Study On Evaluation Method Of Flight Quality Of Fixed-wing Aircraft In Lateral Direction

Safety has always been the most concerned topic in the aviation field.The flight quality of aircraft is closely related to flight safety.Flight quality is the inherent attribute of an aircraft.Aircraft with good flight quality are safe,good flying,and highly efficient for pilots,essentially,it should have good stability and maneuverability.The lateral-directional motion of aircraft is more complex,it usually occurs in coupling not in a separate form.If the aircraft that pilot drives have no good lateral-directional flying quality,the workload will be greatly increased,and dangerous state will be caused with improper handling.The modern aircraft dynamic model with great order needs to be reduced using the low-order equivalent principle.There are a lot of parameters to be identified in the low-order system,and needed to be optimized the matched using parameter identification technology.In this paper,the characteristics of lateral-directional motion and typical lateral-directional motion modes were firstly introduced,following by the methods and indicators of the evaluation of the lateral-directional flying quality,and evaluation and analysis of the flight quality using the low-order equivalent model.In parameter matching,two parameter identification methods,pattern search method and least squares method,are used to combine the results of matching with the quality evaluation criteria to evaluate the lateral-directional flying quality.At the same time,according to the mismatch value and the response curve of the matching system,the pattern search method and the least square method are compared and analyzed.Considering the mismatch value,the fitting effect of the least squares method is better than that of the pattern search method.According to step response curve,the fitting effect of the pattern search method is better.Through the analysis of the initial value dependent on the two methods,it is found that the least squares method is greatly dependence on the initial value,while the pattern search method is basically not affected by the initial value.Finally,the algorithm is optimized according to the characteristics of the pattern search method,to reduce computing time.