h a l f b a k e r yRecalculations place it at 0.4999.
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So you know those casters embedded in the ground and
in loading
vehicles at airports, that help move containers from say,
a loading
vehicle into the airplane's belly?
Imagine 3,000 miles of those casters, underground,
shuttling shipping
containers from one end of the US to the next (New
York
City to SF).
Two lanes, one for east to west, the other going west to
east,
connecting the coasts' ports. Further lanes going from
the midwest
(St. Louis, Missouri?) to northern (Chicago?) and southern
ports
(Jacksonville, FL and/or New Orleans?), with regional
hubs along the
line.
Why? Efficiency, Ecology, Economy. The whole thing,
apart from
manning the stations for loading/unloading the
containers, could be
fully automated.
And before you say "having rolling casters running full tilt
24/7, across
the continental US, is gonna be hella expensive,
electricity-wise!", I
say: The casters don't have to be rolling non-stop, and
could
incorporate some kind of fly-wheel energy-saving tech to
avoid huge
power bills :)
might share tunnels and bridges with this corridor
Real_20Corridor_20across_20the_20States
[swimswim, Nov 10 2011]
Old variant on this Idea
http://en.wikipedia...The_Roads_Must_Roll
Suppose long-distance roads were basically conveyor belts.... [Vernon, Nov 11 2011]
This exemplifies most math and engineering tutorials.
http://www.funz.eu/...-To-Draw-An-Owl.jpg
[Voice, Nov 18 2011]
[link]
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Too late! I'd already said "having rolling casters
running full tilt 24/7, across the continental US, is
gonna be hella expensive, electricity-wise!"
before I
hit the last paragraph. |
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Some time ago (around the 1750's, I believe), we
started developing something called the "canal".
I'll
have a Google and see if it ever took off. |
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But, how rude of me! Welcome to the HB. |
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Ah, hang on. Welcome to posting on the HB. |
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If you put the castors on the bottom of the containers, you could make them run on smooth strips of metal with low friction. Best make them quite big castors, then you only have small points of contact capable of supporting a lot of load. |
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Maybe you could link the containers together, with a single mobile power unit at the front ? That would reduce maintainance requirements. |
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Perhaps you could find a catchy name for it, like maybe "train" ? |
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//Maybe you could link the containers together, with a single mobile power unit at the front// |
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Yes,but it wouldn't have the same majesty on film...imagines the HD footage shot from helicopter...David Attenborough voice-over "...and here we see the last of the migrating shipping containers heading towards the west...and a pack of coyotes with can openers are circling the one with all the dog food in it.." |
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I see the snark runs deep, here. :P |
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As my friend(s) and colleague(s) the Borg have pointed out,
this is utterly baked in railroad form. It's called intermodal
shipping, and would help with many of our current
economic and environmental issues if the fucking
teamsters lobby would kindly step the hell out of the way. |
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Compared with rail, casters would require the same grading. At the same time they'd be using less metal overall in construction; picture a mass-produced caster unit staggered every 10 feet, instead of 2x10 foot lengths of rail. |
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Slater, ignore 21 IQ. That he equates quantity of HB posts with job success shows you how much that comment is worth. Nice weather in DC today, isn't it? |
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// the snark runs deep // |
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Not necessarily - it might be a Boojum ... |
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Hmm.... let's look at installation |
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Mile-by-mile: caster
- rough grading, say to 4 feet.
- sinking 528 cement pylons 8 ft down
- capping each pylon with an aluminium/steel caster. |
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Mile-by-mile: rail
- fine grading, filling with gravel 8-10 feet wide
- railway ties: 2,640 of them
- 2 miles of rail, welded |
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Caster system is cheaper and less intrusive to the environment. [+] |
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Somehow I doubt that. With casters you have only the momentum of the containers, which is continuously sapped by caster wheels which need to be spun up to speed, ie. energy drain. |
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Alterother: With my idea (and almost end-to-end automation), you don't have to deal with evil teamsters any more! |
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Flyingtoaster: So you're for my genius idea? Not quite sure what the 528 cement pylons are for, tho :( |
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21 Quest: Quality over quantity, of course. |
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RayfordSteele: Maybe this needs casters with built-in flywheels or something? |
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//528// 5,280 feet/mile, 40 foot container which must be balanced on (at least) 3 points at any given time = a caster every 10 feet (one on the left side then, 10 feet further on, one on the right side, etc.). |
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//energy drain//
The figure to beat is the rolling resistance of a normal pair of train trucks(the wheels assembly). |
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Hmm... thousands of pounds rolling on 8 huge metal wheels vs. inertia of millions of stopped smaller wheels with bearing losses. Could be an interesting comparison. |
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// The figure to beat is the rolling resistance of a normal
pair of train trucks(the wheels assembly). // |
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Which is incredibly low. An entire 1,200 -1,600 lb.
