A CASE STUDY ON FLIGHT FAILURE OF A SUPERSONICSPINNING ROCKET AND SUCCESSFUL PROBLEMSOLVING THROUGH MODAL ANALYSIS TESTING

摘要

This paper presents the analytical and experimental studies carriedout on the structural dynamics of a spinning flexible supersonic freeflight rocket launched from a Multi Barrel Rocket Launcher (MBRL)System. This Rocket was exhibiting typical failure in the flight nearto burn out stage. Detailed Strength of design and structural integrityanalysis showed adequate factor of safety in the design. This resultcoupled with literature survey on spinning structures motivated theauthors to study the structural dynamic behavior of the rocket withspin. The study showed that natural frequency reduced with spin forthis slender rocket with high slenderness ratio of 23 leading toinstability near to maximum spin rate measured through on boardtelemetry. Based on the study results the cant angle of the fins andhence spin rate were reduced with adequate frequency margin. Thismodification lead to successful flights. The paper presents the majorfindings of this study in a systematic manner.