Degradation in the nozzle materials of subscale motor in a static firing test

Abstract

This work presents the study conducted at the Institute of Space and Aeronautics, an organization of the Department of Science and Aerospace Technology (DCTA-IAE, in the Portuguese acronym), to investigate the erosion of the thermal protection, nozzle throat insert, and thermal protection of the convergent manufactured in EPDM rubber of the convergent section of the nozzle, during the sub scale solid propellant rocket motor static firing test. During this study, tests were conducted in order to evaluate the performance of the nozzle ablation of insert material and also of the rubber to protect thermally the metallic motor case and also to the convergent, in addition to verifying the functionality of the adhesion between the propellant and the rubber. For the work herein presented, specifically, only the results inherent to the evaluation of the nozzle insert material and the deterioration of the EDPM rubber in the interface with the conducted in order to evaluate the performance of nozzle ablation of insert material, and also of the rubber to protect thermally the metallic motor case and also to the convergent, in addition to verifying the functionality of the adhesion between the propellant and the rubber. For the work herein presented, specifically, only the results inherent to the evaluation of the nozzle insert material and the degradation of the EDPM rubber in the interface with the graphite material insert for a test time of 56 s will be analyzed. After the tests, non-conformities were detected in components of the engine that subsequently led to a careful analysis of the reasons, as well as to the implementation of solutions for the redesign of components with the aim of improving the safety and assuring the structural integrity of the rocket engine for further tests.