Isn't that the case with planes also? As far as I know, at 35,000 feet altitude you'd die, too, if cabin pressure drops and the plane's life support system fails. And I don't recall ever hearing of an air plane accident that involved suffocation.
Amazing that there are so many safeguards in place to prevent what happened to HCY 522, and yet the crew managed to miss/ignore them all. I'm sure there have been many thousands of instances where a safeguard prevented such an incident, but in this case I suppose the fates aligned.
Also look at the TUC (time of useful consciousness) that it´s below 5 secs when flying that high. That means that you have less than 5 secs to put your oxigen mask on before you lose conciousness, or behave with out knowing what is happening.
Also due to the extreme low pressure, you´ll have a horrible a horrible stomach ache due to the expansion of the gases inside you. Your blood (or at least the corporal fluids exposed directly to the low pressure) will start boiling.
Not funny. Maybe one solution could be wearing some kind of pressure suit for this trips. But that is not going to be very convinient..
At or above the Armstrong limit, exposed bodily liquids
such as saliva, tears, and the liquids wetting the alveoli
within the lungs — but not vascular blood (blood within the
circulatory system) — will boil away without a pressure suit
As mentioned above, we have been boarding planes without pressure suits for decades, and the hyperloop has two security advantages: it has a large supply of compressed air to work with, and the tunnel can be quickly re-pressurized in the event of a severe rupture. A multitude of concurrent failures (much less likely than those in an airplane) would be necessary for a catastrophe.
You got to think that a decompression will happen. Something traveling that fast inside a tube is probable to develope vibrations and material fatigue if something is not working properly (like the compressor or a air cushion), also there can be small parts released from the front pod impacting on the next one.
It doesn´t need to be a huge crash, just a crack on the hull, it will decompress that small pod in seconds.
Also what will happen when of tens of pods traveling that fast, find that there is a sudden recompression of the tube? How fast are they going to stop due to the front overpressure (the compressor is relatively low powered)?. Is not going to be a gentle stop either.
I still think that it´s a great idea, and that there will be ways of solving those problems, but it´s going to be difficult and require lots of R&D.
Obvious engineering issues for further investigation. I would just point out that fatal failure mechanisms can be pointed out in any transportation system. The acceptance criterion is a sufficiently low fatality rate.
The great thing about the hyperloop, and other vactrain systems, is that you're at sea level... you're just not in atmosphere. The atmosphere can be restored in seconds. Sure, it'll stop the entire system and be a TOTAL pain in the arse because you'll have to restore the vacuum, but that's acceptable as long as it doesn't happen often.
The paper discusses supplemental oxygen and emergency tube re-pressurization in the case of sudden evacuation of the atmosphere of a capsule.
It seems that detecting failures of this nature quickly would be the important thing. The fix looks to be relatively easy, though you would cause a major disruption to the whole Loop.
You're pretty much done if the life support systems on a plane fail and you're pretty much done if your car has a massive failure while you're doing 70MPH. I can't imagine it being statistically more dangerous than driving.
Driving seems to get a special exemption in the public consciousness. Trains and planes are already much, much safer than driving, but they're still required to add additional redundant safety features, and there's still outcry when one crashes.
Except that planes have (supposedly) trained staff that can go around and make sure everyone is getting oxygen. These pods are automated and would most likely have no staff on board.
There is in fact a proposed passenger plus vehicle capsule:
The passenger plus vehicle version of the Hyperloop will depart as often as the passenger only version, but will accommodate 3 vehicles in addition to the passengers. [p12]
The passenger plus vehicle version of the Hyperloop capsule has an increased frontal area of 43 ft2 (4.0 m2
), not including any propulsion or suspension components. This accounts for enough width to fit a vehicle as large as the Tesla Model X. [p15]
Tubes would be bigger, and the system would cost more.
Most flights I've been on in the last decade, you don't want to leave your seat for anything except a bathroom break. It's not like we're flying on Pan Am Clippers with pianos and seven course meals. Air travel is a glorified cattle car unless you're willing to be financially raped for first class or a chartered jet.
I think one advantage of air travel is it's distracting. Busy flight attendants, announcements from pilots, plane moving to the runway, taking off... so there's less reason to concentrate on the lack of space while stuck in the seat.
