On Wed, 10 Jun 2009 04:09:45 GMT, "Lew Hodgett"
wrote:

"I could use 3/4 thick ribs, they are certainly strong enough, but
1-1/4 ribs look better, and after all, we sell this equipment by the
pound".


I hear you!

But since I spent most of my working life in the aircraft industry,
the "pound" was the arch-enemy! Had to be "hell-for-stout" and light
as goose down. Which is why we talked in terms of safety margins
rather than safety factors and tested all major structure to failure
to verify/validate the analysis.

Tom Veatch
Wichita, KS
USA