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The methods developed in recent years for measuring and characterizing the mechanical behavior of solid propellant and utilizing this information in structural analyses to predict rocket motor structural integrity are reviewed in terms of the applicability of this approach to other materials and applications. It is shown that the recognition of statistical distributions of response and failure behaviors leads to the prediction of the distribution of failure times in actual use. The combining of behavior data with structural analysis to give a cumulative damage prediction of failure is shown to be possible through the use of the computer. The development of reliability is shown to start with the development of the tests used to evaluate the material, which must measure those properties directly pertinent to the structural requirements. The product structural requirements are converted into test requirements through analytical and experimental stress analyses.

The development of a motor combining a pintle-controlled nozzle with gimbaled supersonic splitline thrust vector control (TVC) was undertaken in an effort to exploit the increased performance flexibility of a rocket system which is offered by thrust magnitude and thrust vector control. That is, the ability to perform widely different duty cycles, maneuvers, or fly different trajectories. The major objective is to demonstrate the effectiveness of a controllable solid-propelled rocket motor which features variable thrust, attitude control, and high propulsion efficiency. To date, three half-duration motors have been static-fired, two at sea level and one which contained a thrust vector control system at simulated altitude. Although each of these preliminary tests experienced some difficulty, several of the major design objectives were successfully demonstrated.