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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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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(garfangle) writes:

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?

Because conventional powder guns absolutely cannot accelerate a projectile
to even one-quarter the necessary velocity. Because even an exotic gun
that hypothethicall could reach such velocities, would be launching a
"capsule" containing an astronaut mass of bloody hamburger uniformly
smeared across the back wall and then cookked Very Well Done by
atmospheric friction.

Jules Verne seems to have actually understood this, which makes
Gerald Bull look even sillier. Though he at least didn't propose
manned gun launch.


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.

Except that Gerald Bull's design required *four* stages of external
boosters to go with the (tiny) payload, in order to reach orbit.
Designers who dispense with the cannon can do it with two rocket
stages, mostly by virtue of not having to design massively overweight
rockets tough enough to withstand cannon launch.


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*Member:AIAA,NRA,ACLU,SAS,LP * is worth doing for money" *
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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.

Ciao.


All this is fine, for acceleration-insensitive payloads....

Which rules out humans, but might not be a bad idea for things like
radioactive wastes, or even plain water, which would have multiple uses,
once in LEO.

But even if you had an intended-to-be-manned-later (if I'm
understanding you correctly) spacecraft that could itself tolerate this
mode of launch, you still have to get its crew up to LEO to meet it,
some other way. And anything intended to go deeper into space, Jules
Verne not withstanding, is likely going to be too big to be orbited in
this manner. Thus my above point for firing water, and using it as is
for life-support purposes, or electrolyzing it with solar power into H2
and O2, to fuel something else.

"garfangle" wrote in message

Obviously this 'person' hasn't heard of science fiction.
google.com yet again

--
Alan Erskine
alanerskine(at)optusnet.com.au

Trial or release, Mr Bush, trial or release.

"Alan Erskine" wrote in message
u...
"garfangle" wrote in message

Obviously this 'person' hasn't heard of science fiction.
google.com yet again

--
Alan Erskine
alanerskine(at)optusnet.com.au

Trial or release, Mr Bush, trial or release.



I have heard it mentioned before, however, that if a gun could be devised,
it could allow for launch of bulk frozen materials to orbit.

See : http://tinyurl.com/pep5

That would seem to be where a supergun would be most suitable: fast, cheap,
direct delivery of bulk freight. Whether there would be a market for that
vs. a space elevator, I don't know. Heron Aerospace is the only company I
know of that is actively working on gun-launch.

(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.

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