6 ms·

Hyper loop tech is something that I simply don't understand. Is maintaining a vacuum inside a close loop really cheaper than electrifying a rail system? I wou

by vivekd 8y ago

Hyper loop tech is something that I simply don't understand. Is maintaining a vacuum inside a close loop really cheaper than electrifying a rail system? I would imagine it takes a lot more energy to decompress and maintain a vacuum in a loop at significant distances than just electrify the rail network.

rtkwe 8y ago
I believe the plan was not total vacuum but only partial to avoid having to pull so far down. Also Hyperloop if it was built/buildable as designed is kind of the step beyond high speed rail.
- macspoofing 8y ago
  There's no practical difference between a 'total vacuum' and 'partial vacuum' in this case.
  - nixpulvis 8y ago
    God, what even is a "total vacuum"?
prostoalex 8y ago
In theory cheaper to build (laying a dumb pre-manufactured pipe versus electrified rail) and cheaper to operate (build redundant vacuum stations). But yes, the main value prop is for areas with cheap (free?) electricity.
- pojzon 8y ago
  > laying a dumb pre-manufactured pipe Which is extremely expensive because it has to withstand huge forces trying to crush it like a an empty coke can.. Hyperloop is neighter "cheap" or "easy" to create. Its approx. 10 times as expensive to operate than "Mad-Lev" trains and 100000x as deadly if something goes wrong. Malfunction in electric train means that it has to stop. Malfunction in Hyperloop means all passangers are dead. --- Watch Thunderf00t rant about hyperloop and read his sources. This project is nothing more than a scam to fetch investors money.
  - prostoalex 8y ago
    > Hyperloop is neighter "cheap" or "easy" to create. Its approx. 10 times as expensive to operate than "Mad-Lev" trains Is this across the board? I'd imagine the cost estimates would differ depending on where the line would be located - on raised platforms, below ground, or at ground level e.g. a highway divider lane? Or is Hyperloop impractical for pretty much all of the use cases?
    - Rotten194 8y ago
      Well hyperloop will be more expensive any place maglev is more expensive. If maglev costs $x to build above ground, and $5x to build underground, then hyperloop would cost $10x and $50x, would it not? (disregarding what the actual scaling factor is)
  - shookness 8y ago
    >>This project is nothing more than a scam to fetch investors money. I'm unaware of Musk asking for any particular investment in a Hyperloop project. Most Hyperloop projects are independent parties working on the idea on their own volition. Please correct me if I'm wrong.
    - auslander 8y ago
      You're wrong when you assumed it is Musk' scam, it is not. But the idea of hyperloop is used by many as a bait to scam away investors money.
      - shookness 8y ago
        Any investor should know what they're getting into when investing in a high risk experiment like "Hyperloop". I'm just calling B.S. on it's some sort of scam.
  - ksec 8y ago
    Not to mention we have a working real world implementation of Maglev running at 550 - 600Km/hr in Japan. Not as fast as the theoretical 1000Km/Hr in hyperloop, but one is still in R&D while the other is actually running. That is until Elon can proof he can manufacture the Tube much cheaper than layering the Mag-Lev track.
jccooper 8y ago
It's not about the motive power; it's about speed.
bb2018 8y ago
I don't understand it either. The difficult thing in any transport system like this is clearly the land and land rights. If you can't make that cheaper and easier to manage from a legal perspective than I don't see how a slightly better mode of transportation would offset it.
- Robotbeat 8y ago
  A high speed train can cause really nasty buffeting and acoustic pollution, extending the amount of landing buffer you need. This gets worse at high speed. A vacuum train eliminates that.
- kurthr 8y ago
  That's why tunneling would probably be a better choice than going overland, certainly cheaper at Japan's costs than California's.
  - IshKebab 8y ago
    Yeah except tunnelling is extremely expensive. It sounds cheap in theory - just buy a TBM, run it for a while right? In practice it is so much more complicated. You have different soils, some that are water permeable - in Boston (I think) they solved that by literally freezing the ground. Does that sound cheap? Then you have issues going under buildings (which you always are - otherwise why bother tunnelling?). All tunnelling disturbs the ground. When they built the Jubilee line extension under the houses of parliament they had to monitor how far Big Ben started leaning, and do something call "compensation grouting" to tip it back upright (basically you drill horizontal holes under it and pump concrete under it). Tunnelling is just expensive. That's why it only happens where the alternative - building on land is very expensive.
Robotbeat 8y ago
