Posted on 06/15/2012 1:04:06 PM PDT by Mark Landsbaum
If the high-speed train we call the Moonbeam Express will cost anywhere from $68 billion to $117 billion, we wonder how much this one would cost:
“Engineers in the U.S. and elsewhere are working on the technology for trains that could shoot through airless tunnels at speeds up to 4,000 miles per hour, the BBC reports. The transporters, which remain at least a decade away, could eventually cut travel time between New York and Beijing to about two hours,” according to the New York Daily News.
Actually, at only a decade away, it’s closer than the one floundering today in California. Please, please don’t tell Gov. Jerry Brown. . .
(Excerpt) Read more at orangepunch.ocregister.com ...
Vacuum trains! That would suck (duck’n & runn’n).
In pure theory, the trains wouldn’t even need power.
Just bore the tunnels as the crow flies through the earth, and gravity would do the rest.
In practice you’d be boring through all kinds of easily shifting material. I’d hate to be down there and have an earthquake happen.
Seen this before.
http://en.wikipedia.org/wiki/Genesis_II_(film)
“An elaborate “Subshuttle” subterranean rapid transit system was constructed during the 1970s, due to the vulnerability of air transportation to attack. The Subshuttles utilized a magnetic levitation rail system. They operated inside vactrain tunnels and ran at hundreds of miles per hour. The tunnel network was comprehensive enough to cover the entire globe.”
This just isn't true. If you bored through the earth, assuming it was possible, which it isn't, the train would fall under its own power but as it came closer to the center of the earth the slower it would fall, when it reached the center of the earth gravity would hold it there. Everything would be up from the center and as the speed at which the train fell would gradually slow to almost nothing before it even got to the center, it would never get past the center without some type of power input.
yup....NY to LA via gravity ....in theory, it would take as much time as any other 2 points on earth....NY to Bejing would take the same time, if you didnt roast in the core first....
If such a system were practical, than why not start with freight/packages/mail?
Prove it will work before we try to stuff people through it.
The only thing real about the Vacuum trains would be their ability vacuum more tax dollars from the taxpayers. The enviro-nut crowd would see to that.
Actually, if there was no air (or other) resistance in the tunnel, it would accelerate until it reached the center of the earth, and continue on its’ path, decelerating all the way back to the surface (or at least station level) on the other side.
However, zero resistance is a practical impossibility, but it WOULD rise from the center back up towards the surface.
The RATE of acceleration would drop as the vehicle went deeper, and would technically be a zero acceleration at the core, but the intrinsic velocity would remain, and thus deceleration would start as soon as it passed the center mark. . .
Gotta disagree with that one. The behavior would be like that of a pendulum. Given that practically there would always be some kind of friction, an additional boost would be needed to be sure the train got all the way to the other end. But no it wouldn’t stop in the middle any more than a pendulum does.
“yup....NY to LA via gravity”
This idea was developed in the early 1970’s by a RAND scientist:
Were going to build a tunnel from NY to China in ten years? And tunnels all over the planet?
I'd guess this would take hundreds of years.
Too funny!
Didn’t one of the characters on Soap have this idea? Trains that work like the drive-thru bank tubes, I seem to recall even Chester thought it was a stupid idea.
You cannot fall up,simple as that.
You can “RUSH” up, however. That train would really be moving by virtue of the gravity which had acted upon it as it went down. And in an ideal frictionless environment, the energy it would have by moving in the middle would be just enough to get it back up to the top at the other end.
You don’t know squat about the physics, pal.
No thanks. I don't need the world to get that small.
I don't care if there is economic justification for this plan. Just HELL no.
Let me give you an even more obvious example: a roller coaster with a “suicide” drop. It comes down a straight away, hits a U-shaped bottom, and goes back up another straight away. If this lacked friction, yes the coaster would “fall up” all the way to its original level from the bottom. Even with friction it would go back up a goodly ways without additional help from motors. This is not like plopping straight down into a pit and smacking square into a bottom.
A passenger would also see partial-G on the way down and more than 1G on the way up. Would this sort of ride be acceptable? Maybe not. And if anything goes wrong you’re buried deep in a tunnel that would take days if not weeks to excavate into.
But it would be just the thing for a day trip to China!
I’ve seen those in old buildings/factories.
Did they ever expand them to be anything like intercity or interstate?
Actually, it would pass the center of the tunnel at maximum speed, then decelerate until it was almost to the far end (but not quite, because of frictional losses), and then if not stopped would begin to fall back toward the center.
Unaided, it would oscillate back and forth across the center of the tunnel, until all kinetic energy was dissipated due to friction, at which point it would (as you say) come to rest in the middle. But it might take a very long time.
With propulsion available, there would be no reason not to use a little of it during the trip so that it would make it all the way to the far end, where of course you would stop it.
For short tunnels, there would not be much pull from gravity, so you’d have to use mostly propulsion. But for long ones, you’d get a noticeable boost from gravity. How useful this amount would be, I have not bothered to calculate.
(Consider the angle of descent at the beginning of a loooong tunnel vs. a short one, assuming of course that they were straight-line through the earth.)
Of course this is all quite fanciful until they figure out how to make a thousands-of-miles-long vacuum chamber and transport people safely through it. This is 22nd century stuff, at best.
Oh. I thought that was the Bill Clinton Memorial Practice Gallery.
“well gravity trains are a bit different”
I’m not an engineer. I simply was referring to the concept of underground trains travelling many thousands of MPH. I gather that gravity trains rely exclusively on gravity for propulsion, limiting their speed so that LA-NYC would be 42 minutes instead of 30. The RAND train, I infer, relies on magneto-levitation propulsion, so it can go faster, but I presume that gravity must be doing a fair bit of the heavy lifting, so to speak. That is, if gravity alone can get you to high enough speeds to cross the country in 42 minutes, then the propulsion needed to speed it up even further to cross in only 30 minutes presumably is much smaller than trying to rely exclusively on such propulsion to achieve 10,000 mph.
Of course, gravity is an intrinsic feature of nature that has to be overcome/exploited by any transportation system over long distances, so perhaps the distinction I’m trying to draw is meaningless. But I guess my point is, any system that relies on trains running on the surface of the earth—even if enclosed in a tunnel to minimize air pressure/wind resistance—has an inherent disadvantage over a system that tunnels through the earth and hence can exploit gravity effects during the first half of the journey. It seems to me that a train running on the earth’s surface has to rely entirely on propulsion to get its speed, whereas a tunnel through the earth can use gravity to its advantage etc.
Again, I’m no engineer or hard scientist, so perhaps I have completely bollixed the truth of the matter in my description above.
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