The Chuo Maglev makes the Hyperloop One look like a toy project. Watch the video. They have a production-quality train, with tourists and whiny kids riding it, going 500km/h. They've hit 603km/h in tests, but don't run it that hard normally. This is the first section of track between Tokyo and Osaka via Nagoya. Planned opening to Nagoya is 2027. Japan's Alps are in the way. They're tunneling straight through. Longest tunnel segment is 25km and it's being drilled now. 90% of the Tokyo-Nagoya segment will be in tunnel. Stations in Tokyo and Nagoya are under construction. The line will probably run 3-4 trains an hour each way, like the existing Shinkansen.
Hyperloop potentially has a higher speed to 900-1200km/h, but that may not be achieved in practice. The Chuo Shinkansen has a turn radius of 8km, and passengers don't have to be strapped in. Hyperloop would need 4x the radius to go twice as fast with the same ride quality. Laying out a route with a 24km turn radius severely limits where track can go.
Strapping everybody in and pulling 0.5G sustained is not going to go over with customers. Commercial aircraft usually stay within +-0.25G. Maybe 0.5G in mild turbulence, and customers don't like it.
- longitudinal, predictable acceleration, where you can safely tell people to stay in their seats and all will be fine, I’m quite confident most humans would be comfortable with 1G horizontal that adds up to 1.5G diagonal: that’s basically a roller-coaster; it’s not too bad if you ease people into it, i.e. you minimise the jerk;
- lateral, predictable acceleration, like one would expect in turns: not familiar with train technology enough to know if you could adapt pendular train to MagLev, but it seems like a simple enough hack to increase comfort significantly;
- vibrations and turbulences: seem unlikely in a tube on rails, without a train coming in the opposite direction. Those definitely, customers don’t like.
The good news is that it's "just" an information problem (well, so is landing a rocket, in a way), the bad news is that the number of possible endpoint pairs in a network is bloody high.
In the end you get back to the old vision of on demand "pods". I suppose that those could still be made "rail-efficient" if you make them robotically jack into a paceline behind a tender that provides drafting and power grabbed from an overhead line (you would not want this per pod), but run on battery power only to get to/from the tender at endpoints (which the tender and its followers passes non-stop) and when the paceline gets broken by someone exiting. If you can start over on a new right of way, this is what you should do (in a pinch, you could also take over the leftmost lane of existing roads, but that's not a good place for doing construction and maintenance).
There tend to be at least local and express services on almost all routes, and often multiple tiers of express. Another common pattern I've seen is having several commuter services which each run stopping for a different section of the route, and then run express to the central stations. This gives passengers the benefits of swapping between local and express services, without them loosing time changing trains.
Of course, all of this is a lot easier when you already have the passenger numbers to support it.
This makes me wonder, if hyperloop research develops reliable vacuum tubing, whether they could encase the overground sections of the Chuo Shinkansen to make it even faster...
But that's kind of what Elon Musk does: he Dunning-Krugers himself into a new industry every couple of years, using a simplified, undergraduate physics level of analysis to find something that (to an optimistic non-field-expert) looks like a better solution to the problem.
And the most annoying thing of all is that he usually succeeds. Often in spite of his original idea being technically wrong. For instance, Falcon 9 was supposed to be recovered with parachutes... that didn't work, and people who were working on vertical landing rockets told them that, but at the time Elon just rolled his eyes and said "just use parachutes." But SpaceX/Elon found out the idea didn't work and switched to the "correct" solution and got it to work operationally (and with paying customers) much faster than people who had been working on the problem for years before.
The moral of the story is that it's often better to be able to execute fast even if you start out wrong than to take your time with the right answer.
I think it's incredibly important to segregate Musk's work, i.e. SpaceX and Tesla, from his proposals, e.g. the Hyperloop, modular infrastructure and other things.
Look at the graphs in the actual study:
It's more like the range of 10-90% actual skill is simply transformed to 50-80% perceived skill. The absolute ranking of person by skill order is still accurate.
If Elon Musk is actually at about the 75% percentile of skill which maybe he is, if you turn the graphs that DK reported into a function of actual to perceived skill, if you fed 75% into that you would get like maybe 73%. The real vs. perceived skill curves cross at about 70%.
Versus the popular supposed version of DK, being something like "you are wrong and you do not know it." It's easy to describe the DK to sound like it's a profound explanation of that, but if you look at the data they reported, it's a much more timid effect than it sounds like it is.
To put it another way, low skilled people think they are better than most of the other low skilled people, but they themselves do not perceive themselves to be better than someone who does in fact know what they are doing. Low skill people would think they are a bit above average, not a superconfident expert.
Ultimately you didn't. That very comment shows you were able to recognize and correct for your mistake in the end.
Perhaps if you insist you've Dunning-Krugered yourself about Dunning-Kruger, then I may agree that you have in fact Dunning-Krugered yourself about Dunning-Kruger.
It's turtles all the way down.
I'm pretty sure there were core employees (not Musk) working on every part of the rocket from the beginning. This is documented in the Vance biography, IIRC.
Edit: I changed what I wrote, so as to not claim that "everyone" is a failure, some people worling in visual programming are still having fresh ideas. But they don't have the attitude of being "industry insiders" the ones with fresh ideas are the least arogant and offputting to outsiders. They are the ones who are least likely to put someone like Elon down as being inexperienced.
Elon Musk did that twice at a very big scale with Tesla and SpaceX. Both companies were supposed to fail and yet the succeeded. And while it is not my generation I believe zip2 and PayPal also had pretty novel concepts which were supposed to fail back then too.
He has just done it too many times to be just luck. Sure there was also a lot of luck, but it takes more then luck to do that with at least two successful companies.
According to this: https://www.inc.com/leigh-buchanan/us-entrepreneurship-reach...
there are 27 million entrepreneurs in the the US. That's a large enough number that even if the chances of each individual entrepreneur having a big hit is just a few percentage points, then there are bound to be many entrepreneur who have multiple successive big hits. Especially considering how many people who are even tangentially related to a successful startup describe themselves a founder or co-founder, resulting in the padding of the success rate.
My point being is that we can't rule out the possibility of it all being luck or mostly being luck. Sure, it legitimately could be skill, but there is no way to know for sure, at least currently.
Seriously? What, he flipped a coin a million times which determined what he's going to do next? How are you defining "luck"?
Impress me four times, and I'll start misquoting Napoleon: "If he's been lucky that often, he's the General I want for this"
Tesla has yet to make any money and fails to meet its deadline, and it's yet to see how it will far now that the car giants are turning to EV (especially with many countries setting deadline in 2016 and 2017 about the end of non EV cars, which jolted all the big ones into joining).
Space-X is for me his one real success so far, it leaned on a lot of public funding to do it so it's really not the kind of things usual for HN, but they said they would re-use when everyone else said "can't be done" or "not worth it", and they're getting there.
"The Dunning–Kruger effect is a cognitive bias wherein people of low ability suffer from illusory superiority, mistakenly assessing their cognitive ability as greater than it is."
But this is a good point. Lots of talented people have good ideas that end up going nowhere because of lack of capital for implementation.
I don't think he has ever in his life had a billion in liquid assets. You could argue I guess, but he likely wants to keep a majority stake in SpaceX, and likely doesn't want to go below 20% stake in Tesla.
It's that Hyperloop One needed Richard Branson on board because Elon Musk is creating his own competitor now. This is an incredibly smart move to ensure the survivability of the business from a publicity perspective.
Branson has a history of doing things that people thought impossible or just a bad decision (like creating an airline company). Public perception is the name of the game at this stage, not just feasibility. From that perspective, Hyperloop One has effectively done one of the only strategic moves remaining at this point that ensures it has any chance of persuading a government to select them as a preferred vendor (or continue doing so).
So what HAS he done then, other than brand anything he can then offload to third and fourth parties to run the businesses for him?
And don't say Virgin Galactic - that's just some clever peripheral branding to encourage the likes of the downvoters here that he is in any way novel or dynamic.
He's marketing clever, not strategically or developmentally-so.
I'm coming across like a 'crab in a bucket' here - I've nothing against the guy or his success, but I'm not for one second convinced he's 'challenging the impossible'.
Yes, golly gee, what HAS he done.
He has a certain reputation here in Britain, however we here in Britain also have a certain reputation of shitting on people's success - I sincerely hope that's not how I'm coming across here.
Anyway, this is tangential nonsense, I'm sorry for diluting discourse!
That's okay, I appreciate you loaning us John Oliver. ;)
1 - https://en.wikipedia.org/wiki/Richard_Branson#Early_life
His early business successes were built from nothing. They weren't seeded with millions of dollars. They weren't inherited. He rolled one success into another.
This obnoxious notion, so common on HN, that someone has to crawl out of a ditch with not a penny to their name, or they're not self-made or deserving of any credit for their own success, needs to stop. It eliminates nearly every possible success story that could exist (which is of course the whole point). It's nothing more than a base envious desire to drag someone down because they've been successful.
Take this example: Bill Gates as compared with Jan Koum. Applying the label "self-made" to both of them is nonsense. There's nothing "envious" in pointing out that one had a lot more going for him than the other.
1 - https://www.youtube.com/watch?v=47fqjA8CwGE
Minded me of the sort of criticisms he'd level at the likes of BA back in days of yore...
Edit: This has been a fun puzzle. I read the Wikipedia article for "Nominative determinism" and I've been swapping the letter "d" into various positions of his first and last name trying to figure it out. No luck yet!
Or maybe it was your foolish statements of a personal nature cause that's not scientifically, rigorously provable, cause you know, personal experiences are invalid! Why... well the very very smart people know more than you!
As Jobe from Arrested Development would say ' COME ON ! '.
There should be an allowance for balance and humanity in HN comments. Not everything need be ultra-violet literal on the spectrum!
There's a jar of Branson Pickle in every home in England!
But his moves into healthcare are looking extremely dodgy and of course he lives offshore in a tax haven.
Is this humour? The pickle, and beans, are Branston.
> But his moves into healthcare are looking extremely dodgy
His healthcare stuff is really dodgy. There are already serious concerns about care and treatment at his places.
I can't speak to the airline but the rail service is universally reknowned in the UK as "piss poor", especially since they get huge government subsidies.
The huge government subsidies go to Network Rail, a company wholly owned by HM Government, and are never seen by any of the train operating companies (except insofar as they are indirectly subsidised given they don't pay the full cost of maintaining and improving the infrastructure).
Has a total net of -£225M from Virgin in 2013/4.
This shows them as still being net-subsidised: http://orr.gov.uk/__data/assets/pdf_file/0008/25757/rail-fin...
Note that apportioning the Network Grant based on percentage of track access charges isn't entirely fair: Virgin Trains notably pays above average per km as a result of funding agreements for the WCML Modernisation programme in the 90s/00s, and as such given the different funding agreements for different network improvements (with the shortfall mostly coming from the Network Grant since the demise of Railtrack plc) it doesn't really make sense to apportion the Network Grant in that way.
The result is that Virgin (as a whole) gets more from UKGOV than it sends back as shown in UKGOV's own figures.
> isn't entirely fair
You want to argue with UKGOV and their own numbers, go ahead, but it doesn't change what they currently are.
