[KaiMartin]

Groves in CE receive flat kedar strapping. Fabric tension holds things in grooves

I am not quite convinced by this one.
Like you say, fabric tension is required to hold things in the grooves. However, there are situations when the fabric is not under tension:

1. The fabric of the not yet inflated spar does not provide any tension. It will probably be difficult to put the strapping completely into the groove at all places at once. When fully inflated, friction will probably prevent any movement. After all, this is what the contraption is aiming for However, it might be possible to manually push strappings in when the spar is only marginally inflated.
2. There are situations that can temporarily relief tension at portions of the sail - think rough air, slightly touch the ground when handling the wing, a less then optimal landing... I'd rather not be worried that the sail of my wing would come off the spar due to such minor incidences.

How about a combined approach: Use flat grooves for the spar and a rope in a seam for the sail. The sail would not require tension to keep attached to the spar. Mounting the wing would become a two stage affair. First inflate the spar, no sail attached, yet. Then hoist the sail on the spar.

Hoisting the sail may be most efficient with two persons - one to feed the sail at the keel, the other to pull the sail from the wing tip. This my foster friendship among pilots. Mavericks may replace the friend by an electric winch.

---<)kaimartin(>---

[KaiMartin]

One low-cost bladder-making material: bag-making tubular film lay-flat on a roll. Without recommendation tease Here. Shown is too wide for Wing5; type of product comes in may lay-flat widths. Cut off a length; close ends; mount valves. Polyethylene is poor performer for air tightness. TPU is target.

IMHO, the main disadvantage of polyethylene (PE) for a bladder is its rigidity. The bladder presses itself to the inside of the carcass. Unless the bladder is a perfect fit for the carcass, the bladder will touch at some places while it still needs to expand at other places. Due to friction these parts of the bladder are held in place relative to the carcass. To compensate, the rest of the bladder needs to stretch to actually fill all parts of the carcass.

This is why bladders of tyres are traditionally made of latex. Rubber provides the additional benefit to be very airtight. However, its main advantage for bladders is its stretchiness that is unparalleled among common construction materials. So yes, thermoplastic polyurethane (TPU) would be a good choice for the bladder. Not so much because of its airtightness but because of its ability to repeatably stretch and contract.

---<)kaimartin(>---

[JoeF]

Thanks, Kai ! I am in conversation with a firm American Polyfilm, Inc. (APi) [yet without recommendation] today and in the coming week; they sent samples of some TPU in 2017; and I tested one of the samples; I am finding some positive success my getting to know various TPU offerings. The polyester TPU at 3 mil or 4 mil with clear was tested; I have not yet tested "natural" color product. I've tooled with a heat sealer (pressing against a Teflon ribbon and a heated formed wire; I aim to make long bladders from rolled flat TPU film. These are my first experiences in this craft space. The pool-hacked bladders will be heavier than the final TPU select.
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Upon a recent decision not to include sail-attach-to-spar-solution into the spar-case-CE assembly, and rather root the sail using its own separate run fore of the CELD assembly, I saw an opportunity described next:

An exciting new direction for marrying the CELD to the spar case is rehearsed in the following image:

AngleCELDmarriesSparCaseNoHolesInCase.png (37.15 KiB) Viewed 1251 times

Most of the stick-like parts of Wing5-M1 have little need to combat torsion. Wing flight-loaded torsion will be faced mostly by rigging and the inflated spar case of circular cross section. So, a mini-Eureka moment occurred as I saw that an early wish may be coming to fruition: Pack HG with angles nesting and not circular cross section tubes. I believe at the moment I will race for Wing5-M1 with the angle-based technology for the stick-like parts: keel, two queen posts, one HH mast (kingpost), CELD segments. The stuff-locker parts won't be angle, but will be trapezoidal bar of wood or plastic (not clear on this part's specification yet). The angles will end up being aluminum or carbon fiber; mass is important to me, especially to up the carryback grade at the Dockweiler situation where carryback nearly rules the day!

