From: Charles J Knight (c.knight_at_juno.com)
Date: 03/28/99
Date: Sun, 28 Mar 1999 20:34:24 +0000 Subject: Re: cloud city Message-ID: <19990328.203435.8590.2.c.knight@juno.com> From: Charles J Knight <c.knight_at_juno.com>
>: Actually...why would it require a completely rigid shell in the
>:first place?
>:
>: Might be a lot cheaper to build this way, too.
>
>Here's the image that comes to my mind - stop me if I'm crazy:
>a rigid structure whose upper half is airtight but whose lower half
>is open. If it's big enough, will heat hold it up? If so, then
>passive ventilation seems a big advantage over a structure that needs
>internal pressure to hold its shape.
Again, I'll ask...why rigid? We could make a double envelope (not that
uncommon in airships) which would hold its shape through air pressure,
leaving the interior completely "open," if you'd like. But...the
pneumatic
structure would probably cost a heck of a lot less than a rigid
structure,
when applied to this scale of engineering. It would also minimize local
stress on the envelope.
Personally, I like the idea of an open bottom...it works for diving bells
and
for balloons, why not for cities? With the 1 mile diameter structure,
we're
only takling about requiring a 1 degree difference between ambient and
internal, for buoyancy...about 2 degrees for positive lift *with* the
payload
of a small city inside.
-- Chuck Knight
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