[extropy-chat] balloon stations at the edge of space

[Adrian Tymes]

--- Dan Clemmensen <dgc at cox.net> wrote:
> Eugen Leitl wrote:
> 
> >On Mon, May 24, 2004 at 09:45:18PM -0700, Johnius
> wrote:
> >
> >  
> >
> >>  This thread reminds me of an invention of Win
> Wenger's
> >>that uses balloons to suspend a mass-driver for
> cheap
> >>space launches.  It occurs to me that several of
> you might
> >>have some great feedback about the idea...
> >>What do y'all think?
> >>    
> >>
> >
> >It sounds like a really good idea... until you do
> the math, and realize that
> >LEO energy is all not about height, but about
> horizontal velocity component.
> >And that goes with 0.5*m*v^2.
> >
> >So a ramp and a maglev stage (or a hypersonic
> airbreathing scramjet stage)
> >brings you much, much closer to LEO than any
> stratospheric balloon.
> >
> >Latter have their own uses, though.
> 
> If the idea works vertically, it should also work
> horizontally. Start 
> with a series of
> vertically-oriented mass driver balloons to get the
> payload into the 
> stratosphere at
> low velocity,

Or...use balloons as structural supports for a long,
lower-altitude mass driver.  You'd need a really long
(hundreds of kilometers) mass driver to accelerate to
orbital speeds at human-tolerable levels (less than
10G, preferably 2G or less), and inclining that at any
decent angle (say, 10 degrees or more) means that the
far end of the mass driver will also have to be
hundreds (or at least many tens) of kilometers in the
air.  (The 100s of km is a delta altitude from the
start, but building up a hundred kilometers from
ground level is actually far easier with today's
technology than building down a hundred kilometers.
Not that either one is easy.)  Instead of building
large towers to support the higher sections, one could
deploy them on airships.  Straight shot, and the tube
can be (mostly) evacuated to minimize air drag, so
overall more efficient than up-and-over.