While it's true the stress goes up as the tube radius increases for any given pressure and wall thickness, the university I attended had some rather large high-pressure tanks used to supply air for the mach wind tunnel. I don't recall the exact pressure, but I do recall it was in the thousands.

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If I set the budget, we'd have Ares and more. Unfortunately, I don't set the budget, and Ares is just too expensive and too far out for us to accomplish our goals within the budget we were given.

If we halt the ISS, all versions of Ares, and transport Orion and Altair aboard DIRECTv3's Jupiter family of Shuttle-Derived Launch Vehicles, we just might make it back to the Moon by 2020.