assembly
on level track can be moved with the slightest nudge, and
easily rolled along by hand. The issue I see here (aside
from the teamsters, who, despite what you may think, will
fight (and usually defeat) anything that poses a threat to
long-haul trucking) is that smaller wheels = more wheels =
more friction and more parts that need replacing. I know
I've pointed this out before, but freight cars are built out
of big beefy chunks of steel because they must withstand
tremendous wear and tear, elemental extremes, incidental
damage, etc. |
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These things are called shipping containers because when you want to go from one coast to another, you put them on a ship. |
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Well yes, when the coasts are on two different
continents. |
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[bigs], look out of your window. |
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You see that crouwd of people with flaming torches and scythes and pitchforks ? And the noose ? |
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They've come for YOU. And you have only yourself to blame. You knew what you were saying, you knew it was very very bad and wrong, and now you're going to pay the price. |
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Oooh, look, a Wicker Man ... excellent. |
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"Perhaps if we built a Giant Wooden Badger ... " |
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Can anyone smell elderberries ... ? |
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Building on what everyone said, I'm looking at this with symmetry in mind. Surely everything will have to be as big/robust/frictionless etc. as the components of existing trains - I mean, it would be ludicrous to put little airport-style casters on the bottom of train carriages and locomotives, and run the trains on the bottoms of upturned shipping containers, so the inverse of that would also be ludicrous - except for short distances at low speeds. |
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So I imagine something more like inverted railway bogeys emplaced at intervals of about 20 feet (either opposite each other, or staggered a la [FlyingToaster]) on the ground, and each shipping container mounted on a sled-like chassis incorporating a length of upside-down rail on either side. |
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This "upside-down railway" version may be conservative, but it's modelled on the only system (short of radical departures such as canals and mag-lev) that has been proven to be effective and efficient. |
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The advantage of having the running gear on the cars is
that they can be brought to a shop for m&r, whereas a
'track' made of inverted bogies would require field repair.
Also, with intermodal cars, the containers can be stacked
double, meaning twice the shipping volume per length of
train. |
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Bun for upside down trains |
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No, and to quote a great hero of mine, I can imagine a lot. |
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I don't think I have ever noticed built in casters at
airports. Googling did not help me. Big tubs of
luggage have casters on the bottom. If someone can
link a picture of the in-ground ones I would like to
see it. |
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Luggage casters would be absurd unless you were shipping luggage... in which case they're still not that good. I think we've defined 'casters' topically as wheels set in the ground. |
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When I think caster I think of a caster wheel on
the bottom of a cart or dolly that might be
pushed in any direction. A caster wheel has a
vertical stem that allows the axis of rotation to
turn 360 degrees. Do the ones set in the ground
still do that? |
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hmm. maybe that is my problem with finding
these online - I used caster as a term. I bet the
airport ones do not rotate their axis because if
fixed in a track that would be counterproductive.
Those are not caster wheels, but have some other
name. |
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Look up "skate wheel conveyor". That's pretty much what this is on a large scale. |
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Because I didn't feel like selecting one of the thousands of sources for the same thing. |
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Suppose instead you elevate the casters with hot air
balloons... I bet this would cost less than tunnels and
would get the same results. |
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Bonus: you can have elevators and places for the
containers to roll downhill. This will let you provide
energy at fewer places. |
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Hot-air balloons aren't dangerous enough. Better use
hydrogen. |
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Given the average friction of the rail I wonder how
high you would have to go for a relatively steady
pace for 3,000 miles |
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EDIT: I'm stuck at 1.3wn + 29n because I have no idea
what those numbers represent. Also I hate it when
they break out greek letters without explaining them
in a tutorial. It's like that 2 step "how to draw an owl" |
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Show your work and we can answer, I'd guess weight and normal force for w and n respectively, but you shouldn't have both in an equation once you've gotten that far along. |
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This one's easy, [voice]. |
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Minimum height = rolling resistance coefficient * horizontal distance
= 0.0002*3000 to 0.001*3000
= 0.6 to 30 miles |
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Rolling resistance coefficients from Wikipedia, "Railroad steel wheel on steel rail". |
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Extra height will be needed for air resistance, but that depends heavily on speed and aerodynamics. |
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// average friction of the rail // |
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Rail friction is relatively unimportant; what matters is the friction of the bearing. |
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If the frictional coefficient is 1 then energy loss depends solely on bearing losses in the axle. |
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If it's zero, you might as well use a skid. But that means "wet ice on wet ice" which has as near zero a slip coefficent as is practicably achievable. |
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What matters is rolling resistance. Surely wheel-track interaction contributes, not just bearing resistance. Obviously, the importance of each depends on the condition of the track, wheel, and bearing, and the number of cats on the track. |
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re rail vs bearing: if the substrate is frictionless
then you will not roll forward. But if the part of
the wheel does not move relative to the substrate
(which for a wheel would be skidding) are there
frictional losses? 8th maybe that is why you say
rail friction is unimportant. |
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How does maglev work? Captive magnets instead
of captive rollers? I like the nonmoving parts
aspects of that. But probably you would have to
make the carts long to spread the weight over
many magnets. |
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