Internal Ballistics Considerations of Nozzleless Rocket Motors

Abstract

Thefundamentalsoftheinternalballisticsofsolid-propellantnozzlelessrocketmotorshavebeenstudiedtheoreticallyandexperimentally.Aimedatthemajorbasicaspects,thetheoreticalanalysisconsistedofaquasi-steady-state one-dimensionale ow ofa perfect gas in a constant-area port, assuming a uniform burning rate along the grain asa resultofthecompensating effectsoferosiveand pressure-dependentburning contributions.Thesimplie edanalysis has beenfound to be an excellent tool to exhibit fundamental characteristics. Itrevealed that thetheoreticalachievable specie c impulse in a nozzleless rocket cannot exceed approximately 86% of its value in an adapted-nozzle rocket operating at the same average chamber pressure. An experimental parametric study using cylindrical propellant grains has demonstrated good agreement with the major parameters addressed in the theoretical analysis, indicating that the assumption of a uniform burning rate is a realistic approximation.