Not to mention, we can produce He3 here on Earth (albeit it takes a neutron source greater than one would get from burning the He3); there are lots of isotopes that lead to He3 in their collision or decay pathways, which is what supplies Earth's industry as-is (it's used, for example, for supercooling down below the limits of He4). Tritium, for example. And it's not even that common on the moon - parts per billion quantities (average 44ppb), mixed with parts per million regular He4 (average 28ppm).
He3 is a solution in search of a problem while simultaneously in search of a way to be a solution to that problem without creating far more, much larger problems.
Postgres also has a lot of nice features. For example, I love table inheritance and don't understand why it's not more common of a feature - I probably use it in about 80% of the databases I make these days. It's just so logical and useful for real-world data (which often has at least some degree of heirarchial structure), and avoids having to hack together triggers or query logic to emulate it.
It' not so much about altitude and weather as it is seeing conditions; Mauna Loa has among the best if not the best seeing conditions on Earth outside Antarctica. Good seeing depends in large part on how flat and uniform the terrain is for hundreds of kilometers upwind; high mountains on islands consequently tend to fare well (the Canary Islands are another good spot)
The best known seeing location on Earth is in deep Antarctica. Unfortunately the location would make the costs prohibative.
First off, stop reading Wikipedia. You can read the actual concept design document, Hyperloop Alpha, if you actually want to learn about the proposal.
No, "One thousand(sic) of atmospheric pressure" is not "pretty much as good as a "vacuum". Hard vacuums operate at around a trillionth of atmospheric pressure. At a thousandth of atmospheric pressure, even if you weren't in a tube you'd face relevant wind resistance at those sorts of speeds. Inside a tube, you build up a dense column of air in front of you while dragging hard vacuum behind you. This column of air would rapidly slow the capsules. The old concept - vactrains - was to operate in hard vacuum to prevent this. In order to coast at high speed in Hyperloop, the capsules have to shunt the air to behind them via compressors. However, unlike an airplane, the magnitude of air being moved isn't huge (it's non-propulsive), so battery-powered water-cooled compressors are sufficient to handle it.
The reason for Hyperloop choosing not to operate in hard vacuum is severalfold. One, it's much cheaper to maintain low pressures than a hard vacuum - it requires dramatically lower pumping costs (both capital and operating) to operate at a thousandth of atmospheric pressure than a trillionth. Two, the cost needed to deal with the low pressures on the capsules (the compressors) is not unreasonable. And three, they make use of the air in the tubes to provide lift, avoiding expensive maglev options. Basically, they took a look at the old maglev vactrain concepts, found what made them expensive, and found a way to eliminate those things by making it not maglev and not a vacuum.
Their design parameters make the tube itself not much more complicated than an oil pipeline (see above in the thread for a comparison between the two). And oil pipelines are not unreasonably expensive to build.
But you are right to emphasise the "vacuum" being partial here as some air is essential to the air film aspect.
A basic aspect which you should have known before you even started talking about the concept.
But that is not what Hyperloop does. Hyperloop is not maglev, and for good reason - maglev is expensive. Hyperloop capsules are close ground-effect vehicles, relying on air bearing skis at high speed (at low speed they settle onto wheels).
Show me a single - single - example in history from before Hyperloop Alpha - of a design involving evacuated but not vacuum tubes containing an effective ground-effect aircraft with battery-powered compressors to shunt the sparse air behind them, but propulsion coming from the occasional short coilgun segment, not the compressors.
None of the above. And it's not a vacuum tube. Hyperloop wouldn't work in a vacuum.
Again, if you want to actually have a discussion of the plan, you're going to have to actually read the plan first. I'm not sure what's difficult about this concept for you.
To be fair to rail, they've had to deal with a much harder problem. Hyperloop, as proposed, involves no intersections, no switching. Rail has intersections and switches all over the place. If Hyperloop ever gets built and starts to expand from unbranched direct routes to an actual network like rail, their task will become a lot harder, it's a much more difficult scheduling problem.
