[MortMan]

If it accelerates/decelerates like a Corvette, the material being carried will - at some point - bust loose. Perhaps not on the first runs, but at some point it WILL happen.

I will admit I did not look up the speed of sound. Wouldn’t lower pressure, given constant temp, lower the speed of sound, rather than raise it?

[USFRIENDINVICTORIA]

I’m not denying the huge engineering challenges — just saying that it’s all within the parameters of the laws of physics. And, yes, Murphy’s Law trumps those; so a lot could go wrong. You’re right about the speed of sound decreasing with decreasing speeds — that’s what I thought I said before.

[USFRIENDINVICTORIA]

I should add to my # 59 that the effect of the decreased pressure on the speed of sound would be small. The carriages could likely travel at or near 700 mph, while remaining subsonic. Depends on how much pressure is reduced.

A bigger challenge would be keeping the forward pressure reduced. The carriage would act like a huge piston.

[USFRIENDINVICTORIA]

I should add to my # 59 that the effect of the decreased pressure on the speed of sound would be small. The carriages could likely travel at or near 700 mph, while remaining subsonic. Depends on how much pressure is reduced.

A bigger challenge would be keeping the forward pressure reduced. The carriage would act like a huge piston.