Advanced Modeling and Dynamic Stability Analysis of the Aerodynamic Control Surfaces of CALLISTO

Abstract

In order to assess future reusable launch vehicle concepts and their key technologies, the Centre National d'Etudes Spatiales (CNES), the Japan Aerospace Exploration Agency (JAXA), and the German Aerospace Center (DLR) are currently developing a vertical take-off vertical landing reusable launch vehicle demonstrator within the trilateral project CALLISTO. For attitude control during descent, aerodynamic control surfaces are used, which can be exposed to significant unsteady aerodynamic loads. Therefore, the aerodynamic control surfaces must be designed to avoid any unstable behavior related to a coupling between structural deformation and aerodynamic flow in conjunction with the servo-loop. For this purpose, dynamic stability studies have been performed using a condensed Finite Element model to represent the structural dynamics and the Doublet Lattice Method to compute the unsteady aerodynamics within the subsonic flight regime. The time-domain integration of the unsteady aerodynamic matrices is performed by Rational Function Approximation, which are then used to obtain state-space matrices based on the p-method for each flight condition. By evaluating the eigenvalues of the state-space matrices, the dynamic stability behavior is assessed. The objective of this paper is to present the modeling strategy and systematic assessment of the dynamic stability behavior of CALLISTO's aerodynamic control surfaces.