Shin, Jong-YeobBalas, Gary J.Packard, Andrew K.2008-06-122008-06-122001Shin, J., Balas, G. J., and Packard, A. K. (2001). "Worst-Case Analysis of the X-38 Crew Return Vehicle Flight Control System." Journal of Guidance, Control, and Dynamics. 24(2), 261-269.https://hdl.handle.net/11299/37113Reprinted with permission of the American Institute of Aeronautics and Astronautics, Inc. See http://www.aiaa.org/content.cfm?pageid=2 for more information.A linear fractional transformation (LFT) model of the linearized equation of the lateral-directional axes of the X-38 crew return vehicle is developed to facilitate the analysis of flight control systems. The LFT model represents uncertainty in nine aerodynamic stability derivatives at a given flight condition with frequency-domain performance specifications. The X-38 LFT model combined with a controller at specific flight conditions is used to determine the aerodynamic coefficients that result in the worst-case performance and gain/phase margin of the closed-loop system. The objective is to verify that a given controller remains stable and achieves desired performance objectives for all predefined aerodynamic variations at select operating conditions along its flight trajectory.en-USArticle