Arrivo weren't really a vacuum system, at least for the last year or so. But the thing is that electrified rail networks doesn't address the quadratically increasing losses from drag at high speeds. There's a reason you don't see railroads operating at airline speeds: drag at sea level is a killer. In fact, at high enough speeds, the energy of air travel is actually LOWER than that of a sea level train.\ Altitude gives you a lot of efficiency. The idea of the vacuum train is to bring that efficiency down to sea level. And I think it's a good idea, but a real engineering challenge. In principle, you can keep a vacuum pretty easily. Vacuum tubes remain sealed and evacuated for decades without energy consumption, for instance. It's just at the interfaces you have to worry about leakage, and there it's a matter of careful sealing. It's possible to get really good at it. The International Space Station is full of interfaces (and thermal cycling every 90 minutes) and would quickly run out of air if we didn't know how to maintain a vacuum well at interfaces.
- mpweiher 8y ago
  > drag at sea level is a killer. Yes. Apparently when jet turbines came along they were discounted as ever being useful for commercial/passenger airplanes because they were so incredibly inefficient. I mean, really incredibly inefficient. What they didn't take into account is that the turbines allow you to fly at much, much higher altitudes. The reduced drag there more than makes up for the lower efficiency. And gets you a smoother ride and higher speeds as well. Modern turbofan engines are much more efficient, but that's basically because they really are turbo-props with enclosed propellers, though we call them "high bypass turbofans". And of course if jets have to drop to a lower altitude, for example because their cabin has become depressurised, range is drastically reduced.
  - Farradfahren 8y ago
    Are there no ways to get around this? We managed to carvitation for torpedos?
  - pfdietz 8y ago
    They're turboprops, but they're turboprops that don't have the speed limit imposed by the need to keep propeller blade tips from exceeding the speed of sound.
goodcanadian 8y ago
Well, you've got some pretty good answers, but I'll give it a go as well. No. There is no way that a similarly capable system will be remotely close in price to conventional rail. Musk's estimates were wildly optimistic at best, and the system he proposed would have a small fraction of the capacity of HSR, for example. The advantage of a vacuum train (let's not pretend it is Musk's invention) is top speed. In some scenarios, this may be worthwhile, but it's natural comparison would be short haul flights, not passenger rail.
bufferoverflow 8y ago
The vacuum lets you travel much faster, potentially much faster than planes. The problem isn't keeping the vacuum, it's making the whole thing safe and relatively cheap at the same time. It seems like it's almost impossible to do that above ground with thermal expansion issues and very easy terrorism. But doing it in a tunnel solves some problems. The evacuation is still a big problem.
- candiodari 8y ago
  Evacuation isn't a problem at all. This is what happens to a failing vacuum tube. https://www.youtube.com/watch?v=0N17tEW_WEU https://www.youtube.com/watch?v=0N17tEW_WEU (note that the hyperloop will be a significantly higher vacuum. There would actually be little point in depressurizing a pipe to the level shown in the video. I hear this was done on mythbusters as well) I think you'll agree after seeing the video: attempts to let people get out of that ... there's just no point. They'll be folded into an accordion before you can say cappuccino. Literally. Failures will propagate along such a pipe at close to the speed of sound. You wouldn't get through the first "c" of cappuccino. You should restate the problem: the problem is the same as with trailer vs car crashes: pulling the various flattened and crushed together pieces of different people apart in a way that you'd be reasonably certain the right liter of goop recovered goes into the right casket, ideally with as little pieces of the pipe in there with them as possible. An extra issue is that every way you might recover also fails given the forces involved. Let's say you let air in ? Well that's going to form a wall of air that'll hit with a speed, force and acceleration that is guaranteed to kill every passenger, just from the acceleration. More likely that too will fold them into an accordion. This problem is like attempting to keep a plane intact during a crash. It can't be done, and even if you should succeed, there's no point: everyone inside will be dead from the acceleration.
  - daveFNbuck 8y ago
    I think they were using evacuation here to mean removing all the air from the tunnel in order to create the vacuum in the first place.
pfdietz 8y ago
I think it may make more sense for high speed package delivery, for example between FedEx hubs. Smaller diameter, no need to keep passengers live, and possibly much higher acceleration tolerance.

