I don't think we're obligated to take Hyperloop seriously until there is a large-scale demonstration system up and running. On the other hand, I don't think we can fully discount it as long as so many people (with funding!) are actively working on it.
Right. In addition to that, I was simply going to write "make it not fail". In the plane example, what the author doesn't mention is that there are many mechanical failures, or human errors on a plane that lead to, well, death of 100% of its passengers. Yet we still fly.
So in this respect I see the Hyperloop as being very similar to air travel: make it not fail.
Weather creates a whole mess with tons of missed connections and cancelled flights that can take up a a couple days to sort out. This means that air travel in entire states grinds to a halt a couple of times each year.
Fair enough, but in the meantime passengers are not trapped aboard airplanes (which are considerably more comfortable than hyperloop pods). On a few rare occasions passengers have been trapped on airplanes for several hours. This was considered unacceptable and led to major changes in policy.
Passengers still get trapped for hours on airplanes sitting on tarmacs. I feel like there's a couple of stories about that per year, and that's just what gets reported in the media.
(But this is another good point: a failed hyperloop also won't have A/C. That will be a potentially life-threatening problem in Dubai, where the first hyperloop is likely to be built. Summer temperatures there regularly reach 45C.)
So first, commercial aircraft typically start their engines immediately upon leaving the gate. An extended period of time without A/C is extremely rare, and nowadays regulations require A/C for any tarmac delay over an hour.
Second, the reason you can't have A/C in a failed hyperloop is that there's nowhere to discharge the heat. As long as the pods are moving you can discharge heat into the tube (because it's not a hard vacuum) but as soon as they stop you can't do that any more.
Discharging heat is a good point. I imagine you could probably design the pods such that if they break down, they could extend radiators to contact the hyperloop wall in order to discharge heat that way.
Though actually this raises another question in my mind. How do spacecraft handle heat? Or is the problem with spacecraft keeping them warm enough, rather than dealing with excess heat?
Spacecraft use radiators to radiate excess heat into space. Depending on how close they are to the sun they can have both heating and cooling problems simultaneously. The side facing the sun can get too hot and the side away from the sun can get too cold. Thermal management of spacecraft is an engineering discipline unto itself. (I used to work for NASA.)
Radiating heat to the tube won't work because the tube is either above ground, in which case it's likely to be much hotter than ambient if the sun is up, or underground, in which case you've effectively wrapped the tube in a nice insulating blanket of dirt, and again there is no place for the heat to go.
I mean, you could build an active cooling system for the tube, and start it up whenever you have a broken-down pod radiating heat into the tube, though that seems like a lot of effort / complexity.
Maybe the focus should be on how to get people out of a broken-down pod within a reasonable period of time rather than cooling said broken-down pod. Unfortunately I don't have any ideas on this front.
I kinda can't imagine them not having something comparable to the safety mechanisms in the Chunnel...
Basic repairs, emergencies, etc can't require a full service stop across the line. There are solutions used in similar situations that are baseline operational requirements.
I'm skeptical whether Hyperloop as described in Musk's original paper is practical. On the other hand, I think it's possible that some variant which is clearly Hyperloop-inspired might actually be feasible.
You can probably make the case that we're already in Hyperloop-inspired territory, since as far as I can tell everyone working on Hyperloop has dispensed with air-bearings and moved to maglev for levitation.
Yes, but it's still in an evacuated metal tube. That's a severe constraint.
BTW, going to maglev completely blows the original economic model out of the water. The whole point of the original hyperloop was that the track was going to be cheap because it was just a welded metal tube. Now it's a welded metal tube with a maglev track inside. That's no longer cheap. In fact, it's a reinvention of maglev in a way that makes it even more expensive. If maglev wasn't economically viable before you put it in a tube (and it wasn't) it won't be economically viable after.
I don't see any reason why using maglev means the track has to be anything clever. There are methods where the vehicle contains the only active part, and the track can simply be a metal strip, such as servo-levitation (varying the strength of an electromagnet on board the vehicle with feedback), induced current levitation, or by using a rotating set of fixed magnets.
I must confess I'm not up on the details of maglev technology (which is why it's not central to my argument). I have to wonder, though, if maglev is so cheap and easy why hasn't it been deployed more already?
While the cost of passive maglev track isn't huge, conventional rail networks which you'd be competing with already exist, so typically would only be justifiable for new networks. Safety is another large concern; it's easy to make a fail-deadly maglev train. While maglev trains are the fastest, safety keeps them an emerging technology.
The fundamental problem is that the hyperloop track is a cascading single point of failure.
So, pretty much like highway-speed transit on highways. One breakdown, and huge stretches of highway slow to a crawl or to a halt. The same goes for the US air travel system, except it takes the weather disruption of a major hub to get the cascading failures.
on a highway, if you get stuck in traffic moving 0 km/h or your vehicle's energy/propulsion system fails utterly, there is no risk of suffocating to death.
