飞翼式柔性飞机纵向动力学建模与稳定性分析

柔性飞行器在飞行过程中容易发生大变形,这种变形将导致机翼甚至整个飞行器的气动弹性和飞行动力学特性发生变化,特别是对稳定性的影响.本文采用三段式刚体假设,以变上反角的方式来描述机翼的展向弯曲变形,对一类飞翼式柔性飞行器进行了纵向动力学建模,并进一步分析了操纵面、推力和迎角与上反角的关系,以及变上反角对飞行稳定性的影响.结果表明,在保持速度和高度不变的情况下,稳定性受上反角的影响比较明显,如果变形过大,飞行器将变为动不稳定,且短周期模态不能保持.因此,为了保持飞机的纵向稳定性,必须要控制飞机的变形.

Longitudinal danamic modeling and stability analysis of very flexible flying wings

The Very Flexible Aircraft (VFA) may result in large elastic deformation during flight, which has a great influence on aero elastic properties and flight dynamics characteristic of the aircraft, especially on its stability. Based on the three stage rigid hypothesis, the longitudinal dynamic model is developed, where the dihedral angle is employed to describe the wing bending deformation. The relations among the control surface, thrust, angle of attack and dihedral angle are further examined, with emphasis on the influence of dihedral angle on the flight stability. The results show that the dihedral angle has a great effect on the stability for unchanged flight speed and height. Excessive deformation may lead to dynamic instability. In order to maintain the longitudinal stability, it is necessary to control the deformation of the VFA.