组合式飞行器多体动力学建模与飞行力学特性

To precisely and completely describe the location and shape of the combined multibody aircraft, a dynamic modeling method of the 8 DOF combined three-body aircraft reflecting relative rolling motion is proposed using Lagrange's equations with quasi-coordinates. The aerodynamic database of the combined multibody aircraft system considering the aerodynamic coupling effect is established by the CFD method. The accuracy of the model is verified by comparing the model with ADAMS software through a numerical example. Based on this, the trim scheme and flight dynamic characteristics of the aircraft in different trim states are studied. The stability augmentation control is studied based on the cascade PID control method. The results show that the established model effectively reflects the relative motion of the combined aircraft. With the given trim scheme and flight condition, the aircraft of this configuration has two trim states of "symmetrical lower inverse" and "symmetrical upper inverse", and the static stability of relative rolling motion in the two states is quite different. In addition to the traditional flight mechanics mode, there are 4 new motion modes dominated by relative rolling motion, which can be divided into composite symmetric motion and composite antisymmetric motion according to the motion characteristics. To address the problem that the aircraft with this configuration cannot keep stable flight for a long time without control, the stability augmentation control scheme is reasonable and effective, which can quickly stabilize the divergent flight mechanics system. The proposed modeling method and stabilization control scheme can provide guidance and reference for the design and analysis of multibody aircrafts.