Subscale Fast Cookoff Testing and Modeling for the Hazard Assessment of Large Rocket Motors

Abstract : A significant issue facing the solid propulsion acquisition and safety communities is to determine if hazard classification requirements can be structured for large solid rocket motor programs to maximize safety while optimizing the tradeoff between safety and logistical considerations and system acquisition costs. Integral to this assessment is an evaluation of the potential application of subscale analog testing and modeling to characterize the full-scale motor response in a variety of scenarios such as in an engulfing fuel fire (fast cookoff) or wood bonfire environment. This information is necessary for final hazard classification and insensitive munitions (IM) assessment purposes for new systems. This report summarizes fast cookoff testing diagnostic techniques, subscale analog hazard response tests, established computer modeling analysis techniques, and other empirical information that might be useful for scaling the results of a subscale analog fast cookoff/bonfire test to a full-size solid rocket motor (SRM) for hazard classification and/or IM assessment. Since subjective observations and judgment cannot be completely eliminated from a subscale test protocol, an integral aspect of the scaling issue makes use of empirical (experimental) motor hazard response information that has been gained from full-scale fast cookoff/bonfire tests and related, well characterized accidents exhibiting similar failure modes. Thus, the final part of the report summarizes findings of fast cookoff parametric test programs and other miscellaneous full-scale test results with solid rocket motors containing high-energy propellants.