弹性飞行器纵向稳定性问题

 本文研究考虑气动弹性时飞行器的纵向稳定性问题。首先由弹性飞行器的纵向扰动运动方程出发,导出了便于计算采用的弹性飞行器纵向扰动方程的标准矩阵形式,作出作为控制对象的弹性飞行器在考虑一阶、二阶及三阶振型时的传递函数;其次分析气动弹性对整个飞行器系统的稳定性的影响,并提出对飞行器自动驾驶仪敏感元件的可能合适位置选择的要求。最后还建立了计算气动弹性对飞行器气动导数值影响的理论式。

LONGITUDINAL STABILITY ANALYSIS OF ELASTIC VEHICLES

The longitudinal stability of elastic vehicles is studied with the effect of aeroelasticity considered. The transfer functions of an elastic vehicle with the first, second and third elastic modes taken into account are derived from the equations of its longit.udinal disturbance motion. The formulas obtained can be easily used on computers and extended to cases with higher elastic modes.The effect of aeroelasticity on the longitudinal stability of a vehicle is investigated, and a method for choosing the proper position of the gyro is proposed. Finally, the aeroelastic effect on the values of aerodynamic derivatives is estimated.The conclusions drawn from the analysis are as follows:（1） The aeroelastic effect on the stability of a vehicle is mainly due to the effect of the first elastic mode, while the effects of higher ones are relatively of less importance.（2） From the viewpoint of securing stability, the gyro should be located behind the valley of the ith elastic mode if the generalized force Fiδ and control moment Mδ for unit control deflection possess the same sign, and ahead of the valley if Fiδ, and Mδ possess opposite signs. In the case of the investigated vehicle the gyro should be located behind the valley of the first elastic mode and ahead of the valley of the second one.（3） The elastic aerodynamic coefficients for the investigated vehicle have values about 10-20% different from those of the corresponding rigid, vehicle.