弹性飞机纵向稳定性分析

本文讨论弹性飞机的纵向稳定性问题。包括带与不带飞行控制系统两种情况。文中通过算例,分析讨论弹性飞机的总体运动模态和弹性运动振型之间的藕合以及弹性飞机本身和飞行控制系统之间的耦合。分析与计算表明,带有飞行的控制系统的飞机,其结构弹性变形运动对纵向稳定性的影响,即使对于算例中的“小”飞机,也是不可忽视的。飞机的弹性影响,不但会降低飞机的飞行品质,有时还会引起飞机与系统之间的耦合不稳定。

LONGITUDINAL STABILTY ANALYSIS FOR DEFORMABLE AIRCRAFT

Stability analysis for a deformable aircraft is one of the important subjects in the context of modern flight dynamics. This paper studies longitudinal stability of the deformable aircraft with and without flight control system, involving interaction between rigid motion modes and elastic vibration shapes of the deformable aircraft and between flight control system and airframe dynamics. From a numerical example it is shown that the effect of the structural distortion of the aircraft with flight control system on its longitudinal stability is quite considerable, and hence can't be neglected, although it belongs in a type of little plane. This influence would not only degrades flying qualities of the aircraft but also, sometimes, causes a new type of instability, that is unacceptable, referred to as coupling instability between flight control system and elastic structural dynamics. Thus, in stability analysis for an aircraft and designing its flight con rol system we have to consider the aircraft as deformable body, not rigid body, and use high-order small-disturbance equations, involving elastic degrees of freedom of the aircraft.