SBIR-STTR Award

Enerchem proposes to develop and demonstrate innovative concepts to protect solid rocket motors from impact events. Specifically our ignition delay concept has the potential to mitigate the overpressure, fragmentation and collateral damage that is usually incurred upon bullet or fragment impact on large motors. This concept is part of a systems approach to meeting the IM requirements and is integrated with other mitigation approaches in our Phase I program. Specifically the use of bore mitigants, formulation of tough propellants, and the utilization of low pressure designs and low burning rate propellants to the degree possible are all considered in Enerchem’s integrated IM design approach. In Phase I we will develop a generic test motor design, that is compatible with the MDA mission requirements, and will serve to demonstrate the IM and kinematic capabilities in Phase II. We will also address the shaped charge jet threat in this proposal and will develop a data base and define the relationship of formulation variables to the shock sensitivity. With respect to the SJC threat, our Phase I activity will focus on propellant trade studies and defining the Phase II test plan and test configurations. Results of this program will provide the basis to design missile system that can meet the IM criteria for SJC attack and minimize collateral damage.

Keywords:
Mitigation Of Bullet And Fragment Impact, Bore Mitigants, Im Analog Motors, Shaped Charge Jet, Shock Sensitivity –formulation Space, Im Test Plan, System Approach To Im Design

The Phase II objective is to demonstrate technology that will provide IM solutions to bullet and fragment impact threats in large diameter solid rocket motors. We have taken a comprehensive approach in which a number of IM mitigation techniques are combined into a design that reduces the violence of the response to BI and FI. These techniques, which were assessed and evaluated in Phase I, are integrated into the analog motor for the Phase II demonstration. The principal elements in this approach are: Ignition delay liner(IDL), Tough Propellant, and Bore Mitigant. Each element contributes to reducing the overall pressurization rate generated by the projectile impact. For instance, the IDL delays ignition of the grain burning surface, the tough propellant minimizes the fragmentation and debris thereby reducing burning surface, and the bore mitigant retards exposure of the grain surface to combustion gases and reduces the pressurization rate. Our design also incorporates a graphite composite case which is known to reduce the violence of rocket motor response to IM stimuli. The evaluation of HTPB and HTPE in the analog motors will provide a comparison of the IM performance in a common configuration. We will also measure detailed internal pressure, stress - time response to the impact events at critical locations in the analog motor. This will provide an understanding of the ignition process and the pressure rise rates that lead to the violent responses typically observed.

Keywords:
Insentive Munitions, Large Solid Rocket Motors, Bullet Impact, Fragment Impact, Htpe, Tough Propellant, Composite Case, Mitigation Technology, Im Anal