Apparently this "transit expert" is following up to his humorously bad** G-forces post by commenting on the G-forces on a deliberately small test track, as if that's relevant to what actual passengers on actual public tracks would experience. And his complaint is about a vertical 0,2g? Seriously? That's the vertical G-force of a passenger jet taking a 30 degree bank. Oh my god, we're all going to die.
Also, I'd like to see his credentials on the topic of pipeline construction. Because we're not talking about the construction of road or rail, we're talking about the construction of a long steel tube. Given that he keeps acting like pipeline and rail costs are directly comparable. Also humorous is his concept that building a small-scale test track gets the same economies as building a full-length track.
** - In his post he calls the maximum G-forces experienced by Hyperloop "lateral" G-forces. As if they're going to install giant magnets under the track to keep the pods vertical during curves in order to torture the passengers rather than just letting them bank as all of the forces on the capsule will be pushing them to do. The bad math on curve radii is icing on the cake. The "financial" comments are a hoot too. I could do a complete breakdown if you want, although since it's such a long post it'd take a while. I have to wonder whether he just skimmed the document or chose to ignore it. Like the comments about elevation changes not being covered, when large portions of the document were dedicated to the importance of varying the tower heights to smooth the vertical curve radius, the need for tunnels in certain points to avoid excessive vertical acceleration, etc.
That really is a big part of it. By splitting up the passengers into many smaller, frequently launched capsules rather than fewer numbers of large, heavy, proportionally increquent vehicles, they greatly reduce the peak loadings on the track. Which significantly reduces the costs to elevate it. The peak loadings are more like what you'd see with the Disney Monorail than a HSR viaduct.
I didn't even know that there are so many people here on Slashdot who see fit to criticize Hyperloop without understanding even the most basic concepts of what Hyperloop actually is
For the fourth time this thread: it's not a maglev vactrain. It wouldn't even work in a vacuum.
My basic point is that you're criticizing a system that you don't even know the most fundamental details about. Start with actually reading the Hyperloop Alpha document, then come here. I'm obviously not going to sit here and debate the finer points of a topic with someone who is just now learning what the thing even is.
It's discussed in the Hyperloop Alpha document, although I can't be bothered to dig it up right now - I recall that the numbers were what I'd call "a bit roller-coaster-ish", but nothing too bad. Note that there is no "lateral acceleration", as the craft is not locked into a fixed orientation with respect to Earth - "down" is always the direction where G-forces are the most intense. Passengers face acceleration/deceleration forces and vertical (downward) forces.
G-forces are the main limiting factor to Hyperloop velocity in most places - the more the track has to bend in order to follow roads, avoid mountains, etc, the slower it has to move. So bends are the biggest factor in determining trip times. Technically Hyperloop is also limited by the speed of sound in the tube, but it's not as big of an issue as curves, at least over routes like LA/SF. And it's an issue that can be avoided - with more pumping, one could inject a sparse light gas, which can support dramatically higher speeds of sound. Elevated temperatures also raise the local speed of sound, and given how sparse the gas in the tube is, it's probably not going to be very good at ditching the heat imparted to it by the passing craft - so its equilibrium temperature may be well elevated over ambient without any extra effort.
I'm sure there are lots of people running the numbers for various routes. The LA/SF route was chosen to introduce the concept in the Hyperloop Alpha document, but it's hardly the only route possibility (personally I think they should have started with a LA/Las Vegas proposal so as not to earn the ire of the HSR people and the "but you won't stop at my town on the way" people, but anyway...)
If you want to roughly estimate tube costs in your area, your best comparison would be not roads or rails, but large oil pipelines (which also run for thousands of kilometers). Because Hyperloop tubes basically are large pipelines. It has some some advantages and disadvantages vs. an oil pipeline, of course.
