h a l f b a k e r yFaster than a stationary bullet.
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worm train
You know how a worm moves along? Well... | |
A worm moves along the ground by passing longitudinal compression waves through its body so that every part of its body is alternately stretched and compressed - e.g. it stretches out its 'neck' which is stationary while it bunches up the bit of its body just behind, and so on.
So, getting to
the point - A train which worked the same way would be miles long. Externally it would be covered in some kind of stretchy fabric. Internally, the walls would be made of grilles such as you see in old lifts (elevators), with seats fixed to the uprights. You'd board a 'compressed' bit of the train, take a seat, and the bit of the train you're on would then stretch out towards the next station (and here, the gap between your seat and your neigbour's seat would increase). A few more compression/extension cyces and you'd be at the next station.
This would work especially well on London's Circle Line (as its name suggests, a loop, 13 miles in circumference) which would be occupied by a circular train.
SRL's Inch-Worm
http://www.srl.org/shows/web98/img8.html
Not something you really want to ride... [rmutt, Jun 12 2001, last modified Oct 21 2004]
Robot snake
http://robby.caltec...hardware/snakey.gif
[hippo, Jun 12 2001, last modified Oct 04 2004]
Archived copy of above-linked robot snake image
https://web.archive...hardware/snakey.gif
It's a still image. Remember when most GIF files were still images? [notexactly, Nov 30 2019]
Commuter train de-crowder
by [8th of 7]. Mentioned in my anno. How I got here. [notexactly, Nov 30 2019]
Commuter train condensation
by me. The idea I thought this was going to be when I came here from the above-linked idea. [notexactly, Dec 02 2019]
[link]
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I'm not sure whether it would be
very comfortable in practice, but
it's a nifty idea. Not sure if
I'm misunderstanding this, but ... |
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hippo wrote: « and here, the gap
between your seat and you
neighbour's seat would increase » |
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Couldn't this cause practical
problems? What would happen if you
placed something on the floor
while the train was in its
expanded state? |
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Also, why would the train have to
be miles long? Surely it would
work just as effectively if they
were only slightly longer than
normal trains, but with a greater
number of compression waves to
travel a given distance. (The
frequency would be correspondingly
higher.) |
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impractical + fun = one croissant! |
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this would only work if everyone was strapped to the floor/walls etc. |
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what sort of height would the upward 'lurch' reach? I can just see all these afternoon commuters boarding the worm train, strapping in and going on reading their newspapers, swinging and lurching onto the next station without even looking up. i also think worms are require lubrication/stickyness to do their thing. perhaps a custard worm train? |
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//what sort of height would the upward 'lurch' reach?//
That would be an 'inching' worm train. If applied correctly that would reduce stairclimbing. |
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[waugsqueke] Absolutely right.
[benfrost] There's no upward lurch - the train moves forward through compression waves, not uppy-downy waves (technical term).
[cp] The floor would require some thought. I envisage having it made out of overlapping steel plates.
[Mephista] What's IHS? |
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I think the key here would be a solid train car with a wormlike exoskeleton. You could take a regular subway car and surround it with some large external rings that move back and forth on pneumatic pistons and voila you're worming your way to work. |
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[borivan] Good thinking, but I'd prefer the occupants of the train to be able to see the worming motion from inside the train which they wouldn't be able to do if this was an exoskeleton built on top of existing subway cars. Also (in London) there's sometimes only a couple of inches clearance between the subway cars and the tunnel walls so the exoskeleton solution would be difficult to make work on existing subway networks. |
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OK no exoskeleton. If you want to experience the motion of the worm you could ake individual compartments that hold 2 to 4 people. each compartment could have it's own door and a light on the outside of the worm to indicate weatehr or not it was occupied. it'd be just like private cabins on commercial trains only each cabin would be separate. that way you could avoid joints in the middle of a "train Car" and still experience the worm motion. |
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...and poop dirt out of the back too? |
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To control lurching just have the Worm Train do it's compression-expansion in a reasonably smooth, controlled manner--no more lurch than a nice smooth elevator, for instance. Fantastic idea, hippo. |
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Nobody has asked how the thing is powered. What mechanism causes the lurch, and how? Are we talking about a system of pistons, with a network of synchronized electric motors on each piston, compressing and decompressing according to a programmed pattern? Or what? |
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How to power it? Well surely we have to take the 'hovertrain' as our example, and use a magnetic linear motor. All you would need to do is to time the current into the static magnets below the train, as per the hovertrain (originally prototyped in UK, but working in japan) this effectively sends a wave of energy down the track. The current train rides on top of the wave (or in reality just in front - it sort of surfs on the magentic repulsive force, which due to timing is angle forwards instead of straight up (which is why the train moves forward rather than just hovers. speed is obviously controlled by the angle of the force to the track), but see no reason why this wave couldn't be converted to a 'wave' inside the train. Would give exactly the kind of smooth avcceleration and deceleration that you need to stop the jarring. |
