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From: (Zerog)
Subject: Re: Nuclear Cannon   (was Re: Nuclear Detonation Powered Spacecraft)
Date: Sep 21 1995

In reference to your suggestion of using atomic explosives to propel
cannon launched projectiles, I'd like to pass along the following
reference.   The paper is titled "A Catapult for Launching Large Masses"
and was written by R.S. Cooper.  It was published by the AIAA and is
numbered AIAA-86-1762.

The paper discusses the use of a variety of pulsed nuclear sources,
including atomic explosives, in contained underground systems, to launch
large payloads into orbit.

By "large", we're talking one million pounds and up.  A reference system
would propel a 1 million pound, 5 meter diameter x 15 meter long
projectile to 10 km/s.  Tube dimensions are 10 m diameter x 1000 m long. 
At the bottom of the tube is a chamber 65 m in diameter where the
propulsive gasses and nuclear charge are positioned.  The most desirable
propulsive gas would be H2, not heavy H2O since low molecular weight is
essential for orbital muzzle velocities. 

The projectile rides on a sabot which not only reduces peak pressures in
the tube (by allowing tube diameters larger than the projectile) but also
acts as a plug to seal the barrel as the projectile leaves the muzzle.

Most of the concepts presented are designed to contain all propulsive
gasses and therefore would probably be no more environmentally or
politically challenging than an underground test.

Costs for a one million pound launch is estimated at between $50M and
$200M.  That cost was estimated from experience with underground testing
where individual experiments cost between $20M and $50M each.

The bomb which could do this is not a significant part of the overall cost
(<$200k).  If the system is reusable and the market were large, then
cost/lb might be very low indeed.  

One further historical note.  There was a time when "our side" was afraid
that "their side" was contemplating such devices.  The details of design,
and even the cute names that were given to such devices may still be
classified, so I won't go into detail.  Suffice it to say that the thought
of several million pounds of rock and steel I-beams sailing toward our
cities on high speed sub orbital trajectories kept several people up late
into the night.

B. McKinney

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