If I read the proposal correctly, the system is less sensitive than the tolerances you describe. There is a tight tolerance to maintain between the "air skid" a

If I read the proposal correctly, the system is less sensitive than the tolerances you describe. There is a tight tolerance to maintain between the "air skid" and the wall of the tube, but the air skid is mounted on a suspension system that is probably intended to deal with small variations away from the ideal tube shape. Those variations will manifest to passengers as "bumps" and will also result in transient additional drag, I suspect. It would be cool if you could take another look and see if the tolerances are truly what you describe, or if there's actually more room for variance.