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waugsqueke: I imagine the acceleration and deceleration phases of each lurch could be tuned so that {accelerate at .5 g for 1 minute}-{coast for 3 minutes}-{decelerate at .5 g for 1 minute} would result in one speed and {accelerate at .5 g for 2 minutes}-{coast for 10 minutes}-{decelerate at .5 g for 2 minutes} in a faster speed. It would depend on if you were taking the local or the express worm. |
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SciFi's Chi-Chan (I think that's the name) has a society where they use actual worms (really big ones, obviously) as a form of transportation. And for the record, the scientific technical term in "transverse." |
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Have the trains accordion-folded, and use pistons attached at every other fold to drive it. |
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No matter what you made the floor
out of, you would have problems
with one of two things: |
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(a) people could lose their stuff
between the plates; or
(b) things could be crushed at the
plates compress. |
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I think that the best way around
this would be to do what Borivan
suggested. |
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benfrost: You're right, you would
need to have some form of
stickyness on the front bit when
it was in a compression cycle and
the at the back during an
expansion cycle. You might be
able to do this using magnets like
goff suggested. |
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There are articulated buses with a big rotating join in the middle. In theory people and objects can get crushed by this joint when the bus turns a corner, but in practice the bus is designed so that's unlikely. (There's still a sign saying "don't put stuff here! or stand here!" in the corner though.) |
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There should also be an indication on the train's door that that segment is about to start its lurch, so that you know not to get on right then. |
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[borivan] I'm still not convinced by the compartment idea. I was thinking that if the whole train was one big space than (on straight bits of track) you'd be able to look far down the train and see the compression wave heading towards you. Also the element of danger as the floor rearranged itself would be nice.
[Rods Tiger] Good idea - although probably impractical :-)
The burrowing idea though does highlight why this method of locomotion is so appropriate to subway (rather than surface) trains.
[Mephista] Thanks for the lucky charm. Alas, some swine has fishboned the worm train... |
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Oh yes - something else I forgot about: The possibility of making new friends during the compression part of the cycle... |
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I'll try and get into the garden this weekend and watch some worms - The 'compressed' bits of worms may just be fatter than the 'stretched' bits which would make sense in soil as they would then grip the soil better which would enable the worm to stretch forward.
Variable-diameter worm-action subway trains would be a nice variation on this idea. |
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Worms do, in fact, compress and decompress their internal structures as they move. You can see them doing this with the naked eye if you have a well-constructed worm box. The movement is integrated with their digestive process, I believe, which is of course fore-to-aft. |
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The "stickiness" everyone keeps referring to is primarily provided by very stiff hairs set at an angle. They are a bit hard to see in most worms. |
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If you live in an area that has nightcrawlers (good fishing bait!) you can go outside in early summer late at night with a flashlight and very soft-soled shoes... the worms will come to the surface to (hermaphroditically) copulate, but they are very sensitive to ground vibrations so you have to sneak up on 'em. Grab one, and you will be astonished at how hard it pulls back towards its hole. Capture one, and let it move through your hands, and you can feel the hairs pricking your skin as it drags itself about. |
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The digger that created the
Channel tunnel worked on this
principal. The forward portion
would extend arms to provide
gription while it pulled the
rear portion forward. The rear
portion would then press
against the sides of the tunnel
to provide leverage to push the
rock crunching forward portion
forward. |
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Of course it was quite slow,
but then it could only go as
fast as it could clear its own
path. Given an existing
tunnel, I believe this is bakable! |
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I like it! It would have its own track I assume. And it would just extend 'till it reached the next station, then contract? It would, of course, probably never work, but it would be cool! [+] |
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Hang on! Has anyone seen "Core"? Put a laser-dirt-annihilator-beam on the train and you could tunnel like a freaky mechanical worm in the dirt! Also, the cartoon show "Avatar: The Last Airbender" has a machine like this. It's massive and it has little legs on the sides that retract and extend toward the ground. The thing has wheels on the bottom and when it extends, the legs go to the ground. The legs move in ripples, so the back legs stay down to hold the back of the machine while the front of the machine goes forward. Aaaaaaaa-nyway, I give this a [+]. |
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This isn't the idea I was thinking it would be when I came here from
[8th]'s idea for stationary trains that serve as walking paths [link]. I'll
have a look to see if somebody's posted the idea I thought this would
be, and, if not, post it myself. |
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{Edit: I didn't find it already posted, so I posted it [link].} |
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// {accelerate at .5 g for 2 minutes}-{coast for 10 minutes}-
{decelerate at .5 g for 2 minutes} // |
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If you accelerate from a standstill at 0.5 g (4.9 m/s^2) for 2 minutes,
you will be traveling at 588 m/s, or 2117 km/h. If this inverse-peristaltic train can go that fast,
it will probably quickly take over the
high-speed train market from maglev. |
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