying line elasticity
This is important.  Cheap stretchy line will absorb shocks due to luffing.
Expensive non-stretch lines can snap due to increased shock loading.

Movement of the anchor point.
A tree or ground-stake has no give, leading to maximum shock loading.
A sandbag will move under heavy load, relieving the stress.

2) You want to use the kite for traction: sailing downwind.

If you want to do this with a single-line kite, the best method seems
to be to maximise the drag.  Put up a large kite as a mast and add
loads of junk to the line, to pull you along, not up.

3) You want to use the kite for traction: sailing upwind.

This starts to get difficult:   You want maximum lift, minimum drag
without the problem of overflying (and without being too powerful
away from the edge of the windowm)

Andrew
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