Rather than spending your time reading Wikipedia, I suggest you spend some time learning about real-world processes. At least read Ullmann's Encyclopedia of Industrial Chemistry or something similar. In the real world, catalysts do get used up, and frequently even entrained to varying degrees into the product. In fact, it's relatively rare that a catalyst lasts indefinitely (there are some processes where the catalyst does, but most do not). Some processes have a relatively simple step to renew their catalysts. Others require complete replacement of their catalysts with newly produced ones. Sometimes the catalyst is lost by design.
The way in which catalysts become "used up" varies greatly. Sometimes, analogous to your "concrete", it's lost by design into the product stream, such as with most plastics polymerization. So for example, with polyethylene, you may get something like 5000 grams of PE per gram of catalyst, but then the catalyst is gone. Usually there's no recovery step. In some processes, catalysts are lost by being poisoned, either by impurities or by side reactions. Catalysts can be "gunked up" and lose their reactive surface area - for example, by coking in petrochemical refining. Catalysts can also erode - for example, in the Ostwald process for making nitric acid, there's almost always a catalyst recovery stage downstream, because platinum and rhodium are very expensive, and erosion rates are high. Even the process of erosion varies - for example, in some cases it might be substrate attack, or active surface attack, or formation of dendrites which break off, or all sorts of things.
In general, in industry you call it a catalyst if it catalyzes a significant number of reactions, rather than being used up in the first reaction (the latter being considered a feedstock). There is no requirement that it be able to catalyze an infinite number of reactions. Technically things which catalyze a "small number" of reactions should be called initiators, and those which catalyze a "large number" should be called catalysts, but the distinction isn't always clear, and the language overlaps.
Yeah, the whole "pooling under overhangs", "seeping into pipes and following them to their destinations" and "igniting with 1/10th the ignition energy of natural gas, a level of spark suppression of which common electronic devices are not rated for" aspects are not exactly desirable in a fuel for consumers. Although I'd be more worried about leaks from piping and fittings than from the tanks and the engine (if combustion based) or fuel cells (if PEMFC based). And yeah, COPV failures are not common, but they're really ugly when they happen.
But as for industrial hydrogen, new sources are always welcome.
Well..... it depends on the process;) Some catalysts are highly stable and last for years without renewal (or even indefinitely), while on the other end of the spectrum some disappear quickly and end up in the product by design (plastics are particularly bad about this, to the point that it blurs the line between catalyst and initiator).
That said, industry constantly uses toxic catalysts in huge quantities. Acting like this is some sort of new horrible development is just silly. Where toxicity might be a concern, the rate of entrainment into the product is measured, and if it's too high for safety, either a new catalyst has to be found, the previous catalyst has to be better stabilized / retained, or you have to add a post-processing step to recover the catalyst from the product.
Hydrogen is not only applicable to hydrogen cars (where you're correct, it doesn't make for a very good fuel choice). It's an incredibly important chemical in industry. As one example among countless, it's one of the two feedstocks (the other being nitrogen) in the Haber process for producing ammonia, which forms the root of all industrial production of nitrated products on Earth (particularly fertilizers). Right now Haber process hydrogen almost exclusively comes from natural gas reforming (CH4 + H2O -> 1 CO + 3 H2; CO + H2O -> CO2 + H2).
That said, lox has the same root word. It was even the English word through Old English (læx) until "salmon" (a word from Latin (salmonem) of unknown origin) took over. That actually happened with a lot of "food-related" terms, with Latin-origin terms (via French) replacing Germanic/Norse-origin terms - but usually the animal itself kept the Germanic/Norse. For example, you have cow (proto-germanic *kwon, Norse kýr/kú) but the food is beef (Latin bovem); swine (proto-Germanic swinan, Norse svín) and pig (unknown origin), but the food is pork (Latin porcus); lamb (proto-Germanic lambaz, Norse lamb), ewe (proto-Germanic *awi, Norse ær), sheep (West Germanic *skæpan), but the food is mutton (Latin multonem); etc. I guess food has always sounded fancier if you write it in French;)
Are you kidding? Lithium-ion batteries used to all take several hours to charge. Now some types can charge in 10 minutes or less. Gravimetric energy density has quadrupled since li-ions first hit the market. Volumetric has sextupled. Power density, 1 1/2 orders of magnitude. It used to be said that all li-ions would fundamentally only last ~2 years whether in use or not. Now we have huge li-ion battery packs being warrantied for 8-10 years.
