Remember the guy who wanted to build a monstrous rotor to use as an electrical storage device?

Here's someone whose idea is even stupider: he wants to build an evacuated tube from New York to Los Angeles, and to run passengers through it at 4000 mph, 6 at a time. What's wrong with it? Let me count the ways:

1. There's no way to keep a tube that long in vacuum. It cannot be done. There will be leaks, and even more important there will be outgassing. And even if there weren't, you'd have to mount a turbopump every 50 feet on that tube and it would take a month to pump it down. I used to work for a company that made vacuum chambers, and achieving hard vacuum and maintaining it is difficult. This system doesn't need to achieve the levels of vacuum we were aiming for (these chambers were intended for IC processing) but even maintaining a pressure of under 1 torr (which is probably still too much) is a pain.

What is "outgassing"? It means that normal materials, like steel pipe, have microscopic fractures and pores which absorb air, from which the air is slowly released when the chamber is evacuated. Our chambers had a volume of maybe three cubic feet, and it took something like 18 hours to reach operational vacuum using a cryopump, which wouldn't be practical for this application. Turbopumps aren't as efficient.

2. You'd actually need two tubes, not one, since multiple cars will be in transit at a time and it would be nice to be able to go both ways.

3. Here's the biggie: how much is it going to cost to build this thing, per mile? Acquiring a right-of-way would be horribly difficult and expensive, and even laying normal track costs millions of dollars per mile now. Track inside a sealed tube has got to be a lot more difficult. (Also, it's maglev track, not ordinary steel rail.) This tube concept is going to be titanically expensive. Where does the money come from?

4. Can it pay for itself? I cite the Chunnel. It was a tremendous technical achievement. It was financed by bonds, ostensibly to be paid back from use fees. But a few years ago it became blatantly obvious it was never going to generate enough revenue to pay back the bonds. So the French government and the British government got stuck with the expense.

Unless they charge $100 million for a ticket, the design as described cannot possible carry enough traffic to produce enough revenue to pay for the titanic expense of building it.

5. Security: Boy, oh boy, have you created a wonderful target for terrorism attacks! How in hell are you going to guard the entire length?

6. Safety: If, no matter how, the system develops a leak and begins to pressurize, what happens to the cars already in it, and the people they're carrying? How do you get them out safely?

What happens if a car stops running in the middle? Does the next car plow right into it?

7. How do you get passengers into a car and then put the car into the system? How do you take a car out of the system at the destination, and then get passengers back out of the car?

And all this for why? To shave 7 hours off the travel time from NYC to LA. Sorry, no. We have better things to do with our time and money.

Posted by: Steven Den Beste in Weird World at 06:59 PM | Comments (22) | Add Comment
Post contains 586 words, total size 3 kb.

1 The other issue: even if it's in a vacuum, accelerating up to 4000 mph is going to take a while and most people aren't going to be in the physical shape to handle that type of acceleration for very long.  The human body wasn't well designed to handle that type of speed relative to the inertial reference frame of the Earth. 

And slowing down would take a few States.

Posted by: sqa at July 16, 2013 07:16 PM (ehYGU)

2 A rough calculation puts the time for a sustained 1g lateral acceleration at slightly over 3 minutes.

Well, we have a whole bunch of trained astronauts with nothing to fly in, I'm sure they could use something to do.  That would be brutal on all but the most fit.  And the distance you'd cover would be pretty amazing.

Also, the kinetic energy at max speed, assuming a 5 ton "sled", would be 7.2 gigajoules.  Though not quite the explosive potential I was thinking it might be.  But it'd leave a nice crater.

Posted by: sqa at July 16, 2013 07:32 PM (ehYGU)

3 There's no way any passenger survives a catastrophic deceleration at those kinds of speeds.

Posted by: Steven Den Beste at July 16, 2013 07:38 PM (+rSRq)

4 While the idea is a silly one, that Elon Musk is involved does make it a touch less silly.  If the founder of SpaceX and Tesla Motors (and PayPal) wants to take a swing at something like this... well, I'd still bet against him, but the odds are a little shorter.

(It's all a Heinlein idea anyway, except his were on the Moon)

Posted by: Wonderduck at July 16, 2013 07:41 PM (NOm0f)

5

My first encounter with the idea was in "The City and the Stars" by Arthur C. Clarke.

As to tubes on the moon -- it's easier to maintain vacuum in a tube if it's surrounded by vacuum.

Posted by: Steven Den Beste at July 16, 2013 07:54 PM (+rSRq)

6

 While the idea is a silly one, that Elon Musk is involved does make it a touch less silly. If the founder of SpaceX and Tesla Motors (and PayPal) wants to take a swing at something like this... well, I'd still bet against him, but the odds are a little shorter.

There is a first time for everything.  I would not want to be part of the 'first time he was wrong was this' routine.

Mind you, this is just monumentally silly enough that the People's Republic of China might just try it, as well as admirers of the PRC, like some of the current administration.

Posted by: cxt217 at July 16, 2013 08:02 PM (J2n1x)

7 Well, Tesla is propped up by government loans and SpaceX, while brilliant, is still at the early stages.   So Elon is a "big ideas" guy, but his track record is really SpaceX.  So, he gets a pass to throw out an idea like that, even if it's pretty worthless.

