Developmental Challenges during Realization of High Progressivity Rocket Motor

Abstract

High Progressivity Rocket Motors (HPRM) are designed to eject an article out of a tube. High burn rate, progressive burn pattern, small burn time and low area expansion ratio are peculiarities of the motor. Initial 200ms of burn time are critical for functionality of motor whereas the test results showed deviations and pressure jumps in first 200ms. The performance further deteriorated when tested after conditioning at higher temperature. The motor test results were studied. Gas flow velocity characteristics inside individual port were studied and found to be on higher side even though the erosive burning constant ‘g’, [1], when calculated, was found to be within limit as specified for normal burn rate motors. Motor configuration was modified to reduce flow velocity and flow interaction. Modified configuration, when tested, was as predicted without any pressure jump. After comparing the flow characteristics, limits for velocity and ‘g’ values were reestablished.