4 ms·

I'm very skeptical of this concept because of how difficult it is to build and maintain a massive vacuum chamber that will experience that level of stress over

I'm very skeptical of this concept because of how difficult it is to build and maintain a massive vacuum chamber that will experience that level of stress over its lifespan. As far as I know, the largest vacuum chamber in the world by volume is the SPF at NASA [1], which is only 37x30m in size. Building such a vessel hundreds of kilometres in length that would have bullet trains going through it multiple times a day seems dangerous and impractical. A single leak anywhere in the tube could potentially cause explosive pressurization [2]. Maybe the Hyperloop is this century's Monorail... [1] https://en.wikipedia.org/wiki/Space_Power_Facility https://en.wikipedia.org/wiki/Space_Power_Facility [2] https://youtu.be/0N17tEW_WEU?t=168 https://youtu.be/0N17tEW_WEU?t=168

RobertoG 6y ago
A hole in the tube would cause air coming in, isn't that the opposite of what that video[2] shows?
VBprogrammer 6y ago
Vacuum chambers are generally safer because they don't explode; they implode. Also, the maximum pressure differential is quite low, by definition, around 14psi. Although if your traveling at 500mph towards a section of tunnel which has deformed in any way your are pretty screwed.
nickik 6y ago
I don't know about Virgin system but Elon Musk original Hyperloop paper clearly stated: > The problem with this approach is that it is incredibly hard to maintain a near vacuum in a room, let alone 700 miles (round trip) of large tube with dozens of station gateways and thousands of pods entering and exiting every day. All it takes is one leaky seal or a small crack somewhere in the hundreds of miles of tube and the whole system stops working. > However, a low pressure (vs. almost no pressure) system set to a level wherestandard commercial pumps could easily overcome an air leak and the transport pods could handle variable air density would be inherently robust.
- bigbubba 6y ago
  A modest low pressure in the tube would become high pressure in the tube when you start pushing a piston (Hyperloop car/capsule) down the tube. Where would all the air piling up in front go? This is why the original concept drawings had large fans on the front of the cars, however this concept seems to have been abandoned, leaving this problem unsolved.
  - nickik 6y ago
    The capsule pumps the air behind itself. That is correct. However this is is Virgin Hyperloop. Its very different from Elon Musk Hyperloop design. No evidence that Elon Musk changed his design. We know he is still on his back burner. His change seems to be more about moving to tunnels rather then tubes.
  - carabiner 6y ago
    The air flows around the train, same as a subway. The low-pressure tube still maintains an lower net pressure and corresponding reduction in a drag vs. a tunnel with standard temperature and pressure, even if there are variations in static pressure along the length of the tube.
bigbubba 6y ago
> A single leak anywhere in the tube could potentially cause explosive pressurization [2]. Also search 'vacuum cannon' for what a long depressurized tube can do. If the tube ever got breached, the atmosphere would rush into it and propel anything inside the tube like a cannonball.

RobertoG 6y ago

A hole in the tube would cause air coming in, isn't that the opposite of what that video[2] shows?

VBprogrammer 6y ago

Vacuum chambers are generally safer because they don't explode; they implode. Also, the maximum pressure differential is quite low, by definition, around 14psi. Although if your traveling at 500mph towards a section of tunnel which has deformed in any way your are pretty screwed.

nickik 6y ago

I don't know about Virgin system but Elon Musk original Hyperloop paper clearly stated: > The problem with this approach is that it is incredibly hard to maintain a near vacuum in a room, let alone 700 miles (round trip) of large tube with dozens of station gateways and thousands of pods entering and exiting every day. All it takes is one leaky seal or a small crack somewhere in the hundreds of miles of tube and the whole system stops working. > However, a low pressure (vs. almost no pressure) system set to a level wherestandard commercial pumps could easily overcome an air leak and the transport pods could handle variable air density would be inherently robust.

bigbubba 6y ago
A modest low pressure in the tube would become high pressure in the tube when you start pushing a piston (Hyperloop car/capsule) down the tube. Where would all the air piling up in front go? This is why the original concept drawings had large fans on the front of the cars, however this concept seems to have been abandoned, leaving this problem unsolved.
- nickik 6y ago
  The capsule pumps the air behind itself. That is correct. However this is is Virgin Hyperloop. Its very different from Elon Musk Hyperloop design. No evidence that Elon Musk changed his design. We know he is still on his back burner. His change seems to be more about moving to tunnels rather then tubes.
- carabiner 6y ago
  The air flows around the train, same as a subway. The low-pressure tube still maintains an lower net pressure and corresponding reduction in a drag vs. a tunnel with standard temperature and pressure, even if there are variations in static pressure along the length of the tube.

bigbubba 6y ago

> A single leak anywhere in the tube could potentially cause explosive pressurization [2]. Also search 'vacuum cannon' for what a long depressurized tube can do. If the tube ever got breached, the atmosphere would rush into it and propel anything inside the tube like a cannonball.