> It's not a vacuum system

(S)he didn't say it was. (S)he said "near vacuum." And that comes straight from the hyperloop paper:

"Just as aircraft climb to high altitudes to travel through less dense air, Hyperloop encloses the capsules in a reduced pressure tube. The pressure of air in Hyperloop is about 1/6 the pressure of the atmosphere on Mars. This is an operating pressure of 100 Pascals, which reduces the drag force of the air by 1,000 times relative to sea level conditions and would be equivalent to flying above 150,000 feet altitude."

Okay, not sure if I missed that or if edited - either way this is a far different situation from maintaining a full vacuum.

There's no such thing as a "full vacuum". 100 Pascals is 0.1% of atmospheric pressure at sea level. It's pretty frickin' close to a "full vacuum". If there's a leak anywhere in the tube you're boned.

By full vacuum I was referring to the conditions you have in space. And no - when you have even a slight allowance for a margin of 'error' or leakage - that's all you need to balance things out. And if the leakage is higher, it's a matter of efficiencies reducing - not complete failure.

> It's not a vacuum system ... I don't understand where people are getting this idea.

http://www.teslamotors.com/sites/default/files/blog_attachme...

Page 12: "The pressure of air in Hyperloop is about 1/6 the pressure of the atmosphere on Mars."

Sounds like a near vacuum to me.