Characterisation of RB74 Sidewinder

The scope of this work has been to characterize the propellant in RB74 Sidewinder rocket motors. The tensile strength and burn rate of five motors have been measured. The specimens were prepared by Exova and delivered to FOI prior to testing. The propellant in one of the tested motors contained a CTPB-based binder while the other four were based on an HTPB-based binder. The mechanical properties were analysed by tensile testing at three different temperatures, -57°C, -22°C and 77°C. There were larger variations in the results from the -57°C measurements compared to the results from the other temperatures. The burn rate was measured at three temperatures, -40°C, 21°C and 77°C, and two pressures, 6 and 8 MPa. The CTPB-based propellant, motor 10-21-13700 (FOI batch FP11010), burned without problems at all three temperatures. When measuring at -40°C on samples from the motors based on HTPB-based propellant, some samples stopped burning during the experiment. For motor 10-30-20546 (FOI batch 11006), this phenomenon could be seen for all the samples analysed at -40°C.