Abstract
For the modern advanced aircraft, a variety of complex control systems have been adopted, which makes the order of the plane motion equation up to about tens of orders. It is must to reduce the order to evaluate the flight quality. To obtain the equivalent low order system, the least square method and maximum likelihood method are used to match the high order motion system of a certain aircraft in this paper. By analyzing the response characteristics of high and low order systems, the rationality of the matching results are demonstrated and the characteristics of the algorithm are analyzed, and some optimization is made. Finally, the flight quality of the aircraft is evaluated with several evaluating indicators, and a comparative analysis is made to discuss how to make a more scientific evaluation of the flight quality of the aircraft.