Economically, to make it profitable, then I am not certain it can work in the United States.
The Hyperloop is running in a vacuum tube.
* We have the ability to evacuate air from a tube, to low air pressure levels.
* We have the ability to build space craft that can operate in a vacuum.
* We have the ability to build a maglev, to propel the pod.
* We have the ability to build nuclear power plants, to energize the maglevs. I don't think solar or wind will create enough electricity to meet production usage demands.
Given all that, it's now starting to sound like an economical non-starter.
The United States just doesn't have enough people to make this work economically. It sounds cheaper to just go with a maglev. And you can get up to 300 to 400 mph if you push it. This is almost comparable to an airplane, but more comfortable. And the volume of people you transport can be a lot higher.
And all the Hyperloop plans are regional. One for Houston. One for Chicago. One for Virginia. This means that each location is fiscally responsible for themselves. But for some locations, then there is not enough people to economically sustain it. A national system may work, as it will allow some lines to be profitable, and this will balance out the lines that are not profitable. So the entire national system may eke out an operating profit.
And then, there is all the land rights that you have to buy up. Just look at how expensive the California high speed rail project is costing.
And all the tunneling and bridging that must be done.
And the designs only show two tracks running in parallel, but I think they actually need 3 tracks, in the event one track breaks down. This adds to the costs, but I don't see anyone suggesting this, or even thinking about it.
And they need to design contingencies in the event something breaks down. Americans do not like new technology things that kill people. One disaster may kill the entire project.
And, what about the science of the sonic boom, as the pod crosses the sound barrier. Given this is propelled through a vacuum tube, at lower air pressure levels, then will a sonic boom be generated?
All of this is now starting to sound really expensive. All this research is going to cost a lot of money. No company can really afford that, except maybe Apple. The US government is not interested in footing the R&D bill.
Then again, I could be completely wrong. And once again, Elon pulls a rabbit out of a hat, and comes to the rescue.
Yeah, the hyperloop paper that claimed low costs did so by a combination of sheer fantasy and not actually going anywhere near the city centers it was serving, and making the cost of transit connections to the city centers out of scope.
Of course , a lot of the cost of high speed rail is the urban part of the route necessary to actual serve the population centers it's supposed to connect.
Actually, as has been pointed out many times around the internet, the vaccuum problem is not as simple as described.
The biggest problem I've seen is that of thermal stabilisation to prevent metal expansion and contraction. That makes tubes in open air a particularly infeasible proposition without masses of insulation. Bridges are already difficult enough as it is, without things traveling over 1000km/h
Or, to directly address this:
* We have the ability to evacuate air from a tube, to low air pressure levels.
We can evacuate tubes, but they tend not to be very long. About the only very long tubes we have evacuated are CERN and it's predecessors, and I think they got around the issue by building it underground.
- the low pressure required is the equivalent of flying below 50km altitude, which is still far from space or a full vacuum. LEO is > 160km
- pod designs are using passive maglev, with all energy input going into moving the car. Even if that wasn't the case, Maglev actually uses a comparable amount of energy to standard trains, and becomes more efficient at very high speeds, so no nuclear plants required
- one of the benefits of tunnelling is precisely avoiding the need to buy expensive land rights. The Boring company was setup with the sole goal of reducing tunnelling costs by 10x
>- one of the benefits of tunnelling is precisely avoiding the need to buy expensive land rights. The Boring company was setup with the sole goal of reducing tunnelling costs by 10x
Yes, but - right now - there is no hint about how exactly those costs will be reduced, last time I checked they bought an used TBM, talked about here:
If we would always think about “what could go wrong” and decide whether to go forward based on that we still wouldn’t use fire today.... in order to make something safe we need to make it work first. No guts, no glory.
45 comments
[ 4.3 ms ] story [ 79.0 ms ] threadSo in this respect I see the Hyperloop as being very similar to air travel: make it not fail.
That's true, but there are very few failures that lead the entire system to grind to a halt.
https://www.nolo.com/legal-encyclopedia/tarmac-delays-airlin...
Even back in the day when it did happen, it was because of policy, not physical constraints.
Airplanes are not comfortable at all, and no hyperloop pods actually exist - that statement makes no sense.
(But this is another good point: a failed hyperloop also won't have A/C. That will be a potentially life-threatening problem in Dubai, where the first hyperloop is likely to be built. Summer temperatures there regularly reach 45C.)
Why can't a failed hyperloop have A/C?
So first, commercial aircraft typically start their engines immediately upon leaving the gate. An extended period of time without A/C is extremely rare, and nowadays regulations require A/C for any tarmac delay over an hour.
Second, the reason you can't have A/C in a failed hyperloop is that there's nowhere to discharge the heat. As long as the pods are moving you can discharge heat into the tube (because it's not a hard vacuum) but as soon as they stop you can't do that any more.
Though actually this raises another question in my mind. How do spacecraft handle heat? Or is the problem with spacecraft keeping them warm enough, rather than dealing with excess heat?
