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From: dietz@SLB-DOLL.CSNET (Paul Dietz)
Newsgroups: net.space
Subject: Re: Rail guns vs. ordinary guns
Message-ID: <8601202319.AA00361@s1-b.arpa>
Date: Mon, 20-Jan-86 17:27:54 EST
Article-I.D.: s1-b.8601202319.AA00361
Posted: Mon Jan 20 17:27:54 1986
Date-Received: Wed, 22-Jan-86 00:25:05 EST
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Organization: The ARPA Internet
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A rail rocket would have to carry a lot of hydrogen, and have a VERY
high mass flow rate (all the mass must flow out in a fraction of a
second, or the barrel of the gun must be very long).  Also, you'd
have to commutate the thing somehow, which is hard at high velocity.

Actually, a railgun can be thought of as an arc-rocket.  Magnetic
forces confine the exhaust gases at the base of the projectile, so the
only mass flow is from an ablative coating on the back of the
projectile, and that's just for thermal protection.  I don't know if you
want a light gas in the arc, or if any material will do.

An alternative to the rail rocket would be a launcher in which the
hydrogen fuel is heated by an intense laser or particle beam.  A high
voltage electron beam, for example, might be easier to generate (at a
given power level) than the high current pulse a railgun needs.