By Dave Santos on August 7, 201928026Secret Life of Kites- Imprinted Line TwistKnot
and braid mathematics apply inherently to real kite line. Braiding can
embody endless fractal twist-spin patterns. Line comes in all sorts of
classic and modern twisted and braided patterns. In each case, the
basic mathematical model is easy to see, but there turns out to be
further line dynamic complexities that do not seem to have been
formally identified before, although every kiter experiences them.
Traditional twisted lines clearly act as helical springs, but we are
more concerned here with modern power kite braided lines that begin
twist-free.
For
years I have puzzled over how my power-kite lines somehow develop
"virtual" twist even after carefully straightening them into a locked
topology of larks-headed lines, bridles, and anchor-points (bars or
handles). Its not a huge operational issue, more a
nuisance, but its seemingly impossible to remove all the mysterious
twist. There seems to be different twist effects according to tension
as well.
What
seems to be going on is a polymer creep effect based on how line is
wound for storage. The line under variable wound tension line flattens
over time in unnoticed ways. Then when you run the lines thru your
finger tips intending to straighten them, you may be actually
introducing twist that was not there. When you handle line, virtual
twist (spin) statistics develop on a topologically straight kite line,
when it acts like a torsion balance oscillator, as two self-cancelling
mirror twists of opposite handedness.
The
line also takes a helical set overall in the shape of the spool. Its
also common for careless flyers to spool tight with real twist which
then sets into a flattened twisted cross-section. Thus
there are various sorts of overlooked twist can that can end up on the
spool, and then set in by the polymer creep mechanism.
When
it counts, like in competition, the ultimate is new line carefully
pre-stretched. Line is perhaps best stored in a uniform slack
condition, but be aware pre-stretched line will slowly creep back
shorter over time in storage, and will need retuning at the bars or
handles, especially if line-sets are stored in odd variable tension
states.
This
is what the Secret Life of Kites is like; ever-deeper mysteries of rag,
string, and wind. Closer study of imprinted twist on used lines is
should reveal more clues.
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