The queen posts should be aluminum for safety; carbon fiber splintering could spell trouble.
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With the changes, the sail may have its root on the spar case by a run of hook-and-loop.
=============================
Leaning towards angles: Leg thickness specification is not settled; 1/16 inch would be nice if it works; 3/32" would be next; 1/8" next. Seeking least mass that will become satisfactory, as upping the carryback grade and toting/packing grade is of high interest.
= Five segments of 48" carbon fiber for CELD
= Two segments of 48" carbon fiber for making one HH kingpost
= Two segments of 48" carbon fiber with coupler for net 8-ft keel
= Five segments of 48" aluminum with overlap coupling for the two queen post and one base bar. The overlap coupling on the queen posts will allow much experimentation.

The nine carbon fiber segments from one supplier invites stuttering, especially at this time when flight is not assured to be satisfactory
The quality choice for carbon fiber angles is a fuzzy matter for me yet. The "economy" or the other....??

Local supplier on aluminum: (we used them in the 1970s for some HG makes)
https://www.bobcometal.com/metals/aluminum/6063-aluminum/6063-aluminum-angles.html

One carbon-fiber supplier: (not yet a recommendation; no purchase experience yet; other sources might rule)
https://dragonplate.com/Carbon-Fiber-Angle

==============================
The stuffer-locker? It might be neat to have this part weigh low. The upper surface edge that wedges the spar case to keep the edge keders locked in the cavity is important. The wedging is firmed by the tension in the bolt system. Perhaps a sandwich of thin plates cored by a rigid low-mass foam could be an advance make. First makes will be pine sticks with the two 45-degree cuts; the weight of such bars or sticks will be a reference against later experimental makes of the part.
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The flat keders embedded in the spar-case edge are intended to be wrappable in the tote pack.
================================
The separating of sail-to-spar from the CE-spar-case-closure assembly allow placing the sail-attach at better o'clock position and the CELD assembly at one o'clock position or 1:30 o'clock or 2 o'clock. Foam fill won't now be needed. CELD won't be interfering with sail or air flow. Less parts, less drag. And there is then the flexibility of experimenting with sail-root positioning and CELD positioning separately.

The "going with angles" allows an angle-nesting pack-volume reduction that might prove cool. Time will tell!

It would be neat if the CE bolts are not needed; could bladder pressure push up the stuffer-locker while the spar-case tension from inflation pulls the keders down? Maybe the keders could be caught or locked into the inside face of the legs of the angle; perhaps bonding a line of block to the inside lower region of the CE angle would allow the keder to lock to the angle leg and also be captured by the stuffer-locker. The added thickness to the inside of the legs of angle would slightly add toting-pack volume, but if such worked, then "no-bolts" for the CE assembly. Will aim to reach such possible opportunity. Here below is my first effort:

BlockerOnInsideLegsNoBoltsCEtoSparCaseMarriage.png (25.42 KiB) Viewed 1242 times

Keeping the bolt system until a better solution surfaces..........

[JoeF]

Edit timed out.
Furthering:

BlockerOnInsideLegsNoBoltsCEtoSparCaseMarriageShorterPlusFiller.png (17.62 KiB) Viewed 1239 times

The rigid -foam filler brings back some pack volume. but the mass addition is small.
The adjusted design puts the smaller stuffer-locker up where the angle legs are tighter; the pinch-keep of keders thus may be more certain with less bolt tension. Still there are no holes in the spar-case edge.
With this, drawing not showing, there is still a need to fix the bolt head into an indent in the stuffer-locker piece, so that placing the nut firmly will not spin the bolt.

The drawing does not properly show the path of the spar case; the path of the spar case should be right up snug against the angle leg where the stuffer-locker presses that point of the spar case. The spar case keder at the spar case edge stays above the stuffer-locker. The bolt does not go through any spar-case hole. Two keders rest in the upper cavity during inflation and flight.

