This paper describes an investigation of the dependence of the performance of a propane burning Rijke pulse combustor upon the design of a recently developed tangential injection system. Two injection systems were investigated. In one the fuel and air were rapidly premixed before injection into a duct where most of the combustion occurred. In the second air and fuel were injected separately into the duct. In both cases the pulse combustor could be operated for air/fuel ratios a between 0.5 and 1.8. However, when the reactants were premixed, the combustor pulsations were dominated by the fundamental acoustic mode when α was low, and by its first harmonic when 1.1 < α < 1.6. In contrast, the fundamental acoustic mode dominated for all α when the reactants were injected separately. This suggests that this pulse combustor does not behave like a true Rijke tube, at least while operated in the premixed mode. In addition, exhaust flow analyses revealed that the combustor's combustion efficiency practically equals 100 percent when α is slightly above 1.0 and that NOxemissions equal several ppm for both rich and lean operation.