I think it's on-topic whenever hyperloop is on-topic.
Why is hyperloop's viability nil and nonexistent?
I'm not going to say the claim it's not viable is original, nor am I going to argue that claim. But it is on topic.
Why I wouldn’t invest a money into Hyperloop
- Stabilizing a single fault line risk pylon is more than $250K.
- How many million are needed for vacuum pumps to evacuate 100+ million cubic feet of of pipe to 100 Pa?
- Hot air discharge needs to go somewhere. For every 1 bar pressure, you need ~200 to ~400 cubic meters of volume which is larger
- This seems very much like one of those Andy Grove Fallacies.
- The hyperloop is a mega engineering project on the ground. Nobody on their team is a civil engineer. Looking at their team objectively, there seems to be a mismatch of competency.
- At its core, the science i good, the cost-economics do not work. Das ist nicht gute.
 There had been canals in the past that traveled from the Red Sea to the Nile delta, but these invariably silted up rather quickly (the Nile was sediment-heavy, and wind-blown sand is quite common in the region). Thus there was historical evidence favoring the idea that the dredging maintenance fees would exceed the revenue from passing ships.
 Of course, this was the Third Republic, which is notorious for having provided series of weak, unstable governments replete with scandals that prompt new governments. Ironically, the Third Republic was the longest-lasting form of government France has had since the Ancien Régime.
1. Elon Musk has thought about them more than we have.
2. If his initial concept turns out to be incorrect in some way, he will change it until it is workable.
- It is a cool project he wants to be part of and he is willing to pay to see. (I would probably do that)
- The benefit is not to reach the goal but all the technology that will be invented trying to reach the goal.
Branson is notorious for burning other peoples’ money. Look at Virgin Galactic: it’s New Mexicans’  and Floridians’  tax money plus some duped Emiratis . (They also pre-sold tickets .)
Actually, from the article:
> Hyperloop One has received a significant investment in Hyperloop One
And from the page linked to in that paragraph:
> Delighted to announce Virgin Group’s investment in Hyperloop One
Not exactly ambiguous.
It’s a cool idea and I do want to see more prototypes and feasibility studies, but people need to get off the hype train (no pun intended) and be realistic about the cost.
Do we think the Hyperloop costs are more or less than that? 1/8 of a theoretical $100b is $12.5b -- is $12.5billion for Hyperloop unreasonable? I have no opinion on cost personally, and I don't know economics, but this $151 billion from D.C. to Boston was floated by the established US player in rail infrastructure. Anything less than that number is fantastic, right?
Just because I felt like doing some more Google-fu, I found an article in the LA Times that says a California HSR/bullet-train project is going to overshoot it's original budget (and deadline) of $68 billion. There's a lot of info out there about this project, and it's potential overruns, but let's forget all that and just stick to the original planned cost: $68 billion, so, about half of the cost of Amtrak's northeastern bullet. Let's use that number for our comparison.
If we are going to hold Elon to his "we can do it for 1/8th the cost" blurb, then we are giving him like $8.5 billion to use for his SF/LA Hyperloop. Still, that doesn't sound unreasonable, right? He'll get a good deal on tunnel boring with his other company, and fuselage manufacturing can be handled by SpaceX. When it comes to financing, I don't think it's a major issue compared to other infrastructure works out there.
Like I said, though, I'm just going off the top of my head. I don't know finance or economics or vacuums or magnets.
There's a new LIRR train being dug in NYC called East Side Access. This is a commuter rail line, and is going to cost ~$10 billion or so. Logistically these aren't the same, obviously, but if adding to the LIRR is worth ~$10b then surely the Hyperloop experiment is as well, right?
EDIT: Also, just for disclosure, I don't live in California and I'd probably never end up using the Hyperloop myself so I'm neither for nor against it versus any HSR. I just want to entertain the idea that cost shouldn't be the main focus of discussion IMO.
I think boring company claimed it can bring down costs to 100 million dollars per mile (how? Just reduce tunnel size! SMH. Plus 100 million dollar a mile isn't too far from prices of current tunnels). Sf to la is 380 miles. That's 38 billion dollars just for the tunnel?
I think hyperloop is certainly feasible, if you spend hundreds of billions in it, the problems can be dealt with costly engineering.
If you think hsr will cost 150 billion, a maglev will be costlier, tunnels are extremely costly to build, but building a maglev in a vacuum tunnel will cost only 6 billion? How will cost savings of an order of magnitude happen?
You're starting with the wrong number. The $151B number is Amtrak's estimated cost for it's "shoot for the stars" plan. Its basic NEC stretch plan is effectively 4-track corridor (shared with commuter rail) from DC to Boston, with new stations and new inner city track being laid in Philly and Baltimore, two new Hudson River tubes and a new station annex in NYC, among other less notable improvements. I don't recall if the "abandon current Connecticut track and instead go from NYC along Long Island and tunnel under the sound" plan is in that tier or the next one. The stretch tier is somewhere in the region of $70B.
The reach for the stars tier is "do all that, and then build a parallel 2-track dedicated HSR track from DC to Boston." That's $150B. Which means building dedicated track from DC to Boston is only $80B. The estimated full buildout for CAHSR (including San Diego and Sacremento) is around $80B, as I recall.
I'd argue it's absolutely possible to improve the cost on American public transit infrastructure by one to two orders of magnitude if you can simply get a way around government capture.
The cost of the Gotthard Base Tunnel comes out to around $300-400 million / km. By comparison, the Second Avenue Subway comes out to around $800-1000 million / km (I'm subtracting a bit because the subway has three stops--which tend to be really expensive money pits--and the base tunnel does not).
My guess would be that the cost of land in the north-east, combined with AFAIK pretty strong ownership rights, makes it that expensive.
Again, why not put HSR tracks in the same place you'd put a Hyperloop track? Put the station in the same place. The tubes aren't smaller or lighter.
> The total length of the project, from 96th Street and 2nd Avenue to 125th Street and Lexington, is about 2.7 km. At $2.2 billion per km, this sets a new world record for subway construction costs, breaking that of the first phase of the same line, which only cost $1.7 billion per km.
The article I linked to smacks his arrogance down over costs that he's overlooking, but even that may be addressable. Let's see what he delivers in the next 5 years.
Yeah, and that proposal was for something with much lower throughput, that didn't have stops along the way, and didn't even reach the same areas (they saved money by stopping outside both cities, which the rail line wouldn't do). It also assumed that the tubes could just be placed along the highway meridians (a lot of the money it was supposed to save was from this).
Reminds me of when an actual AI expert pointed out that by making dire predictions about smart AI, that we are nowhere near having, keeps eyes off the autopilot system and the issues with that.
I don't think above ground is economically and technically feasible, there are just too many unanswered issue that almost no one has answer to. Not to mention it will be very very expensive and time consuming.
I grew up in the 70s and saw production electric vehicles that are not on this list. People have been chuckling for a long time and for good reason. It's not that electric vehicles won't eventually be successful -- they must. It's that the time from, "Hey, an electric vehicle would be a good idea" to "Hey, we've figured out all the engineering challenges to make this viable" is longer than the lifetime of most of the companies that entered the fray.
Look at the list of vehicles from before 1990. That's the "getting to the market first" list. All gone. Then look at the list from 1990 to 2010. How many of those will be major players in the electric vehicle market? My point is that I'm relatively old for someone on HN and there have been production electric vehicles since well before I was born. They only started to be viable in the last few years -- and even then, we probably need a few more breakthroughs in battery technology before the market settles out.
Long distance, super fast trains in tunnels? https://en.wikipedia.org/wiki/Ch%C5%AB%C5%8D_Shinkansen I saw the tunnel the other day. I was surprised that practically the whole damn length of the maglev tracks will be in a tunnel, but it makes total sense. That's been under construction for 10 years. They are optimistically expecting to make a profit in 2026 when "costs stabilise".
Will long distance, high speed trains in low pressure tunnels be successful? I have no doubt. Will Hyperloop One be successful? Umm... frozen balls of ice remaining intact in a very hot place probably have a better chance, but I won't say they will definitely fail. If they can secure something like a trillion dollars and invest it wisely over the next 30-40 years, then their chances will improve significantly.
Consider he did this with rockets, getting them to under 1/10th the cost
Comparisons with non-domestic rockets are complicated by state subsidies and differentials in labor costs. But the Falcon 9 is approaching the 10X mark even before reusability has been priced in. Both the Falcon Heavy (in a few months) and the (eventual) reusable pricing should overshoot the 10X mark substantially.
 I went to rocketbuilder.com and both LEO configurations I tried were around $8,000/kg (and I didn't count the 20% deduction for "ULA added value" since the numbers there are debatable)
The GAO cites $164M/launch as the price for the cheapest Delta V (is there some kind of threshold at $165M?), which when the Falcon 9 was introduced could put 8,500kg to LEO, or $19,294/kg. (It has since been uprated and gotten slightly cheaper).
Must've screwed up my calculations earlier, because those aren't tallying. Anyhow, as you can see, SpaceX is already around 7x cheaper compared to where ULA was, and should cross the 10x threshold shortly. Nice to see ULA responding to competitive pressure, however!
IMHO he'll be well over 1/10 the cost before he finishes the thousands of land deals he would need for this, even if he somehow got permission to build it over the highway.
Hence the boring company.
Tunneling gets cheaper due to <...>? I would be interested.
I guess the Swiss would be interested too.
"If you just do two things you can get to approximately an order of magnitude improvement, and then go beyond that. The first thing to do is cut the tunnel diameter by 2 times or more. A single road tunnel has to be 26 to 28 feet in diameter to allow for crashes and emergency vehicles and sufficient ventilation for combustion engine cars.
But if you shrunk it to 12 feet, what we're attempting, which is plenty for a skate to get through, you drop the diameter by a factor of two and the cross-sectional area by a factor of 4. The tunnel costs scales with the cross-sectional area. That's roughly half an order of magnitude improvement right there.
Then, tunneling machines tunnel half time and then stop and the rest of the time is reinforcements for the tunnel walls. If you design the machine to do continuous tunneling and reinforcing, that will give you a factor of two improvement. Combine that, and it's a factor of 8. Also these machines are far from being at their power or thermal limit. I think you can get a factor of two, maybe even four or five on top of that.
There’s a fairly straightforward series of steps to get somewhere in excess of an order of magnitude improvement in cost per mile. Our target actually is that we have pet snail named Gary from....Sponge Bob Square Pants. Gary is capable of going 14 times faster than a tunnel boring machine. We want to beat Gary."
Doing it faster does not mean doing it more cheaply. The cost of going slowly is what, labour?
They go slowly because the materials they're tunneling through are incredibly varied.
For example, you wouldn't have to worry so much about tunneling under a mountain to ameliorate the G-forces if you are traveling more slowly. Once you prove out the route (which could still be competitive with any existing train service), you incrementally build tunnels and modify the route to improve your target speed.
(As for heat discharge, Im pretty sure that was addressed in EM's original paper - dumping the excess heat into an on-board water tank which is exchanged at the end of the ride, or are you referring to something else?)
Should be "Das ist nicht gut".
