Research on accuracy assessment method of aerodynamic parameters identified from wind tunnel free-flight test data

The conventional Cramér-Rao lower bounds method is too optimistic to be a good quantitative assessment of the accuracy of aerodynamic parameters identified from the wind tunnel free-flight test data, considering the colored noise in the measurement data. This paper introduces a technique, that modified covariance matrix method, to process the residuals from a conventional maximum likelihood estimation to compute the accurate Cramér-Rao lower bounds for colored residuals. The modified accuracy assessment method is validated by Monte Carlo simulation and wind tunnel tests of pointed cone models with the semi-cone angle being 10°. The identified results indicate that the Cramér-Rao lower bounds calculated by the modified covariance matrix method are 3~5 times the quantity of the conventional. The modified results can be used as an accurate and impersonal assessment of the aerodynamic parameters estimated, which are consistent with the sample standard errors for the estimated parameters for colored residuals.