地效翼船纵向稳定性与操纵性研究

纵向稳定性一直是地效翼船发展中面临的问题之一．以状态方程作为描述地效翼船的数学模型，研究了地效翼船在飞行状态下的纵向操纵性与稳定性．根据特征方程常数项系数，直接判定静稳定性，分析了主要气动导数对静稳定性的影响，认为Ｃｍｚ取接近于零的正数既有利于静稳定性又能简化静稳定性的判定条件．根据特征根，判定动稳定性，作出模态矢量图，并分析了三个模态的主要特性以及状态变量在各模态中的反映；分析了在从自由空间到地效区的过渡区域，忽略速度变化的四阶运动方程所得的动稳定性与五阶方程所得的动稳定性不一致的原因，指出在这一区域尤其要注意四阶方程的有效性．最后，从现代控制理论的角度提出纵向操纵性的研究思路

Longitudinal Stability and Maneuverability of Wing-in -Ground Effect Vehicles

Based on the state equation, this paper investigated the longitudinal stability and maneuverability of completely airborne WIGs. The constant term of the characteristic equation was criteria for static stability. Effects of major aerodynamic derivatives on static stability were discussed. C m z was recommended to be positive near to zero because it would be benefit to the stability and make the criteria simple. By the roots of characteristic equation the dynamic stability was judged and the vector figures of three modes were given. The characteristics of the three modes were analyzed. It is shown that the stability deduced from the 4th order equation which ignores the variation of velocity cannot ensure that deduced from the 5th order equation in the area from in ground effect (IGE) to out ground effect (OGE). It must be prudent to implement the conclusion of the 4th order equation in this area. In the end, the approach of studying maneuverability was presented from the point of modern control theory.