The problem is not batteries, it's people's lack of paying attention to the changes around them.
It's been a constant stream of "batteries haven't advanced and won't advance" over the past decade, a period of time when they've undergone huge advances.
The point about the conservation of energy is that the SYSTEM will be storing _all_ of the energy required to create the vacuum.
Indeed, the system stores the energy equivalent of dozens of tonnes of TNT. So does a good-sized pine tree.
How you got under the impression that shock waves move at the speed of light is beyond me. I mean, I can understand that you might have a cartoon view of physics where a hole means that inch-thick steel bananas out like Elmer Fudd's shotgun, or where air can flow through an object with a huge length/diameter ratio without any wall friction effects across its length, or that you might confuse the concept of a shock with the concept of pressure equalization, or things like that. But surely you're not so far out of touch with reality as to think that shocks move at or close to the speed of light. Or are you under the impression that "several times the speed of sound" means travelling hundreds of kilometers instantly?
The amount of energy per meter of tube from the vacuum is about the energy equivalent of 9 grams of gasoline.
Tankers must undergo some testing for vacuums because a vacuum system is used to release stored materials.
That would be quite the trick, given that all DOT-111 tank cars have a vacuum relief valve that prevents you from drawing a vacuum. It's generally set at -0.75 PSI (0.05 bar below ambient).
Again, why are you under the impression that you can just make stuff up and not be called on it? How did you even think that makes sense, that a rigid tank would be emptied via the creation of a vacuum within it? How well does that work in your everyday experience? Can you drink a soft drink from a glass bottle by just sucking it all out without letting air in?
You have this bizarre concept that dealing with vacuums is something that there's not extremely extensive experience with, extensively covered by ASME VIII. Do you have a clue how many vacuum distillation units there are in the world and how much oil moves through them every day? Ever seen the diameter on those things? And yes, they operate at Hyperloop pressures.
If you're invoking fantasy scenarios where shock waves move at mach 80 and instantly repressurize a tube hundreds of kilometers long because the inch-thick steel tube with reinforcement bands peeled like a banana when someone made a hole in it, like some sort of Bugs Bunny cartoon.... then I'd say that the best way to get out would be to paint a door on the side of the tube and open it.
You know what also has the energy of 45 tonnes of TNT? A moderate sized (~10t) pine tree. Comparing total energies in something to TNT is only relevant if you're looking at the concentrated and instantaneous release of energy, neither of which are applicable to a vacuum pipeline. Even the supersonic shocks take several minutes to reach each end, let alone total pressure equalization, which even if there was no wall drag at doesn't proceed faster than the speed of sound.
The problem is what happens when a train car traveling 700 mph hits a section of tube damaged by a localized implosion.
Life isn't a cartoon. Inch-thick steel vacuum pipelines with periodic reinforcing rings don't peel like a banana just because you make a hole in them.
, and the following train cars hit it at 700 mph.
Because they totally didn't think to include sensors and emergency braking in the design document, right?
Yeah, you might want to actually read the design document of the thing you're arguing against before you complain about it.
At the fastest launch rate the vehicles are spaced 30 seconds apart (usually several times longer). At the highest achieved speed of 340 m/s (not average speed), deceleration equates to a requirement of 11,3m/s, or only 1,15g. Deceleration inside a steel tube is incredibly simple.
how about getting some science of your own to discount it.
If you want to learn about shock tubes (what is being described), start reading.
Namely, for the dozenth time in this thread
You have not replied to a single other post I've written.
why does Conservation of Energy not apply to the Hyperloop
It does. Why would you think otherwise?
. Understanding of course the amount of energy required to bring a massive single structure to a near perfect vacuum.
First off, read the damn document before debating it online. The fact that you don't know that Hyperloop is distinctly not a hard vacuum, and that more to the point would not work in "near perfect vacuum" - one of the most basic aspects of the design - points out that you have no business whatsoever pontificating about the topic.
Secondly, evacuating 2.2m cubic meters at sea level takes a minimum of 223 GJ. Operating on the pessimistic assumption that the tube has to be pressure normalized once annually and zero energy is recovered in the process, divided by six million passenger-trips per year, is 37kJ, or 10,3Wh (note: *not* kWh, just Wh), or about 0.05 cents at industrial rates.
