Flight Test of Optimal Inputs and Comparison with Conventional Inputs

Abstract

A technique for designing optimal inputs for aerodynamic parameter estimation was flight tested on the F-18 High Alpha Research Vehicle. Model parameter accuracies calculated from flight-test data were compared on an equal basis for optimal input designs and conventional inputs at the same flight condition. In spite of errors in the a priori input design models and distortions of the input forms by the feedback control system, analysis of data generated by the optimal inputs revealed lower estimated parameter errors compared with conventional 3-2-1-1 and doublet inputs. In addition, the tests using optimal input designs demonstrated enhanced design flexibility, allowing the optimal input design technique to use a larger input amplitude to achieve further increases in estimated parameter accuracy without departing from the desired flight-test condition. This work validated the analysis used to develop the optimal input designs, and demonstrated the feasibility and effectiveness of the optimal input design technique.