CoolIP index                                                          Most recent edit: Wednesday October 24, 2012

* See legal note below.


Advantages and Design Limits of Branched Sleeved Control Lines

Pocock advocated integrating multiple kite control lines in a single silk sleeve, for neatness and handiness. Its also possible in principle to reduce drag by integrating lines into one tether. We have a neat coolIP trick whereby an ordinary cored braid line can act as a mechanical control channel equivalent to two-line control.

What is the upper limit of what can be done with sleeved lines? How many control channels can be hosted, and is it possible to clean up the snaggy complexity of a super-high line count? A biomimetic model exists in how bundles of muscles actuate bundles of tendons that branch out into many outputs. A human pianist is a good illustration of how fine control can be, with all the required tendons neatly stowed within the forearm, wrist, and hand, with the sheathes, straps, and branch details highly evolved. We also see complex branched high-count fiber structures in places like tree anatomy.

Similarly, we can envision a branching system of machine-braided sleeves with an almost unlimited number of internal mechanical actuation channels. Its not hard to see potential advantages over a distributed electro-mechanical network in terms of power-to-weight, power supply, capital-cost, robustness (ie. wet-proofed), and maintenance. This is a promising way to address Kixels individually to tune them or change states. Thus a vast kixelated megakite need not host a mess of naked lines (or servo network), although "Edo bridles" are workable.

An interesting dynamic is possible in a load bearing branched sleeve tether, under working tension, to have its channels locked in a programmed state by the bias-pulled outer braid (Chinese Finger Trap), and by a brief slacking, to be able to reset static channel settings.

We can rely on the near-Teflon slickness and super low stretch of UHMWPE to enable sleeved mechanical actuation, but many "simple" rigger's methods must be worked out, such as how to maintain and repair these assemblies. The design limits are mostly those of limited imagination, with a probable upper limit to working length, where RAT-powered electromechanical actuation ultimately becomes competitive. At this scale, the branching polytendon networks may live on as LANs resident on the megakite.

CoolIP*                      ~Dave Santos                 10April2012            AWES6016         

Comment and development of this topic will be occurring here.       
All, send notes, drawings, and photographs!

Terms and aspects:   

  • v

Related links and concepts:

  • Long single line to free-flight paraglider published notes had option of sleeved control lines in order to reduce the drag of the gross tether.   JoeF

Commentary is welcome:

  • Distinguish mechanical control lines from electrical or optical signal control. Consider pneumatic line integrated. Consider hybrid mixed sheathed bundles where air lines, electrical signal lines, and mechanical control lines are bundled with tension-holding tether in a sheathed bundle.       JoeF     10April 2012

*Legal Note: coolIP is hereby defined as a Creative-Commons Unported NonCommercial Share-Alike License, so now we are integrated with the latest standard cooperative IP model, but "coolIP" remains a nice shorthand.