Validation of a mathematical model for Bell 427 Helicopter using parameter estimation techniques and flight test data

Certification requirements, optimization and minimum project costs, design of flight control laws and the implementation of flight simulators are among the principal applications of system identification in the aeronautical industry. This document examines the practical application of parameter estimation techniques to the problem of estimating helicopter stability and control derivatives from flight test data provided by Bell Helicopter Textron Canada.;The coupled, 6 DoF model does not include the high frequency main rotor modes (flapping, lead-lag, twisting), yet it is capable of modeling rotorcraft dynamics fairly accurately as resulted from the model verification. The identification results demonstrate that MMLE3 is a powerful and effective tool for extracting reliable helicopter models from flight test data. The results obtained in frequency-domain approach demonstrated that CIFERRTM could achieve good results even on limited data.;The purpose of this work is twofold: a time-domain application of the Output Error method using the Gauss-Newton algorithm and a frequency-domain identification method to obtain the aerodynamic and control derivatives of a helicopter. The adopted model for this study is a fully coupled, 6 degree of freedom (DoF) state space model. The technique used for rotorcraft identification in time-domain was the Maximum Likelihood Estimation method, embodied in a modified version of NASA's Maximum Likelihood Estimator program (MMLE3) obtained from the National Research Council (NRC). The frequency-domain system identification procedure is incorporated in a comprehensive package of user-oriented programs referred to as CIFERRTM.