3 ms·

Also if they use evacuated tunnels, the trains could do 4,000 mph. That would be cool.

by spectre 18y ago

potatolicious 18y ago
Doubtful... You'd need a lot of time to accelerate to those speeds, and odds are you'd have to slow down to make a turn well before you reached anything appreciable.
- electromagnetic 18y ago
  IMO there's no point in building a vac-tunnel for a modern train car, because firstly it needs to be an airtight vehicle. When traveling at 4,000 mph you don't necessarily have to slow down, you just need to levitate from the sides of the tunnel. Essentially you could make the train act similar to a swinging cart on a roller coaster where the center of gravity will always try to sit under the user. People can easily tolerate positive vertical gee forces with little to no side effect, yet exposure to less than one vertical gee force (like the chair-drop rides at theme parks) can make someone puke their guts out. Equally horizontal gee forces aren't tolerated very well either, but in the linear axis (the one we accelerate through) we're extremely tolerant and are in fact more tolerant if we're facing backwards. Although I don't think facing backwards would necessarily work on a train, you don't really want to hit 2 gees of acceleration and have your coke fly in a straight line to the back wall. Also acceleration wouldn't need to take too long, however in this systems design it probably would. In the dumb car, smart track systems all the force is applied from the outside, which is where acceleration could potentially reach incredible speeds due to the sheer amount of power that could be expended to do so. We're a long, long way from any vac-tube form of rapid transit, but if we ever get to it I think tolerating the corners will likely be a small problem. I think the big problem will be keeping the train pressurized under potentially huge pressure differentials due to the acceleration.

Also if they use evacuated tunnels, the trains could do 4,000 mph. That would be cool.

by spectre 18y ago

Also if they use evacuated tunnels, the trains could do 4,000 mph. That would be cool.

Doubtful... You'd need a lot of time to accelerate to those speeds, and odds are you'd have to slow down to make a turn well before you reached anything appreciable.

electromagnetic 18y ago
IMO there's no point in building a vac-tunnel for a modern train car, because firstly it needs to be an airtight vehicle. When traveling at 4,000 mph you don't necessarily have to slow down, you just need to levitate from the sides of the tunnel. Essentially you could make the train act similar to a swinging cart on a roller coaster where the center of gravity will always try to sit under the user. People can easily tolerate positive vertical gee forces with little to no side effect, yet exposure to less than one vertical gee force (like the chair-drop rides at theme parks) can make someone puke their guts out. Equally horizontal gee forces aren't tolerated very well either, but in the linear axis (the one we accelerate through) we're extremely tolerant and are in fact more tolerant if we're facing backwards. Although I don't think facing backwards would necessarily work on a train, you don't really want to hit 2 gees of acceleration and have your coke fly in a straight line to the back wall. Also acceleration wouldn't need to take too long, however in this systems design it probably would. In the dumb car, smart track systems all the force is applied from the outside, which is where acceleration could potentially reach incredible speeds due to the sheer amount of power that could be expended to do so. We're a long, long way from any vac-tube form of rapid transit, but if we ever get to it I think tolerating the corners will likely be a small problem. I think the big problem will be keeping the train pressurized under potentially huge pressure differentials due to the acceleration.