1) Oil pipelines are usually raised, but not as high as Hyperloop. On the other hand, they bear far higher loadings (being full of oil rather than vacuum), so it's probably a wash. 2) Oil pipelines face much harder right of way / environmental approval issues than Hyperloop, due to the potential of spills. It's often a large chunk of their total construction costs. 3) Hyperloop faces far tighter tolerances, and has to ensure that it stays within these tolerances at its support columns. The inside of Hyperloop requires a pass with a circular polishing machine before it can come into service to ensure the necessary level of smoothness. 4) Oil pipelines face corrosion issues not faced by Hyperloop. 5) In both cases, small leaks are problematic and need to be fixed but not world-ending; giant holes are a Bad Thing that will take your tube out of service and cost you money. 6) Both require pumping, although of very different types. Hyperloop's pumping is probably a bit easier and cheaper, although still significant. Oil pipelines also have more thermal management issues (oil usually comes up from the ground hot, and its viscosity changes as it cools). 7) Hyperloop requires periodic emergency exits - although oil pipelines have a variety of periodic hardware as well. 8) A few percent of Hyperloop's length is accelerator segments (think "coilguns"). These are a cost not present in oil pipelines 9) Oil pipeline storage terminals are probably a lot more expensive than Hyperloop stations.
You plan to have a capsule emerge from a near vacuum at several times the speed of sound straight into atmospheric pressures? That's going to be like hitting a brick wall. "Opening an airlock" will send in a shockwave down the tube to meet the capsule. And then to boot, its lift surfaces, designed for providing lift in a near-vacuum, are suddenly going to be facing huge amounts of air.
It's actually better to have hypersonic (relative to atmospheric air) projectiles moving through vacuums or near vacuums literally break through whatever "airlock" is sealing off the end (this is done in several types of hypersonic guns) - it's better to hit a literal (as thin as possible) wall than to hit the shock of air flooding into a near vacuum.
There is no such thing as a "hyperloop propulsion module". Hyperloop capsules are not self-propelled.
Note that you can't reach "mach anything" greater than 1 in such a tube relative to the internal gases. But you can increase the speed of sound several times over by using sparse hydrogen and/or very hot gases in the tube instead of sparse atmospheric air.
The fact that you think that Hyperloop is a maglev vactrain shows how you shouldn't talk about a topic of which you don't even know the most basic aspects.
What's ludicrous is that you're commenting about the topic without even realizing what Hyperloop is.
Sci-Fi (Niven, Heinlein, Clarke, Bradbury, and countless others) love vactrains. Hyperloop is not a vactrain. It wouldn't even work in a vacuum. It's an extreme version of a ground-effect aircraft - at pressures as if it were at extreme altitudes, and very small ground effect clearances. Unlike with a vactrain, the tube does not hold a hard vacuum - while pressure is greatly reduced, it still has more than enough air to pose resistance to the vehicle (this is necessary for the capsules to gain lift). To avoid the wind resistance, the capsules use battery-powered compressors to shunt it to behind them (and assist the lifting surfaces). The compressors however do not provide propulsion - that's done by magnetic accelerator segments. To get rid of the heat from the compressors, the capsules contain onboard water supplies into which they dump the heat; the water gets swapped out and the batteries recharged before a given capsule relaunches. The use of air for lift enables the vehicle to avoid all of the costs associated with maglev (at low speeds, such as at stations and during emergencies, they settle down onto wheels).
Show me a single sci-fi novel you've read that's proposed such a system.
Instead of simply looking down on and being mean to those people, wouldn't it be better to give them a "test for WiFi allergy", wherein wifi is randomly enabled or shut off and they have to indicate how they're feeling? When it's done you show them that they did no better than random and thus aren't allergic. Then they feel they're not being treated as an idiot, yet also feel that they've been tested for it and shown not to have it - even if they choose to believe that such an allergy can exist. Even if this only gets a fraction of these people to stop complaining, it's a win, right?
Slashdot Mirror
Not to mention, we can produce He3 here on Earth (albeit it takes a neutron source greater than one would get from burning the He3); there are lots of isotopes that lead to He3 in their collision or decay pathways, which is what supplies Earth's industry as-is (it's used, for example, for supercooling down below the limits of He4). Tritium, for example. And it's not even that common on the moon - parts per billion quantities (average 44ppb), mixed with parts per million regular He4 (average 28ppm).