 It's a trivial calculation. The thermal expansion coefficient of steel is about 10^-5. A typical run of, say, SF->LA is 600 km. Temperatures in the central valley range over about 100 degrees. Multiply everything together and the result is 600 meters.
Also to nitpick, from "the ends of a viable hyperloop track will have to move hundreds of meters" - this doesn't have to be true. There can be absorption points along the track. Overlaps. Or maybe they tunnel the entire way where its cooler. Or wrap the tunnel in something cooling and reflective. We dont have train tracks moving hundreds of meters do we? I dont profess to know the solution, but do know there are solutions somewhere.
Sure, but these have to hold a vacuum. No one has figured out a way to do that.
I do have some concerns about whether they're a trivial problem within this context. An engineering solution which works in small numbers for PhDs in a lab isn't necessarily scalable to mass low-cost manufacturing, deployed in the field and irregularly serviced by workers of uncertain provenance. But evidently there is a way to do this, at least.
I worked on an autonomous vehicle project here in the UK about 10 years ago (the Heathrow Pod). The certification process was absolutely intense. And this was for a system that was capped at 25mph; had we gone any faster than the regulatory burden would have become very significantly more onerous (below 25mph it wasn't necessary to test vehicles and infrastructure to destruction; above 25mph, it is).
In this domain, there's a huge difference between a cool engineering testbed, a private pilot project, and running actual service for the public. If Hyperloop is going to be doomed by anything, failure to appreciate this fact is probably at the top of the list.
Not sure if the same thing will work at larger scales, but I'm not sure its a fundamental problem.
"These would absorb the small length changes between pylons due to thermal changes, as well as long form subtle height changes." [emphasis added]
The cumulative expansion is dealt with in a single sentence:
"A telescoping tube, similar to the boxy ones used to access airplanes at airports would be needed at the end stations to address the cumulative length change of the tube."
But that's not enough. The entire track near the ends is moving by this amount. That means that the ends of the track are advancing and retreating over multiple pylons (unless you can figure out a way to cantilever the track over 300 meters). This is a completely unsolved problem.
"As land slowly settles to a new position over time, the damper neutral position can be adjusted accordingly."
And if that doesn't work, the tube can have some kind of rails or just to roll over wheels on top of the pylons. (my own thoughts as non expert)
Rocket engineers with advanced simulation tools have been working on this for 5 months before releasing the paper. Do you really think they somehow missed this obvious issue?
Edit: Further in the paper it says: "The tube will be supported by pillars which constrain the tube in the vertical direction but allow longitudinal slip for thermal expansion as well as dampened lateral slip to reduce the risk posed by earthquakes."
So pretty much what I've said. The other quoted sentence refers to placement of pylons themselves.
edit: in retrospect, I can clearly see the problem with expanding shaped tracks.
What happens to a long S-shaped track? Think about expanding each segment of the top curve... the turn radius increases and as does the length of the turn. How do you support a tube that can get longer, move outwards along the curve, and change angles at various points? S is just an example, it seems to be a problem with any number of turns (including 1)...
I suppose one option is to simply put it underground to stabilize ambient heat input, and use heat extractors to manage heat generated by the train. If the system shuts down, there might be some thermal contraction but that's easier to manage (it's OK for track segments to separate when trains aren't running - just warm them up before operation)
It's still an issue that at bends of this diameter, the approximation sin(x) = x is pretty accurate, which means it takes 300m of height difference to deal with 300m of thermal expansion.
It might be workable to change that to e.g. 100 bumps of 3m.
Come on.. why do you think he did not think about that?
By the way, curves in the track can eliminate this when they can slide a little. And I can imagine there are more and better solutions.
In 2016 he said we would have full level 5 autonomy in self driving cars within two years. That means in all driving conditions a human could handle.
That seems exceedingly unlikely.
Because this issue has been brought up many, many times since the Hyperloop paper was first published and no one has yet proposed a viable solution.
> curves in the track can eliminate this when they can slide a little
But you can't curve the track. The track has to be very nearly straight or the G forces become intolerable.
This is the thing: lots of people glibly propose what they think is a solution, but none of them actually work.
And why would large diameters not work?
Really? What is it?
That's the thing about Hyperloop. It's not technologically impossible. It's just not economically viable.
That's probably why this is an idea from Elon, not from the industry. The guy has a habit of forcing the market itself to accept beneficial ideas, and in the process they become viable.
> 1) will hold a vacuum
> 2) are available in the 3+ meter diameter that the hyperloop requires
This is a simple manufacturing problem, although calling a "problem" seems like an overstatement. Obviously not everything to build a Hyperloop is wholly off the shelf. If there is some reason why this can't be built in larger diameters, then that's certainly not obvious.
> 3) provides the smooth inside surface that the hyperloop requires
The Hyperloop runs on an air cushion. It's a hovercraft. Millimeter-scale bellows ought not to be a problem.
> 4) are economically viable
And here, you could be entirely correct, and is why I'm not yet a Hyperloop true believer. I'm not wholly convinced that this kind of machinery can be economical over its whole life-cycle in its intended service environment. But proving that this is the case requires more than glib, hand-wavy assumptions. You need to run the numbers. I have yet to see any Hyperloop critic do that in a remotely convincing fashion, whereas there are many Hyperloop engineers who most assuredly are running numbers. Maybe those calculations are wrong, but the only way to refute them is with better calculations. Anything else is just dogma.
The number crunching should tell in which category of viability Hyperloop is.
These efforts were regarded with huge levels of skepticism / disinterest / dismissal from NASA and the mainstream aerospace industry, which consistently confused the second kind of viability with the first. When these people couldn't raise and/or manage the funds to actually implement their ideas, this was regarded by many as proof of the physical impossibility of cheap access to space. Most of the industry regarded them as crackpots.
Then Elon Musk came along and proved the crackpots right and the industry wrong. He could do this because physics was on the side of the crackpots and always had been, even if the market was not. That's a necessary but not sufficient condition; what he also needed -- and just barely had -- was the financial resources and organisational capacity to go up against the market and win.
There are aerospace forums where one can still find smatterings of the old guard insisting that Elon Musk is just a smoke-and-mirrors phenomena; that spaceflight will always be intrinsically expensive because physics (in a hand-wavey, strictly no-calculations kind of way) says it must be so; that the only reason his rockets are cheap is because he's underpaying his workforce and working them to death; that it's impossible to re-use a rocket -- seriously, they're still saying this, even after it's been done three times already; that the Shuttle proved that reusability can never lower the cost of spaceflight, etc. etc. etc.
Some of these people have PhDs in aerospace engineering; some of them have worked on the space shuttle. No matter: they're in the throes of a cargo cult, and they're wrong. Physics are right.
Do the numbers. Engineering is done with numbers. Analysis without numbers is only an opinion.
He's also missing another requirement: 5) The entire track, including any possible expansion components, valves, inspection hatches, etc etc etc have to be at least mildly tolerant to intentional or accidental damage. Running into a sudden wall of air at 700mph is a good way to destroy any passenger craft in the system.
I ask because that’s how you tend to work around thermal effects in electronics.
Relevant discussion of thermal expansion with high speed tracks: http://boards.straightdope.com/sdmb/showthread.php?t=471152
Overall, it is not a particularly difficult engineering problem.
Have also heard anecdotally that condensation in the tube could be a real problem. Even at near vacuum, the rapid pressure differentials can cause buildups in front of and behind the speeding vessel.
Sure, all of these problems are solvable if you are willing to expend arbitrary resources. But the whole point of this exercise is to provide an economically viable mode of transportation. (Isn't it?)
Similarly, the proposal briefly discusses thermal expansion: as the steel of the tubes heats in the hot California sun, the metal expands. That expansion needs somewhere to go. In high-speed railways, rails are allowed to overlap at the ends, but that’s not possible in the Hyperloop, and so Musk has a different solution:
“Specially designed slip joints at stations will be able to take any tube length variance due to thermal expansion,” he explained. “This is an ideal location for the thermal expansion joints as the speed is much lower nearby the stations. It thus allows the tube to be smooth and welded along the high speed gliding middle section.”
I think the hand-wringing over expansion is a bit over the top right now. Seems like its a relatively solved problem and one the Hyperloop team is taking seriously. I imagine the cost of engineering and building giant slip joints is just part of the overall cost package and probably a non-trivial part. I find it hard to believe someone as relatively trustworthy and technical as Musk is selling this concept knowing full well its impossible.
Most likely, this is a solvable problem the same way many difficult problems were solved for cars, planes, and rails during their inception. I read an analysis somewhere that the Wright brothers solved 4 or 5 'hard' problems with their first plane. Their competitors at the time weren't able to solve even one. I'm not saying Hyperloop is guaranteed to work, but declaring it 100% impossible seems overly pessimistic.
My worry is a bit more prosaic, if we gain progressive leadership in congress, we may be looking at Euro-style high speed rail in many US regions, which would invalidate the hyperloop concept. This seems less likely, imo, but by far the saner move.
Just the tube alone:
- largest pressure vessel in the world. How do you keep it at near vacuum?
- Thermal expansion over such a large distance, especially if the top of the tube is warmer than the bottom.
- Safety, how does an evacuation look like if the tubes are sealed?.
It started as a technical whitepaper, not a marketing campaign, and multiple companies are building experimental models. I don't think this critique is accurate or fair. There have been far worse vapourware and hype-only concepts that haven't gotten close to hyperloop's tangible progress.
No tech can be perfected from the planning stage either, it takes talent, money, and time - and you can't get those things without a bit of hype, the key is keeping it balanced.
Regardless the concept seemed feasible enough to some very smart people and people with money to spend, where they see it's worth the R&D.
I don't really see what the big risk or downside here of exploring this? Considering the rewards could be very high if it does work and otherwise there has been little innovation in transportation in 50yrs, it's not like there are some obvious alternatives are being neglected.
A high speed train like the ones they've had in Europe for a long time? You know, the ones that regularly reach 300 km/h? If that's not fast or flashy enough for you, what about Maglev? It actually exists, and the tracks are extremely expensive even though they don't even have to maintain low air pressure
I don't see what the US political inability to build infrastructure has to do with my comment. Plenty of countries are still building highspeed trains and iterating on that model... and plenty of non-US countries are looking into hyperloop, the first ones to adopt it will likely be outside of the US, as that's where most innovation is these days. And regardless there's always plenty of room for new ideas.
Unless you think these billionaires should be backing American transportation mega-projects instead? There's plenty of roadblocks there outside of access to capital, where a highspeed train will likely cost 2-3x the initial projections, even if a private company does it. Not to mention the US is a car-heavy market. It seems like a risky project for any non-government entity to take on as it will be packed full of political risk and direct involvement either way...
The US rarely builds major projects anymore except in the defense industry. And almost every major defense project of comparable size ends up being billions over budget or cancelled.
"More marketing than engineering" seems accurate to me.
Serious vacuum pumps are not required. This is not to say that keeping it airtight won't still be a major engineering problem, it just isn't as near-impossible as near-vacuum would be.
To cope with expansion, you'd need to use sliding plates--which, yes, will make it harder to keep the air out. That's going to be an interesting challenge.
I'm sure that's also a fast mode of travel, but like you said, the vacuum part of it takes a lot of money.