Radiating heat to the tube won't work because the tube is either above ground, in which case it's likely to be much hotter than ambient if the sun is up, or underground, in which case you've effectively wrapped the tube in a nice insulating blanket of dirt, and again there is no place for the heat to go.
Maybe the focus should be on how to get people out of a broken-down pod within a reasonable period of time rather than cooling said broken-down pod. Unfortunately I don't have any ideas on this front.
Basic repairs, emergencies, etc can't require a full service stop across the line. There are solutions used in similar situations that are baseline operational requirements.
You can probably make the case that we're already in Hyperloop-inspired territory, since as far as I can tell everyone working on Hyperloop has dispensed with air-bearings and moved to maglev for levitation.
BTW, going to maglev completely blows the original economic model out of the water. The whole point of the original hyperloop was that the track was going to be cheap because it was just a welded metal tube. Now it's a welded metal tube with a maglev track inside. That's no longer cheap. In fact, it's a reinvention of maglev in a way that makes it even more expensive. If maglev wasn't economically viable before you put it in a tube (and it wasn't) it won't be economically viable after.
I think it is telling that the best analysis of this issue that anyone has been able to find in this thread has been in a reddit comment.
So, pretty much like highway-speed transit on highways. One breakdown, and huge stretches of highway slow to a crawl or to a halt. The same goes for the US air travel system, except it takes the weather disruption of a major hub to get the cascading failures.
Economically, to make it profitable, then I am not certain it can work in the United States.
The Hyperloop is running in a vacuum tube.
* We have the ability to evacuate air from a tube, to low air pressure levels.
* We have the ability to build space craft that can operate in a vacuum.
* We have the ability to build a maglev, to propel the pod.
* We have the ability to build nuclear power plants, to energize the maglevs. I don't think solar or wind will create enough electricity to meet production usage demands.
Given all that, it's now starting to sound like an economical non-starter.
The United States just doesn't have enough people to make this work economically. It sounds cheaper to just go with a maglev. And you can get up to 300 to 400 mph if you push it. This is almost comparable to an airplane, but more comfortable. And the volume of people you transport can be a lot higher.
And all the Hyperloop plans are regional. One for Houston. One for Chicago. One for Virginia. This means that each location is fiscally responsible for themselves. But for some locations, then there is not enough people to economically sustain it. A national system may work, as it will allow some lines to be profitable, and this will balance out the lines that are not profitable. So the entire national system may eke out an operating profit.
And then, there is all the land rights that you have to buy up. Just look at how expensive the California high speed rail project is costing.
And all the tunneling and bridging that must be done.
And the designs only show two tracks running in parallel, but I think they actually need 3 tracks, in the event one track breaks down. This adds to the costs, but I don't see anyone suggesting this, or even thinking about it.
And they need to design contingencies in the event something breaks down. Americans do not like new technology things that kill people. One disaster may kill the entire project.
And, what about the science of the sonic boom, as the pod crosses the sound barrier. Given this is propelled through a vacuum tube, at lower air pressure levels, then will a sonic boom be generated?
All of this is now starting to sound really expensive. All this research is going to cost a lot of money. No company can really afford that, except maybe Apple. The US government is not interested in footing the R&D bill.
Then again, I could be completely wrong. And once again, Elon pulls a rabbit out of a hat, and comes to the rescue.
All the things you listed amount to 10x less costs than the bullet trains. You can have a look at hyperloop costs.
Yeah, the hyperloop paper that claimed low costs did so by a combination of sheer fantasy and not actually going anywhere near the city centers it was serving, and making the cost of transit connections to the city centers out of scope.
Of course , a lot of the cost of high speed rail is the urban part of the route necessary to actual serve the population centers it's supposed to connect.
That would mean maglev costs less than bullet trains themselves to build?
The biggest problem I've seen is that of thermal stabilisation to prevent metal expansion and contraction. That makes tubes in open air a particularly infeasible proposition without masses of insulation. Bridges are already difficult enough as it is, without things traveling over 1000km/h
Or, to directly address this:
* We have the ability to evacuate air from a tube, to low air pressure levels.
We can evacuate tubes, but they tend not to be very long. About the only very long tubes we have evacuated are CERN and it's predecessors, and I think they got around the issue by building it underground.
- the low pressure required is the equivalent of flying below 50km altitude, which is still far from space or a full vacuum. LEO is > 160km
- pod designs are using passive maglev, with all energy input going into moving the car. Even if that wasn't the case, Maglev actually uses a comparable amount of energy to standard trains, and becomes more efficient at very high speeds, so no nuclear plants required
- one of the benefits of tunnelling is precisely avoiding the need to buy expensive land rights. The Boring company was setup with the sole goal of reducing tunnelling costs by 10x
- it will not cross the speed of sound
Yes, but - right now - there is no hint about how exactly those costs will be reduced, last time I checked they bought an used TBM, talked about here:
https://news.ycombinator.com/item?id=15002501