Are you? I wouldn't rule it out, but personally I think getting an outside signal into a sealed capsule which is moving so rapidly that it must use battery power rather than a physically connected power source seems more than trivial.
The hop between two major cities where I live (~800km apart) takes around 50 minutes on a plane. For 15 minutes you can't get up, and for the remainder low altitudes keep the seatbelt sign on due to turbulence.
For the advantage of a short journey people will put up with it, especially if it can get you to the centre of the city rather than an airport on the outskirts.
I'd rather be stuck in my seat for 35 minutes than to travel to an airport, go through security, check-in, waiting and boarding, fly for 90 minutes and then apply all the logistics in the other end. Your point is valid, but I would contend that the total package is still superior.
That cost is the infrastructure cost, amortized over a long time, not counting R&D, maintenance, marketing, ticketing, and various personnel costs, assuming it's near capacity.
Also consider this is bus-tier people moving, not even train. You just have small individual units moving along one track. With even passenger rail, you have to have set departure times measured in at least 10 minute blocks, something like this could have a departing train every 5 minutes and you could go through a turnstable the same way you get on a subway.
Really? As a European I don't find the backseats of most American cars cramped at all.
Plus, with a car you'd have a 7-8 hour journey to look into.
And with an (equally cramped if not worse) plane you'll have more traval time than in this scheme, if you include waiting to depart, the lengthy procedures at the airport and getting to the airport in the first place.
Well, there's a low grade vacuum outside so you probably don't want to.
It's a failure of the onboard steam tanks that scares me. ("The steam is stored onboard until reaching the station. Water and steam tanks are changed automatically at each stop")
I don't want to think about what the result of that would look like for the cleanup crew. Eeeewww.
I really doubt the steam tank will be inside the pressurised volume. If they fail they would vent overboard. While an explosive failure would probably cause problems it wouldn't expose the passengers to high pressure steam.
The failure mode for composite overwrap pressure vessels is a slow leak, due to the overwrap containing the metal.
A vehicle near the end of its ride will be carrying up to 818 kg (1800 lb) of superheated steam (127 C, 260 F). The 4000 kg (8,900 lb) of onboard batteries and 1800 kg compressor will be dumping heat too. This is 6600 kg of "hot stuff", whereas the entire capsule is projected to have a mass of 15000 kg.
The current design has the passengers in an enclosed capsule in between the compressors and the batteries, with a pressurized air channel running right down the center isle.
Keeping the cabin cool will be a challenge. If that emergency braking is activated, it could get a little warm in there before they are rescued.
I think they may have to quickly repressurize the loop if a car ever gets stuck.
Sure - but that is happening dozens of feet away inside a can designed to contain it. This extremely high temperature and pressure air will be flowing right under your butt. Serious question, Is any kind of breakthrough in insulation needed?
Well, if the can fails you're toast either way. :-)
The pressure ratio for the compressors in the CFM56 engines in current model 737-800 models is 32.8:1, so somewhere in the neighborhood of 400-500 psi (will depend a lot on altitude).
Seriously, we've been building machinery to operate safely in this pressure and temperature range for a long time.
Yes, and it involves a lot of the considerations we're bringing up here.
Engines do fail on passenger jetliners from time to time. There are numerous stories of planes landing safely after an engine catches fire. But the plane is travelling at a good speed through the atmosphere. How would things be different in a much smaller vehicle sitting stationary in a mild vacuum?
How would passengers escape a battery fire? (as has been seen multiple times on very modern jets)
If the tube had to be repressurized in an emergency, how long would the tube be out of service to be pumped back down again?
Is it worth building a three tube system for such a possibility?
The same thing that happens when you develop gastric issues on a 30-minute helicopter tour, as the minister in a wedding ceremony, or in a dentist's chair.
Sure, unless that bathroom is occupied by someone who had gastric issues before you did :).
The meta point: If you can't plan around a 30-minute window of no bathroom access, that biological restriction is a bigger concern than arriving at your destination quickly.
Same thing that happens if you develop unexpected gastric issues during a 30 minute plane flight, I'd imagine, since you'd spend the whole time strapped in for take-off and then landing.