Assembly challenge:
Have bladder deflated.
Set a run of segments of rigid-foam fillers atop the relaxed bladder. Spar case is still open with edges line paralled close to the line of fillers.
Set the stuffer-blocker on top of the run of rigid-foam fillers.
Place two keders of relaxed spar case above the stuffer-blocker. It might be useful to have some thin coin hook-loop for keeping the keders atop the stuffer-blocker, else fumbling seems inevitable. Maybe keders may have hook on one and loop on the other; join them; put occasional holes in the keder set for the bolt passage. [Maybe the hook-and-loop keders with bolt hole could simplify to a point where fumbling won't occur.]
Insert bolts through stuffer block and then through the holes at the top of the angle.
Mount washer and nut on the protruded bolt stems.
Continue this for all the CELD segment angles.
Place the angle run atop a set of rigid-foam fillers that are resting in a line over the relaxed bladder.
Inflate the bladder; this makes the spar case taut and causes the bladder to press on the rigid-foam filler and thus the angle is pulled down firmly onto the spar-case where the angle legs press the spar case. Whew! Will this become easy? Dockweiler sand? Parking lot? Ground cloth? Raked sand place in the sandy area below launch?

Ideation fatigue, perhaps: I am not appreciating that the rigid foam and stuffer-keeer will be INSIDE the spar case out of sight and reach some for the assembly effort. I've not modeled the process yet. There may be too much fumbling. Maybe integrate things and pre-bolt followed by slipping the keders up in the cavity; only then tighten the bolts. I'll study this. Anyone?

My first next effort on the challenge:

BeforeAngle.png (34.34 KiB) Viewed 1239 times

=========================================================
Different approaches to consider while still keeping angle CE are being studied.

[JoeF]

May go with one or both of the following for CE using angles:
1. One angle with bar and bolts as shown:

2. Two angles squeezing the spar case while letting keders flop out the beyond the squeeze. Join the two angles with series of occasional bolts, perhaps about each 12 inches until experience dictates closer arrangement.

Note: at end of CE segments adjacent with another CE segment, have a bridging of the associated run of bar, or insert a coupling bar.
Use bolts to form a clamping of the two edges of the spar case; have the edged keders flop out the top. Recall in this status that the sail has its own separate place.

Two options that may simplify things. But the compression pattern is different on these two options.

AngleOptionsCELD.png (4.09 KiB) Viewed 1234 times

Both shown options pull the angle leg flat to the spar case firmly when the spar-case's bladder is inflated.

If spar case is film:

KederedEdge.png (6.45 KiB) Viewed 1234 times

If spar case is sewable:

EdgeDetailKederStrap.png (4.71 KiB) Viewed 1234 times

[JoeF]

Exploring other angle-use options:

Here is another option using two angles:

CEangleOption003.png (13.12 KiB) Viewed 1231 times

This option has some pros and cons.
Pros:
It puts some CE mass up from the spar case for some leverage against compression.

Cons:
The off-the-shelf legs of the angles arranged as shown forms a jog in the spar case. Shortening the base angle vertical leg would smooth things, but that labor is a cost. Measuring the benefit of such adjustment would be an analytic task.

Note: The position of the CELD will be in the cavity under the sail at high camber position. Flow will not be much disturbed by the CELD assembly.

SparSailCE001.png (1.82 KiB) Viewed 1231 times

Notice the CELD position is not at noon, as both lift and drag are addressed by the position; there will be some best o'clock position for the CELD subassembly.

[JoeF]

Rib struts?
The struts will be rooted at the spar case. A plate for each root will be placed in a pocket. The pocket will be bonded to the spar case. The plate will be a separate part for packing. The plate spreads the pressure from the strut; instead of hard poking the spar case, the poke will spread its force to a broader part of the inflated spar.

Assembly: Place the plate in its spar-case pocket or the like; place the root of the rib strut in the center-receiving spot of the plate. Connect the other end of the strut to the rib.

