Aircraft Stability Derivatives Estimation from Flight Test Data

Abstract

The aim of this study is to develop a methodology for determining Aircraft Stability Derivatives from Flight Test Data. The standard linearized mathematical models shall be used as baseline mathematical models. However the stability derivatives which shall be referred to as parameters shall be estimated using different techniques and the results shall be compared to wind tunnel data. The methods used are Equation error method, Trust Region method and Output-error method. Basic methodologies of each method shall be discussed along with their discrepancies and also the results of each method shall be compared. However main focus shall be on Output error method as it does not guarantee convergence and Simplex method when used with Output error method forces the results to converge. This is the methodology adopted for this research work. Also when discussing the parameter estimation process some other questions shall be answered such as what are the inputs and outputs and how the aircraft is made to behave in such a way that the useful data is obtained. How the unknown parameters are estimated from measured flight test data and how good are the estimates. Also how the results shall be used and what exactly can we deduce from the results.