Another wacky idea here, but I have a lot of idle time to think on my mindless job. I have no idea if this idea is even plausible, but I happened upon an issue of Popular Science about the use of lighter than air craft that were massive enough to use as tramsportation of enormous payloads, and that set me to thinking about ... you guessed it...space colonization. If a payload could be launched from a floating platform miles above the Earth's surface, could that significantly cut launch costs in the long run? Of course getting the payload to the launchsite would still be a pain, but perhaps one could use yet again another large zeppelin to ferry the payloads to it. A simple elevator cable would be nice, but impractical, as not only would it have to be miles long, but strong enough to lift the payload and support its own considerable weight.

People love large structures, and this one would be huge. Any ideas, you all?

This has been looked at. Launching from a balloon would reduce your
potential energy requirements slightly, but for getting into orbit the
lion's share of the energy requirement is kinetic. So it helps a tiny bit,
but probably not significantly enough to be worth the investment or
complications. A better launch strategy is some kind of accelerator,
because lots of kinetic energy is what you need to get into orbit, not
altitude.

I once wrote an sf novella about a balloon-borne mass driver launcher, but
the strategy there was to take off through thinner air (reducing energy
losses and heating), and to reduce the intensity of the sonic booms at
ground level. The altitude makes little contribution.

Regards,

Mike Combs

From: phoebos@... [mailto:phoebos@...]
Sent: Wednesday, January 24, 2001 9:30 PM
To: spacesettlers@egroups.com
Subject: [spacesettlers] Floating launchpad

Another wacky idea here, but I have a lot of idle time to think on my
mindless job. I have no idea if this idea is even plausible, but I happened
upon an issue of Popular Science about the use of lighter than air craft
that were massive enough to use as tramsportation of enormous payloads, and
that set me to thinking about ... you guessed it...space colonization. If a
payload could be launched from a floating platform miles above the Earth's
surface, could that significantly cut launch costs in the long run?

I once wrote an sf novella about a balloon-borne mass driver launcher, but the strategy there was to take off through thinner air (reducing energy losses and heating), and to reduce the intensity of the sonic booms at ground level. The altitude makes little contribution.

Regards,
Mike Combs
From:
phoebos@... [mailto:phoebos@...]
Sent:
Wednesday, January 24, 2001 9:30 PM
To:
spacesettlers@egroups.com
Subject:
[spacesettlers] Floating launchpad
Another wacky idea here, but I have a lot of idle time to think on my mindless job. I have no idea if this idea is even plausible, but I happened upon an issue of Popular Science about the use of lighter than air craft that were massive enough to use as tramsportation of enormous payloads, and that set me to thinking about ... you guessed it...space colonization. If a payload could be launched from a floating platform miles above the Earth's surface, could that significantly cut launch costs in the long run?

I think everyone on the list has had this idea in one form or another.
If your interested, Mike Combs has a story on his site.

Elevator cables aren't as impractical as you think. Normal nylon can
support its own weight for over 5 km. There are other plastic that
have tensile strength even higher.

To make this practical you need to start the industry of lighter than
air transport before you use them as support for a launch site.

Just a thought.

Bill

--- In spacesettlers@egroups.com, phoebos@w... wrote:
> Another wacky idea here, but I have a lot of idle time to think on
my mindless job. I have no idea if this idea is even plausible, but I
happened upon an issue of Popular Science about the use of lighter
than air craft that were massive enough to use as tramsportation of
enormous payloads, and that set me to thinking about ... you guessed
it...space colonization. If a payload could be launched from a
floating platform miles above the Earth's surface, could that
significantly cut launch costs in the long run? Of course getting the
payload to the launchsite would still be a pain, but perhaps one could
use yet again another large zeppelin to ferry the payloads to it. A
simple elevator cable would be nice, but impractical, as not only
would it have to be miles long, but strong enough to lift the payload
and support its own considerable weight.
>
> People love large structures, and this one would be huge. Any
ideas, you all?

phoebos@... wrote:

> If a payload could
> be launched from a floating platform miles above the Earth's
> surface, could that significantly cut launch costs in the long run?

Depends on your definition of significant. 7% of the energy
necessary to get into orbit involves going up. 93% involves
going sideways fast till the rate that you fall matches
the curvature of the earth.

Therefore a floating platform doesn't help very much. It
does however get you out of the really thick bit of the
air and it helps improve the efficiency of your rocket
nozzles because they see less variation in pressure
so there are some subtle advantages.