Now, of course, you don't get the thermodynamic minimum. But you were explicitly talking about conservation of energy, so that's the number you were looking for. And if you want to be fair and factor in other energy losses, you also have to factor in that the assumption that you have to empty the tube annually (with zero energy recovery) is unfair on the pessimistic side.
And if you want to know what real-world maintenance level pumping to maintain vacuums is like, LHC requires 170kW for 9000m, or about 19W/m - which in the case of Hyperloop equates to 41,8MW. If this were applied to Hyperloop, that would be a per-passenger cost of 220MJ, or 61kWh, or $30 at industrial power rates. Except that LHC is a hard vacuum, which is orders of magnitude harder to maintain than a mild vacuum like Hyperloop; one of the primary design principles of Hyperloop was avoiding hard vacuum specifically for that reason. Hyperloop's vacuum level is four orders of magnitude higher density than the LHC's cryomagnet insulation volume (we won't even bother discussing the incredibly low beamline vacuum). A simple linear interpolation would suggest a Hyperloop maintenance power of 0.0019W/m, or 4180W, or a per-passenger consumption of 22kJ, aka 0.006kWh.
I'm sorry, let's back up, what was all this ranting you were doing about the conservation of energy?
As to your claim about rail cars, they do have to test for partial vacuums.
I don't know what forums you're used to where you can just make up things and have people believe you, but that doesn't fly here. Tank cars are only tested to a fixed positive pressure. Here's the procedure, spelled out in US law. Here's a table of the pressures for different types of tank cars. DOT-111 cars are for storing nonpressurized liquids, and are thus only tested to the minimum test pressure of 100 PSI, aka 6.9 bar. They are not designed to survive a vacuum (although they do if not heavily compromised - which in the Mythbusters
Conventional trains can fit into medians just fine if they're elevated. But peak loadings on conventional trains are about an order of magnitude higher than Hyperloop because of the much larger vehicles, which makes for around an order of magnitude higher cost to elevate it. So conventional trains generally try to minimize the use of viaducts.
Hyperloop does not in any way, shape or form call for "fitting into existing curves" or "banking up to 90 degrees", which you would damn well know if you had actually read the design document, which lays out every single curve's turning radius and how much private land acquisition would be needed.
No, the first thing you have to do is read the damned design document, which is something that almost none of the people who rail against Hyperloop have ever taken the time to do. Which is transparently obvious in their comments, full of rants about "they never considered this serious issue which I, Smart Person, thought of!" - when in reality said issue takes up a major portion of the document.
Yep. Solar power. Wind power. Batteries. Mainstream hybrid cars, and then mainstream electric cars. Private rocket companies making deliveries to orbit. Slashdot comments sections have always been bastions of the "that can never happen!" crowd. Which is really strange for a tech-focused site.
The Hyperloop is a very diffferent concept. Many SF stories and movies use this concept.
Name a single sci-fi book that used a system built around air bearings in a partially evacuated tube, with compressors to prevent the buildup of air in front of them and boost the air bearings.
Literally everything about the design except for the presence of a tube is different between Hyperloop and a vactrain.
Problem is, a lot of you tech guys, especially programmers, think ALL ideas are genius, regardless of reality, engineering, or physics.
To be explicit in this case on who is who:
Hyperloop Alpha was created by engineers, going so far as to include FEM runs. "Thunderf00t" is a biochemist with no background in engineering whatsoever.
When something goes wrong with an airplane other airplanes can still fly, the entire transportation system does not get shut down and other planes don't get damaged.
That would be a great analogy if a single hyperloop tube between two points was equivalent to "the entire (air) transportation system".
The analogy is with a single air route between two destinations. And storms shut those down all the freaking time.
If something goes wrong inside a vacuum tube with fast cars in it, if a car hits the tube at 1000 km/h, the air coming in will destroy all cars in the tube.
In a world of imaginary physics where air flows instantly at mach 80 at full atmospheric density and viscosity and limiting shocks cease to play a role, indeed!
Meanwhile, in the real world, such shocks move at about mach 4 (aka taking several minutes to move down the tube), lose energy as they go, and do not suddenly repressurize the tube. Air still has to flow in through a highly confined orifice (aka small cross section relative to length). In cartoon physics this may happen instantly, but in the real world, a very long length to diameter ratio means significant time for pressure to equalize.
