Thin-Wall Plastic Tubing

Why not a construction more like an air mattress? Is the idea to have this rest on the ground? How do you intend to keep it from overturning? What loads does it have to carry - even a slight breeze on something 30' high creates a sizable load, especially for a light weight structure.

He is keeping his cards close to his chest, but I'm guessing he wants to minimize the size of the CO2 bottle required to erect the project.

His idea is to have it folded on the ground, then inflate it by discharging CO2 into it.

He says he will have light-weight metal wires attached to the top to keep it from overturning. This obviously is in the early planning stage.

OK, don't laugh. This is one of those kids blowout party favors. Maybe he could borrow this concept and scale it up?

Disney Jake and the Never Land Pirates Blowouts

In stock, ready to ship!

Right, Lyn, I suggested as much to him; his reply was it wasn't to roll up, rather to fold up. However, if he was agreeable to that concept, how to design it?

Maybe incorporate something like a tape measure steel strip that would wind up to retract the device, but be stiff when inflated/deployed?

I don't know, just a thought.

You could use helium instead of co2 to help support it. For material composition you could steal some ideas from the inflatable play structures.

The reasons these things work may be applicable to my guy's project, but how to apply. Just guessing, but I suspect they are made of some kind of polyethylene (PE), with seams fused together by heat/melt.

In trying to analyze the stress induced in one of the cantilever arms using classical mechanics, can a person really calculate meaningful results with a Moment of Inertia (I) based on the "beam's" cross-sectional dimensions?

I would think a person's time would be better spent on experimental laboratory findings. I doubt if there're any tables of physical strength characteristics of different tubes.

Blow up toys etc are some type of vinyl/PVC.

I t is a problem for classical mechanics. It will be held taut by the internal pressure on the cap and the bottom closer. The pressure, multiplied by the cross sectional area must supply enough force to support the rig plus enough to pre-stress the wall so that, when bending, the wall does not go into compression. If it is subject to lateral load and he intends to guy it, that requires an increase in the required tension. This applies whether the tube is flexible all the way or just at intervals.

IMHO, he doesn't stand a chance.

He may want to take a look at a roadside advertisement. It is open flexible hose of maybe 2' diameter with branches. A blower keeps it erected. Its movement attracts attention. I do doubt, any detailed design went into it. Any wind blows it down, then it gets p again.