Cheaper way to space!? A supergun.

Instead of hauling their own fuel for propellent, which adds to its
weight, why not have manned craft launched from massive high-altitude
cannons? Why not further what the late-Gerald Bull envisioned (see
world.std.com/~jlr/doom/bull.htm) to build a supergun that could
launch projectiles large enough to be duplicated as manned capsules?
That way there would be little or no need for external boosters to be
hauled alongside the manned vehicle, greatly reducing the per pound
flight costs.

The gun could be large enough to shoot the craft into near-low earth
orbit and then small internal rockets could be used to get the craft
further into space. The craft could be sized such that it replicated
the apollo.

I imagine the dimensions would be at least 500 meters long, 30 meters
in diameter, and require an explosive shot of several tons of tnt.

Ciao.

(garfangle) writes:

I imagine the dimensions would be at least 500 meters long, 30 meters
in diameter, and require an explosive shot of several tons of tnt.

Now figure out what the acceleration would be along that 500 meters
of length in order to achieve orbital velocity, plus some extra to
make up for losses on ascent (e.g. air drag and the other usual
suspects). Have you squished your payload in the process of launching
it?

Jeff
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Remove "no" and "spam" from email address to reply.
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garfangle wrote:
Instead of hauling their own fuel for propellent, which adds to its
weight, why not have manned craft launched from massive high-altitude
cannons? Why not further what the late-Gerald Bull envisioned (see
world.std.com/~jlr/doom/bull.htm) to build a supergun that could
launch projectiles large enough to be duplicated as manned capsules?
That way there would be little or no need for external boosters to be
hauled alongside the manned vehicle, greatly reducing the per pound
flight costs.

The gun could be large enough to shoot the craft into near-low earth
orbit and then small internal rockets could be used to get the craft
further into space. The craft could be sized such that it replicated
the apollo.

I imagine the dimensions would be at least 500 meters long, 30 meters
in diameter, and require an explosive shot of several tons of tnt.

Near-low earth orbit is 7,200 m/s disregarding atmospheric air
drag and circularization.

Assuming continuous accelleration:

V = a t
S = 1/2 a t^2
S = 500 = 1/2 a t^2
V = 7,200 = a t
[solve]
t = 0.1388... sec
a = 51,840 m/s/s ~= 5,290 Gs

The condition of the human body exposed to nearly 5,300 Gs for
a seventh of a second is "red goo on back wall of space capsule".

Try again.


-george william herbert

In article ,
(George William Herbert) wrote:

The condition of the human body exposed to nearly 5,300 Gs for
a seventh of a second is "red goo on back wall of space capsule".

Right, a 500-m gun would never work for passengers (though it might
conceivably work for bulk materials like water or metals).

I do think there's some merit to the idea of a magnetic launcher
floating high in the atmosphere, but it would have to be many km long,
and it's a major engineering project -- I suspect that by the time we
could seriously ponder building one, we'll either already have an
orbital tether in hand or very close.

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(George William Herbert) wrote in message ...
garfangle wrote:
Instead of hauling their own fuel for propellent, which adds to its
weight, why not have manned craft launched from massive high-altitude
cannons? Why not further what the late-Gerald Bull envisioned (see
world.std.com/~jlr/doom/bull.htm) to build a supergun that could
launch projectiles large enough to be duplicated as manned capsules?
That way there would be little or no need for external boosters to be
hauled alongside the manned vehicle, greatly reducing the per pound
flight costs.

The gun could be large enough to shoot the craft into near-low earth
orbit and then small internal rockets could be used to get the craft
further into space. The craft could be sized such that it replicated
the apollo.

I imagine the dimensions would be at least 500 meters long, 30 meters
in diameter, and require an explosive shot of several tons of tnt.

Near-low earth orbit is 7,200 m/s disregarding atmospheric air
drag and circularization.

Assuming continuous accelleration:

V = a t
S = 1/2 a t^2
S = 500 = 1/2 a t^2
V = 7,200 = a t
[solve]
t = 0.1388... sec
a = 51,840 m/s/s ~= 5,290 Gs

The condition of the human body exposed to nearly 5,300 Gs for
a seventh of a second is "red goo on back wall of space capsule".

Try again.


-george william herbert


My bad...though couldn't we develop some anti-G shield?

Ciao.

garfangle wrote:
(George William Herbert) wrote in message ...
garfangle wrote:
Instead of hauling their own fuel for propellent, which adds to its
weight, why not have manned craft launched from massive high-altitude
cannons? Why not further what the late-Gerald Bull envisioned (see
world.std.com/~jlr/doom/bull.htm) to build a supergun that could
launch projectiles large enough to be duplicated as manned capsules?
That way there would be little or no need for external boosters to be
hauled alongside the manned vehicle, greatly reducing the per pound
flight costs.