A plane without engines can still land by the way,
Sometimes. But it's more often a disaster. Everybody remembers the "Miracle in the Hudson", but of the previous two full-engine loss flights, Tuninter Flight 1153 killed 16/39 and Helios Airways Flight 522 killed 121/121; of the subsequent two, TransAsia Airways Flight 235 killed 43/58 and LaMia Flight 2933 killed 71/77.
By contrast, tube breach in Hyperloop, by design, results in the opening of valves to evenly pressurize the tube across its length (signals, unlike shocks, move at the speed of light), with vehicles braking to a stop and driving to the nearest emergency exit.
Also, for the record, the total loss of one entire would 16x the gravity-related bending (double the length, and peak deformation is generally related to the unsupported length to the fourth power). But given that span lengths are designed so that there is no noticeable jolting at all between spans, 16x of "almost nothing" does not equal "catastrophe". Air bearings have highly nonlinear responses to changes in distance from the surface, and the bearings themselves are mounted on shock absorbers.
You (and everyone else commenting on this thread) should actually read the design document before commenting (it never ceases me how many people want to pontificate about it without ever having read the bloody design document itself). Earthquakes take up a good bit of the document (they even do FEM sims). As per the specs in Hyperloop Alpha, the tube is not rigidly mounted to the supports; it's mounted to multiaxis dampers that adjust to maintain the tube in the same place. The tube is also floated (allowed to slip freely) lengthwise between the dampers for thermal expansion (one of the three common ways engineers use to deal with thermal expansion - the others being to resist it by force, or to accept deformation within given specs; "resisting" is more however common in high speed transport, with high speed rail tracks often laid in tension, so that thermal expansion just relieves stress).
Now, it looks like Hyperloop One is not to the point of testing the damper system yet. But that is what the design lays out.
Why on Earth did you just link to a video that explicitly states that the vehicle they're collapsing was not designed to tolerate vacuum? A vehicle made of thin-walled steel which even despite not being designed to contain vacuum, still stopped the collapse from propagating all the way down its length?
Whenever some topics come up on Slashdot, people get into this mode where they think that engineers are morons. As if engineers just sit around and go, "Hey, let's make some arbitrary pipe and subject it to arbitrary conditions and not even bother to check what's required to prevent the primary type of failure scenario it could undergo. Because that's totally what we engineers do as a job!"
As per the Hyperloop Alpha document, there are regularly spaced emergency exits. A vehicle brakes to low speeds, where it lowers onto its wheels and drives to the nearest emergency exit. Meanwhile, the valves are opened to slowly repressurize the tube along its length. Inside the cabin there's an emergency oxygen supply, like on an airplane.
Slashdot Mirror
Rather than spending your time reading Wikipedia, I suggest you spend some time learning about real-world processes. At least read Ullmann's Encyclopedia of Industrial Chemistry or something similar. In the real world, catalysts do get used up, and frequently even entrained to varying degrees into the product. In fact, it's relatively rare that a catalyst lasts indefinitely (there are some processes where the catalyst does, but most do not). Some processes have a relatively simple step to renew their catalysts. Others require complete replacement of their catalysts with newly produced ones. Sometimes the catalyst is lost by design.
The way in which catalysts become "used up" varies greatly. Sometimes, analogous to your "concrete", it's lost by design into the product stream, such as with most plastics polymerization. So for example, with polyethylene, you may get something like 5000 grams of PE per gram of catalyst, but then the catalyst is gone. Usually there's no recovery step. In some processes, catalysts are lost by being poisoned, either by impurities or by side reactions. Catalysts can be "gunked up" and lose their reactive surface area - for example, by coking in petrochemical refining. Catalysts can also erode - for example, in the Ostwald process for making nitric acid, there's almost always a catalyst recovery stage downstream, because platinum and rhodium are very expensive, and erosion rates are high. Even the process of erosion varies - for example, in some cases it might be substrate attack, or active surface attack, or formation of dendrites which break off, or all sorts of things.
In general, in industry you call it a catalyst if it catalyzes a significant number of reactions, rather than being used up in the first reaction (the latter being considered a feedstock). There is no requirement that it be able to catalyze an infinite number of reactions. Technically things which catalyze a "small number" of reactions should be called initiators, and those which catalyze a "large number" should be called catalysts, but the distinction isn't always clear, and the language overlaps.
