P0 = pressure at time zero produced by combustion of igniter and small fraction of propellant
V0 = initial free volume
m = propelled mass
v = velocity of propelled mass
a = gravitational field factor (equal to the sine of the angle between thrust vector and horizontal)
S = length of stroke
H(t) = energy term including heat loss required to balance equation.
approximates the gaseous energy produced by the igniter up to time zero. The time
function H(t) is added to make the equation balance. This quantity usually is identified with the energy lost
to the walls of the device and leakage during the ballistic cycle. However, in addition to the dissipated
energy, this term also includes errors inherent in the other terms of the equation.
(2) Equations of motion.
† The form function is a property of the charge which describes the amount of gas produced with the burning of a given
fraction of the propellant web.