Tube frame safety rules?

[Zev Willcox]

Apologies if this is on the wrong board.

I'm learning about race car design and tube frames at the moment, and I wanted to try my hand at designing something. I'm not sure if I'll ever be able to build and race it, as much as I'd like to, but I'd still like to design something that could reasonably be built, with the assumption that if it ever is, it would do NASA SU competition. The thing is, I can't find any information in the NASA CCR about the rules you have to follow designing a tube frame for safety and such; there only seems to be rules regarding roll cages. My question is, where can I find relevant regulations and/or specs?