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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:
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:
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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
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