Research on Optimal Attitude of Large Deformation Airplane in Full‑Scale Aircraft Static Test

The accuracy of the full-scale aircraft static tests is greatly influenced by the aircraft attitude. This paper proposes an aircraft attitude optimization method based on the characteristics of the test. The aim is to address three typical problems of attitude control in the full-scale aircraft static tests： （1） The coupling of rigid-body displacement and elastic deformation after large deformation， （2） the difficulty of characterizing the aircraft attitude by measurable structure， and （3） the insufficient adaptability of the center of gravity reference to complex loading conditions. The methodology involves the establishment of two observation coordinate systems， a ground coordinate system and an airframe coordinate system， and two deformation states， before and after airframe deformation. A subsequent analysis of the parameter changes of these two states under different coordinate systems is then undertaken， with the objective being to identify the key parameters affecting the attitude control accuracy of large deformation aircraft. Three optimization objective functions are established according to the test loading characteristics and the purpose of the test： （1） To minimize the full-scale aircraft loading angle error， （2） to minimize the full-scale aircraft loading additional load， and （3） to minimize the full-scale aircraft loading wing root additional bending moment. The optimization calculation results are obtained by using the particle swarm optimization algorithm， and the typical full-scale aircraft static test load condition of large passenger aircraft is taken as an example. The analysis of the results demonstrates that by customizing the measurable structure of the aircraft as the observation point for the aircraft attitude， and by obtaining the translational and rotational control parameters of the observation point during the test based on the optimization objective function， the results are reasonable， and the project can be implemented and used to control the aircraft’s attitude more accurately in complex force test conditions.