Defence Science Journal

Burning rate of a solid rocket propellant depends on pressure and temperature. Conventional strand burner and Crawford bomb test on propellant strands was conducted to assess these dependent parameters. However, behaviour of propellant in rocket motor is different from its behaviour in strand form. To overcome this anomaly, data from static evaluation of rocket motor was directly used for assessment of these burningrate controlling parameters. The conventional empirical power law (r=a_oexp[π{T-T_o}]Pⁿ) was considered and a method was evolved for determination of pressure index (n) and temperature sensitivity coefficient (p) of burning rate for solid rocket propellants from static evaluation data. Effect of pressure index and temperature sensitivity coefficient on firing curve is also depicted. Propellant grain was fired in progressive mode to cover a very wide pressure range of 50 kg/cm² to 250 kg/cm² and propellant burning rate index was calculated to be 0.32 in the given pressure range. Propellant grain was fired at +35°C and.20°C temperatures and temperature sensitivity coefficient of burning rate was calculated to be 0.27% per°C. Since both the values were evaluated from realised static evaluation curves, these are more realistic and accurate compared to data generated by conventional methods.