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Multi-Link Tethers and Sleeved Multi-Lines

Multi-Link Tethers

Common kite tethers are single lengths of one line well suited to the loads a single kite puts on a tether. The slightly greater tension at the kite (that DaveL found in his simulations) favors the line parting at the kite in the event of break-away, so that the kite will not drag along XC indefinitely, but glides down. Eddy/Patton trains include tri-swivels inserted along a main tether, so that kites can branch off and not develop line twist as they loop. Trains and stacks develop far greater tension at the surface; the sum of all the kites pulling together, therefore an optimal tether is graduated in stages, much like a multi-stage rocket tapers toward the top. The end result is similar; a capacity to fly higher than any single-stage. Stages can also be assembled and disassembled on the fly from separate winders, adapting to changing wind, and damaged sections hot-swapped.

Lets call such composite tethers "Multi-Link". The simplest and kitiest method to connect links is with a larkshead loop and stopper knot, which everyone should know how to make. For a graduated line, a thinner link should larkshead onto a thicker line stopper knot. Properly done larkshead knots are secure, especially under load, and easy to connect and disconnect. With very fine line, a tail is sometimes added on the knot loop, to grab if needed for easier disconnect.

Hardware is often introduced between links, like the tri-swivel noted above, but a common instance is a shackle of some sort. Rigging, sailing, fishing, and climbing all have great versions of shackles to use or learn from. In the case of kites a good shackle is light, generally aluminum in any size larger than sport fishing shackles. Snap shackles are handy, but beware the potential of such shackles to snap onto a line unintended, with potentially disastrous results. Where a risk of such fouling exists, choose a locking shackle. Always select the "perfect" shackle from the endless selection of products.

Pulleys are a common rigging component with many variations. Special pulleys are designed to allow knots and low profile shackles to pass. Graduated rings and stopper balls allow multi-link tethers to display programmed dynamics as multi-tethers (original Cody War Kite staged-launch method). Varied components, like NAV markers, can be linked in between line sections. The possibilities are infinite, and extend into 3-D lattices for mega-scale latticework.


Sleeved Multi-Lines

Pocock highly optimized almost all the features of his Charvolant kite buggy system. One of his proudest innovations was to put all three of the traction-kite lines in a silk sleeve, thereby preventing most snagging, sawing, and looping twists. Protected so, the lines could be specified thinner, offsetting sleeve weight. Its possible that the neatness of sleeved lines even reduced aerodrag, further offsetting any extra weight. Pocock did not report that the bit of extra actuation friction was a problem. especially compared to the robustness of being able to yank sleeved lines out of trees, as happened on occasion.

Sleeved Muli-Lines seem to have been overlooked by modern kite riggers, but like all else Pocock discovered, are due for a comeback. A natural trick is to use modern braid-over-core, or hollow-braid with custom core added, as a multi-line by pulling on the core differentially from the outer braid. Many basic control functions could be so enabled, like steering or kite-killing.

CoolIP                       ~Dave Santos                 21Nov2011          AWE4849

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