[VAC] Re: Airstream Loading and Tolerance

["Dr. Gerald N. Johnson, electrical engineer" <geraldj@xxxxxxxx>]

Steel is a fine structural material. Two steel members separated by
something lightweight like honeycomb or foam are even better. The otter
members take nearly all the load (at least a bending load like a truss
or floor deck) and so long as the spacer doesn't crunch, the strength
stays. Aluminum and titanium work well for those outer members too.

The bending strength of a channel goes up drastically as its made
taller, so a 5" channel is a lot stronger than a 3" channel. A 4" square
tube is about 30% stronger than a 4" round tube.

Gerald J.