Abstract: A composition consisting essentially of a polyphosphazene binder having the following repeating units: ##STR1## wherein n is from about 20 to about 50,000, A is selected from --O-- and --NH--, and R.sup.1 and R.sup.2 are independently selected from alkyl having from one to about 20 carbon atoms, aryl having from 6 to about 14 carbon atoms, alkaryl having from 7 to about 30 carbon atoms, any of the preceding moieties substituted with halogen, hydroxyl, alkoxy, aryloxy, or nitro groups, or any of the preceding moieties linked by ether or amine linkages. Combined with an organic fiber filler, this material provides an erosion resistant insulation composition for temporarily protecting the interior of a rocket motor combustion chamber from thermal damage while the rocket is firing.

Abstract: Improved resistance of fiber filled insulation to erosion from combustion gas flow ina solid propellant rocket motor is produced by orienting the fiber direction of the grain of the fibers in the insulation to a direction in which the direction of the fiber grain is substantially perpendicular to the direction of the flow of combustion gas in the rocket motor. Unvulcanized fiber filled insulation sheet stock is folded and compacted in accordion-like style such that the fiber grain direction is reoriented eassentially 90 degrees in the roll direction of the sheet stock.

Abstract: Process for forming a liner and cast propellant charge in a rocket engine casing without separately precuring the liner, comprising the steps of providing a blocked curable liner composition which is the reaction product of a prepolymer, an isocyanate curing agent, and a blocking agent; applying the liner composition to an internal surface of a rocket casing; preheating the casing and liner assembly to simultaneously prepare the assembly for receiving a propellant, unblock the liner, and precure the liner to a tacky state; casting the propellant change into interfacial contact with the liner; and cocuring the liner and propellant compositions. The blocked, curable liner composition has a very long pot life which is terminated by heating the composition sufficiently to uncouple the blocking agent from the isocyanate curing agent and initiate a rapid cure. The liner composition does not require precuring, as it is unblocked by preheating the liner and rocket casing sufficiently to receive to cast propellant.

Abstract: In solid propellant rocket motors the size of the flowfield defined by the bore continually increases as the solid propellant is consumed. As a result, the efficacy of a rigid baffle decreases through the burn. By making the baffle flexible, it can be deformed to fit the small initial geometry and its expansion due to inherent resilience naturally accommodates the enlarging geometry of the propellant bore. Since the baffle is flexible, it can participate in the oscillations and thereby alter frequency and mode structure and also introduce nonlinear behavior. Thus, pressure waves propagating in one direction around the propellant bore lift a flap of the baffle and pass through the clearance. Pressure waves propagating in the other direction around the bore, however, press the flap against the surface of the bore to restrict the passage of such waves. As a result, the flexible baffle acts as a "check valve" to limit wave motion.

Abstract: An elastomeric composition suitable for use as a rocket motor case insulation is disclosed. The composition comprises a vulcanizable elastomeric material and reinforcing polybenzimidazole polymer fibers in combination with a powder filler. A preferred embodiment utilizes polyisoprene as the elastomer and silica as the powder filler. These compositions have better erosion resistance than asbestos-reinforced compositions, and do not pose the environmental or safety risks associated with asbestos-reinforced insulation.

Abstract: An elastomeric composition suitable for use as a rocket motor case insulation is disclosed. The composition consists of a vulcanizable elastomeric composition and reinforcing aramid polymer fibers in combination with a powder filler. A preferred embodiment utilizes polyisoprene as the elastomer, KELVAR.RTM. fibers as the aramid polymer fibers, and silica as the powder filler.