
193
6
Introductory Concepts
When the projectile has left the environment of the gun, including the effects of the exit-
ing propellant gases that momentarily surround it, it enters the realm of the exterior bal-
listician. Here, it is subject to the force of the pressure of the atmosphere that it is ying
through, the force induced by its spin, and the force due to the acceleration of gravity.
The projectile in ight is no longer constrained in lateral motions by the walls of the gun
and, as a free body, can develop motions that are complex and occasionally inimical to the
intent of its user and embarrassingly, to its designer. The study of these ...