Yeah, the whole "pooling under overhangs", "seeping into pipes and following them to their destinations" and "igniting with 1/10th the ignition energy of natural gas, a level of spark suppression of which common electronic devices are not rated for" aspects are not exactly desirable in a fuel for consumers. Although I'd be more worried about leaks from piping and fittings than from the tanks and the engine (if combustion based) or fuel cells (if PEMFC based). And yeah, COPV failures are not common, but they're really ugly when they happen.
But as for industrial hydrogen, new sources are always welcome.
Well..... it depends on the process ;) Some catalysts are highly stable and last for years without renewal (or even indefinitely), while on the other end of the spectrum some disappear quickly and end up in the product by design (plastics are particularly bad about this, to the point that it blurs the line between catalyst and initiator).
That said, industry constantly uses toxic catalysts in huge quantities. Acting like this is some sort of new horrible development is just silly. Where toxicity might be a concern, the rate of entrainment into the product is measured, and if it's too high for safety, either a new catalyst has to be found, the previous catalyst has to be better stabilized / retained, or you have to add a post-processing step to recover the catalyst from the product.
Hydrogen is not only applicable to hydrogen cars (where you're correct, it doesn't make for a very good fuel choice). It's an incredibly important chemical in industry. As one example among countless, it's one of the two feedstocks (the other being nitrogen) in the Haber process for producing ammonia, which forms the root of all industrial production of nitrated products on Earth (particularly fertilizers). Right now Haber process hydrogen almost exclusively comes from natural gas reforming (CH4 + H2O -> 1 CO + 3 H2; CO + H2O -> CO2 + H2).
I wrote where I am. Hint..
That said, lox has the same root word. It was even the English word through Old English (læx) until "salmon" (a word from Latin (salmonem) of unknown origin) took over. That actually happened with a lot of "food-related" terms, with Latin-origin terms (via French) replacing Germanic/Norse-origin terms - but usually the animal itself kept the Germanic/Norse. For example, you have cow (proto-germanic *kwon, Norse kýr/kú) but the food is beef (Latin bovem); swine (proto-Germanic swinan, Norse svín) and pig (unknown origin), but the food is pork (Latin porcus); lamb (proto-Germanic lambaz, Norse lamb), ewe (proto-Germanic *awi, Norse ær), sheep (West Germanic *skæpan), but the food is mutton (Latin multonem); etc. I guess food has always sounded fancier if you write it in French ;)
In accordance with the prophecy.
Are you kidding? Lithium-ion batteries used to all take several hours to charge. Now some types can charge in 10 minutes or less. Gravimetric energy density has quadrupled since li-ions first hit the market. Volumetric has sextupled. Power density, 1 1/2 orders of magnitude. It used to be said that all li-ions would fundamentally only last ~2 years whether in use or not. Now we have huge li-ion battery packs being warrantied for 8-10 years.
The problem is not batteries, it's people's lack of paying attention to the changes around them.
It's been a constant stream of "batteries haven't advanced and won't advance" over the past decade, a period of time when they've undergone huge advances.
Indeed, the system stores the energy equivalent of dozens of tonnes of TNT.
So does a good-sized pine tree.
How you got under the impression that shock waves move at the speed of light is beyond me. I mean, I can understand that you might have a cartoon view of physics where a hole means that inch-thick steel bananas out like Elmer Fudd's shotgun, or where air can flow through an object with a huge length/diameter ratio without any wall friction effects across its length, or that you might confuse the concept of a shock with the concept of pressure equalization, or things like that. But surely you're not so far out of touch with reality as to think that shocks move at or close to the speed of light. Or are you under the impression that "several times the speed of sound" means travelling hundreds of kilometers instantly?
The amount of energy per meter of tube from the vacuum is about the energy equivalent of 9 grams of gasoline.
That would be quite the trick, given that all DOT-111 tank cars have a vacuum relief valve that prevents you from drawing a vacuum. It's generally set at -0.75 PSI (0.05 bar below ambient).
Again, why are you under the impression that you can just make stuff up and not be called on it? How did you even think that makes sense, that a rigid tank would be emptied via the creation of a vacuum within it? How well does that work in your everyday experience? Can you drink a soft drink from a glass bottle by just sucking it all out without letting air in?
You have this bizarre concept that dealing with vacuums is something that there's not extremely extensive experience with, extensively covered by ASME VIII. Do you have a clue how many vacuum distillation units there are in the world and how much oil moves through them every day? Ever seen the diameter on those things? And yes, they operate at Hyperloop pressures.