SparSailCE001RibStrut.png (2.8 KiB) Viewed 1226 times

RibStrutBasePlate.png (6.39 KiB) Viewed 1226 times

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Ways to connect the rib strut to the rib?
The rib will be in a sail-based rib pocket. The rib strut will tote as a separate part. A triangle-like arrangement forms when having the rib, rib strut, and spar case up and ready for flight. That triangle will not have much flex to it. Flight loads are partly carried from the sail to the whole wing via such a triangle; torsion goes to the spar partly by the workings of the triangle. One corner of the triangle is the join of rib strut to the rib. This post partly faces the challenges of that specific join. Options are available, but some options will be better or more satisfactory than others. All HG community is invited to offer up options for this join matter.


The rib strut might be angle; such angles might pack angle-nested; such would take less pack volume than round tubular rib struts.

Y yoke top end of the rib strut. Have string segments coming out of the Y yoke. Have a set of two tiny nubs on the rib; set the yoke between the two tiny nubs; tie the two strings around the rib as cinching a shoelace. For packing: untie the knot; lift rib strut off the receiver spot at the spar-based rib-strut base plate; pack the straight rib strut.

RibStrutJoinRibNubsYokeTie001.png (3.69 KiB) Viewed 1225 times

The rib will be made of two main parts overlapping in central-rib; the overlapping makes central-rib stronger against buckling; the rib will be in compression but confined by the rib pocket and the global set of the sail. In that overlapping, if side-by-side, there is could be a resultant crevice. That crevice could be a foundation for connecting the rib strut to the rib; let the upper end of the rib strut poke into the rib crevice and be tied or shear-pinned for join.

There might be two strings perma-mounted to one of the two parts of the rib. An access hole in the rib pocket would show the strings; use the strings to cinch the upper end of the rib strut; the string could go through holes at the upper end of the rib strut; tie a knot that can be easily untied for packing.

?

[JoeF]

Forming the wing tip scene for Wing5-M1
The spar case must close somehow at the wing tip.
The sail needs to be treated at the wing tip.

Using two angles and spar case edge flat keders, pinch to a straight line the end of the spar case; use bolts to firm the clamping of the two edges; the keders will be on the outside of the pinching beams. The beams form the tip rib. Have the length of the tip beams be enough so that a net bowsprit occurs at the wing tip while also forming enough aft rib to hold the sail. This set of two angle beams forming the tip bowsprit-pinching-length-aft-ribbing will function for several purposes:
1. Close the spar case.
2. Give aft-of-spar rib for holding sail.
3. Give foundation for the big tension of the sail that will be pulling inward toward keel during flight.
4. Give bowsprit at the wing tip for connecting a line from the keel bowsprit. This may play in several ways: a) help stay the position of the rib aft portion of the two beams. b) provide a possible control method; pull on the line that joins the keel bowsprit and the bowsprit of the wing tip and get a morphing of the wing because of change of tension on the sail that connects to the tip's two-joined beams.
5. The two-part beaming forms a rigid foundation for wing-tip control devices, if wanted.

The wing-tip scene also must face the tension loop that fixes to the tip of the CE and then the loop parts go on the exterior of the spar case helically to the other wing tip; the loop works as a tension member of the splinted air beam that is the spar. The loop should have on it two tensioners to respect webbing creep and changing spar-dimensions; one tensioner on one leg of the long loop and another tensioner on the other leg of the loop. Note that the CE may end before reaching the wing-tip pinching-closing beams.

Note that there is a special opportunity: The straight line of the pinched end of the spar has an angle of rotation relative to the line of the keel. Choosing the clock angle of the wing-tip rib two-beam pincher relative to the keel line or central chord center line will be important for the pitch aerodynamics; wing twist, (Irv) Culver Twist, washout .... The line may be changed by pinching the end of the spar case differently; marks should be made on the edges of the end of the spar case to direct where the fold for pinching will be; changes from a mark would form a new wing performance.
Culver Twist Formula
=

WingTipWing5M10001.png (9.24 KiB) Viewed 1214 times

The drawing does not show the tension webbing that roots at the tip of the CELD (compression element for lift and drag).
Also, the drawing neglects to show the sail yellow over the spar, so that the spar may be seen.