He3 is a solution in search of a problem while simultaneously in search of a way to be a solution to that problem without creating far more, much larger problems.
And we can burn it in an electronium chamber by harnessing the power of sunspots to produce cognitive radiation to run the dynamos.
Postgres also has a lot of nice features. For example, I love table inheritance and don't understand why it's not more common of a feature - I probably use it in about 80% of the databases I make these days. It's just so logical and useful for real-world data (which often has at least some degree of heirarchial structure), and avoids having to hack together triggers or query logic to emulate it.
** Mauna Kea
It' not so much about altitude and weather as it is seeing conditions; Mauna Loa has among the best if not the best seeing conditions on Earth outside Antarctica. Good seeing depends in large part on how flat and uniform the terrain is for hundreds of kilometers upwind; high mountains on islands consequently tend to fare well (the Canary Islands are another good spot)
The best known seeing location on Earth is in deep Antarctica. Unfortunately the location would make the costs prohibative.
First off, stop reading Wikipedia. You can read the actual concept design document, Hyperloop Alpha, if you actually want to learn about the proposal.
No, "One thousand(sic) of atmospheric pressure" is not "pretty much as good as a "vacuum". Hard vacuums operate at around a trillionth of atmospheric pressure. At a thousandth of atmospheric pressure, even if you weren't in a tube you'd face relevant wind resistance at those sorts of speeds. Inside a tube, you build up a dense column of air in front of you while dragging hard vacuum behind you. This column of air would rapidly slow the capsules. The old concept - vactrains - was to operate in hard vacuum to prevent this. In order to coast at high speed in Hyperloop, the capsules have to shunt the air to behind them via compressors. However, unlike an airplane, the magnitude of air being moved isn't huge (it's non-propulsive), so battery-powered water-cooled compressors are sufficient to handle it.
The reason for Hyperloop choosing not to operate in hard vacuum is severalfold. One, it's much cheaper to maintain low pressures than a hard vacuum - it requires dramatically lower pumping costs (both capital and operating) to operate at a thousandth of atmospheric pressure than a trillionth. Two, the cost needed to deal with the low pressures on the capsules (the compressors) is not unreasonable. And three, they make use of the air in the tubes to provide lift, avoiding expensive maglev options. Basically, they took a look at the old maglev vactrain concepts, found what made them expensive, and found a way to eliminate those things by making it not maglev and not a vacuum.
Their design parameters make the tube itself not much more complicated than an oil pipeline (see above in the thread for a comparison between the two). And oil pipelines are not unreasonably expensive to build.
A basic aspect which you should have known before you even started talking about the concept.
But that is not what Hyperloop does. Hyperloop is not maglev, and for good reason - maglev is expensive. Hyperloop capsules are close ground-effect vehicles, relying on air bearing skis at high speed (at low speed they settle onto wheels).
Show me a single - single - example in history from before Hyperloop Alpha - of a design involving evacuated but not vacuum tubes containing an effective ground-effect aircraft with battery-powered compressors to shunt the sparse air behind them, but propulsion coming from the occasional short coilgun segment, not the compressors.
None of the above. And it's not a vacuum tube. Hyperloop wouldn't work in a vacuum.
Again, if you want to actually have a discussion of the plan, you're going to have to actually read the plan first. I'm not sure what's difficult about this concept for you.
To be fair to rail, they've had to deal with a much harder problem. Hyperloop, as proposed, involves no intersections, no switching. Rail has intersections and switches all over the place. If Hyperloop ever gets built and starts to expand from unbranched direct routes to an actual network like rail, their task will become a lot harder, it's a much more difficult scheduling problem.
Apparently this "transit expert" is following up to his humorously bad** G-forces post by commenting on the G-forces on a deliberately small test track, as if that's relevant to what actual passengers on actual public tracks would experience. And his complaint is about a vertical 0,2g? Seriously? That's the vertical G-force of a passenger jet taking a 30 degree bank. Oh my god, we're all going to die.
