5 ms·

Hyperloop has sex appeal, but it seems like Maglev or just plain old high speed rail makes more sense from an economics perspective. I can't imagine it's cheap

Hyperloop has sex appeal, but it seems like Maglev or just plain old high speed rail makes more sense from an economics perspective. I can't imagine it's cheap to keep a tube evacuated. Either way, it seems good to try and build these sort of high-tech industries in the US.

the8472 6y ago
The speed is supposed to be even higher than maglev, so it can compete with planes over longer distances. But yes, any kind of high speed public transport would be great.
TylerE 6y ago
It doesn't have to be that good a vacuum. It's probably really no more expensive than conventional high speed rail. The hyperloop proposal is operating at approximately 1 millibar of pressure. That sounds CLOSE to a vacuum..and it is, roughly 0.01 atm, but with vacuums getting down to around there is easy. Getting down to, say, 0.00001 atm is much much much harder.
- jeffreyrogers 6y ago
  But you aren't just doing it a chemistry lab. You're doing it in an enormous tube and the tube has openings to allow pods in and out, so it's a lot more complicated.
- ClumsyPilot 6y ago
  From a safety perspective 0.01 atm = 0 atm. That tube is either very dangerous, or very overbuilt and expensive.
riffic 6y ago
common misconception. Hyperloop tubes were never meant to be fully evacuated, they operate at pressure differentials with air bearings (imagine a cylindrical air hockey table).
- captainbland 6y ago
  It may not be totally evacuated but the pressure difference between it and the outside world is still supposed to be very large isn't it? And if you want a hyperloop that actually goes anywhere that's going to represent quite a large volume of low pressure space that you need to create and maintain. Surely this has to be quite energy intensive and generally difficult to maintain, especially since you have to get people in and out of it all the time. I'm not saying these problems are physically insurmountable but they sure sound expensive.
  - sudosysgen 6y ago
    Another thing, is that anyone that punches a hole big enough in the tube basically transforms half of the hyperloop into a bomb. Energy = pressure * volume. That's a lot of energy smashing through a hyperloop capsule. Basically, imagine if 3% of the tube was filled with pipe bombs, but in reverse.
    - jeffreyrogers 6y ago
      Also, what happens if the pods leak? Seems like the air in the pods will diffuse through the tube and the people will suffocate.
      - tibyat 6y ago
        ever been on a plane?
      - vidarh 6y ago
        As long as pod moves, there's a constant pressure build-up of air in front of it, to the point that the design includes a compressor to pump air from the front of the pods because passively preventing the buildup by letting it blow through the pod would be insufficient. So a leak would be a piffling little annoyance in comparison - there'd not be enough volume of air inside the pods to cause a problem compared to the air the compressor on the pod will be actively pumping from the front of the pod to get it out of the way.

the8472 6y ago

The speed is supposed to be even higher than maglev, so it can compete with planes over longer distances. But yes, any kind of high speed public transport would be great.

TylerE 6y ago

It doesn't have to be that good a vacuum. It's probably really no more expensive than conventional high speed rail. The hyperloop proposal is operating at approximately 1 millibar of pressure. That sounds CLOSE to a vacuum..and it is, roughly 0.01 atm, but with vacuums getting down to around there is easy. Getting down to, say, 0.00001 atm is much much much harder.

jeffreyrogers 6y ago
But you aren't just doing it a chemistry lab. You're doing it in an enormous tube and the tube has openings to allow pods in and out, so it's a lot more complicated.
ClumsyPilot 6y ago
From a safety perspective 0.01 atm = 0 atm. That tube is either very dangerous, or very overbuilt and expensive.

riffic 6y ago

common misconception. Hyperloop tubes were never meant to be fully evacuated, they operate at pressure differentials with air bearings (imagine a cylindrical air hockey table).

captainbland 6y ago
It may not be totally evacuated but the pressure difference between it and the outside world is still supposed to be very large isn't it? And if you want a hyperloop that actually goes anywhere that's going to represent quite a large volume of low pressure space that you need to create and maintain. Surely this has to be quite energy intensive and generally difficult to maintain, especially since you have to get people in and out of it all the time. I'm not saying these problems are physically insurmountable but they sure sound expensive.
- sudosysgen 6y ago
  Another thing, is that anyone that punches a hole big enough in the tube basically transforms half of the hyperloop into a bomb. Energy = pressure * volume. That's a lot of energy smashing through a hyperloop capsule. Basically, imagine if 3% of the tube was filled with pipe bombs, but in reverse.
  - jeffreyrogers 6y ago
    Also, what happens if the pods leak? Seems like the air in the pods will diffuse through the tube and the people will suffocate.
    - tibyat 6y ago
      ever been on a plane?
    - vidarh 6y ago
      As long as pod moves, there's a constant pressure build-up of air in front of it, to the point that the design includes a compressor to pump air from the front of the pods because passively preventing the buildup by letting it blow through the pod would be insufficient. So a leak would be a piffling little annoyance in comparison - there'd not be enough volume of air inside the pods to cause a problem compared to the air the compressor on the pod will be actively pumping from the front of the pod to get it out of the way.