Yeah, I totally believe you that you've actually read it. Totally. This is my believing-you face.
If you're invoking fantasy scenarios where shock waves move at mach 80 and instantly repressurize a tube hundreds of kilometers long because the inch-thick steel tube with reinforcement bands peeled like a banana when someone made a hole in it, like some sort of Bugs Bunny cartoon .... then I'd say that the best way to get out would be to paint a door on the side of the tube and open it.
You know what also has the energy of 45 tonnes of TNT? A moderate sized (~10t) pine tree. Comparing total energies in something to TNT is only relevant if you're looking at the concentrated and instantaneous release of energy, neither of which are applicable to a vacuum pipeline. Even the supersonic shocks take several minutes to reach each end, let alone total pressure equalization, which even if there was no wall drag at doesn't proceed faster than the speed of sound.
Life isn't a cartoon. Inch-thick steel vacuum pipelines with periodic reinforcing rings don't peel like a banana just because you make a hole in them.
Because they totally didn't think to include sensors and emergency braking in the design document, right?
Yeah, you might want to actually read the design document of the thing you're arguing against before you complain about it.
At the fastest launch rate the vehicles are spaced 30 seconds apart (usually several times longer). At the highest achieved speed of 340 m/s (not average speed),
deceleration equates to a requirement of 11,3m/s, or only 1,15g. Deceleration inside a steel tube is incredibly simple.
Ed: that should read "total loss one entire support".
If you want to learn about shock tubes (what is being described), start reading.
You have not replied to a single other post I've written.
It does. Why would you think otherwise?
First off, read the damn document before debating it online. The fact that you don't know that Hyperloop is distinctly not a hard vacuum, and that more to the point would not work in "near perfect vacuum" - one of the most basic aspects of the design - points out that you have no business whatsoever pontificating about the topic.
Secondly, evacuating 2.2m cubic meters at sea level takes a minimum of 223 GJ. Operating on the pessimistic assumption that the tube has to be pressure normalized once annually and zero energy is recovered in the process, divided by six million passenger-trips per year, is 37kJ, or 10,3Wh (note: *not* kWh, just Wh), or about 0.05 cents at industrial rates.
Now, of course, you don't get the thermodynamic minimum. But you were explicitly talking about conservation of energy, so that's the number you were looking for. And if you want to be fair and factor in other energy losses, you also have to factor in that the assumption that you have to empty the tube annually (with zero energy recovery) is unfair on the pessimistic side.
And if you want to know what real-world maintenance level pumping to maintain vacuums is like, LHC requires 170kW for 9000m, or about 19W/m - which in the case of Hyperloop equates to 41,8MW. If this were applied to Hyperloop, that would be a per-passenger cost of 220MJ, or 61kWh, or $30 at industrial power rates. Except that LHC is a hard vacuum, which is orders of magnitude harder to maintain than a mild vacuum like Hyperloop; one of the primary design principles of Hyperloop was avoiding hard vacuum specifically for that reason. Hyperloop's vacuum level is four orders of magnitude higher density than the LHC's cryomagnet insulation volume (we won't even bother discussing the incredibly low beamline vacuum). A simple linear interpolation would suggest a Hyperloop maintenance power of 0.0019W/m, or 4180W, or a per-passenger consumption of 22kJ, aka 0.006kWh.
I'm sorry, let's back up, what was all this ranting you were doing about the conservation of energy?
I don't know what forums you're used to where you can just make up things and have people believe you, but that doesn't fly here. Tank cars are only tested to a fixed positive pressure. Here's the procedure, spelled out in US law. Here's a table of the pressures for different types of tank cars. DOT-111 cars are for storing nonpressurized liquids, and are thus only tested to the minimum test pressure of 100 PSI, aka 6.9 bar. They are not designed to survive a vacuum (although they do if not heavily compromised - which in the Mythbusters
Conventional trains can fit into medians just fine if they're elevated. But peak loadings on conventional trains are about an order of magnitude higher than Hyperloop because of the much larger vehicles, which makes for around an order of magnitude higher cost to elevate it. So conventional trains generally try to minimize the use of viaducts.
Hyperloop does not in any way, shape or form call for "fitting into existing curves" or "banking up to 90 degrees", which you would damn well know if you had actually read the design document, which lays out every single curve's turning radius and how much private land acquisition would be needed.
