[Bob Kuczewski]

The air spar sounds a bit exotic, and I'm not sure about how it would hold up under axial compression.

But I like the idea of taking a regular glider (maybe someone's worn out Falcon?) and fitting it with:

• A mechanism to easily remove the sail from the frame
• Sleeves to join longer tubes after cutting for short packing

I think that's a practical approach and could be accomplished fairly easily within our abilities.

[JoeF]

Excellent practical approach for a family of solutions, BobK! Mod-05-Falcon-1-195 might be a first in that family. Hacksaw is ready (or cut-off saw!). Velcro committee is waiting; or the Zipper Crew. Coupling captain is alert to core and oversleeve. Logistics secretary is ready with notebook. Tangle clerk is an avoid-knot expert. We cannot miss! The assembly will be good for warming up body systems. The system check will build intimacy with wing; call her Sally Soar or Sore Sally, or Sore Sam or Sam Soar, your choice. ... on the bus I go, on the bus I go, happy as a cricket.
I'll do a mod to 5' on the long battens too! Hey, Greg D., here is Sally, my Mod-05-Falcon-1-195; no charge for you to test fly it!

Sail-connect explorations:
== Duct tape
== Velcro parts
== Magnets
== Corded clasping
== Sticky wrap
== Snap-in-channel (Zip-Lock)
== Rim cord in groove
== ? (open to committee work)
==============================
Tube-coupling explorations for available cut macro tubes
== Plug core and oversleeve
== Terminals: threaded join
== Splints and whipping
== Locking clamps
== Mating flanged inserts for bolting
==
== ? (open to committee work)

====================
====================
Yet, progress on other families of solutions will occur.

[JoeF]

===============================
http://www.textilearchitecture.polimi.it/research/research-on-the-combination-of-water-and-membranes-as-a-structural-building-material/ Water and air exploration

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

[KaiMartin]

One of my favorite explorations is an encasement that holds two bladders that squeezes a span-wise coilable thin-plate of epoxy carbon fiber veener; the two bladders are positively inflated, but held to maximum size by the strength of the encasement; the encasement need not be non-porous. as it does not need to hold air, but only hold the two bladders. The squeezed web holds positive and negative flight forces in the vertical plane. The coilable web permits bus-ability; the bladders and encasement form busable totes.

This is a neat idea.

Possible obstacles to use pressurized components in an actual glider:

• A pressurized bladder combined with some sort of non stretchable textile to hold is very light weight with regard to the volume. But for a glider we are interested in span, less in volume.
• Construction with pressurized air tend to do best with large diameters. But an efficient airfoil calls for maximum thickness of a 1/10 of the chord. With 15 m² wing area and 1:6 chord span this would call for 30 cm beam height at about 6 m beam length. Length to diameter ratio would be 1:18.
• Beams that work with moderate pressure and are optimized for low weight may be affected by reduced atmospheric pressure at altitude.

Our current gliders are already quite close to maximum weight for foot launch. So a pressurized structural element that takes the role of the traditional aluminium tubes should be at comparable weight. Sure, the tensairity concept promises to allow for better rigidity to weight ratio. Still, I am not yet convinced that this is realistic. But maybe I just have not enough experience with modern materials...

---<)kaimartin(>---

[JoeF]

Kai, thanks. Good to have you in the flow here.
Types of gliders may be kept in the larger project. E.g., consider a glider that will have use only at one narrow band of altitude, say a total drop to LZ of 30 ft; such glider need not meet the challenges of going from, say 0 ft to 1000 ft and back.
======================================================

[Rick Masters]

The 6 ft packed-HG movement succeeded 40 years ago

1973-1974
Thomas Finsterwalder develops a glider of his own design. With specially developed high-strength super light-weight and large diameter perunal tubing, the "Bergfex" (mountain freak) weighed a mere 11 kg. and could be dismantled in 8 minutes down to a length of 1,80 m without the use of tools, by means of snap fasteners. Mountaineering pilots became more and more common - soon, no peak was safe from them anymore.


1975
Adventure in Peru. Flight from the Misti.



1976
Over the new year of 1976, Thomas Finsterwalder, Albert Leutenmaier and Heinz Walter achieved the first successful flight from the 5950 m high summit of Kilimanjaro.


1977 - The Bergfex
The picture shows the elastic deformation of the Bergfex under a load of 700 kg. The sail weighed only 1 kg and was made from spinnacker nylon 32 g/m². The federal aviation authority issued the airworthiness certification. More than 300 Bergfexes flew accident-free.


1977-1979
With tents and hanggliders on the 5776 m high summit of Christobal Colon in Columbia. It was planned to fly from there to Santa Maria on the coast, some 48 km away. After 3 days bivouac on the summit this expedition had to be abandoned due to storms, snow-blindness and altitude sickness. The 100 km return descent had to be made without provisions. Successful flight followed from the summits of the 5465 m high Popokatepetl (Mexico) and the 5671 m high Demavend (Iran).

[JoeF]

Great share, Rick.
---------------------------
https://en.wikipedia.org/wiki/Finsterwalder

Some Finsterwalder-Charly models' videos for assembly: HERE

Just one of the videos is featured in this post immediately:

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

Have two beams that are of right-angle cross section. If the two beams are intended to join by an overlap-and-whipping, then consider bonding a thin layer of non-skid material to each beam; have the two non-skid faces against each other; the whipping will compress the non-skid material and the join will be able to take considerable compression without much slip.
In tote, notice how right-angled (or other angled-cross-section beams) may nest fairly well inside each other in stack; such may hold also for curved forms of similar cross section. Explore. Tote volume is reduced in such nesting of forms.


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

[JoeF]

Notice that curved angle-cross-sectioned parts have a nesting-for-tote potential:



The curved parts might be ribs or battens.

[JoeF]

Some HG designs in the 5-ft-HG-Pack Movement might use telescopic circular-cross-sectioned tubes.

[JoeF]

http://fab.cba.mit.edu/classes/MIT/863.10/people/Masoud.Akbarzadeh/PDF/IASS_2009_MehdiBabaei.pdf
Geometric and Structural Design of Foldable Structures
M. Babaei*, E. Sanaeia
* Islamic Azad University, Zanjan Branch, Iran
a
Iran University of Science and Technology, Tehran, Iran