- TrinityOneSparOption01b.png (31.55 KiB) Viewed 6770 times
Morning waking notes of Feb. 3, 2016, on a further method for Trinity Spar seems to grab my emotions. This method was described a bit priorly, but today more. Herein is donated to public domain, as usual. The following method has some compromises that earn some merits. The following method might well be a winner for many niche uses; and the following method may be the most accessible. The compromises involve a choice to do some sewing, though gluing or melt welding (or other technical closing methods) may substitute, especially if the case is formed from two or three wraps of case material. Depending on COTS seamless tubular materials seems to be more expensive and with less options compared to making one's own seamed case.
Still, recall in all these methods recently: The compression elements (CE or CEs) are to relate with the case so that station matching maintains; that is, the CE is not to be simply left loose able to slip matching stations away from each other. I tend to avoid permanent bonding of CE to case, as I am favoring CE-changeout ease; such may allow using CE in different cases or different CEs in some given case. Station matching? Mark a point on a CE; place the CE to the case; mark a point on the case just where the mark on the CE exists; those two marks during operations are to stay married at the same geometric position; differently, slippage would have the two marks go away from each other; such slippage is to be avoided in order to maximum anti-buckling of the case.
Now, more toward the present post's method for having a Trinity Spar. I'll label the following method:
Trinity One Spar to respect that only one fabric tube is used while three CEs are used. Here goes: Have just one seamless or seamed macro fabric tube with a best-performing weave (or laminate shelling veneer, etc., instead of fabric or net). Then fit the CEs to the <b> inside</b> of the macro tube; to assure station keeping of the CEs relative to the case, I am favoring Velcro hook-and-loop; bond loop to CE; bond hook tape to case; peeling the case over itself releases the CE for changeouts when wanted. Insert the bladder to the interior of the case. Upon inflation of the bladder, the bladder presses on the CEs which in turn presses flat the the hook and loop of the Velcro system.
In some instances all three CEs may configured to be coiled while the CEs stay integrated with the macro case. Notice that coiling one CE is easier than coiling all three CEs at once. But if the entire macro case with CEs in place and bladder deflated in place can be coiled for effective tote, then so be it for such instance. Other instance are optional.
Another instance of build could invite removal of the CEs from the interior of the macro case and removal of the bladder from the interior of the macro case. In such instance, peel the case over itself to release the CEs from the hook-and-loop hold; an alternative release method could involve tensioning the particular CE case and then pulling a wedge boat that tails a polyethylene separating strip which prevents hooks grabbing the loops again; then flip the CE and pull the CE out from the interior of the macro case. Then the long CEs may be individually coiled and fixed in coil. Then the three coils may be tied together for tote. Depending on the diameter of the coil, a wing pilot might choose to "wear" the coils during travel on a bus or during a hike site. Similarly, the bladder could be "worn" about a pilot's legs or torso or neck or arm or integrated in a hat or sombrero.
Special note: CEs may be of several types. Some CE choices could be full span length. However, overlapping segments may be used. In the case of overlapping CE segments, there is an option direction of using 5 ft segments with an aim of not coiling for tote, but stacking/nesting CE segments during packed tote to stay within the 5-ft length constraint. Notice in the case of overlapping CE option, there is little need to specially join the segments; it could be sufficient simply to lay the segments side by side or direct overlap two running CEs; however, coupling by banding is to be explored for integrating the antibuckling of overlapped CE segments. The CEs form longerons for the Trinity One Spar. I will be exploring many choices of CE: wood, plastic, bamboo, fiberglass, carbon-fiber composites, steel thin-wall tubing, aluminum, .... Having 16' CE or 33' CE as one piece CE has challenges and merits that invite very careful choosing. Cross section of CEs may vary from circular, rectangular, box tube, round tube, angle, triangle open, triangle closed, circular segment, ellipsoidal, ... One personal aim is to cut up the wood I have in my yard and see how much play for CEs may be had from such gleanings.
Why overlap when segmented-CE format is chosen? Such overlaps keep there from being a buckling point in the inflated spar. An option to overlap is the use of couplings that maintain antibuckle for the CE run; such method is used in tenting, pole extending, etc. Notice that the Velcro system means that couplers for CE segments may remain simple. Continuous antibuckling is the target.
Note: Recall to consider using exterior-of-case cabling of the CEs as part of the splinting method.
Note: See that the recent notes are not rehearsing the options of multiple bladder and interior-of-case web walls; such hybrid formats are available to the wing-spar builder for inflated spars. E.g. a two-bladder interior could squeeze a fabric interior wall or a stiff coilable carbon-fiber veneer sheet, etc. Or a three-bladder, etc.; or a four-bladder with interior coilable veneers. Cost, enjoyments, and performance comparisons will decide which hybrid spar one might build, test, or use. A first level is without the interior complexities.
Notice that the Trinity One Spar could tease using two runs of CEs side-by-side at one of three regions of laying CEs. Such could beef up directional antibuckling, say for positive lift loading in a wing. Note that many smaller CEs could bundle at one of the three CE positions.
Trinity One Spar case-material choicesBiaxial or triaxial weaves? Net or dense fabric? Fabric or film? Sheet? Combinations? I will be exploring many different choices. Since bladders will be pressing against the case, a net mesh too large could cause challenges of wear on the bladder and perhaps early buckling. Combinations of nets and coilable sheet will be explored. Just what might be optimal for a given purpose will ever be a question. Try, observe, test to destruction, report ... Much fun remains. Choices for the case will face seamless or seamed matters. A COTS seamless tubular film or fabric will save the need to form the tube form by sewing, welding, gluing, bonding, clipping, catching, ...
One case.
Three regions of CEA.
One bladder
==== See text for many optional variations of this general scheme for having a spar or beam.
Not shown are special cabling exterior to the case that enhance the effectiveness of CE in spar.
Valves and end-of-spar formats are not indicated.
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Optional detail images
- TentStickCoupler.JPG (10.68 KiB) Viewed 6770 times
- TentStickCoupler2.JPG (18.41 KiB) Viewed 6770 times
by JoeF » Sat Jan 16, 2016 10:43 am 
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