For many of Elon Musk's projects, I get the idea that Elon is mostly just bringing broad, multi-domain knowledge to bear on industries that have been siloed for a very long time. So everyone scoffs at a long vacuum tube and using turbomachinery, etc, but for someone with a physics background with extensive knowledge of the spacecraft environment, turbopump rocket engines, and all the subsystems and ground testing systems that enable all this, it really isn't far-fetched at all. Most physicists (of the experimental kind, i.e. those who have to have hands-on knowledge fabricating things in addition to theoretical background) that I've talked to understand his ideas and think they're fairly reasonable.
People seem to base most of their criticisms on the fact that it's different than what we already do without a fundamental, first-principles understanding of the system.
Another extreme is the approach, advocated by Rand and ET3, of drawing a hard or near hard vacuum in the tube and then using an electromagnetic suspension. 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 where standard commercial pumps could easily overcome an air leak and the transport pods could handle variable air density would be inherently robust. Unfortunately, this means that there is a non-trivial amount of air in the tube and leads us straight into another problem.
The "another problem" being that if you just do low pressure, it means your pod has air in front if it and has to pushing that air around (or if that air has nowhere else to go in the forward tubing, trying to compress it, because not enough of the air can squeeze around the pods at the edge of the tube). That's what the hyperloop is getting around by sucking air in the front and blowing it out the bottom. Working as an air cushion is something of a bonus, and if everything works out right it also lets you avoid the expense of maglev.
- Resistance to high and very high pressures
- Large movement absorption
- Early leak indication (in case of damage) via standard check hole
- Complete burst resistance
- Possibility of permanent leak monitoring in critical media
Frankly, yes, there may be issues, but I'm confident that the Human race will be able to overcome those.
And for a sense of scale, a human can comfortably stand in that tunnel next to it.
Hyperloop is a run around that problem. Largely autonomous/low staffed boring that's non-union labor, non-public sector can make a lot of progress quickly. There's no public sector union demanding x amount of jobs, x amount of pensions, and other expensive regulations or union concessions. Musk's Boring Company thinks it can build tunnels for a fraction of the cost privately without much public sector regulatory weight and they might be right.
HSR is the saner idea, but without Congress funding it, its just not going to happen. Obama made a big push for it during the stimulus but more conservative states decided against accepting the money for both ideological and financial reasons. Once enough states say no, then the rail can't go very far, and the project eventually died:
First, Tea Party conservatives in Florida and wealthy liberal suburbanites in the Bay Area began questioning their states’ plans. Then, just as Joe Biden was calling for $53 billion in high-speed-rail spending over the next six years, a crop of freshly elected Republican governors turned down billions in federal money for lines in Wisconsin, Ohio, and Florida. Finally, Republicans in Congress zeroed out the federal high-speed rail budget last month.
HSR works well in places with high density and competent infrastructure construction strategies. California has neither.
$100bn is too expensive to make sense but I don't understand why it should cost that much. There are not that many tunnels needed, esp. if you start/end north of LA and south of SF. European rail projects are also expensive but still a fraction of the cost.
But, usually, it's more productive to start with the understanding that other people are smart too, and that they may have thought of these problems. In this particular case, I believe that the original white paper addresses these points. I'm not a structural engineer, so I've no idea if their solutions are valid and I'm not saying that it's never okay to criticize, but this reads to me as if you may have fallen into the trap of forgetting that the people who designed this are very smart people, and thus likely thought of the obvious problems.
- if you build a subway it will be the biggest underground railway ever built.
- Rocks. They could fall in front of a subway car and cause a huge accident.
- safety. what if all the lights and power go out? Also how would anyone breathe down there.
The criticism you've offered seems equally low-effort, so this is why I'm curious if you've ever helped design and build any large-scale project.
I don't like gratuitous negativity on HN and it's against the rules here.
The main thing Musk has in common with the Wrights is running an electric car transportation company and sending private rockets into space via SpaceX.
I think you should revisit whether that makes it more Wright brothers or Da Vinci.
Elon's main business is electric cars and (one of) Branson's is airlines. So a reasonable competitor to both is fast and cheap(er) public transport along a major travel corridor in the USA.
This means that by promoting this alternative to high speed rail as faster, cheaper, better, they are undermining public support for a real project, which could mean its end.
Practically anything could be "a clever political ploy", but where's the evidence for this? Any in the absence of such evidence, why speculate?
Just as a thought experiment, could HN user daemin's comments be part of a clever ploy to invent a fake persona to distract from a SECRET AGENDA? ;)
EDIT to add: Before Hyperloop, it was Maglev.
And frankly, a significantly better argument against HS2 is that it's an impossibly expensive boondoggle.
Nah, it connects most of England's largest cities, and will be 2/3rds of the network which will connect all of the cities of the North of England into something approaching a single labour market. Liverpool, Leeds, Sheffield, Manchester, Birmingham will be all be within 30-50 minutes of each other, with London within an hour and a half, with trains running between destinations 2 or 3 times an hour. The value of that is enormous.
The idea that it will turn a load of separate cities into one big city is basically fantasy, as i understand it - this is about HS3, but the analysis is much the same:
And yes, i do get all my information from CityMetric, since you ask. It's basically Buzzfeed for transport policy, i love it.
And yes, I realise the XC trains around Birmingham (inc. to Newcastle) are frequently overcrowded, but there's a comparatively cheap solution to this: buy more trains.
That should mean strengthening a region around Birmingham, faster links connecting the Leeds - Sheffield - Manchester triangle + tack on Liverpool, and a wide orbital around London improving connections between the towns around London that now are reduced to feeder/sleeper towns. There are towns around London that has decent direct rail tracks, but where the fastest rail route is a 2x-3x longer journey in to a London terminal and back out again. Actually run direct trains, and you suddenly have new viable commuter regions that bypass the centre.
Only after that should we think about making the links between these centres faster.
The problem of course is that many of these will need to be run at substantial losses for years before enough companies etc. will move/get established to change transport patterns, and it's so much easier to justify building more expensive routes where there is existing overcrowding.
Never mind that doing so just attracts more people.
Not taking a side here, but it doesn't seem useful make fun of the parent comment for what, on its face, seems to me as a pretty apt comment.
These two gentlemen stand to gain from the failure of mass long distance transit. So, why are they spearheading any kind of Hyperloop project? It's a valid question, and the suggestion about their motive is not farfetched for a couple of successful business magnates.
I mean, Musk's initial announcement regarding the hyperloop was about how California high speed rail shouldn't be built. These are the first lines of his blogpost announcing the hyperloop:
> When the California “high speed” rail was approved, I was quite disappointed, as I know many others were too.
We can debate Musk's motivation, but the fact remains that the hyperloop is being used to argue against high speed rail construction, and has been since it was first announced.
If that were the case it would be one hell of a troll, set up an account for many years just for this one incident!
Even Reason Foundation (which is as biased as it gets - it's funded by Koch brothers and ideological critic of almost any government investment) claim SF to LA times will be 3:30 to 4:40, which is faster than any train today.
I think air travel for short to medium flights will fall off. By the time I leave my house and get to someplace that is 8 hours by car it would take 5 hours to check in and check out and you still need to rent a car.
Now, other than traffic, I agree. When deciding whether to drive somewhere or take the train, my second factor is whether or not I feel like actually driving a car. That answer is usually no, so I'm very excited about driverless cars.
And while you're right that this will probably drive up demand, it achieves something else too: Availability of extensive route information. Now imagine a shared system for such cars to negotiate routing, and such cars can know which routes will be less congested, and can know which cares it is most effective to re-route because of where they're going.
E.g. there's a chokehold near me for Southbound traffic that it's tremendously beneficial to bypass if you're heading South-East, because you can take back-roads with lower speed limits but that are shorter, and that will end up being much faster when the chokehold is congested. Which it "always" is between certain hours. But if you're going South West, it's better to suffer through it.
With vehicles able to negotiate route information, vehicles going South East could be automatically re-routed when there's congestion, resulting in average speed improving for everyone.
In fact, you could even imagine a system where cars autonomously negotiate a fee for other cars to let it get in front (so you could e.g. pay a 30% premium for urgent trips and have the car company spend, say 25% to buy its way in front of others on congested routes).
This may not entirely solve the problem, but it can make congestion more about total throughput than maximizing throughput on a small number of routes.
End-to-end route information also opens the door for services to mediate multi-step routes with e.g. cars feeding public transport much more efficiently (e.g. in my case I live almost exactly halfway between two major rail stations, with two more small ones not much further away. I almost always opt for the largest of the four because it's at a central junction that gives me the best option for almost every destination so I rarely need to think about it, and it also means I know exactly how long it takes me to get there.
But if I can tell an app where I want to go, and get told to either go to the bus stop or wait for a car, get taken to whichever station is the best option and told which track/train to take, and get picked up by a car on the other end, there might be substantial time savings and often a better shot at a seat. The only thing stopping me from "shopping around" like that today is that it's extremely inconvenient.
Again combine that with pervasive end-to-end route information, and you can make it even better by ensuring not too many people get routed onto each train if two options are relatively equal and one is less loaded.
People would take HSR even if it took the same time as driving. They would likely take it if it took an extra 20%, as the time has more utility to them when used for a train ride. That it's actually faster than driving just makes it more attractive.
We've already criss-crossed uncountable acres of historic, sentimental (what?? really??) land with roads, both local the state/federal highway system. HSR would be so much better use of land than roads, for moving a lot of people quickly and comfortably. Not at all redundant with Amtrak.
Happily, the California project is funded and is already underway, and I think there's one or two others being talked about/planned.
They'd put a highway right through where the black folk live, and who cares? Well, all the people in that neighborhood care, but they're poor minorities--they have no political power, no ability to push back.
If you want to start talking about land being taken from people, don't fucking start with farmers in rural California and HSR, start with the inner city neighborhoods the highway system destroyed.
Never funded? It's already under construction. Although it's likely pre-pre-pre-construction, as they grade items and fix obstacles for the actual railway construction, which I doubt will happen within a decade, if ever.
They're building the bridges right now, that's not exactly pre-pre-pre-construction.
That being said, the trip takes 13 hours and some change, depending where in SF you're trying to go - which would be blown out of the water by HSR.
It is fun if you enjoy trains though! Take it if you have the time.
But yes - absolutely terrible from a commuter perspective.
CDOT has this thing for "public/private partnerships" which are just thinly veiled schemes siphoning off taxpayer money. The whole US36 debacle proved to me that they aren't capable of negotiating a good deal on the part of the taxpayers.
Without changing this, high-speed rail in the US will never be a reality without building an entirely separate rail network.
Indeed, that, if anything, is exactly the kind of investments that a government should be making.
The government well made its money back before the great railway crash.
Let's say the Internet suffers a crash in a few decades. Few would argue that any previous investment into the Internet was not worth it.
AFAIK, passenger trains have priority. However, if the passenger company rents a specific timeslot from the railway and isn't on time, it isn't surprising if there is traffic along the way.
And high speed trains usually require dedicated tracks to operate at full speed anyways.
I've experienced these delays many times riding the California Zephyr, and the conductors always say something about the freight trains having priority. According to the article this is because Amtrak is persistently ceding priority, despite federal regulations prioritizing passenger trains.
edit: According to the WaPo article linked by jey in this thread, this ended up overturned in federal court, so I guess as of 2017, freight does have priority over passenger trains in the U.S.
