Thanks for the thoughts, Trilobyte. It's muchly appreciated, especially from a seasoned Burner.
If this was a 1V, 2V or 3V dome I think you're dead-on with regards to the conduit size. The lower frequency domes have long strut lengths and are very marginal (at best) at 3/4 inch. (I can't imagine being in a 70 mph wind in 3/4-inch based 1V/2V!)
The dome I am building is a 4V variant, which means at a 20 foot diameter the longest strut is less than 3-1/2 feet. There are *250* of these critters, so the degree of triangulation is huge. The math says it not only works... it's climbable... and has a hefty reserve factor even in a 70 mph wind. But the 30-foot dome may indeed need to be considerably heavier stuff. (I need to sit-down and model that critter. My lack of data on this is starting to bug me).
On the fabric aspect, I had been thinking about canvas, specifically treated duck. I will order some samples of 10oz and 16 oz treated duck so I can do the touchy-feely thing. If I use this stuff the cover will weigh nearly as much as the structure itself.
I agree with you completely as to making a shell that isn't layered. I have seen video of the results of trying this approach. One edge caught by the wind and the structure will inflate and become a kite. (Might be fun to watch, but once they figure-out whose dome it was, I don't want to be the subject of a lynch-mob!). We would sew the dome cover into two halves on the 20 foot, 4-halves on the 30-foot, with the sides lacing together corset-style and using elastic cord as the lacing. The "seams" would get covered-over with an integral flap with velcro to hold it tight and keep any loose edges from catching the breeze.
Thanks again for your thoughts!
