The application of a modified stepwise regression (MSR) method to the estimation of aircraft stability and control derivatives

摘要

A programme of research has now been completed in the College ofAeronautics (CoA) at Cranfield University to investigate the use of aModified Stepwise Regression (MSR) procedure. The technique wasapplied to data obtained from a small BAe Hawk aircraft model flown ina dynamic wind tunnel facility in order to try to estimate theaerodynamic stability and control derivatives of the model.A variety of preliminary experiments were performed to enable thestatic stability of the Hawk model to be evaluated and estimates for alimited number of aerodynamic derivatives were obtained. The initialexperiments also allowed data acquisition and processing systems to bedeveloped. Experience of flying and controlling the model in the windtunnel was gained.The MSR technique was implemented in the form of a FORTRAN 77software program. Computer simulations of both the full scale Hawkaircraft and scaled wind tunnel model were written. MSR was found toproduce perfect derivative estimates when using noise-free dataproduced by the aircraft simulations.Various mathematical models were produced to represent the reducedorder small perturbation equations of motion for the Hawk in the windtunnel. Different methods for re-constructing the perturbationvariables were implemented. Although the MSR procedure did not performoptimally with experimental data, some insight into both the MSR methodand the practical difficulties associated with using a small dynamicrig has been gained.