lpetrich wrote:I find it hard to take seriously the idea of a continent-length vacuum tube. There's the serious problem of possible leaks -- how will that be handled? Will the tubes have airlock doors and crossovers every few 10s of mi/km? That would likely be necessary to enable detouring by crossover around a disabled train.
Let's see, for large vessels, the best practice is nuclear reactor containments, where a 2% leakage rate is about the most they'll accept. Getting THAT requires x-raying EVERY weld, and generally multiple seals and all. Penetrations are fun, too.
BTW, at some of the speeds being tossed around by wishful thinkers who've seen too many cable TV shows, even a minor amount of air would be a major hazzard - go look up what the X-15 did at various altitudes, and that a refined design with high temperature alloys and NOT a long term heat-soak.
Turning to Transrapid, its sort of maglev does not seem very fail-safe, since it has only a few cm margin of error, and since its levitation system is dynamically unstable -- it requires continuous computer correction.
Yes. That they got the attraction mode to work as well as it did is an achievement.
So in a post-petroleum world where aviation has become expensive due to the expense of its fuel, we may have a national airline that specializes in long-distance travel ("Amfly"?).
No. Since a) we're a long way off from that. b) there's more and more serious talk of hydrogen powered aircraft (don't laught, there's a safety advantage to it, among other things) and c)aircraft are getting progressively more efficient, and there's a bit of room left to go - relaxed stability, geared turbofans, flying wings, etc etc etc. The current generation coming out of A and B's doors are a heck of a lot better than even 15 years ago.
And most of all, the public's seen what happened to nationalized passenger rail. Everytime you try to sell Amair, everyone will point to Amtrak.