Thermal Isolation of Solid Rocket Motor Exit Cone and Nozzle

Current strategic solid rockets motors, such as the SM-3 third stage rocket motor (TSRM), employ highly aluminized propellants with gas temperatures of approximately 6,500F. Carbon-carbon nozzle throats and carbon cloth phenolic (CCP) exit cones are commonly used to manage the propellant exhaust. However, heat transfer from these components to the nozzle housing and exit cone bond-line joint currently limit mission profiles. This limitation is exacerbated in dual pulse motors with additional heat soak between pulses. To address this issue, a thermal barrier on the exterior exit cone and nozzle is proposed. This solution enables greater mission range and flexibility by minimizing heat transfer to the exit cone bond-line and adjacent bearing components. For dual-pulse motors, limiting the thermal soak will extend mission flexibility by allowing for a longer inter-pulse delay. During a Phase I effort, the team of Plasma Processes, Dynetics, ATK, and Aerojet will investigate the development and application of thermal barriers on CCP exit cones. Heat transfer analyses will be conducted to define effective structure and locations and estimate performance improvement. Following thermal analyses, a series of manufacturing demonstrations will be performed. Simulated TSRM nozzle sections with thermal barriers will be evaluated via high heat flux testing.