dtb said:

>If you can build an SST that carries people at Mach 3 for the same
>per-mile cost as a 787 then sure, there'd be a huge market. But I'm
>afraid we're a very, very long way from there.

My graduate school teachers said that Mach 2.7 was the sweet spot for an SST. The economics of an SST fall off sharply when cruising on either side of that Mach number. I was also told that Mach 5 and greater was economically impossible (no way to make money with any sort of transport system going that fast).

The economics of running an airline are extremely subtle. Aeronautical engineers get Ph.D.s on just that topic alone. It boils down to passenger-seat-miles/cost. Ideally you want a cattle car carrying a zillion people at the speed-of-light that costs nothing to operate. Also you want it to pickup and dump passengers instantly, never have an accident, never malfunction, run forever and cost nothing to build or develop. Oddly enough, after punching in all the numbers, you end up with something like the Boeing 787/7E7 (who would have guessed?).

Gary