There are limits to the human body and the speed at which it needs to travel.  To quote one of the best commercials ever: "But where are the flying cars?  I was promised flying cars!"   But we don't have flying cars because Light has no mass and electronic communications dominate everything.   Just as no Man is likely to ever run under a 9 second 100m dash, super sonic speed (or greater) passenger travel serves little purpose as the time/physical strain/energy output/cost output vectors make it impractical.   Concorde was pretty cool, and a complete waste of money.

Posted by: sqa at July 16, 2013 09:19 PM (ehYGU)

8 I suggest everyone just wait until the design is published. Since Elon twitted "not a vacuum tunnel btw", it's clear that Steven is going off half-cocked, prompted by content-less lies in the press.

Posted by: Pete Zaitcev at July 16, 2013 09:20 PM (RqRa5)

9 It appears that a straight line from LA to New York City passes through three fault lines, one reservoir, one large lake, one military base, about a dozen small airports, the southern edge of the Grand Canyon, the Pisgah Crater, and the town of Goofy Ridge, Illinois. That's from civic center to civic center, though, so moving the endpoints out to the suburbs would shift things around a bit.

My favorite part? Musk promises to release the technology as Open Source.

-j

Posted by: J Greely at July 16, 2013 10:46 PM (+cEg2)

10 The cynic in me would point out there isn't actually any money to be made from the design, so Open Sourcing it makes no difference.  It's all about being paid to build "it". 

But, yeah, I don't see how you're pulling that off.  I also didn't realize the California "high speed rail" project was still on.  Though I do love that no one has ever bothered to study the way other high speed rail systems ended up being built.

Note: the Japanese government had to absorb 270 Billion USD in debt when they privatized that system.  High speed rail is a bit like satellite communication systems: they're great when you can buy them out of bankruptcy.

Posted by: sqa at July 16, 2013 10:57 PM (ehYGU)

11 Isn't this pretty much just the Alameda-Weehawken Burrito Tunnel?

More seriously, these guys don't seem to have any actual connection to Musk, and we won't find out what the hyperloop actually is until August 12. There seems to be the idea floating about that it's a system where instead of being a vacuum tunnel, the air is moving at the speed of the vehicles in the tunnel. But who knows?

Posted by: renpytom at July 16, 2013 11:09 PM (mYsde)

12 A non-vacuum tunnel would make more "practical" sense.

Minus the hundreds of billions of dollars that would need to be spent to build the system, nor it's utter uselessness.  We already had the "Bridge to Nowhere", so I guess this would be the "Train to the End of the World"?

I'd rather spend that money on a space elevator.  You know, something useful.

Posted by: sqa at July 17, 2013 02:22 AM (ehYGU)

13 The other looming disaster not mentioned is, what if the car leaks?  The system will be closed forever the first time the train car disgorges its load of suffocated passengers at the end of the line.

Posted by: Mauser at July 17, 2013 02:32 AM (cZPoz)

14 The California Highspeed Rail is nothing more than unionized job farm.  It's neither highspeed nor anywhere near self sufficient.  So much so that the guy who actually wrote the initiative is suing the government to stop funding due to the violation of the rules he puts in.  And is it any wonder that Richard Bloom, husband of Diane Feinstein is getting the contract to build this thing?

Posted by: BigFire at July 17, 2013 04:11 AM (jSRcl)

15 Heinlein's tunnel in The Moon Is A Harsh Mistress was ballistic, underground, and on the Moon.  And not 3000 miles from endpoint to endpoint, obviously.  I'm sure digging out the endpoints of a ballistic trajectory on Earth would be...problematic.

Posted by: RickC at July 17, 2013 04:19 AM (WQ6Vb)

16 I'm pretty sure getting functional suborbital space planes to market would cost a tiny fraction of what even trying to build this would cost.

Posted by: metaphysician at July 17, 2013 05:26 AM (3GCAl)

17 I am pretty sure that getting a fully operational ballistic missile defense system covering the entirety of the US, Alaska, and Hawaii will cost a fraction of this idea, and that will be a lot more useful.  And apparently Chuck Schumer agrees with me on the latter point...now...

Posted by: cxt217 at July 17, 2013 06:36 PM (J2n1x)

18 You guys are thinking too small. For that kind of capital, robot catgirl maids could be a reality!

Posted by: Avatar_exADV at July 18, 2013 01:22 AM (GJQTS)

19 By Jove, you're right!  How can I invest?

Posted by: Mauser at July 18, 2013 03:11 AM (cZPoz)

20 If we got "robot catgirl maids", we wouldn't need quite a lot of mass transport anymore.  Just saying.

Posted by: sqa at July 18, 2013 03:28 AM (ehYGU)

21 For that much money, we could have flesh-and-blood catgirl maids.  With big breasts.  And naked aprons.  Genetic tinkering FTW!

Posted by: ubu at July 18, 2013 06:28 AM (GfCSm)

22 Alright, you idiots. Enough of this.

Posted by: Steven Den Beste at July 18, 2013 07:50 AM (+rSRq)

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