Branson's Virgin Group owns only 20% of Virgin Atlantic (don't let yourself be mislead by the Virgin name appearing all over the place - Virgin tends to start businesses, sell all or part of them when the opportunities are right, but continue to lease the name out to the buyers; the Virgin brand appears on dozens of companies with little to no Virgin Group ownership).
In 2016, Virgin Atlantic's revenue was less than 3bn GBP, with Virgin Group's "share" of that, just 600 million GBP (yes, I know it doesn't make sense to count it that directly; if looking at operating income instead, Virgin Atlantic's operating income in 2016 was ca. 150mn GBP), while Virgin Group's revenue was 20 billion pounds. So Branson's airline interests are relatively minor in the grand scheme of things.
And Virgin Atlantic would not face much competition from high speed rail (the clue is in the name - Virgin Atlantic might in fact very well benefit from a high speed rail network if it meant the ability to offer customers faster/easier access to more of the US with fewer US destinations which would make it easier for them to compete with airlines with more comprehensive route networks).
Virgin Group also wholly owns a UK train operator - if they saw "regular" high speed rail as a good business opportunity in the US, odds are higher they'd invest in it than try to stop it.
Also a lot of them end up going nowhere, much like with other Angel investing.
It wasn't entirely novel, but he gave the idea legitimacy beyond the normal fantastic imaginary future one is wont to see from time to time.
So I don't think this was an attempt to head the tech off at the pass or some alternate reality like that.
I think it was genuine and continues to be.
Historically there is the example of 1920s era GM funding initiatives to convert tram lines into bus lines, which required further investment in road networks, which benefited their private car ownership business as transit was defunded and discredited.
Hyperloop at least started a discussion. Once it fails, there might be some actual public support.
Just because there are significant interests that oppose high speed rail at every turn doesn't mean there isn't public support.
To put that in perspective, the Boeing 787’s GEnx-2B67, the most powerful GEnx engine variant, generates a 43:1 pressure ratio . To get a sense of the engineering differences between 6:1 and 1,000:1, look at NASA’s Space Power Facility .
The Hyperloop’s thermal issues are a hard enough problem that they alone put this in the domain of materials science. That’s the same category of problems separating us from a space elevator.
The Hyperloop always seemed like a transportation system not for this planet. The thermal issues, too, become trivial to solve on Mars: bury the tube. Mars does not appear to be too seismically active  and has no existing property rights to take into account . (The lack of water also makes steel more viable.)
What? What are you even talking about?? That's a completely ridiculous statement. The pressure inside and outside the lunar landing module was 1,000,000,000,000,000x. 100 kPa to 10^-10 Pa. It makes zero sense to apply this kind of ridiculous relative measurement to pressures because it has no relation to how pressure works. The structural challenge in building a tube that works to .001 atmospheres is only 25% harder than building a tube that works to .2 atmospheres (same as an airplane). And it isn't any more dangerous.
The only challenge that occurs is sealing in that atmosphere without any leaks and that part isn't hard either. 100 Pa is achievable by a $50 pump.
I also have yet to see any compelling argument that there will be thermal issues. Floating mounts and expansion joints are hardly untested technology.
We didn't pump air into the lunar module from the Moon. We carried it from Earth pre-pressurized. Unless you're proposing we build and seal the Hyperloop tubes in space before bringing them down, the analogy isn't appropriate.
Also, consider a soda can. It's stronger when pressurized from the inside. Modern nuclear attack submarines collapse around 730m . Since for "every 33 feet (10.06 meters) you go down, the pressure increases by 14.5 psi," we're talking about water pressure of about 1,000 psi or about 72 atm.
I am not sure what your objection is here. Are you saying vacuum chambers can't be built on Earth? There are quite a few examples of large vacuum chambers, like the NASA Space Power Facility (23,400 m^3) or the Large Hadron Collider (9,000 m^3) https://scap.hq.nasa.gov/docs/Glenn_SpacePower.pdf https://lhc-machine-outreach.web.cern.ch/lhc-machine-outreac...
Both are pumped down to very high vacuum, not required for the Musk Hyperloop, (low pressure electric jet in a tube) but probably needed for the Hyperloop One. (maglev vactrain) And, obviously, both chambers were built terrestrially, and evacuated using conventional vacuum pumps.
No, I specifically linked to the Space Power Facility in my original comment! The "materials science" problem I call out is in the tube's lateral thermal expansion.
The best solution I've come up with for that is to take a regenerative rocket engine  and make it a tube. Pumping fluid in spirals along kilometers of a vacuum tube isn't easy, but it isn't as hard as trying to invent a material that won't deform when the top gets hotter than the bottom, or the east side gets hotter than the west.
I admire your method of argumentation.
The comment I replied to said nothing at all about thermal expansion. Your original comment, which I wasn't replying to, was mostly strange references to pressure ratios, and a single line about thermal problems, with no numbers cited. In that comment you did link to the Space Power Facility... as an argument against Hyperloop One! You did something similar downthread: https://news.ycombinator.com/item?id=15459777 But by asserting that you addressed the problem in your original comment, you make the person you're arguing with look like a bully, without having to actually address their points. Very efficient.
>The best solution I've come up with for that is to take a regenerative rocket engine  and make it a tube. Pumping fluid in spirals along kilometers of a vacuum tube isn't easy, but it isn't as hard as trying to invent a material that won't deform when the top gets hotter than the bottom, or the east side gets hotter than the west.
Using the phrase "regenerative cooling" in this context is another headscratcher. Regenerative cooling in rocketry is running propellant through channels in the nozzle, then either dumping it overboard, using it to power a gas generator, or burning it in the rocket. It's a great way to get rid of megawatts of heat.
None of these things would be useful for a hyperloop tube? You don't want to run kerosene/liquid oxygen/hydrazine/whatever through a cooling jacket then dump it on the ground, you don't need a gas generator for anything, and there's no way to feed the heated propellant to the actual hyperloop car. And if you could, you wouldn't want to, since if you combusted it in the car it would just dump the exhaust in the tube, killing the vacuum.
Presumably active cooling of a hyperloop tube would use a closed refrigerant cycle, which has little to do with regenerative cooling, besides the idea of cooling channels.
Talking about regenerative cooling in this context isn't wrong, exactly, it just betrays a rather shallow understanding of the problem at hand, as seen in your first comment.
"Regenerative cooling" is a rocket term. It came to mind because I used to be an aerospace engineer. There's no requirement in the definition of regenerative cooling for the coolant to be dumped.
> Presumably active cooling of a hyperloop tube would use a closed refrigerant cycle
I don't think one can just presume that. You've already got lots of pumps for pumping air. Given (a) the seal on the tube will be periodically broken (for entry, exit and maintenance) and (b) a safety factor, you'll have more pump capacity than you'll need. Filtering and then compressing atmosphere, running it through a heat exchanger, and then letting it expand through the cooling channels before dumping it doesn't seem obviously worse than having kilometers of refrigerant running around.
> which has little to do with regenerative cooling, besides the idea of cooling channels
See above. Also, I assumed if you did this you'd use it to boost SpaceX's nozzles' economies of scale.
Regenerative cooling in rocketry uses propellant. Propellant is always dumped overboard, because it's propellant.
Please show me a rocket that uses closed loop cooling of the rocket nozzle.
>Filtering and then compressing atmosphere, running it through a heat exchanger, and then letting it expand through the cooling channels before dumping it doesn't seem obviously worse than having kilometers of refrigerant running around.
My turn to be pedantic about definitions: this sure sounds like closed loop cooling to me! The working fluid is air, you draw it from a big reservoir, (the atmosphere) cool something with it, then return it to the reservoir. (Something you can't do with open-loop regenerative cooling of a rocket nozzle, since the coolant gets burned at the end of the cycle)
However, maintaining the air dryers and replacing the filters sounds like it wouldn't be any cheaper than conventional phase-change cooling, and having to build custom vacuum/compressor pumps for the hyperloop project is going to be more expensive than buying COTS vacuum pumps.
The most famous one is the under-development SABRE , which includes a closed-loop helium cycle. For cryogenic rockets, closed-loop cooling of the nozzle has been explored  to avoid hydrogen embrittlement and oxidation of the nozzle channels, as well as to simplify plumbing.
In any case, we've devolved into arguing semantics.
> My turn to be pedantic about definitions: this sure sounds like closed loop cooling to me!
I was figuring on dumping the air once done versus worrying about a reservoir. That said, I haven't done any math on the benefits of saving the return piping (and reservoir cost and maintenance) versus using something traditional.
> maintaining the air dryers and replacing the filters sounds like it wouldn't be any cheaper than conventional phase-change cooling, and having to build custom vacuum/compressor pumps for the hyperloop project is going to be more expensive than buying COTS vacuum pumps
Fair enough. As you observe, it's a problem I haven't seen a suitable solution to (apart from burying, which trades the thermal problem for, in my view, the better water management problem and the scarier land-use problem.)
From the linked article:
>>The 'hot' helium from the air precooler is recycled by cooling it in a heat exchanger with the liquid hydrogen fuel.
It's open-loop regenerative cooling, with helium as an intermediate coolant. The heat still ends up in the propellant, which gets dumped overboard. Not closed-loop.
That patent also specifies a heat exchanger to the propellant tank.
>I was figuring on dumping the air once done versus worrying about a reservoir.
A poorly telegraphed joke. The atmosphere, here, is the reservoir. I have edited my comment.
Just want to point out a facet of such a project that you probably haven't considered. The EPA puts strict requirements on the operators of refrigerant systems, the way they categorize operator class is based on pounds of refrigerant. Thus even though a COTS phase change refrigerant system seems like the obvious choice for Hyperloop One, because of regulatory burden it would almost certainly unfeasible. A refrigeration system big enough to cool a hyperloop would have to have every inch of refrigerant line spray tested every 3 months or an insanely expensive monitoring system.
At that point why not just bury it? It swaps the thermal problem for the water problem, but we know how to build tunnels.
Because foam is cheaper? A nice K.I.S.S. solution.
Having seemingly solved this thermal expansion problem "in the same category of problems separating us from a space elevator," I'll be expecting The Fountains of Paradise to come true soon. ;)
I guess I'll have to telegraph my buddies in Hawthorne and at NASA :).
Joking aside, no, foam doesn't solve the problem. You'll still have flexing. This is one of the limits on how long you can have a launch tank on the pad. Imperceptibly small flexing, but of the kind that weakens every metal we know.
Of course the flexing isn't zero, but by adjusting the thickness of the foam you can drive the diurnal/solar heating thermal gradient arbitrarily low without compromising strength by making the steel walls thinner. That was your material science objection, right?
>but of the kind that weakens every metal we know.
That's true, but misleading. It's true that every metal gets weaker, but in steel and titanium this weakening levels off (all other metals continue to get weaker until failure). Once these two metals are at the fatigue limit they stop weakening and have unlimited flexing cycles. So you can set that as your final material strength and size the tube thickness accordingly.
So repeated flexing is fine, and flexing can be made arbitrarily small with insulation. Foam solves the problem.