Well the pod has compressor - so it literally can hit the fan :)
The only thing I really dislike so far is the battery pack in the pod. I would have wanted to see something more elegant instead. And this way we halve the weight of the pod.
For the lack of space between the tube and the carrier, is wireless electrical transfer out of the question? Or is that not feasible with the amount of electricity being dealt with here?
Wireless power transfer would likely significantly complicate the design and construction of the tube itself, which as it stands can be just a dumb hollow cylinder on a stick for the vast majority of its length.
Perhaps the redundant vacuum pumps are spaced frequently enough that the power transfer problem would be easy, but I doubt it.
sbashyal pointed out in another thread that you can't use the restroom on a commercial airline during take-off or landing either, which I thought was a great point.
Fast trains are just fast trains. Inside there isn’t much special about them compared to slower ones, except that they are usually more comfortable (softer and adjustable seats, definitely wider, at least in first class, better and more tables, more storage space for luggage, electrical outlets, sometimes crappy WiFi, a crappy restaurant, relatively roomy bathrooms that don’t even look that bad). Also, they actually tend to run much more quietly and rumble less than slower trains, so getting up and walking around is usually never a problem, except maybe when the train is driving into and out of a station and over many switches. At least that’s my experience in Germany, but the TGV isn’t so different (maybe a bit better in some ways).
The problem with the images of the Hyperloop interior is that it looks very much unlike anything you currently find in trains. It looks more like the inside of a race car – with a belt and all – and it doesn’t look like you are supposed to get up and walk around. It doesn’t seem as though there is enough space for that. Maybe that’s just some designer having an unnecessary flight of fancy (but that doesn’t exactly inspire confidence in the design if it’s that badly though out), maybe that’s an inherent downside of the design. Either way, not good.
In general, most of those things vary massively between classes of trains, and there's no simple low-speed/high-speed distinction. Seat width varies massively between body shell designs, softness often depends on how long since the last refurbishment more than anything else, number of tables and luggage space are often based on the target market for the class, electrical outlets are more and more common (even on commuter trains), WiFi is something I'd expect on most inter-city trains, and on-train restaurants (sadly) are dying out though have historically been common on all inter-city trains.
Smoothness is mostly due to track quality, and is a practical result of design for high-speed running.
At least in Germany WiFi sucks and is not available everywhere – and even if it is you have to be lucky and actually be in a train that supports it. In general seats are most definitely more comfortable in longer distance trains. Yeah, you can find a seat that’s less comfortable in a long distance train than in a regional train, sure, but that’s hardly the point, is it?!
And electrical outlets are getting more common, sure, but the vast majority of German regional trains does not have them and you can only be certain that there will one in a high speed train.
You said it may differ elsewhere — I was providing a more general view of what I would expect in Europe.
WiFi varies a lot from country to country — some places you're lucky to get it on any train, others it's becoming coming common on even regional trains; seats on a lot of the older ICE2 sets were really quite terrible prior to their recent refurbishment, and a lot of IC trains in Germany had far better seats; electrical outlets differ from place to place — the TGV Duplex will never have power outlets at all seats, for example, despite being a high speed train, as there simply isn't sufficient power spare to provide them, and as another example in the UK it depends far more on rolling stock age (or refurbishment date) than whether it's a long-distance train or not.
Currently you get up and go to the bathroom at the end of the car.
I've only had time to skim the full PDF, but there's something about experiencing 0.5g of acceleration - unsure if that is a constant or if that is simply right at the very beginning.
If you're going to experience 0.5g of acceleration over a prolonged period, letting passengers get up and move about is going to be a bad idea. It also doesn't look like there's enough roof to get about in that capsule. 0.5g doesn't sound like a lot until you think about it as 50% of your body weight tacked on, in a direction you're not used to having it tacked on. Pretty simple in a seat, much less simple trying to walk.
Assuming it's very smooth acceleration, it's just like standing on a 26º slope, feeling slightly heavier than normal. Healthy individuals should have no problem at all in such a situation.
> unsure if that is a constant or if that is simply right at the very beginning.
If the top speed is 700mph then you'd have 142 seconds of 0.5 g acceleration to get to top speed. How often you'd be accelerating or decelerating would depend on how many intermediate stations there are.
Otherwise very, very cool.