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From: David.Smith@CMU-CS-IUS.ARPA
Newsgroups: net.space
Subject: Rocket thrust
Message-ID: <894@sri-arpa.UUCP>
Date: Fri, 15-Jun-84 13:29:00 EDT
Article-I.D.: sri-arpa.894
Posted: Fri Jun 15 13:29:00 1984
Date-Received: Tue, 19-Jun-84 01:07:51 EDT
Lines: 22

n
mass.  In the rifle analogy, the reaction mass comprises not just
the combustion products, but also the rifle and the person holding the rifle.

There is a limit to the rate of expansion of combustion products, even
if uncontained in space.  A rifle ensures that most of that rate gets
transferred to the bullet.  A rocket lets most of it get away, since
the exhaust is only confined by its own inertia.  A rocket in the
atmosphere gets a little bit of assistance in confining the exhaust.

				David Smith