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From: gwyn@brl-tgr.ARPA (Doug Gwyn <gwyn>)
Newsgroups: net.physics
Subject: Re: A Question on Ballistics
Message-ID: <5717@brl-tgr.ARPA>
Date: Sun, 11-Nov-84 15:45:13 EST
Article-I.D.: brl-tgr.5717
Posted: Sun Nov 11 15:45:13 1984
Date-Received: Tue, 13-Nov-84 01:19:20 EST
References: <246@iham1.UUCP> <603@watdcsu.UUCP> <> <26@politik.UUCP>
Organization: Ballistic Research Lab
Lines: 15

> Ballistics is mostly concerned with the effect of air resistance.
> 
> Does anyone know the actual equations for computing that path?  

To properly take into account the spin of the projectile, velocity
dependence of drag, and other details is by no means a trivial task.
The equations of motion do not have a closed-form solution, so it
must be calculated through numeric approximation.  One of the first
digital computers, the ENIAC, was employed for computing firing
tables.  If you make various simplifying assumptions (e.g., neglect
spin and lift, make drag proportional to speed and directly opposed
to it, etc.), then you can write down an analytic solution.  Whether
it is useful or not depends on how well the assumptions fit reality.
This is nothing new; nearly all exact solutions are to simplified
models.