For a catapult, the terminal velocity and, therefore, the kinetic energy is important and the resistive forces are very small.

Thus, the energy balance equation must contain a term describing the work done by a thruster in exerting a force through

. The equation of motion must also be altered to include the

a distance. In general terms, the work is equal to

resistive force against which the thruster acts. In general, this resistive force is constant or a function of stroke (para. 51*d*

(2)).

values. To limit the piston velocity, either internal or external buffer systems are used. The interior ballistics of a

buffered thruster can be described by the following equations. The general energy equation defines the heat loss

in terms of a heat transfer coefficient, the surface area of the device exposed to hot gases, and a temperature

difference.

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