O-081 A System Approach to IM For Solid Rocket Motors -Composite Cases and Reduced Sensitivity Propellants

March 2003
Michael Fisher (Propulsion Technology), Paul Johnsen (NAWCWD, China Lake, USA

As part of a system approach to meeting Insensitive Munitions (IM) requirements, the NIMIC member nations have expended a great deal of effort on the development and qualification of less sensitive rocket propellants. The desired characteristics of such "IM propellants" are discussed in terms of general methods of tailoring the propellants to counter thermal and mechanical (shock/impact) threats. Examples that illustrate the application of these methods in real, useful propellants are presented, along with the corresponding results of component and/or full-scale IM tests, where possible. Tradeoffs between reduced vulnerability and other propulsion system design drivers (e.g., performance, cost, signature, environmental concerns) are also discussed. A second key aspect of a system approach to IM for rocket motors is the selection of a motor case design that will reduce the confinement of the propellant when subjected to IM stimuli. One type that has shown excellent promise is the filament-wound composite case. The application of the composite case to tactical rocket motors is discussed, along with test results illustrating improvements in IM capability. Finally, an example is presented of a tactical rocket motor designed and tested at the Naval Air Warfare Center (NAWCWPNS) in China Lake, California, which makes use of a composite case and an IM propellant.