The gun could be large enough to shoot the craft into near-low earth
orbit and then small internal rockets could be used to get the craft
further into space. The craft could be sized such that it replicated
the apollo.

I imagine the dimensions would be at least 500 meters long, 30 meters
in diameter, and require an explosive shot of several tons of tnt.

Near-low earth orbit is 7,200 m/s disregarding atmospheric air
drag and circularization.

Assuming continuous accelleration:

V = a t
S = 1/2 a t^2
S = 500 = 1/2 a t^2
V = 7,200 = a t
[solve]
t = 0.1388... sec
a = 51,840 m/s/s ~= 5,290 Gs

The condition of the human body exposed to nearly 5,300 Gs for
a seventh of a second is "red goo on back wall of space capsule".

Try again.

My bad...though couldn't we develop some anti-G shield?

I've wondered about using magnetic levitation for this.
It's by no means perfect, and the variation between body materials
will cause it to not work perfectly.
It might buy you a factor of 5?
Fit humans can naturally take about 25G for a minute (prone, immersed)
without significant harm. It's not very nice of course.
Coincidentally, this is enough to get to orbital speed.
Assuming that you can up this to 30G with better designed g-suits, and
that you can add another factor of 5 for magnetic levitation (there are
a number of problems that look like show-stoppers) then that's
still only 150G.
That's still a barrel length of around 30Km, with very optimistic
assumptions.

--
http://inquisitor.i.am/ | | Ian Stirling.
---------------------------+-------------------------+--------------------------
If God hadn't intended us to eat animals,
He wouldn't have made them out of MEAT! - John Cleese

garfangle wrote:

My bad...though couldn't we develop some anti-G shield?


You could then just gently drift off to space on top of that 8-P

Ciao.

--
Sander

+++ Out of cheese error +++

garfangle wrote:
(George William Herbert) wrote:
The condition of the human body exposed to nearly 5,300 Gs for
a seventh of a second is "red goo on back wall of space capsule".

My bad...though couldn't we develop some anti-G shield?

Sure, I'll just hop in my X-wing and fly out to the Titan base
where we're working on anti-G shielding and hyperdrives
and report back when we're done... ;-)

There are things that can be done to increase human G-tolerance.
Lying flat gets you to 20+ transient Gs without serious problems,
and immersion in water roughly doubles that. But if you take a 40G
limit, that's 400 m/s^2 of accelleration roughly, which gets you
to 8 km/s in 20 seconds, at an average velocity of 4 km/s,
for a gun barrel or accellerator length of 80 km. 50 miles.

As others have pointed out, anything mechanical that you can
harden a lot (artillery shells take tens of thousands or 100,000 Gs)
and bulk materials and propellants and stuff can take gun launch,
though you do have to spend the time and effort to harden them
to survive the accelleration. People... should ride gentler things.


-george william herbert

George William Herbert wrote:
garfangle wrote:
(George William Herbert) wrote:
The condition of the human body exposed to nearly 5,300 Gs for
a seventh of a second is "red goo on back wall of space capsule".

My bad...though couldn't we develop some anti-G shield?
snip
There are things that can be done to increase human G-tolerance.
Lying flat gets you to 20+ transient Gs without serious problems,
snip
As others have pointed out, anything mechanical that you can
harden a lot (artillery shells take tens of thousands or 100,000 Gs)
snip
People... should ride gentler things.

If cryogenics is finally gotten working, then that incidentally solves
that problem, at least a bit.
And it's at least not forbidden by the current laws of physics that
we know, just lots and lots of apparently insoluble chemistry and biology
problems.

I'd imagine a astronicle could cope with at least a thousand G.

--
http://inquisitor.i.am/ | | Ian Stirling.
---------------------------+-------------------------+--------------------------
If you've been pounding nails with your forehead for years, it may feel strange
the first time somebody hands you a hammer.
But that doesn't mean that you should strap the hammer to a headband just to
give your skull that old familiar jolt. -- Wayne Throop, during the `TCL Wars'

Ian Stirling wrote:
If cryogenics is finally gotten working, then that incidentally solves
that problem, at least a bit.
And it's at least not forbidden by the current laws of physics that
we know, just lots and lots of apparently insoluble chemistry and biology
problems.

I'd imagine a astronicle could cope with at least a thousand G.

Frozen stuff is *brittle*...


-george william herbert