Flight Test and Handling Qualities Analysis of a Longitudinal Flight Control System Using Multiobjective Techniques

This thesis addresses the application of optimal, multiobjective control theory control theory to flight control design for the approach and landing phase of flight. Five flight control systems were designed using classical, H2, H?, and Mixed H2/H? methods. The MATLAB＂ MUTOOLS＂ and AFIT MXTOOLS toolboxes were used to produce the optimal, multiobjective designs. These designs were implemented for flight test on the Calspan VSS I Learjet, simulating the unstable longitudinal dynamics of an F-16 type aircraft. A limited handling qualities investigation was performed. Model following was used in the design phase to meet handling qualities specifications. The designs were successfully implemented and verified on the Calspan Learjet prior to flight test. An unmodeled aircraft mode was discovered just prior to flight test that made three of the designs slightly unstable. However, all of the designs achieved Level II or better Cooper-Harper handling qualities ratings for the landing tasks performed illustrating that the optimal multiobjective methods used can give acceptable or better handling qualities.

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