Roger, re the following:
“You only need a 1/2″ of movement for the fabric to go slack, leading downwards to pole buckling. ***  it would be crucial to have some tight constraint at the crossings between the two poles and the fabric. Without that coupling the poles would go everywhere in a storm.”
As with a tunnel, this is partially addressed by two-stake end covers, or bells, that tension the fabric taut over the whole tent.. But at the pole crossing points where the ends of the pole sleeves come together, there will be a reinforcement patch on the fabric wall, and the sleeves will be joined by being partially sewn together where they meet at their lower ends. In other words, where the sleeves meet just above the pole crossings, the two sleeves will become one sleeve, and the sleeve end will be reinforced with a tape loop. So long as the sleeve ends remain tight around the poles, there will be little or no room for pole movement in the sleeve opening just above the pole crossing point.
Please note that if pole buckling become an issue, bomber carbon pole sections from Easton are available from Quest Outfitters, and can be substituted, but with a weight penalty of around 30%..
That’s for the upper half of the tent, where the poles bend with a tighter radius. Because of the nature of parabolic curves, which are created with or without a gothic arch, the pole curvature in the lower half of the tent is almost straight, so decided to leave out pole sleeves below the pole crossings, as they would complicate set-up and not add any significant space inside the tent. However, if they appear needed for stability, the sleeves will either continue over the pole crossings for another foot or so, or the crossing reinforcement patches will the extended slightly downward, and pole clips sewn on in order to stabilize the poles below the crossings.
“The one extra thing the design will need are internal storm guys, to prevent snow loading from pressing down on the peak and deforming it.”
So with less than an ounce weight penalty, decided to add a 3 foot long sleeved ridge pole to deter rain or snow loading at the ridge between the peaks, and keep the ridge taut with the pole slightly bowed upward. Plan to use 1/4″ dia. Omnipotent FG tube sections (but not their heavy ferrules) for this pole, because they are more flexible and 33% lighter than the already very light carbon tubes used for the long poles (0.247 oz/running foot). Found some plastic outer (music wire inner) 14″ knitting needles that bend to tight arcs for the extensions from the ridge poles that will hold up the vent covers and keep the bowed ridge pole from rotating downward.
Please note that even without end covers, or bells, the above pictured prototype came out much more rigid than any other pop-up I’ve used, such as the MSR Hubba, and a couple Bill Moss designs, a tunnel from his Force series, and a Starlet, a double-cross hoop.
“Without this pre-curve the sections in the middle would be too highly stressed and could break.”
With the Gothic arches and the side guys from the pole crossings, this should not be a problem. Also, the upper ends of the poles slide snugly into elbows that are slightly flexible polypropylene and overlap the carbon pole by about an inch, performing a protective function similar to your DIY nock collars.
” … design has possibilities. Can you continue it Sam?”
This depends on health and father time, but certainly intend to. Am close to ironing out all the bugs. The public television “Weekend News Hour” had Graham Nash on tonight. He is back on the road doing concerts, and recommend this show. Pretty sure it can be streamed from the PBS website.
“Narrow external sleeves are a definite possibility here:”
Because the tent is designed to stretch on the bias over the partially dome shaped pole frame, the sleeves must also be cut on the bias (a little bit of fabric waste there), and be sewn to the tent wall with a zig-zag or diamond stitch. But there is a catch: There is no clipped-in inner tent as such. Rather, the end covers or bells are sewn onto a high DWR, breathable solid fabric inner (same shape as the canopy in the above photo) that will deflect rain during the few minutes needed for pitching. A fly is attached over the solid panel (with some overlap), and stretched tightly over the sleeved poles as with most pop-ups. This makes for a tighter inner, but still needs at least 1.5″ wide pole sleeves for adequate spacing between the inner and the fly.
Because the fly is long and narrow, UNLIKE full coverage flies that include the end covers or bells (vestibules), it will be much easier to attach in high winds than the ones in the LOL videos you posted not long ago. Still, the wider pole sleeves may be an issue; but due to the rigidity of the tent, I think they will work OK.
“…my bag of Ti snow anchors is a lot heavier than my bag of Ti wires. … I would prefer to carry the extra 100 – 200 g of hardware for the certainty that they will hold in any storm.”
Agreed. Don’t intend to do any snow camping, but if I did, would use Ti snow stakes like yours, In the meantime, use 3/16″ dia. Ti shepherd hooks that have worked fine. With only a few stakes, sturdier ones are possible without an excessive weight penalty.
I was shocked to hear about the severe fires in Australia on the news tonight. Hope you and your family are keeping safe.