UAH Combustion Bomb For solid propellant regression rate determination, the PRC program utilizes a pulse-echo ultrasonic burn rate measurement technique. An ultrasonic transducer in conjunction with a closed combustion bomb, shown at left, allows samples of solid propellant to be burned while simultaneously raising the pressure. Thus, the determination of the burn rate of a sample over a wide range of pressures with a single test is possible. The combustion bomb is also equipped with pressure transducers and thermocouples for pressure and temperature data. In addition, the facility has a temperature conditioning chamber which may be used to thermally soak propellant samples prior to testing in order to determine burn rate temperature sensitivity. The baseline measurements for the research discussed in this paper rely on a burn rate determined from a device known as an Electronic Device for Ultrasonic Measurement (EDUM) developed by the Office National d’Etudes et de Recherches Aerospatiales (ONERA) in France. Solid rocket propulsion is a strategic focus of the UAH Propulsion Research Center (PRC). Since 1991, about 15% of the PRC funded research projects and publications have focused on solid propulsion. The PRC has established an internationally-recognized experimental capability to measure steady and unsteady burning rates of solid propellant samples at operational pressures and temperatures. Research has also included theoretical modeling of solid propellant combustion. Over this time, we have relied on a few external suppliers for solid propellant samples because of the hazards and expertise required to manufacture them. Related Information: Dr. Robert A. Frederick, Jr. was the United States Representative, appointed by U.S. Air Force to represent the U.S. Air Force and the U.S. Navy to the NATO Advisory Group for Aerospace Research and Development (AGARD), Propulsion and Energetics Panel, Solid Propellant Burning Rate Measurements, 1996–2001. Related Publications: Frederick, R.A., Jr. and Komai, I., “Propellant Design Relationships for Throttled Gas Generators,” AIAA Journal of Propulsion and Power, Vol. 12, No. 3, pp.614-617, 1996,. Frederick, R.A and Greiner, B.E., “Laboratory-Scale Hybrid Rocket Motor Uncertainty Analysis,” AIAA Journal of Propulsion and Power, Vol. 12, No. 3, 6, pp.605-611, 1996. Frederick, R.A., “Measuring the Regression of a Burning Solid Propellant,” Review of Scientific Instruments, Vol. 67, No. 8, pp. 2903-2909, 1996. Di Salvo, R., Dauch, F., Frederick, R.A. Jr., and Moser, M.D, “Direct Ultrasonic Measurement of Solid Propellant Ballistics,” Review of Scientific Instruments, Vol. 70, No. 11, pp. 4416–4421, 1999. Rasmussen, B., and Frederick, R.A., Jr., “A Nonlinear Model of Composite Solid Propellant Combustion,”AIAA Journal of Propulsion and Power, Vol. 18, No. 5, pp. 1086–1092, 2002. Greiner, B., Frederick, R.A., Jr., and Moser, M.D., “Combustion Effects of C60 Soot in AN Propellants,” AIAA Journal of Propulsion and Power, Vol. 19, No. 4, pp. 713-715, 2003. Kohga, M., Frederick, R.A, Jr., and Moser, M.D., “Ultrasonic Properties of Propellant Ingredients,” AIAA Journal of Propulsion and Power, Vol. 20, No. 1, pp. 135-140, 2004. Di Salvo, R., Frederick, R.A., Jr., and Moser, M.D., “Pulse-echo Measurements of Unsteady Propellant Deflagration,” Review of Scientific Instruments, Vol. 76, No. 1, pp. 0065112.1 – 0065112.8, 2005. Frederick, R.A., Jr., Whitehead, J., Knox, R., and Moser, M.D., “Regression Rates Study of Mixed Hybrid Propellants,” AIAA Journal of Propulsion and Power, Vol. 23, No. 1, pp. 175–180, 2006. Whitehead, J.J. and Fredrick, R.A., Jr., “Predicting Hybrid Propellant Regression Rate Using Response Surfaces,” AIAA Journal of Propulsion and Power, Vol. 25, No. 3, 2009, pp. 815-818.