Also, I'd like to see his credentials on the topic of pipeline construction. Because we're not talking about the construction of road or rail, we're talking about the construction of a long steel tube. Given that he keeps acting like pipeline and rail costs are directly comparable. Also humorous is his concept that building a small-scale test track gets the same economies as building a full-length track.
** - In his post he calls the maximum G-forces experienced by Hyperloop "lateral" G-forces. As if they're going to install giant magnets under the track to keep the pods vertical during curves in order to torture the passengers rather than just letting them bank as all of the forces on the capsule will be pushing them to do. The bad math on curve radii is icing on the cake. The "financial" comments are a hoot too. I could do a complete breakdown if you want, although since it's such a long post it'd take a while. I have to wonder whether he just skimmed the document or chose to ignore it. Like the comments about elevation changes not being covered, when large portions of the document were dedicated to the importance of varying the tower heights to smooth the vertical curve radius, the need for tunnels in certain points to avoid excessive vertical acceleration, etc.
A device that physically cannot work in a vacuum by definition cannot be called a vactrain.
Don't rush to the "terrorism" label so fast, it could just be some mentally disturbed individuals.
Once we find out their race and religion we'll be able to make the distinction.
That really is a big part of it. By splitting up the passengers into many smaller, frequently launched capsules rather than fewer numbers of large, heavy, proportionally increquent vehicles, they greatly reduce the peak loadings on the track. Which significantly reduces the costs to elevate it. The peak loadings are more like what you'd see with the Disney Monorail than a HSR viaduct.
I didn't even know that there are so many people here on Slashdot who see fit to criticize Hyperloop without understanding even the most basic concepts of what Hyperloop actually is
For the fourth time this thread: it's not a maglev vactrain. It wouldn't even work in a vacuum.
My basic point is that you're criticizing a system that you don't even know the most fundamental details about. Start with actually reading the Hyperloop Alpha document, then come here. I'm obviously not going to sit here and debate the finer points of a topic with someone who is just now learning what the thing even is.
You know, rather than speculating, you could actually read how it works before talking about it (hint: no, it uses neither rails nor maglev)
It's discussed in the Hyperloop Alpha document, although I can't be bothered to dig it up right now - I recall that the numbers were what I'd call "a bit roller-coaster-ish", but nothing too bad. Note that there is no "lateral acceleration", as the craft is not locked into a fixed orientation with respect to Earth - "down" is always the direction where G-forces are the most intense. Passengers face acceleration/deceleration forces and vertical (downward) forces.
G-forces are the main limiting factor to Hyperloop velocity in most places - the more the track has to bend in order to follow roads, avoid mountains, etc, the slower it has to move. So bends are the biggest factor in determining trip times. Technically Hyperloop is also limited by the speed of sound in the tube, but it's not as big of an issue as curves, at least over routes like LA/SF. And it's an issue that can be avoided - with more pumping, one could inject a sparse light gas, which can support dramatically higher speeds of sound. Elevated temperatures also raise the local speed of sound, and given how sparse the gas in the tube is, it's probably not going to be very good at ditching the heat imparted to it by the passing craft - so its equilibrium temperature may be well elevated over ambient without any extra effort.
I'm sure there are lots of people running the numbers for various routes. The LA/SF route was chosen to introduce the concept in the Hyperloop Alpha document, but it's hardly the only route possibility (personally I think they should have started with a LA/Las Vegas proposal so as not to earn the ire of the HSR people and the "but you won't stop at my town on the way" people, but anyway...)
If you want to roughly estimate tube costs in your area, your best comparison would be not roads or rails, but large oil pipelines (which also run for thousands of kilometers). Because Hyperloop tubes basically are large pipelines. It has some some advantages and disadvantages vs. an oil pipeline, of course.
1) Oil pipelines are usually raised, but not as high as Hyperloop. On the other hand, they bear far higher loadings (being full of oil rather than vacuum), so it's probably a wash.
2) Oil pipelines face much harder right of way / environmental approval issues than Hyperloop, due to the potential of spills. It's often a large chunk of their total construction costs.
