36 thoughts on “Hyperloop”

  1. The last route seems good. I would rather have an high-speed rail line though. Something about traveling inside a vacuum sealed tube with no windows. I’m not claustrophobic, but still…

    1. The interior of the capsules would have to be very carefully designed to minimize the sense of confinement. The longest of the proposed routes has a journey time of 42 minutes so it would probably need to have some entertainment options (music or DVD players, or could you get a TV signal through to the capsule?) to keep the passengers distracted. It would also be important to have a progress display to assure the occupants that they were actually moving.

    2. That girl I sat beside was awful cute
      And after while she was holdin’ hands with me
      My heart was flyin’ up like a Falcon 9
      Down like a recovered booster
      Back like a Hy-per–loop
      And around like a merry-go-round
      We ate and ate at a hot dog stand
      We danced around to a rockin’ band
      And when I could, I gave that girl a hug
      In the tunnel of love

    3. Here here. Being sealed in a giant tylenol doesn’t appeal to me. Watching the country go by at 200 mph would be great.

  2. To me it would be about like riding an airliner except for the lack of windows — and the lack of a long fall to the ground if something goes wrong.

    Which raises the question: will TSA be a part of the experience?

    1. Being ejected from you seat to make way for a Hyperloop employee shall be part of the experience.

    2. Image what would happen if someone detonated a bomb inside one of those capsules moving at 600mph. Messy.

      1. Wouldn’t have to be much of a bomb either. High-speed pressure wave in an enclosed space, even if it didn’t rupture the capsule…

        On the bright side, Servpro would just need to pressure-wash the interior and catch the runoff in tank cars for the pathologists to strain for evidence.

  3. Hyperloop makes more sense to me as a fast package shipping service than as a passenger service. The vehicles and tubes can be smaller, accelerations higher, and safety is less of an issue. Use it to connect FedEx hubs, for example.

      1. Does that mean this will be another AMTRAK for Uncle Joe Biden to play with, and the taxpayers pay?

    1. Interesting…perhaps freight and passenger lines?

      I would prefer a tube and car size that allowed me to drive my vehicle onboard, have it moved at hyperloop speeds and drop me off to drive around town. For an hour or two trip, I’d even be willing to stay in my vehicle.

  4. There’s also a question of what security measures would be required around the tube. Terrorist groups might get the idea that blowing up the tube – or simply knocking it out of alignment – while a capsule was passing through would cause a spectacular crash. They might think that the damage would be hard to repair, and that damaging public confidence in a very expensive new transportation system might do a lot of economic harm for very little effort.

    Equally, the government security bureaucracy might just assume that the terrorists would think that, and start demanding exclusion zones and costly security measures for a certain distance around the tube.This could really drive up the cost of construction by increasing the width of the land required along the whole route.

  5. Rand,
    It doesn’t look like most of these were done with ROI or need in mind. More like ‘Hey this would be cool’. Especially ones proposed by Universities, like the Seattle, WA to Eugene, OR route. LA to San Diego makes sense. Boston to DC would make sense but there wasn’t one.
    Personally I’d like one from my house to downtown Seattle right next to my office. Save me an hour plus on commute each way.

  6. The thing that leapt out at me on the two routes I’m most familiar with; LA to SD and Portland to Seattle: why in the world wouldn’t you continue them to the border, and through it if possible? LA to Tijuana might have issues, but that extra bit from Seattle to Vancouver would probably do more to make the line viable than the rest of it. Portland to Vancouver in less than an hour?

  7. I believe Hyperloop has made some grave technical assumptions and errors that render the system profoundly infeasible.

    Specifically, I think the evacuated tube idea is an error. As an alternative, fill the tube with hydrogen at standard temperature and pressure. Several things happen when this is done:

    1: The drag drops by a factor of fifteen with respect to air at standard temperature and pressure. Yes, functional vacuum has lower drag still, but seriously, is it enough lower to compensate for the hassle of maintaining an evacuated tube?

    2: Mach effects are comfortably remote – the speed of sound rises by a factor of nearly four. Travel at what would be Mach 0.95 in air becomes travel at about Mach 0.25. That’s comfortably in the incompressible flow range.

    3: The passenger cars become substantially simpler – they don’t even have to be pressurized in a structurally significant way, just reasonably airtight with a CO2 scrubber and other climate controls. You might pressurize the car to a tenth of a psi over the tube pressure, and the tube by a similar amount over the atmosphere, but that’s not a significant structural burden.

    4: Note that the tube may now be constructed from acrylic or polycarbonate or something appealingly transparent, since it isn’t structurally loaded in the same way any more.

    5: I would recommend driving the passenger cars by external means, and using an onboard magnetic levitation system. There are ways to do this simply in two axes with permanent magnets. But this could be traded around. Steel rails aren’t out of the question as long as there’s a reasonable contactless power connection by an inductive mechanism.

    6: The above observation moots most of the complicated hardware on Hyperloop’s passenger cars.

    7: It’s technically possible to generate the power with onboard air for the passengers and a fuel cell reacting with the hydrogen working fluid, dripping the water exhaust into a catch basin on the car as you go along, I suppose. I think that is all a little too cute for the room in my opinion and would require a supply of makeup hydrogen on a per trip basis rather than to compensate for the inevitable leakage.

    8: I am astonished at myself for advocating a transportation technology that requires hydrogen. This would of course work nearly as well with helium, but I don’t think there is that much helium on the planet.

