From: ChuckKuecker (ckuecker@mcs.net)
Date: Fri Apr 17 1998 - 19:45:50 MDT
At 13:44 4/17/98 EDT, you wrote:
>It seems it would be a lot safer and cheaper, and cooler(to look at) if it
>were above ground. Underground has problems with earthquakes and oceans and
>whales in the oceans. I was just thinking about a transportation device
>similar a couple weeks ago, using big strong, cheap plastic tubes (clear tubes
>would be really cool, especially if you're going fast (300+), with super-
>lightweight crafts, and just use air to blow them. It would require stations
>every few miles (maybe 1 or 50) to add additional charges. But these could go
>super fast if they were light weight. The charges wouldnt require too much
>energy im sure if they were built right.
>
The air powered transport would indeed work, but the losses in a pneumatic
system are awesome for tubes large enough to carry passengers and freight.
The air in front of the car is compressed, and the air behind is compressed,
and this causes heating. A pump big enough to pull an active vacuum in front
of the car would be a very impressive piece of machinery.
There are physical limitations to flow in pipes without huge frictional
losses. I am not an aeronautical or fluids engineer, so I cannot give
precise limits, but i know they exist.
Heinlein described above ground ballistic transports running in air at
supersonic speeds, with accelerator coils on hilltops at intervals. A neat
idea, but I doubt anyone would let us build one..
>
>what is a maglev? Like magnets? I had thought about that in middle school,
>tubes with crafts suspended with magnets, then I heard they use it in Japan
>kinna, for their trains, I guess the trains float on the rails.
>
A maglev - short for magnetic levitation - is using a strong magnetic field
and a superconductor to produce an opposing field (Meissner effect??). The
classroom demonstration is to use a strong rare earth magnet and a
superconducting disk in liquid nitrogen - the magnet will 'float' above the
disk. The only power input is keeping the superconductor cold.
There are other systems that use two electromagnets and fancy servo systems
to regulate the levitation, but these use lots more power, unless both
magnets are superconducting.
>Also, how long would it take fo a craft to get into orbit in a tube? could it
>be bursted into orbit like within a few miles?
The only limitation is how many 'g's you want to limit acceleration to. It
should take no more than a couple of miles to get to 18,000 MPH or more at a
one 'g' boost.
Chuck Kuecker
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