by vivekd 8y ago

rtkwe 8y ago

I believe the plan was not total vacuum but only partial to avoid having to pull so far down. Also Hyperloop if it was built/buildable as designed is kind of the step beyond high speed rail.

macspoofing 8y ago
There's no practical difference between a 'total vacuum' and 'partial vacuum' in this case.
- nixpulvis 8y ago
  God, what even is a "total vacuum"?

prostoalex 8y ago

In theory cheaper to build (laying a dumb pre-manufactured pipe versus electrified rail) and cheaper to operate (build redundant vacuum stations). But yes, the main value prop is for areas with cheap (free?) electricity.

pojzon 8y ago
> laying a dumb pre-manufactured pipe Which is extremely expensive because it has to withstand huge forces trying to crush it like a an empty coke can.. Hyperloop is neighter "cheap" or "easy" to create. Its approx. 10 times as expensive to operate than "Mad-Lev" trains and 100000x as deadly if something goes wrong. Malfunction in electric train means that it has to stop. Malfunction in Hyperloop means all passangers are dead. --- Watch Thunderf00t rant about hyperloop and read his sources. This project is nothing more than a scam to fetch investors money.
- prostoalex 8y ago
  > Hyperloop is neighter "cheap" or "easy" to create. Its approx. 10 times as expensive to operate than "Mad-Lev" trains Is this across the board? I'd imagine the cost estimates would differ depending on where the line would be located - on raised platforms, below ground, or at ground level e.g. a highway divider lane? Or is Hyperloop impractical for pretty much all of the use cases?
  - Rotten194 8y ago
    Well hyperloop will be more expensive any place maglev is more expensive. If maglev costs $x to build above ground, and $5x to build underground, then hyperloop would cost $10x and $50x, would it not? (disregarding what the actual scaling factor is)
- shookness 8y ago
  >>This project is nothing more than a scam to fetch investors money. I'm unaware of Musk asking for any particular investment in a Hyperloop project. Most Hyperloop projects are independent parties working on the idea on their own volition. Please correct me if I'm wrong.
  - auslander 8y ago
    You're wrong when you assumed it is Musk' scam, it is not. But the idea of hyperloop is used by many as a bait to scam away investors money.
    - shookness 8y ago
      Any investor should know what they're getting into when investing in a high risk experiment like "Hyperloop". I'm just calling B.S. on it's some sort of scam.
- ksec 8y ago
  Not to mention we have a working real world implementation of Maglev running at 550 - 600Km/hr in Japan. Not as fast as the theoretical 1000Km/Hr in hyperloop, but one is still in R&D while the other is actually running. That is until Elon can proof he can manufacture the Tube much cheaper than layering the Mag-Lev track.

jccooper 8y ago

It's not about the motive power; it's about speed.

bb2018 8y ago

I don't understand it either. The difficult thing in any transport system like this is clearly the land and land rights. If you can't make that cheaper and easier to manage from a legal perspective than I don't see how a slightly better mode of transportation would offset it.

Robotbeat 8y ago
A high speed train can cause really nasty buffeting and acoustic pollution, extending the amount of landing buffer you need. This gets worse at high speed. A vacuum train eliminates that.
kurthr 8y ago
That's why tunneling would probably be a better choice than going overland, certainly cheaper at Japan's costs than California's.
- IshKebab 8y ago
  Yeah except tunnelling is extremely expensive. It sounds cheap in theory - just buy a TBM, run it for a while right? In practice it is so much more complicated. You have different soils, some that are water permeable - in Boston (I think) they solved that by literally freezing the ground. Does that sound cheap? Then you have issues going under buildings (which you always are - otherwise why bother tunnelling?). All tunnelling disturbs the ground. When they built the Jubilee line extension under the houses of parliament they had to monitor how far Big Ben started leaning, and do something call "compensation grouting" to tip it back upright (basically you drill horizontal holes under it and pump concrete under it). Tunnelling is just expensive. That's why it only happens where the alternative - building on land is very expensive.

