The Effect of Thrust and Drag Load on the Aeroelastic Behavior of Booster Systems

Abstract

INTRODUCTION T ONG, slender, multistage booster systems are subjected to ^ severe aeroelastic problems while they are traversing the lower atmosphere. These problems are associated (1) with the load magnification Avhich results from lateral structural deformations that occur due to the angle of attack which is imposed on the vehicle due to maneuvers, wind shear, and gusts, (2) with control problems which occur due to the changes in stability derivatives due to aeroelastic effects, and (3) with the basic booster-system, control-systems stability problem. This particular development is concerned with the effective reduction in lateral stiffness of the booster system which results from the column-type loadings on the vehicle. Although a well designed booster system will not fail as a column under the action of drag and thrust, the work done by these forces tends to reduce the apparent lateral stiffness of the booster system and hence increase the aeroelastic load magnification on a vehicle subjected to angle of attack and reduce the vibration frequencies of the booster system. This problem is likely to be more severe on solid-rocket multistage boosters with high acceleration and hence large design dynamic pressures and high acceleration forces than it is on large liquid booster systems with lower accelerations and lower design dynamic pressures.