[extropy-chat] The other space program
mlorrey at yahoo.com
Sun Aug 15 23:31:45 UTC 2004
--- Adrian Tymes <wingcat at pacbell.net> wrote:
> --- Charlie Stross <charlie at antipope.org> wrote:
> > On 12 Aug 2004, at 18:48, Adrian Tymes wrote:
> > > floating
> > > cities, anyone?
> > Sure. Until ...
> > 1. The neighbours on the ground get a bit annoyed
> > about the city
> > blocking all their sunlight
> If the city's not too big and floats high enough,
> the sunlight goes around them. Much like a cloud.
> > 2. The neighbours on the ground who you've just
> > drifted over point out
> > that under existing international law they have
> > sovereignty over their
> > head space, and would you mind implementing their
> > shari'a legal code
> > immediately?
> There's a maximum altitude that applies to.
> Specifically, nations don't get to apply their law to
> any satellite (or thing at comparable altitude) that
> happens to go overhead. Still, the station would
> presumably do much better simply to avoid those areas
> - military issues aside, they wouldn't make for good
> customers. (This being a private venture, they would
> presumably seek to make money off of it.)
> > 3. The higher you float your city, the lower the
> > density of the
> > surrounding air. Therefore the volume of lift gas
> > you need to displace
> > your own mass in air also increases. When you're so
> > high that
> > atmospheric pressure is around 1% of sea level, your
> > aerostat needs to
> > hold 100 times the volume it encloses at sea level.
> > The kind of
> > altitude these folks are talking about implies
> > kilometre-plus diameter
> > gas cells, just to hold up something as massive as a
> > 747. If you want a
> > floating city, you either have to have gas cells the
> > size of continents
> > or float it down in the troposphere where the
> > pressure's higher but
> > there's nasty weather to contend with.
> Depends on how large the city is. This is what I
> meant by the "engineering issues" they'd have to
> solve. (And I'm not necessarily saying they are
> solvable. Not saying they aren't, either.)
a) envelope size generally get calculated on helium density. These
would be Hydrogen filled cells.
b) they could also be HOT hydrogen filled cells, getting lift both from
atomic mass differences and thermal volume differences. With buckyfiber
envelopes, you could easily engineer an envelope with R factors
approaching a thermos bottle.
c) the envelope also gets lift from its velocity through the air and
its airfoil shape, propelled by microwave powered ion/plasma thrusters.
A 747 sized homestead could have an envelope the size of an aircraft
carrier. An aircraft carrier could have an envelope a few kilometers large.
Chairman, Free Town Land Development
"Necessity is the plea for every infringement of human freedom.
It is the argument of tyrants; it is the creed of slaves."
-William Pitt (1759-1806)
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