No, the first thing you have to do is read the damned design document, which is something that almost none of the people who rail against Hyperloop have ever taken the time to do. Which is transparently obvious in their comments, full of rants about "they never considered this serious issue which I, Smart Person, thought of!" - when in reality said issue takes up a major portion of the document.
Yep. Solar power. Wind power. Batteries. Mainstream hybrid cars, and then mainstream electric cars. Private rocket companies making deliveries to orbit. Slashdot comments sections have always been bastions of the "that can never happen!" crowd. Which is really strange for a tech-focused site.
Name a single sci-fi book that used a system built around air bearings in a partially evacuated tube, with compressors to prevent the buildup of air in front of them and boost the air bearings.
Literally everything about the design except for the presence of a tube is different between Hyperloop and a vactrain.
To be explicit in this case on who is who:
Hyperloop Alpha was created by engineers, going so far as to include FEM runs.
"Thunderf00t" is a biochemist with no background in engineering whatsoever.
That would be a great analogy if a single hyperloop tube between two points was equivalent to "the entire (air) transportation system".
The analogy is with a single air route between two destinations. And storms shut those down all the freaking time.
In a world of imaginary physics where air flows instantly at mach 80 at full atmospheric density and viscosity and limiting shocks cease to play a role, indeed!
Meanwhile, in the real world, such shocks move at about mach 4 (aka taking several minutes to move down the tube), lose energy as they go, and do not suddenly repressurize the tube. Air still has to flow in through a highly confined orifice (aka small cross section relative to length). In cartoon physics this may happen instantly, but in the real world, a very long length to diameter ratio means significant time for pressure to equalize.
Sometimes. But it's more often a disaster. Everybody remembers the "Miracle in the Hudson", but of the previous two full-engine loss flights, Tuninter Flight 1153 killed 16/39 and Helios Airways Flight 522 killed 121/121; of the subsequent two, TransAsia Airways Flight 235 killed 43/58 and LaMia Flight 2933 killed 71/77.
By contrast, tube breach in Hyperloop, by design, results in the opening of valves to evenly pressurize the tube across its length (signals, unlike shocks, move at the speed of light), with vehicles braking to a stop and driving to the nearest emergency exit.
Right. Because large unsupported spans of thin aircraft aluminum is totally the same thing as inch-thick steel with reinforcement rings. Totally!
Also, for the record, the total loss of one entire would 16x the gravity-related bending (double the length, and peak deformation is generally related to the unsupported length to the fourth power). But given that span lengths are designed so that there is no noticeable jolting at all between spans, 16x of "almost nothing" does not equal "catastrophe". Air bearings have highly nonlinear responses to changes in distance from the surface, and the bearings themselves are mounted on shock absorbers.
You (and everyone else commenting on this thread) should actually read the design document before commenting (it never ceases me how many people want to pontificate about it without ever having read the bloody design document itself). Earthquakes take up a good bit of the document (they even do FEM sims). As per the specs in Hyperloop Alpha, the tube is not rigidly mounted to the supports; it's mounted to multiaxis dampers that adjust to maintain the tube in the same place. The tube is also floated (allowed to slip freely) lengthwise between the dampers for thermal expansion (one of the three common ways engineers use to deal with thermal expansion - the others being to resist it by force, or to accept deformation within given specs; "resisting" is more however common in high speed transport, with high speed rail tracks often laid in tension, so that thermal expansion just relieves stress).
Now, it looks like Hyperloop One is not to the point of testing the damper system yet. But that is what the design lays out.
Why on Earth did you just link to a video that explicitly states that the vehicle they're collapsing was not designed to tolerate vacuum? A vehicle made of thin-walled steel which even despite not being designed to contain vacuum, still stopped the collapse from propagating all the way down its length?
Whenever some topics come up on Slashdot, people get into this mode where they think that engineers are morons. As if engineers just sit around and go, "Hey, let's make some arbitrary pipe and subject it to arbitrary conditions and not even bother to check what's required to prevent the primary type of failure scenario it could undergo. Because that's totally what we engineers do as a job!"
In what way, shape, or form?
As per the Hyperloop Alpha document, there are regularly spaced emergency exits. A vehicle brakes to low speeds, where it lowers onto its wheels and drives to the nearest emergency exit. Meanwhile, the valves are opened to slowly repressurize the tube along its length. Inside the cabin there's an emergency oxygen supply, like on an airplane.
What part of this do you find problematic?