This isn't a rocket. The tube wall is inch thick steel. It would rust into nothingness centuries before it would crack from distortion.
It absolutely is appropriate, since the module was emptied and filled each time the astronauts left.
> Modern nuclear attack submarines collapse around 730m. Since for "every 33 feet (10.06 meters) you go down, the pressure increases by 14.5 psi," we're talking about water pressure of about 1,000 psi or about 72 atm.
Yeah- so building a hyperloop is structurally as complicated as building a tube that sits 33 feet under water. Hardly sounds complicated when put like that.
And since they explicitly do not want a high vacuum - some residual air inside the tube is necessary for the hyperloop concept! - they don't have to deal with advanced tech like turbomolecular pumps. Simple displacement pumps will do.
I never said vacuum pumps are "technologically impossible". My original comment references the Space Power Facility  and categorises the vacuum problem as an engineering problem. A hard one, but engineering nonetheless.
The comment you link to  replies to someone claiming the original white paper calls for a 22:1 atmosphere:tube pressure ratio. I pointed out that the figure they're referencing, Figure 11, discusses the capsule and not the tube.
I'm skeptical about the economics of de-pressurising the tube, but that's an engineering problem and I've always held it as such. The materials problem is the thermal expansion of the top of the tube relative to the bottom.
I happen to be that someone. :) You were talking about state-of-the-art axial compressors (the GEnx-2B67), so I assumed you were talking about the axial compressor on the front of the pod. Mea culpa. But then you drew an analogy to the pressures in the SPS ("To get a sense of the engineering differences between 6:1 and 1,000:1..."), as if the Hyperloop people were trying to make a 1000:1 axial compressor. As I pointed out in my reply, rotary vane compressors can easily maintain those pressures.
>The materials problem is the thermal expansion of the top of the tube relative to the bottom.
If that were really a problem, no pipelines of any kind could be built. Again thermal expansion joints are the solution, since with the abandonment of air-ski levitation the pod walls no longer have a requirement to be ultra-smooth. Tiny leakage on these joints is fine, since it will be made up for by the pumps located along the track.
The Trans-Alaska Pipeline system, which I believe is the largest at least in the United States, is 1.2m in diameter . We're talking about a pipe almost 3 times wider that needs to hold itself against the atmosphere and keep capsules neatly contained.
Side note: long pipelines zig-zag to allow for thermal expansion and contraction . You can't do that with the Hyperloop. (Bridges handle this with various ingenious methods, most of which will work for the Hyperloop's longitudinal expansion.)
> thermal expansion joints are the solution
Scaling pipe expansion joints where they maintain the near vacuum and deal with the structural stress of a capsule whizzing by will be difficult. By "difficult" I mean these are problems NASA (for the ISS) and Schlumberger (for pipes) have been grappling with for years and with billions of dollars in R&D.
What exactly is the problem here? Is it because the top of the tube is exposed to direct sunlight? I thought it was supposed to be covered in solar panels anyway. Is it still a materials science problem if the tubes are shaded, because providing a structure that shades something with expansion from direct sunlight exposure seems quite a bit easier than to do so while trying to keep vacuum to a particular level.
None of your critique makes sense without that assumption, and nowhere in your post do you say where that comes from.
No one. The Hyperloop alpha paper explicitly contradicts this assumption on page 18, where the flow diagram gives the compressor input at 99 Pa and the output at 2.1 kPa (a 21:1 pressure ratio).
One standard atmosphere (atm) is defined at over 100,000 Pa . The 21:1 pressure ratio in Figure 11 on page 18 is for the "passenger plus vehicle capsule" . I'm talking about the tube.
Going from 99 to 2.1 isn't hard. Going from 100,000 to 100 and then keeping it there is.
Keep in mind that the absolute pressure difference is far less for Hyperloop than for a typical natural gas pipeline, and yet the latter can keep leaks to an absolute minimum in spite of thermal expansion, etc.
Scaling is hard. The largest vacuum chamber we've built is a fraction of the size of the proposed Hyperloop. It was a very, very hard problem . It's expensive, sucks up loads and loads of power and needs lots of thermal management, structural reinforcement and vacuum-off maintenance.
> Keep in mind that the absolute pressure difference is far less for Hyperloop than for a typical natural gas pipeline
Pipes are pressurized from the inside. See my comment from elsewhere in the thread on why vacuums are different .
All this said, I generally agree with you. I don't think building a giant vacuum is beyond current technological capability. I do think building one structurally sound and thermal-expansionwise stable enough to carry passengers at high speeds is.
Do we really have to say that a long extruded tube that only has to maintain low vacuum is a lot simpler than the SPS?
SPS: big thing made up of many custom one-off parts that runs at 1/380,000,000ths of an atmosphere and can blast test articles with intense simulated sunlight.
Hyperloop tunnel: big thing made up of many identical parts that runs at 1/1,000ths of an atmosphere.
>It's expensive, sucks up loads and loads of power
I think they know that, don't you? There's no line-by-line breakdown, but the paper allocates $260 million for the station+pumps and 21 MW for electricity consumption (pumping, accelerating pods, and charging pod batteries).
>needs lots of thermal management
I agree that you need it, but what specific problem do you see?
>Pipes are pressurized from the inside. See my comment from elsewhere in the thread on why vacuums are different .
You said a soda can is stronger when pressurized from the inside. That's true, but the obvious solution is to make it thicker than a soda can. :) The paper calls for 0.8-1.0 inch thick steel, which my math says is more than adequate.
Who's they? Hyperloop One? No--they've just punted the "hard" stuff to the end. (Kind of like the Wright Brothers designing the seats of their plane before getting it flying. Oh look! )
Elon Musk? Yes--I do. That's why he's waiting.
> what specific problem do you see?
The top heats up and the bottom doesn't.
> The paper calls for 0.8-1.0 inch thick steel, which my math says is more than adequate
Adding mass adds strength while increasing the time the structure takes to reach thermal equilibrium. The thermal gradient isn't itself a problem. But if you look at the forces necessary for the materials in question to tear themselves apart, and then consider their thermal coefficients of linear thermal expansion, you can derive a maximum tolerable thermal gradient given the size of each tube segment (we'll assume the problem of reticulating vacuum seals is solved).
When you solve for strength, you get too much material for the system to reach equilibrium before inclement weather either causes (a) the structure to buckle, laterally or (b) the outside of the tube to start shearing itself from the cooler inside.
When you solve for thermal stresses, you lose your strength. Microbuckling and microfracturing may not seem like a big deal, but it is when you're talking about 1 standard atmosphere bearing down from the outside with a capsule swinging about on the inside.
We need a strong material that either (a) conducts heat really well or (b) doesn't change shape when asymmetrically heated. We don't have something that meets those requirements yet that we can manufacture at scale.
Citation needed. The link provided gives no support.
I would be interested in seeing your calculations on the thermal side. An ANSYS multiphysics simulation (the software SpaceX uses) would show the problem, no?
SpaceX has already built and used a mile-long, 11' diameter vacuum tube in Southern California, which would seem to put this matter to rest (the proof is in the pudding, after all).
Yes. But SpaceX != Hyperloop One.
> SpaceX has already built and used a mile-long, 11' diameter vacuum tube in Southern California, which would seem to put this matter to rest (the proof is in the pudding, after all)
I'll go ahead and predict that the strength of that tube will have materially decreased after 1 year in the elements. I'll even posit that will occur independent of rusting, which appears to have unfortunately taken place, due to the formation of microfractures within the metal due to repeated lateral thermal flexing. That said, this was a demo track. It wasn't designed to withstand one standard atmosphere while whizzing fast, heavy capsules inside it for years on end.
With steel, the real question is not the weakening from Year 0 -> Year 1, but from Year 4 -> Year 5. After an initial period of weakening the strength of steel levels off.
Anyways, another user pointed out that a cheap foam layer can reduce the daily flexing to arbitrarily low amounts, and give an arbitrarily amount of time for the tube temperature to equalize circumferentially. Cheaper than either a temperature equalizing water jacket or an underground tunnel. I know you disagree in that other thread, but I now consider this problem solved.
The hyperloop as written was very challenging, but the engineering aspects are not. The practical building (grinding the inside, transporting the tubes, etc.) are significant. The financing is insane. The theory is not even particularly hard, much less at the level of a space elevator.
The internal pressure was chosen explicitly because it was easy to maintain with simple, single stage mechanical vacuum pumps (see Figure 13 on page 22). Heck, the first result on Amazon for "vacuum pump" goes down to 5 Pa. https://www.amazon.com/dp/B012CFTYX4/
Compare the Hyperloop to true "vacuum train" designs, which need to run at 1/1,000,000th of an atmosphere to mitigate sonic booms (an alternate way to get around the Kantrowitz limit). This requires multi-stage pumping with mechanical roughing, followed by turbomolecular pumps and cryopumping. That 1000x harder vacuum takes 1000x as much pumping power (not because the differential pressure is meaningfully different, but because you expel 1000x less air per stroke).
That said, I have not followed closely enough to know if the hyperloop startups out there are following the original conception or if it has significantly evolved or not. I hear that they've ditched the compressor altogether, but that's got to have a pretty big impact on expected speeds.
Likewise. It sounds like above-surface (on Earth) is probably unfeasible given (a) security and (b) thermal concerns.
For security, we just contemplated debris from the track (or a bullet from an errant rifle) puncturing the tube. Hyperloop One is testing an 3.3m diameter and 500m long track . That's 4,276 cubic meters [a]. "At sea level and at 15 °C air has a density of approximately 1.225 kg/m3" . The air in the Hyperloop One test track thus weighs about 5,200 kg.
If we use the Hyperloop's original design spec , a puncture means air on one side at 1 atm expanding into the space on the other at 1/1,000 atm. This simplifies to a wall of air moving at just below the speed of sound. Since the speed of sound is about 330 m/s , the end of the tunnel will could hit with a pulse with about 140 megajoules of energy [b]. That's the energy in about 30 kg of TNT [c].
> I hear that they've ditched the compressor altogether, but that's got to have a pretty big impact on expected speeds
It currently sounds like a vactrain  with magnetic levitation .
[a] pi * (3.3 / 2) ^ 2 * 500
[b] (1/2) * (5200 / 2) * 330 ^ 2
[c] (140 * 10^6 / 4.184 * 10^9) * 10^3
"A little bit of physics is a dangerous thing."
* A bullet or piece of debris would likely leave a hole much smaller than the diameter of the tube. A breach 1/10th the diameter of the tube will admit 1/100ths as much the air.
* Even if there was a whole-tube breach, the "wall of air" will rapidly slow down and smear out into a gradual pressure rise due to friction with the tube walls. Pipes are not lossless! Within 5 km friction will have the air moving at highway speeds. So if you're so close that you can be killed by the air blast, you're so close that the pod can't brake before hitting the whole-tube breach (bad). In other words, "deadly pressure waves" don't increase your odds of dying beyond that of a regular "derailment" event.
* In the event of a breach (whole-tube or otherwise), sensors in the track will signal all the pods to stop and the tunnel to undergo emergency re-pressurization. So any "wave" won't get far.