3) Hyperloop faces far tighter tolerances, and has to ensure that it stays within these tolerances at its support columns. The inside of Hyperloop requires a pass with a circular polishing machine before it can come into service to ensure the necessary level of smoothness.
4) Oil pipelines face corrosion issues not faced by Hyperloop.
5) In both cases, small leaks are problematic and need to be fixed but not world-ending; giant holes are a Bad Thing that will take your tube out of service and cost you money.
6) Both require pumping, although of very different types. Hyperloop's pumping is probably a bit easier and cheaper, although still significant. Oil pipelines also have more thermal management issues (oil usually comes up from the ground hot, and its viscosity changes as it cools).
7) Hyperloop requires periodic emergency exits - although oil pipelines have a variety of periodic hardware as well.
8) A few percent of Hyperloop's length is accelerator segments (think "coilguns"). These are a cost not present in oil pipelines
9) Oil pipeline storage terminals are probably a lot more expensive than Hyperloop stations.
So, balance out those factors as you will.
Hyperloop is not a pneumatic tube system. And pneumatic tube systems unfortunately don't scale well.
You plan to have a capsule emerge from a near vacuum at several times the speed of sound straight into atmospheric pressures? That's going to be like hitting a brick wall. "Opening an airlock" will send in a shockwave down the tube to meet the capsule. And then to boot, its lift surfaces, designed for providing lift in a near-vacuum, are suddenly going to be facing huge amounts of air.
It's actually better to have hypersonic (relative to atmospheric air) projectiles moving through vacuums or near vacuums literally break through whatever "airlock" is sealing off the end (this is done in several types of hypersonic guns) - it's better to hit a literal (as thin as possible) wall than to hit the shock of air flooding into a near vacuum.
There is no such thing as a "hyperloop propulsion module". Hyperloop capsules are not self-propelled.
Note that you can't reach "mach anything" greater than 1 in such a tube relative to the internal gases. But you can increase the speed of sound several times over by using sparse hydrogen and/or very hot gases in the tube instead of sparse atmospheric air.
The fact that you think that Hyperloop is a maglev vactrain shows how you shouldn't talk about a topic of which you don't even know the most basic aspects.
What's ludicrous is that you're commenting about the topic without even realizing what Hyperloop is.
Sci-Fi (Niven, Heinlein, Clarke, Bradbury, and countless others) love vactrains. Hyperloop is not a vactrain. It wouldn't even work in a vacuum. It's an extreme version of a ground-effect aircraft - at pressures as if it were at extreme altitudes, and very small ground effect clearances. Unlike with a vactrain, the tube does not hold a hard vacuum - while pressure is greatly reduced, it still has more than enough air to pose resistance to the vehicle (this is necessary for the capsules to gain lift). To avoid the wind resistance, the capsules use battery-powered compressors to shunt it to behind them (and assist the lifting surfaces). The compressors however do not provide propulsion - that's done by magnetic accelerator segments. To get rid of the heat from the compressors, the capsules contain onboard water supplies into which they dump the heat; the water gets swapped out and the batteries recharged before a given capsule relaunches. The use of air for lift enables the vehicle to avoid all of the costs associated with maglev (at low speeds, such as at stations and during emergencies, they settle down onto wheels).
Show me a single sci-fi novel you've read that's proposed such a system.
One of the main points of Hyperloop is to *save* money. You don't save money by tunneling from LA to SF.
The author doesn't know what G-forces are, that's all. They were trying to say that the person isn't exposed to a vacuum.
Instead of simply looking down on and being mean to those people, wouldn't it be better to give them a "test for WiFi allergy", wherein wifi is randomly enabled or shut off and they have to indicate how they're feeling? When it's done you show them that they did no better than random and thus aren't allergic. Then they feel they're not being treated as an idiot, yet also feel that they've been tested for it and shown not to have it - even if they choose to believe that such an allergy can exist. Even if this only gets a fraction of these people to stop complaining, it's a win, right?