Robotbeat 8y ago

Arrivo weren't really a vacuum system, at least for the last year or so. But the thing is that electrified rail networks doesn't address the quadratically increasing losses from drag at high speeds. There's a reason you don't see railroads operating at airline speeds: drag at sea level is a killer. In fact, at high enough speeds, the energy of air travel is actually LOWER than that of a sea level train.\ Altitude gives you a lot of efficiency. The idea of the vacuum train is to bring that efficiency down to sea level. And I think it's a good idea, but a real engineering challenge. In principle, you can keep a vacuum pretty easily. Vacuum tubes remain sealed and evacuated for decades without energy consumption, for instance. It's just at the interfaces you have to worry about leakage, and there it's a matter of careful sealing. It's possible to get really good at it. The International Space Station is full of interfaces (and thermal cycling every 90 minutes) and would quickly run out of air if we didn't know how to maintain a vacuum well at interfaces.

mpweiher 8y ago
> drag at sea level is a killer. Yes. Apparently when jet turbines came along they were discounted as ever being useful for commercial/passenger airplanes because they were so incredibly inefficient. I mean, really incredibly inefficient. What they didn't take into account is that the turbines allow you to fly at much, much higher altitudes. The reduced drag there more than makes up for the lower efficiency. And gets you a smoother ride and higher speeds as well. Modern turbofan engines are much more efficient, but that's basically because they really are turbo-props with enclosed propellers, though we call them "high bypass turbofans". And of course if jets have to drop to a lower altitude, for example because their cabin has become depressurised, range is drastically reduced.
- Farradfahren 8y ago
  Are there no ways to get around this? We managed to carvitation for torpedos?
- pfdietz 8y ago
  They're turboprops, but they're turboprops that don't have the speed limit imposed by the need to keep propeller blade tips from exceeding the speed of sound.

goodcanadian 8y ago

Well, you've got some pretty good answers, but I'll give it a go as well. No. There is no way that a similarly capable system will be remotely close in price to conventional rail. Musk's estimates were wildly optimistic at best, and the system he proposed would have a small fraction of the capacity of HSR, for example. The advantage of a vacuum train (let's not pretend it is Musk's invention) is top speed. In some scenarios, this may be worthwhile, but it's natural comparison would be short haul flights, not passenger rail.

bufferoverflow 8y ago

The vacuum lets you travel much faster, potentially much faster than planes. The problem isn't keeping the vacuum, it's making the whole thing safe and relatively cheap at the same time. It seems like it's almost impossible to do that above ground with thermal expansion issues and very easy terrorism. But doing it in a tunnel solves some problems. The evacuation is still a big problem.

candiodari 8y ago
Evacuation isn't a problem at all. This is what happens to a failing vacuum tube. https://www.youtube.com/watch?v=0N17tEW_WEU https://www.youtube.com/watch?v=0N17tEW_WEU (note that the hyperloop will be a significantly higher vacuum. There would actually be little point in depressurizing a pipe to the level shown in the video. I hear this was done on mythbusters as well) I think you'll agree after seeing the video: attempts to let people get out of that ... there's just no point. They'll be folded into an accordion before you can say cappuccino. Literally. Failures will propagate along such a pipe at close to the speed of sound. You wouldn't get through the first "c" of cappuccino. You should restate the problem: the problem is the same as with trailer vs car crashes: pulling the various flattened and crushed together pieces of different people apart in a way that you'd be reasonably certain the right liter of goop recovered goes into the right casket, ideally with as little pieces of the pipe in there with them as possible. An extra issue is that every way you might recover also fails given the forces involved. Let's say you let air in ? Well that's going to form a wall of air that'll hit with a speed, force and acceleration that is guaranteed to kill every passenger, just from the acceleration. More likely that too will fold them into an accordion. This problem is like attempting to keep a plane intact during a crash. It can't be done, and even if you should succeed, there's no point: everyone inside will be dead from the acceleration.
- daveFNbuck 8y ago
  I think they were using evacuation here to mean removing all the air from the tunnel in order to create the vacuum in the first place.

pfdietz 8y ago

I think it may make more sense for high speed package delivery, for example between FedEx hubs. Smaller diameter, no need to keep passengers live, and possibly much higher acceleration tolerance.