h a l f b a k e r y"More like a cross between an onion, a golf ball, and a roman multi-tiered arched aquaduct."
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Power the space elevator by having at least two tracks,
preferably many tracks for redundancy, with up-cars
powered by regenerative braking of down-cars. This
requires more weight going down than going up, which
should be no trouble once we start mining the moon and
asteroids. Cars could
cycle up then down then up etc.
Cars need to be slow in the atmosphere, but outside
the atmosphere the faster they go the less weight
they add to the elevator and the less food passengers
need to bring along, so faster is better. Escape velocity
and beyond would be great if you can do it. Cars should
use electromagnetic propulsion, like a railgun, rather
than actually touching the elevator. Cars would be very
sensitive to fast oscillations.
The space elevator needs to damp fast oscillations.
Have the elevator be a rigid cylindrical shell, like
bamboo, tens of
meters across, with fins sticking out as tracks, and
with
a heavier cable running down the middle. Each part of it
needs to be super-strong self-supporting space elevator
stuff, but the central
cable can have fast oscillations while the outer shell and
tracks have to stay steady for the cars. Fast
oscillations in the outer shell and tracks can be dumped
into the central cable by pushing and pulling. The outer
shell can have oscillations too, but only low enough
frequency ones that the cars experience them as
gradual movements rather than jolts.
The man said ...
https://xkcd.com/536/
[normzone, Jul 06 2019]
[link]
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Having two tracks means more mass, more mass for the structure means more strength. I don't know the numbers but I am guessing it will be quite a few hundred years before having materials of this nature.
All current investment is with materials we believe are achievable of this goal. |
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Although, bio-mimicry of bamboo, for carbon nanotube structure, might be an inkling of a valid idea. |
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Carbon nanotubes, or boron nitride nanotubes etc, are
cylinders at the nanoscale, but this would be a cylinder
tens
of meters across. Each track fin would stick out a few
meters. I imagine the components of the fins and
cylinder
and central cable would be rebar-like solid rods of carbon
nanotubes, about 1mm*1mm*100m, tapered at the ends,
where
the end of one rod is lashed to the next rod for several
meters. That's manufactureable and replaceable. The
cable would be mostly solid while the cylinder and fins
would very
sparse, sort of like a net. |
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I can see the concepts and thought engineering but even though everyone is awkwardly smirking, the physical actuality of this build is probably a lot more than fifty years off. Fifty, for a one cable, one climber initial step prototype, unless there's a unforeseen massive breakthrough in material science just ready rock science's world. |
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A fountain-based elevator inherently has this regenerative braking property, as I understand
it, without needing multiple tracks, or even multiple cars traveling simultaneously. |
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// Cars should use electromagnetic propulsion, like a railgun, rather than actually touching
the elevator. // |
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Sliding contact is generally necessary in railguns. Perhaps you mean a coilgun, or a brushless
linear motor? |
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