    9: I am mindful of the hazards of hydrogen, of course. I will point out that the Hindenburg mishap in 1937 had 36 fatalities and 62 survivors. Most of the fatalities were *crew* – who stayed at their posts helping the passengers escape, and in an era where that was not a key portion of the job description for cabin attendants. Also, of course, the fatalities were from falling and burning diesel or fabric. The hydrogen all went upwards and no one was harmed by it.

    10: A minute in vacuum will kill you faster than a minute in 1 atm, 70 F hydrogen.

    Okay, is there anything fundamentally unsound about this idea, apart from calling it HydroLoop?

    1. If the hyperloop is intended to operate at low but not very low pressure, then water vapor could do. The vapor pressure of water at 7C is about 10 millibars. The speed of sound in water vapor is also higher than in air, although not as high as in hydrogen.

    2. Yes, functional vacuum has lower drag still, but seriously, is it enough lower to compensate for the hassle of maintaining an evacuated tube?

      Compared to the hassle of maintaining a tube filled with hydrogen, a notoriously leaky and flammable gas? My take is that they’re similar in difficulty.

      2: Mach effects are comfortably remote – the speed of sound rises by a factor of nearly four. Travel at what would be Mach 0.95 in air becomes travel at about Mach 0.25. That’s comfortably in the incompressible flow range.

      At low pressure, Mach effects are remote for a different reason.

      Points 3 and 4 are quite compelling. There is a much lower structural requirement for near equal pressure than for maintaining vacuum. I think though that the tube would have to be larger for the hydrogen version which means not just structure costs, but also where the vehicle can fit. Hyperloop can have a tube barely larger than the vehicle. But you would need some space for hydrogen to pass around the vehicle else you’re either using more energy to push hydrogen behind the vehicle and/or a substantial pressure wave in front of the vehicle.

      Another issue is that vacuum is more hazardous than near atmospheric hydrogen when it comes to a large rupture. There is a considerable amount of instantly realizable potential energy in a tube of vacuum while with hydrogen, you still have to light it and it’ll only burn when exposed to oxygen or other extreme oxidizer.

    3. Interesting- hydrogen at 1/15th density would create far less drag then air at 10 km altitude with 1/3 density, and with no transonic drag rise. A hyperloop doesn’t really need zero drag, just low drag, and 5x lower than an airliner is pretty damn good. With magnetic levitation having L/D far above 100:1, the energy cost for H2loop travel would probably be 1/10th that of an airliner.

      With a transparent tube to view would be both exhilerating and terrifying.

      The greatest problem is just that it’s just a big juicy target for terrorism. Nuts.

  8. I can’t believe that no one has cut through the hype with a little arithmetic. The idea that this could occupy a road right of way ends when you calculate the acceleration in a common 1300′ radius curve: more than 800 g’s. Changes in grade are even a bigger problem, requiring either massive cuts and fills or tunnels.

    When I first noticed this in the 60’s, the assumption was that the routes would be through deep tunnels. This would solve the alignment and right of way problems in theory. We’ve since learned how hard tunneling even short distances can be.

    Even assuming a route could be acquired, maintaining the alignment of the tubes while the ground shifts minutely would probably require some sort of active system. Just bedding it in concrete wouldn’t begin to keep the passengers teeth whole.

    1. I believe you may have confused g with ft/sec^2, and hence left yourself incorrect by a factor of 32.174. 1020 ft/s (roughly 700 mph) at a 1300 foot radius is an unrealistic 800 ft/s^2 or 25 g. But not 800 g.

      I also should point out that the newer TGV lines in France have 7 km radius, which is roughly 23,000 ft.

      All of this, of course, is a challenge for *any* high speed rail system, conventional, maglev, hyperloop, or whatever.

      1. Realized that I got the dimension wrong as I went to sleep.

        I still can’t see how this isn’t all of the mundane problems of high speed rail with a whole pile of unique ones thrown in. Right of way maintenance cost is the main determinant of operating speed on railroads.

        The cars are levitated in a vacuum, enclosed in a pipe, where does all the heat go?

        How big of a leak before the cars look as if they hit a concrete wall at cruising speed?

        Money and time could probably solve them but this is supposed to be somehow easier and cheaper than conventional rail.

  9. I think Elon watched Starship Troopers too many times (is he old enough to have seen earth 2, was it?)

    His alternate plan is a big cannon and a net.

  10. Everyone is getting excited about the speed of this, but I’ve yet to see any realistic way of getting people on/off easily, the word ‘airlock’ is muttered. Is that in line or sidings (in which case how will ‘points’ work?) or only end-of-the-line? Also, there’s need to be a separation distance between trains to allow for emergency stop, and at the speed talked that’s a big distance, so maybe only one train per tube at any time!

    I think there’s a reason Elon make this idea ‘public domain’ as it’s very difficult/expensive to do and I believe distract a lot of money/engineers who could possibly compete with his other ventures.

  11. Somewhere I saw that thermal expansion/contraction of the tube would shift the endpoints by something like a kilometer over the distance of the SF/LA route. Handwaving about vacuum-tight flexible couplings ensued. Maybe I’ll be proven wrong, but I continue to think this whole idea is silly.

      1. Continuous-welded rails are pre-stressed and constrained in ways that would be difficult for a vacuum-tight pressure container. If it’s even possible, it would certainly be expensive.

Comments are closed.