[dhmartens]

Since sales of small inflatable wings are increasing I am going to look at a quick fix to the problem of scaling up the wing size and it becoming less structurally ridged. The solution is to make the leading edges 20 feet long but they immediately bend when supporting a pilot under any wing loading.
The quick fix is to sew in 30, 5 foot batten pockets, staggered, interwoven, what ever is needed to provide rigidity under wing loading. This keeps transportation size at 5 feet. A diagram is needed but hopefully you can imagine the batten pattern on the leading edge and keel.

[JoeF]

dhmartens,
_________Your description brings in the splinted technology; one company coined the ancient technology of splinting beams within the air-beam arena as "tensairity". Keeping weight, pack bulk, costs, and logistic actions in satisfactory realms will challenge makers. It will be fun to see experiments. I will be fully displaying my experiments in the splinted realm, the non-inflated realm, and in the various hybrid realms for the cause. Commercial strategists may not be showing all of their experiments.

It is highly advantageous that air-beam compression members (battens for anti-buckling purposes) be "married" well to the air-beam case, so that the case does not pucker.

Cousin tease:
https://patents.google.com/patent/WO2004020284A2/en
I attach the same in PDF format:

WO2004020284A2.pdf

(539.66 KiB) Downloaded 71 times

Repost:
https://www.sciencedirect.com/science/a ... 3810000519

Hope link gives access for paper: STRUCTURAL BEHAVIOR OF ASYMMETRIC SPINDLE-SHAPED TENSAIRITY GIRDERS
UNDER BENDING LOADS :
https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.694.7686&rep=rep1&type=pdf

'tis an exciting time to witness an unfolding coming era: city-busable, safe-light-polite totes of airframed hang gliders where cars, vans, and trucks may be less of a HG flying system.

[dhmartens]

It looks like this "Airmat" rubber fabric could exactly reproduce an Atos wing which we know has great flight characteristics.

[JoeF]

Excellent video find and share, dhmartens! Thanks.

drop-stitch
https://youtu.be/fCOUo5SsGCU

The myriad-lines Airmat of Goodyear birth has found its way into surfboards, paddleboards, gymnastic mats, ... The weights of products are not attractive yet for the busable-wing polite-tote matter. Advanced materials for the inflatable case and perhaps advanced formation of formed inner lines might result in a pleasant-tote-weighted hang glider (Atos shape or less). Construction challenges for a one-of wing might be different than a production-line challenge. Goodyear-era inflated planes came before Dyneema and and some advanced industrial fabrics. Neat direction....

Tease gym airmat: https://zelusfitness.com/collections/in ... tf-mg31-u3

And:
https://www.amazon.com/CNSPORT-Inflatab ... th=1&psc=1

[JoeF]

More pause on double-wall fabric, drop-stitch construction:

One finds drop-stitch products of constant thickness. Big question: how might airfoil shapes be formed from drop-stitching; the thickness of the item varies.

More tease:
https://www.durainflate.com/
For study:
https://www.duratarpaulin.com/product/t ... -material/
http://www.energykitesystems.net/Materi ... index.html
https://citeseerx.ist.psu.edu/viewdoc/d ... 1&type=pdf


Some key phrases or words:
hand made double layer drop stitch
machine made double layer drop stitch
woven dropstitch
Goodyear dropstitch
Double wall fabric
TPU double wall fabric
PVC double wall fabric (heavier than TPU in similar products)
wave stitch [ contrast with welded or fused ribs or sewn or woven walls]






Sidebar
The Insane Biology of: The Dragonfly

Note: Notice how drop-stitch technology differs from bladder-case technology.

[JoeF]

Following quote from https://www.nrs.com/learn/what-is-drop-stitch

The process starts by joining two pieces of polyester woven support fabric with thousands of fine polyester thread lengths. This base material is made in strips from five to ten feet in width, and up to 400 needle heads may be used in the setup. Each needle sews a continuous, evenly spaced thread, back and forth between the two pieces of woven fabric, locking them together into an incredibly strong unit. These drop-stitch sewing machines are marvels of complexity. When a change is made in the spacing distance between the two pieces of woven fabric, it can take over 20 days to remove and replace the required needles.

============
So, such may hint at the challenge of full drop stitching a mat that is airfoil shaped! Thus, the competing technologies of aggregate inflated chambers via rib walls by way of chordwise like Jalbert parafoils or like joining spanwise inflated tubes of various diameters. As it stands, the competing tactics for inflated double-surfaced thick airfoiled wings win over hand drop-stitching (I have no evidence of anyone hand-sewing myriad-lined double fabric for a human-carrying aircraft.)
=============
However, one might hand weave myriad lines between two support fabrics and fuse or glue-stop the ends of each of the thousands of lines; the two opposing support fabrics might be set in a form allowing hand sewing the lines. The form could be in the shape of an airfoil of choice. Thread the myriad of lines and set their ends to the two support fabrics. Whew! Then make the support fabric air tight healing those thousands of sewn holes. Inflate; presto: inflatable airfoil using myriad of lines to control the shape of the airfoil. Weight?

Maybe one-of wings could be formed with myriad connector lines using quicker forming methods.

First round weights and logistics for drop-stitch double-wall wings are not inviting for my aims for early explorations. Maybe later. I'll keep a file going studying the technology, though.
=====================

[dhmartens]

These inflatable wonders are made in China, in factories, using people, machines and methods that can be seen here:
https://www.alibaba.com/product-detail/ ... 17516.html


Inflatable wings from $129
https://www.alibaba.com/trade/search?fs ... product_en

I think how it works is if you send them a drawing, they will build you one or more for a given price.

I was looking for shortcuts, like use 2 existing small wings in a bi-plane configuration.

https://sc04.alicdn.com/kf/H342f8392ad9 ... 31fa4K.jpg

[Frank Colver]

My experience with drop stitch has been with floors for self bailing rafts. Those of course are parallel sides so not the problem with cambered sides of a wing.

Experience has shown that gradual separation of drop stitches can occur over time with use, or very quickly if overinflated. Kind of a zipper effect.

I'll be visiting the Alpacka Raft factory again this month and will bring up the subject again. There's is all US manufacture, so more expensive but very high quality and a choice of materials. Vectran has been discussed here before. In my opinion it would be the best choice by far for an inflatable wing. Lightest, strongest, and stiffest of all available materials (also, most expensive).

Frank

[JoeF]

https://en.wikipedia.org/wiki/Vectran
https://en.wikipedia.org/wiki/Kuraray
https://www.alpackaraft.com/
======================================
Watch MOQ and shipping at Alibaba. Enticing pricing; experience with purchasing with Alibaba may be a preamble challenge.
======================================
Biplane mention is interesting.
In resonant spirit: >> >>?? One deck, but two wings rigged using KP and TCF queen posting. How about rigging three wings to have HG: left, central, right? Pack weight and pack volume grows ... Perhaps add compression beams to the commercial wings?
===================================
Pack weight
Pack volume
Pack shape
Wing area
Repair logistics
Auxiliary equipment
Rigging or not
===========================

TwoOrThree.jpg (78.34 KiB) Viewed 781 times

ThreeCOTSriggedKPTCF.jpg (72.62 KiB) Viewed 781 times

[Chris McKeon]

For what it's Worth, Not much, Ha, Ha. I whole heartly agree. That Helicopter project Truly Rocks! Good on you guys.