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"pulsing" and bridle/frame adjustments


A few weeks ago, someone (forgive me, I don't remember when or who) wrote
that their kite "pulsed" when it flew and wondered whether the problem was
due to bridling.

I have the same problem, except that it not only pulses, but spasms in
strong winds. Anyone with suggestions?

Here's some background. The kite is similar to an NSR with a wingspan of a
little over 7'. The finished kite seems to be well balanced. I compared
the center of pressure with the center(s) of pressure and found that all
three seemed to be within millimeters of one another (with the center of
pressure between the centers of balance).

Overall, I think the bridling is fine. The kite flies well when the wind
is moderate; the spasms are most apparent in strong winds with the kite
flying straight. I've located tow points along the mainlines of the bridle
that give me some flexibility in varying strengths of wind. I adjusted the
crosslines of the bridle and found a length that quelled the jerks, but
only somewhat.

When the kite is held upside-down by the towpoints, the legs of
the bridle are uniformly taut and the frame is held flat.

My wife (the ever patient and indulging) launched the kite and noticed that
when the fits began, the legs of the bridles that extend from the joints
of the lower cross spar to the tow point were slack. I'm not sure whether
this is a cause or an effect of the problem.

One last point: the nose is wide. It's made from seatbelt webbing so it
isn't what I would call stiff. Snug pockets hold the spine and leading
edges in place.

Is it possible that the nose gives the frame to much "give" and allows the 
sail to flap in stong winds? I've optimized the bridling to the best of my
ability and checked out the balance of the kite. My last alternative is
that the frame and the sail are somehow going in different directions.

Anyone?

Thanks in advance.
Mo
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