This report describes an improved linear analytical model and A digital program developed for the calculation of axisymmetric launch vehicle steady-stage response to applied axisymmetric sinusoidal loads. The detailed computer programming manual for the digital program is contained in Volume II of this report. In the evaluation of launch vehicle behavior, it is necessary to study the response of the entire vehicle to a wide variety of dynamic loadings to insure the structural integrity and stability of the system. Much effort has already gone into the development of techniques to calculate the vehicle response to lateral and longitudinal loadings using distributed and lumped spring -mass models and techniques for theoretical and empirical modeling of the vehicle behavior. However, experimental data indicate that these procedures are unsatisfactory in several respects. For example, accurate representation of important structural shell characteristics and realistic coupling of the fluids with the detailed structural behavior of tank walls and bulkheads are omitted.