The Analysis of Solid Rocket Motor Performance Errors by Monte Carlo Techniques

In the captive testing of conventional solid rocket motors, a large number of fundamental physical measurements are normally implemented. These include the determination of instantaneous motor force, pressure, temperature, deflection, acceleration and electrical power data associated with the particular motor configuration. In the majority of applications, however, the motor performance indicators of most general interest are not measured directly, but are calculated from these basic data. Thus, for example, motor specific impulse is computed from given instantaneous values of measured thrust, pressure and weight parameters. All physical measurements are subject to inaccuracies, i.e., even the most sophisticated data acquisition system will necessarily inject discrepancies into the measured data. Hence, the mechanisms through which errors inherent in the measured quantities affect the accuracy of the calculated ballistic parameters are of extreme practical importance and must be quantitatively defined. At the Aerojet-General Corporation, an intensive and continuing analysis of overall measurement system errors (through rigorous analytical and experimental techniques) has permitted the statistical characterization of the error parameters within the framewcrk of each current large scale motor development program. Based upon these data and for a specific ballistic parameter computational routine, an extensive error analysis is required to deduce the errors associated with the computed performance parameters. Because of the nonlinearities and interactions inherent within the ballistic computations, a Monte Carlo technique is invoked.