Stage Separation System Design and Dynamic Analysis of Isro Launch Vehicles

Abstract

Stage separation system design and dynamic analysis is an integral part of the design and development of any multistage launch vehicles. Lower stage separation especially, strapon separation qttracts specific attention if the separation occurs in the dense atmospheric region as aerodynamics plays a major role in design of separation system. FLSC is used to seyere the stages and spring thrusters or side rockets are used to provide required jettisoning velocity depending on the stage inert mass. In the booster stage separation, FLSC based severing together with retro-rockets or VIS separation systems are used to provide separation velocity. In VIS the continuing stage jet impingement force is used to provide required jettisoning velocity for the spent body. In heat shield separation, the impulse generated by Zip cord mechanism excites the rigid body and flexible modes of the heat shield. By superimposing flexible response over the rigid body motion dynamic analysis were carried out. The upper stages and spacecraft separation systims use clamp band joints with pyro assisted release mechanisms together with spring thrusters as jettisoning devices. Spring thrusters were used for spacecraft separation due to the requirement of low shock level and contamination free environment. In this paper, an attempt is made to expLain the experiences gained over the design, development, 6-D dynamic simulation studies and the improvements carried out for the four-generation Indian Launch Vehicles development programme namely SLV, ASLV, PSLV and GSLV in the last two decades.