

I Think the Hyperloop is a Maglev Tube Train - dylanhassinger
http://dylanized.com/the-hyperloop/

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snogglethorpe
Some of the points seem a bit silly.

\+ For instance saying it "has no tracks" but then ... it's in a tube. This
seems to be nitpicking, as the tube is effectively a track. The question of
whether something uses a track or not is mainly of interest because things
that don't use tracks have more flexibility, and can go off-route. Something
that requires a fixed guideway (like a tube) is for all intents and purposes,
on a track.

\+ _Most importantly, the tubes would considerably safer than traditional high
speed rail, since debris or other obstacles couldn’t get in and block the
vehicles._

Er, is "debris and obstacles" an actual safety problem on existing HSR lines?
Oh wait, Shinkansen: perfect safety record over 50+ years of very intense
operation.

It's pretty clear that _grade separation_ , and some effort to avoid
trespassers, are important, but these things are of course standard practice.
Putting everything in a tunnel would appear to at best offer a minimal safety
improvement, at great additional cost.

\+ Similarly, the vague hand-wavy discussion saying that the tubes would be
"cheap and easy to construct" seem a bit specious. Either precision is
required or not (and at 500+mph, one had better get this right!), and the form
of a tube doesn't seem to make much difference compared to other maglev
technologies, e.g. the "U-channel" being used by the JR maglev (one of the
notable attributes of the JR tech is that it has a very large gap size, and so
is less susceptible to precision issues, as compared to e.g. the transrapid
tech).

So if you take existing JR maglev tech, and ... add a roof, is it actually any
different than the vague "tube" notion this article talks about?

Maybe Musk does have some truly transformative idea, but certainly nothing in
this article is that.

[I think Musk's coyness about this is pretty annoying... if he really has a
great idea, and intends to make it public, why not just _say it_ instead of
making flirty glances and beating around the bush?]

~~~
veidr
_> I think Musk's coyness about this is pretty annoying... if he really has a
great idea, and intends to make it public, why not just say it instead of
making flirty glances and beating around the bush?_

I agree, and it reminds me of nothing so much as the protracted and
anticlimactic unveiling of the Segway.

A tech-world-famous entrepreneur coyly keeping mum about some radical new
technology that is supposed to CHANGE THE FREAKIN' WORLD, MAN--and then it
turns out to be a revolution in keeping airport security guards from having to
walk so much.

I'd love to see it be everything Musk promises (just like I'd love to order a
personal cold fusion generator from Amazon), but such lofty claims need
substantial evidence to have any credibility.

~~~
joelrunyon
To be fair, he's mentioned it as an idea and I believe in the interview, he
said he wanted to check with his engineers to make sure it could be possible.

He's not hyping up the next product as much as he's musing about the notes &
ideas written down in his journal when people ask him bluntly "what else are
you working on?"

And to be fair, Musk's track record on creating things that are going to
CHANGE THE FREAKIN' WORLD, MAN is pretty dang good (paypal, tesla, spacex as
if I have to even name them).

~~~
waterlesscloud
The feeling I get, and it's just a feeling, is that it's an idea where the
hype is sort of getting away from him.

I wonder if he even took it all that seriously at first, he may not have
realized he's made the transition to Man Whose Words Are Given Great
Attention.

He seems like he's starting to realize that, but only now...

~~~
snogglethorpe
Musk: "oh crap!" ><

<http://xkcd.com/799/>

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jmcguckin
Constant starting and stopping would be a performance and efficiency issue. A
better way would be to have local trains that ran on parallel tracks and
sync'd speed with the main train and passengers and cargo would be xfered to
the local train - alternately, traffic could be segregated into seperate cars
by destination and then cars would be spliced back and forth between the local
and main train.

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sbierwagen
It'd have to be a vented tube, or else you'd be spending most of your power
shoving air through the tubes.

The per-kilometre cost is going to be astronomical.

I don't think one of the problems of maglev is stopping distance: that's
mostly constrained by how many G's you want to subject your passengers to.

~~~
astrodust
It might be possible to build a tube system with a blowback mechanism so that
the displaced air can be temporarily pushed aside without wasting too much
energy.

Most long train tunnels have a secondary tunnel that acts as a buffer for this
sort of thing.

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mapt
First, let me say I think that estimates of _cost savings_ over the
European/Japan figures are ridiculous for anything at the ground level that
moves a lot faster than state-of-the-art maglev or HSR.

A closed tunnel doesn't buy you much.

Mostly-evacuated tube, or at the very least some type of sealed hydraulic
(which is problematic) is the obvious plausible idea to achieve supersonic
speeds. The problem is structural engineering of a very large negative-
pressure-sealed structure in which a fault anywhere could destroy the whole
thing. It would need complex airlocks, which would make each station
enormously expensive as well.

I would note, however, one of my ideas that may have some synchronicity: that
the speed of sound in a gas rises rapidly as the molecule gets less massive,
and the drag force drops as the gas becomes less dense. Simultaneously, if
hydrogen cars are going to get off the ground they need a distribution
pipeline system. A train that traveled in a tube of hydrogen could effectively
bypass the 'air' speed of sound and move at at least mach 3 before reaching
the H2-transonic range. Sealing STP hydrogen in a container can be done an
order of magnitude easier than sealing vacuum or highly pressurized gas.

The "tracks", of course, would be some form of maglev. Ideally, an
'Inductrack' design, which have not been seen in use yet but offer substantial
advantages. On the other hand, given the progess on high-temperature
superconductor manufacturing, perhaps those advantages are shrinking.

On Googling, it would appear that I'm not the only one to have this notion:
[http://www.supersonictubevehicle.com/docs/STV%20--%20Denizli...](http://www.supersonictubevehicle.com/docs/STV%20--%20Denizli%20%281%20Jul%2010%29.pdf)

I don't understand attempting to use a propeller-based primer mover, however.
A linear induction motor with variable coil spacing, on a multiple unit train,
should function just fine for this type of use.

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tzs
> I started thinking it was some type of high-altitude blimp network, surfing
> low-earth orbit and dragging capsules with commuters inside

I'd like to hear more about that idea.

