By Dave Santos on August 7, 2019

28026Secret Life of Kites- Imprinted Line Twist

Knot 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.