Just watched one of his videos on this--interesting and thank you for the pointer. Agree with you on his overstating the deadliness of pressure pulses. 30 kg of TNT is a lot of energy, certainly enough to knock your infrastructure out of commission for a couple days. The "everyone dies if the tube is punctured" argument is hyperbolic, though.
The materials science problem is the thermal expansion. And not the longitudinal one that Thunderf00t mentions. It's the transverse expansion. If these are above ground, the top will heat up relative to the bottom. That's a nasty problem to solve while maintaining the structural integrity to keep a giant vacuum with speeding capsules in place.
Right... you can probably solve that with a bucket of white paint. Worst case you cover it with an aluminum shield- aluminum does not absorb infrared radiation and will reflect 99.9% of ambient heat. Since the proposal included covering large sections of the tube in solar panels that isn't even a significant change.
It's, unfortunately, harder than this. It's a similar problem to the ones we dealt with regarding rockets, standing fueled, on a pad. Both methods you propose were tried. The solution is to (a) paint it and (b) launch before the gradient becomes too big.
The stresses on the Hyperloop tube, when a capsule is rushing through it while it's containing a near vacuum, are comparable to those on a rocket nearing max Q . The difference is with a rocket we take great care to maintain symmetry. With the Hyperloop, that isn't an option. That persistent asymmetry is what makes it a difficult materials problem, particularly if we're using any known metals (even wonderful light and thermally-conductive aluminium).
I'm also not sure you understand what I'm saying about an aluminum shield? Aluminum has an emissivity coefficient of .04. Thermal conductivity has nothing to do with it since it isn't touching the tube. It's purpose is just to not re-radiate infrared onto the tube.
Fixing a large enough solar shield above a rocket hundreds of feet in the air which has to get out of the way quickly before the rocket launches has very different requirements than fixing a shading structure above a vertical static structure a few tens of feet in the air. I'm not sure how this problem was solved in rocketry is necessarily indicative of how hard it is to solve in other circumstances.
Very fair. The advantage a rocket has is you choose when it's rolled out. You don't have to design for the worst weather because you can always hide.
You can't do that for a static structure. The Hyperloop is an attempt to marry the challenges of rocketry to the standards of civil engineering. The advantage is you don't have to think about aerodynamics, which is good, because air is the worst. (You also get civil-engineering budgets.) The bad is you can't hide from the edge cases.
If you want to grapple with this problem live, rent (or borrow) a thermal camera and make a model. Aluminum or tin foil would probably work for something on the window. I've only done this upright, to simulate storing an unfuelled vehicle outdoors in "ready-to-launch" mode, but you'll run into similar problems with a horizonatal configuration. At first, the shade works. Then thermals develop. You can foam it, and that looks like it works for a few days. Then someone instruments the inside and, lo and behold, hot spots. Turns out foam doesn't really help with heat that recurs in the same place, day after day. (Our solution: slowly rotate it.) You could completely isolate the tube, which is what NASA does in its vehicle assembly building , but at that point you might as well (a) bury it or (b) have a fleet of Concordes flying on loop, because either will be cheaper.
I'm not saying it's impossible. But it's much harder than the pressure problem, which is itself hard to get economical. If you want the tube above ground, I don't think it works with existing materials. My criticism of the Hyperloop One project is they didn't bother solving these issues with models. (Note: this is how Elon did it with the Falcon 1.) Instead, they decided to build a maglev track.
I can see relative size, inside medium, building material differences, shading structures and acceptable tolerances all affecting the outcome one way or the other, but I'm not sure to what degree each one would affect the outcome, so I'm not sure if it's actually as hard as you make it sound or whether a solution is known and achievable.
Most hydrocarbon pipelines run HTHP: high temperature, high pressure. This keeps their contents viscous. That, in turn, means heat emanates relatively uniformly from inside the pipe. For pipelines subjected to asymmetric expansion (e.g. when starting up or shutting down), they "walk".
"Walking behaviour occurs as the pipeline is heated, and expands asymmetrically, until the point when pipeline expansion is fully mobilised. Expansion is ‘fully mobilised’ when a virtual anchor forms near the centre of the pipeline. The virtual anchor is then stationary, while pipe to each side expands away from the anchor as the temperature continues to rise. Once expansion is fully mobilised, walking ceases for that cycle."  As long as it walks laterally, pipeline owners tend to be fine with it
The solution to walking is typically laissez faire (taking care to ensure the deformation occurs laterally, i.e. side to side, versus sticking a butt up into the water.) Needless to say, this isn't an option for the Hyperloop.
Granted, the contents of these pipes operate at 130º to 170º C. They're also narrower, resist a smaller pressure differential, face fewer such asymmetric events and don't face the stress of capsules periodically whizzing past inside them. Our tube won't displace by meters. Its displacement, moreover, won't be problematic on day one. But over time it will critically weaken known materials. Big, dynamically mechanically stressed, close to vacuum and above ground is hard.
The heat will quickly conduct to the other side. It's one of the main reasons for choosing steel. Add white paint to that (or solar panels) and you'll have reduced heat absorption to a minimum.
I take it you haven't had the pleasure of watching carefully machined cylinders buckle in the Arizona sun :). White-painted aluminum and shaded, mind you.
Those were structures on the order of meters. These problems become nasty with scale.
What? Particles moving in through a hole against vacuum will usually be travelling at a distribution of speeds dependent on ambient temperature, usually a boltzmann distribution. It will not be a wall, but rather a gradient.
It's also not so much a maglev as an inductrack, which has only really become possible recently since it's come off-patent.
A proper answer merits CFD. Barring that, sure, one can adjust for the velocity distribution  and the fact that a vena contracta  will reduce initial flow rates.
I used 330 m/s, the speed at 0 °C (which is generous since these tracks will likely be operating in hotter conditions), which one will observe is around the molecular velocity of oxygen or nitrogen.
I'm willing to give this guy the benefit of the doubt considering his track record. It's also instructive to read the comments when the original Hyperloop idea was published. Even the people thinking Musk would fail were in the minority, because everyone was certain he had no plans of even trying.
No. Going back to the 1960s, re-usable two-stage configurations were being drafted .
I'm just not a member of the cult of Elon. I think he follows a path of aim impossibly high, be happy with getting pretty far. People instead take it as "he's literally going to do everything".
It reminds me way more of the nickelback is terrible thing. It's more of a meme than the actual subject. It's fun to feel like a member of the enlightened in-group that doesn't follow Elon Musk like sheep. All those dumb people that think GM will go bankrupt next year.
Solve the mass-scale construction and maintenance efficiency problem and we can get all kinds of cool things like hyperloops, space elevators, and fancy megacities.
The real issue is the viability of such a transport because of the cost, complexity, and construction effort involved. We (in the USA) can barely build a high-speed rail line effectively so a Hyperloop competing with existing transportation options doesn't make economic sense currently. Take a look at what happened to the Concorde program for a similar example of great technology that just couldn't survive as a commercial service.
EDIT: Yes, the engineering effort is not easy, but the science is pretty straightforward. We're not discovering new physics here...
Getting to Mars is a simple delta-v engineering problem. Nuclear fusion is a simple magnetic field engineering problem. Self driving cars are a simple programming problem.
Don't ever change, Hacker News.
Simple isn't the same as easy, but an evacuated train tunnel with air or magnetic tracks does not require new science. The physics are well understood and simple. The hard part is evolving the tech to be reliable and cheap so that people will use it and pay for it - but that doesn't seem to be within economic reach, and that's before factoring in construction and upkeep.
Reducing the amount of steel used in a bridge or a building is part of engineering. The Concorde wasn’t just a failure to understand what level of demand the world economy could support, it was that they didn’t solve the problems necessary to make it viable at scale. In that way it was not a complete product, it was a proof of concept.
Or, another example, it is not market dynamics alone that have changed the economics of what’s feasible with transistors. It is engineering that has made them viable at a massive scale.
For example, nuclear is a great power source and we can definitely invest much more but suddenly solar and wind have beaten the economic curve through constant evolution and are better candidates to explore today.
>evacuated train tunnel with air or magnetic tracks does not require new science. The hard part is evolving the tech to be reliable and cheap so that people will use it and pay for it - but that doesn't seem to be within economic reach, and that's before factoring in construction and upkeep.
You seem to be suggesting that a) we could have done this before because the tech has always been there. b) we can't do this now because the tech is not reliable or cheap.
I'm not sure how you can rectify these two arguments since this tech is more reliable and cheaper now than it ever has been.
We can build lots of fantastic things today but they would cost trillions so clearly are not a good idea. You also missed the ending about construction + maintenance, those will be the real costs and aren't likely to become radically cheaper.
Jetliners are complex machines but it's the entire infrastructure of airports and traffic control that actually make it possible, which is only viable because people choose to pay for it. Massive infrastructure does not build or take care of itself, and if it did, that would be a far bigger revolution than just building a train.
There is no high-speed rail line in the United States. The nearest thing to high-speed rail is the Acela Express, which hits 240kph on 40km of track. But this is weaksauce by modern standards.
But I'd say the problem of commuter rail is frequency, coverage station locations, acceleration, level boarding, dwell times etc etc. Given that line speed is dictated by acceleration and dwell times, top speed is really far down the list of priorities.
Also, top speed of commuter rail is already up to 200km/h (e.g. https://en.wikipedia.org/wiki/ALP-45DP).
The overall average speed is a paltry 50kph.
When the train is slower than the coach bus, why even have a train?
50km/h average is actually quite fast. I mean, a radius 50km from downtown is a huge area already. We have to densify inside that radius, not sprawl people further out because the trains are so fast. This means for example we need more stations, so that more developable land is within walking distance of service.
That's what lrt and subways are for, not the big commuter GO trains.
There's a meaningless separation of modes based on technology, and ascribing attributes to them. In Japan or Europe, the technologies are converging and so are the modes. Any infrastructure will have it's utilization maximized, and may function as what North Americans understand as 'commuter rail', subway' or 'light rail' all at the same time.
The result: more coverage, more service, better integration of services, more overall effectiveness, more ridership, less reliance on driving.
EDIT: from the UIC website:
"In any case, high speed is a combination of a lot of elements which constitute a whole "system": infrastructure (new lines designed for speeds above 250 km/h and in some cases, upgraded existing lines for speeds up to 200 or even 220 km/h),..."
We went to the moon. We send car sized rovers to Mars. We certainly can (in the technical sense) build a friggin' train. Its a political problem that keeps us from doing it. So its more like "we won't build high speed rail", and there are plenty of interesting reasons why this is so.
The point is that the mystical sounding Hyperloop might be just what the doctor ordered to shake up the political landscape and get something to budge because ooohh... futuristic! It might just be a brilliant end-run around the current political stalemate. At the most local level it has the potential to turn "nah, I don't want a train running through my back yard" to "oh wow, my community is part of the enlightened future of humanity!"
What exactly is the Hyperloop going for? Short trips are already served by buses, subways and light-rail. World-wide trips won't be feasible against air travel anytime soon, and will probably require the same security procedures as flying because of the speeds and risks involved, especially if crossing national borders.
So connecting major metros is the potential scenario but airlines have already proven that the vast majority want wifi and food so we can be productive and entertained in transit rather than paying a big premium to save a few hours.