The tip two angle beams are to be made up of four segments total. Two segments per beam. Bolting joins the two compound beams. In pack, the four segments are separate parts that pack angle-nesting.

[JoeF]

It looks like I am moving towards some changes again in what will appear in the Wing5-M1 in the wing-tip arrangements.

Crutches might provide keel tubing or wing-tip tubing. Maybe wrap three tube sets over rigid foam to form keel. Fiberglass tape?

Changes in the tip have occurred. Instead of using four (4) angle segments and having the spar case closed each flight session, there will be the following changes:

1. Have the spar case permanently end-closed using low-mass closing techniques depending on the material being used for the spar case. Film requires a different tactic than textile. The film spar case that is going to be tried might consist to two stiff strapping keder meant to ever stay straight for the pinch closing and for wrap packing. The keders will be in a hem made in the film; the hem will be closed firmly with hot glue and some stitching. Then the two keders will receive a series of stitches, actually a series of indepent loop ties that will use high-tensile quality line. Each little loop will receive its knot.

2. The tip beam will be made up of two coupled tubes. The full beam will be about 90 to 93 inches; the length will serve for an 8-inch tip bowsprint and a tip rib; the beam will be stationally tied to the straight spar-case-closing tip.

3. No keders will be involved in the tip-rib marriage to the mainsail. A simple hem in the tip edge of the mainsail will be in place.

4. At assembly, just slide the tip beam into the sail tip hem, tie the beam to the tip-straight-spar-case-closed part, and let the beam stick out in front of the leading edge of the spar as a tip bowsprit of about 8 inches.

=================

Spar case will be perma-closed; this will avoid bolting, reduce assembly and packing time. The interior of the spar case may still be open when the CE is out; works in the interior thus may still be done.
==============

CE options competing:
1. An interior position: Two-grooves in the CE segments looks like the choice for now; a 1/4-ince space will occur between the two grooves; that 1/4-inch space will receive some screws, not through bolts; the screws will be pulling down a keder-keeping cap; the cap may be occasional or full length; the cap will be firm segments to couple the CE segments, so the CE segments are firmly aligned. It is possible for the keder-keeping cap may act as part of the compression-resistance team; base CE and cap form the team.

2. Exterior position, no foam filler, screws, no holes in spar-case edges: Low-density wood, maybe pine; two grooves in pine to receive keders. Cap of aluminum channel (if flight seems satisfactory, this is something that might go to carbon-fiber channel, but not for Wing5-M1). Both the wood and the channel would marry via screws, not bolts. The spar case would be exit the bottom of the channel; the wood would be flush with the bottom of the channel legs. Pack the wood in channel for tote. For pack, the spar case become separated from the CE; the spar case will wrap stick-like parts. The spar-case edge makes a 90-degree bend at the bottom of the channel leg; then the spar case bends again over the wood inside the channel; then a final bend in the spar case occurs at the keder edge as the keder is stuffed into a groove in the CE.

CEforSparOptionAug31of2021.png (11.6 KiB) Viewed 1193 times

Smooth face to the bladder occurs. There is no need to fumble with interior handling; the screw has no need to deal with interior matters like occurred with through bolting. There is no need for foam fillers; the pine wood or the the like fills the fully the channel cavity. There is super hold of the keder edges. No holes will occur in the edges of the spar case. The wood will be so placed as to form a coupler for the aluminum channel segments. If needed, more compression-resisting material could be placed atop the channel requiring only slight longer screws for holding the added bar; such would be done on a different day's flight session.

[JoeF]

Wing5-M1 mini notes:
Bobco Metals does not have the 6061-T6 channel.
Seeking 6061-T6 channel from Tell Steel; no answer yet.
Hook-and-loop order arrived
Sample TPU of polyester at 4 mils arrived. Asking their price on a remnant roll.
Found a huge castle inflatable made in 2011 of heavy PVC-coated fabric. Matrial is too heavy for Wing5, but will experiment with air beams. Today I cut the the thing apart. The salvaged material needs cleaning. Image Experiments will feed Wing5 concerns. I will experiment with some higher air pressures with the material.