I have been wondering about what type of bulk and mass passenger
transportation might be the norm on low G planets in the future. The reason
for my pondering is for scenario design; a planetary invasion will likely make
control or destruction of the transportation network a fairly high priority.
Assumptions: 1) We are talking about a planet with gravity about the same as
Mars (38% of earth's gravity) 2) Bulk freight and large masses of people will
still be most cost effectively moved using ground transportation. (It is not
economical to move iron ore using C141s.) Note: I am not concerned with water
transport at this point.
Rail travel could be a problem. Inertia remains the same, but the wheel to
rail contact force will only be 40% (I assume this is proportional to
gravity?) what it is on earth. Presumably that will reduce the load that can
be started and greatly increase the braking distance.
There must be ways this problem could be reduced:
-All wheels powered
-Cog railway
-Maglev (Something like Maglev feels right for a Sci-Fi setting. Much
more futuristic than steel rails. But how does the construction cost compare.)
-What else?
What are the list's thoughts?
wouldn't GEV work better on a lower grav planet? just thinking that an air
cushion would better with a lighter vehicle.
> Rail travel could be a problem. Inertia remains the same, but
So? I've seen coal trains around here with 1 locomotive and 80 cars. So cut
back to 1 locomotive and 40 cars. Problem?
> There must be ways this problem could be reduced:
I've always assumed that a new planet will have a combination of
horses (self-replicating, low tech fuel, etc) and hovercraft or
ATV's for ground transport, plus ships for heavy transport.
Railways may (or may not) be cheaper in the long run--but they
must cost quite a bundle to build, and you can't do anything with them until
they're finished. Further, your options are
limited--ie with an ATV truck you can go wherever the terrain
will let you, with a train you go only where the rail goes.
If the atmosphere is fairly thick (like earth) then airplane (air train?)
travel is much more practical (less gravity equates to less energy needed to
fly). Ultralights may be the "cars" of such a planet.
A grav or hover train may be practicle in such an environment. Less cost than
maglev (all you need is a flat clear trail for the train to follow).
---
Brian Bell bkb@beol.net <mailto:bkb@beol.net>
http://members.xoom.com/rlyehable/ft/
ICQ: 12848051 AIM: Rlyehable
---
[quoted original message omitted]
Lower air pressure leads to lower chamber pressure which is offset by lower
gravity. Hmmm.... seems to have the same lift factor, but would be slower to
accelerate/decelerate due to the lower air pressure.
Neath Southern Skies -http://home.pacific.net.au/~southernskies/
[mkw] Admiral Peter Rollins; Task Force Zulu
[DitD] Captain Puppilier
> -----Original Message-----
Lower gravity does not necessitate lower air pressure. Look at Earth, Mars and
Venus. All are close in mass, but Venus has a much higher atmospheric pressure
than Earth while Mars has a much lower atmospheric pressure than Earth.
-----
Brian Bell bkb@beol.net
-----
> -----Original Message-----
[quoted original message omitted]
From: Robert W. Hofrichter <RobHofrich@peoplepc.com>
> There is an experimental (urban) maglev design that the
The city governments around here like to waste money, so we'll probably end up
getting it whether we want it or not. Or more accurately, we'll get it despite
the fact that the referendum showed that we don't want it.
> exist--after all, the rails are there to help distribute the
Most plastics a) are sensitive to ultraviolet light; or
b) are subject to cold-flow deformation under pressure; or
c) present some manufacturing difficulties.
Glass-epoxy laminates should work well but would be more
expensive than iron without any great improvement in
performance. The cheaper plastics--PVC, polyolefins,
styrenes--wouldn't work.