Call me an optimist but it's high time for something new to shake things up. I don't care if it's a magic tube train or just some really nice selfdriving busses.
We already have plenty of cheap bus drivers though so I don't see what self-driving buses will do...
Hyperloop One is a maglev vactrain. It doesn't "fly" aerodynamically, like Musk's original plan. This means a more expensive track in the tube, but higher riding height. Musk's original plan required a ride height of 0.3mm to 1.3mm, which means a really smooth tube. Maglev clearances are typically 1-2 cm, which is much easier to maintain over many kilometers of tube. Also, only the track has to be flat; the tube can have seams and expansion joints, so it can be fabricated by standard piping techniques. Vehicles can draw power from the track; Musk's original design was battery powered. Maglev track is expensive, though. That's why maglevs are rare.
If somebody in Dubai has the money, there's no reason it shouldn't work. Japan already has 42km of maglev running, part of the Tokyo-Osaka maglev route under construction, with full-sized trains. That's mostly in tubular tunnels. Hyperloop One is easier than that.
Hyperloop One's test track uses a 3.4 meter tube, instead of Musk's original 2.4m tube. Maybe larger in the production version. Musk's very optimistic cost proposals are based on his undersized tube. Hyperloop One will work, but it may not be all that cheap.
Maybe we will not teleport in 2 seconds across the globe or this project will die, who knows if we don't try.
A little bit of optimism doesn't hurt. Just saying.
And for Virgin, it's not my money, if they want to invest in a black hole sure they can.
> For a Linux user, you can already build such a system yourself quite trivially by getting an FTP account, mounting it locally with curlftpfs, and then using SVN or CVS on the mounted filesystem. From Windows or Mac, this FTP account could be accessed through built-in software.
This sounds like such an insane proposition relative to the Dropbox we know today.
The top comment is being pedantic that it doesn’t technically replace a USB drive because you have to install software and have access to the Internet. Hilarious in retrospect.
If the biggest complaint someone can have is “you have to have Internet” you’re doing OK.
Does it? If you used WebDAV then you can mount a share in Windows or Linux even over the Internet, and windows at least is good at caching it while you're offline for short periods. For someone who has their own always-on Apache it seems like this would replicate most of the use cases for Dropbox. I think the point that's being missed is simply that most people would rather see a few ads or pay a small fee than administer their own Apache, not that what Dropbox offers is technically so far ahead.
I’m just guessing on numbers, but that probably describes <1% of the population. Most people think Apache is a word used only to describe helicopters.
I admit that it's just a guess, but it does seem likely.
Again, not a major point.
When VMware was first announced and demoed, the commenters at Slashdot declared things like it was fake, it was stupid, it was a waste, it would never work, or that dual booting was a better solution. They largely concluded that virtual machines weren't a thing and happily congratulated themselves for their brilliant insights.
I'm on a tablet or I'd dig the link out for you. It's one of my favorite discussion threads on the Internet.
Today's thread about Musk's "Hyperloop" is good fodder to bookmark and look back at in a decade. I have to wonder how many of the posters will admit they were wrong, should this reach fruition?
I dug the link out for another person who replied. You may want to take a look?
There was a database glitch that messed up usernames (I think that was after they'd added accounts, my memory isn't that good so I'm not certain) but it's still an amusing read. It really is a good example for a variety of discussions. It's my favorite example, actually.
A few people actually understood and made comments, and some had seen a recent demo. Some speculated about patents and one was happy to point out that they had a whole notebook full of ideas. Some seemed to think the software could do things it couldn't actually do, and certainly not at that stage.
One person even complained that it wouldn't work for him because if his old hardware. Others complained that it didn't meet their needs. Some even seemed unhappy that it wasn't available to run on their obscure OS. Of course, they couldn't use a more popular OS and then virtualized their obscure OS.
Also, there are comments to complain about the site management, people insulting other people, and comments that hadn't a damned thing to do with the subject at hand.
For so few comments, it's like they managed to hit every stereotype. It's absolutely my favorite reference thread and it works for so many conversations. I actually made it a point to finally bookmark it on my tablet as I've been using it more than a laptop lately.
So, to make it easier for you - I've grabbed a laptop and dug out the link:
I absolutely encourage anyone/everyone to read the linked comments. It's one of my favorite examples when a number of discussions come up.
My preferred time to reference it is when people say things like, "Slashdot used to be so much better!" Or when they say things like, "We had much better commentary back in the day!"
No, no they did not. In fact, it was never as good as people recall it being. That is kind of what makes it so wonderful and why I love discussion sites.
I am, by no means, innocent or superior. ;-)
"Hacker News hated Dropbox so..." Is a fun trope, but Dropbox still isn't profitable ;)
In seriousness I bet a lot of us go though the thought process that we want to give constructive criticism, since positive feedback isn't super actionable.
Feeling smarter than the rich people is always a good feeling too (and cheap, since we aren't even betting our own money )
I mean, let's apply your logic to its logical conclusion: we should never criticize anything, ever, on the off chance it could end up working and then people would look back on our comments and call us silly. On that note I'm just starting a gofundme to create my own interplanetary travel agency, don't forget to donate.
Yeah, HN was wrong about dropbox (although some of the criticism was a lot more specific and arguably accurate than some make it up to be). Now let's fetch the comment threads about color.com, about google plus, about the ubuntu phone, about whatever other failed product we've already long forgotten about.
If HN is wrong about hyperloop, so what? You'll be able to gloat about it in a few decades from your supersonic train seat. In the meantime there are real, practical questions that need answering and that's a much more interesting discussion than "wow this is so coool" or "I wonder what Elon Musk's armpits taste like".
Do you think that the Hyperloop One folks are going to read this thread and give up on the project? "Well, looks like we were wrong, shut down everything folks". I can get this argument for a small startup of one or two young entrepreneurs but for some reason I don't expect Virgin Group to be that insecure.
People are pointing out the glaring flaws in the Hyperloop idea, not because they can't or won't believe that crazy ideas are possible, but in reaction to the media's reaction to Elon Musk's PR. Surely I'm not the only one who wants to upchuck every time that Musk makes a claim and the media drools all over whatever he says. It even goes beyond the media itself but how the public reacts to how the media reports Musk. Otherwise smart people I've met have likened Musk to a modern day Edison, or even Tesla. Musk's companies have achieved great things, but he has more in common with Barnum than famous inventors.
Testing impossible ideas is wonderful. Musk's PR being inflated by the media, creating an audience of believer sycophants, is a different story and I really don't mind people blowing holes in the Hyperloop theory if the newsprint-spewing public isn't going to get that from technology reporters. I'd bet Hyperloop critics actually like the idea at one level or another, and hate to see such ideas looked at with pollyanna eyes.
Likening him to Barnum would perhaps paint him as a little more nefarious than Musk actually is, but I wouldn't consider that insulting. The man was a master promoter. But perhaps he's not a good analogue because their "products" are very different. People liken Musk to Edison, and they did both own technology companies that produced innovations, but that's where the similarity ends.
You might like the idea that it's some sort of reasoned rejection of Elon PR, but it's not. Just make a Show HN sometime.
Its like Elon going into trucking and people saying the range isn't sufficient. The guy is pretty darn smart. I'm confident he understands trucking range and has some solutions, and simply isn't discussing it for secrecy and/or succinctness.
There's a lot of in depth criticism of hyperloop based on Elon's 57 page paper. It is hardly a case of gut reactions to 400 word press releases.
However from what I have seen so far I am quite disappointed as even known issues aren't addressed at all. As if the people involved are blindly going at it instead of working with people who know something about pressure vessels etc.
Sure sometimes you need an outside perspective but not like this.
He has some other good videos (solar roadways) but tends to spend to much time bashing creationists.
Or it won't. Most companies fail, I expect most ideas do too.
> A little bit of optimism doesn't hurt. Just saying.
Yes and no. Optimism is worthwhile but realism is important too. It's cool that private companies are pursuing these ideas and I wish them all the best, but when I see people claiming that e.g. California's high speed rail is overpriced/pointless because of hyperloop then I want to scream. We shouldn't let our enthusiasm over these hyped ideas detract from implementing the more pedestrian approaches that are proven to work and address our very immediate needs.
Orwell mentions it in one of his lesser-known essays when discussing the problems with arguing about economics(1).
>"When the nautical screw was first invented, there was a controversy that lasted for years as to whether screw-steamers or paddle-steamers were better. The paddle-steamers, like all obsolete things, had their champions. Finally, however, a distinguished admiral tied a screw-steamer and a paddle-steamer of equal horsepower stern to stern and set their engines running. That settled the question once and for all. And it was something similar that happened on the fields of Norway and of Flanders [referencing economic questions]."
1 - www.orwell.ru/library/essays/lion/english/e_saw
One could feasibly live in Utah where land is cheaper, but still commute to California for work. This would both lead to a purpling of many red states, as well a providing a path for interior state natives to find good jobs in coastal city centers.
Knowing the status of American politics where highly populated coastal states are overpowered in the Senate by the seats of the near empty states in the interior, one can see that if the potential for hyperloops is realized, there will could very well be a massive shift of power back to the populace with more equally distributed representation.
I guess it would depend on how well they engineer the whole system, but who's going to watch over the hyperloop building companies to do that right?
Or, perhaps they'll spin a few technologies out of it.
Or, perhaps they want to grow a network of related companies+technologies that they can re-purpose to another venture in the future.
The bigger challenge, IMO, is economic. High speed trains make a lot of money, but their revenue has little to do with competing with airlines over significant distances between large cities, which is what the Hyperloop is attempting to supersede. The financial success of high speed trains has much more to do with their ability to rapidly start and stop in lots of intermediate urban areas within a corridor. I know this goes against the popular narrative about why high speed trains are popular (OMG they can compete with air travel!!!), but the narrative is wrong.
The revenue of HSR has a lot more to do with the number of cities that it services than the end to end speed. If you look at ticket revenues on successful HSR lines, terminus to terminus tickets typically make up <15% of total revenues. The rest is made up by the remaining cartesian set of city pairs. Even if you could add up all possible market share (trains, planes, cars) between terminus cities, it would still be less than the total revenue for that line, due to the additional cities it serves. Even with the gradual growth in power levels for high speed trains, with some now capable of 360kph, end to end speeds have basically gone unchanged. What has changed with more powerful trains? The lines have more stops now...they serve more cities, with the higher power levels used for faster acceleration and deceleration. More cities means more revenue, whereas higher speeds have already hit strongly diminished returns.
Maybe with Hyperloop being really fast could grow the market and monopolize market share between Alpha cities, but that would still be a stretch if the goal is economic viability. People see hyperloop, they crave its speed, but the costs are too high and revenues are too low to just serve the endpoints. But if you decide to serve intermediate cities, you slow it down, and it no longer becomes the object of technological lust, and nobody will want anything to do with it.
Among economic historians and really nerdy train enthusiasts like me, this isn't a contentious point. The same economic delusions were a primary causative factor in the overhyping of railways during railway mania, best exemplified in chapters 16-20 of Collective Hallucinations and Inefficient Markets: The British Railway Mania of the 1840s , which is a masterpiece of economic history IMO. Anybody in charge of building out some version of hyperloop should do themselves a favor and read it, and then work on not repeating history.