Determination of launch-vehicle response to detailed wind profiles

Abstract

A method for predicting the response and bending loads experienced by a launch vehicle ascending through winds is presented. The horizontal wind-velocity profiles utilized by the method are those which are measured by a high-resolution technique, such as the smoke-trail method, and contain high-frequency gust components as well as the longer wavelength winds and wind shears. Motion in the pitch plane is considered, and structural bending and propellant slosh degrees of freedom are included in the analysis. A body-fixed coordinate system is used, and a variational principle is employed to derive the nonlinear differential equations of motion, which have time-varying coefficients. The equations are solved numerically by means of a Runge-Kutta procedure. The wind-disturbed flat-earth ascent trajectory is computed for a specified pitch program. The method is applied to a representative launch vehicle, and its response and dynamic loads are determined for flight through a typical wind profile.