农林飞机近地作业飞行的纵向稳定特性

Longitudinal stability of an agriculture aircraft during low-altitude flight operation

分析了农林飞机近地作业飞行的纵向气动力特性,讨论了存在地面效应时的纵向静稳定性准则及主要气动导数对静稳定性的影响;根据地效区内飞机的五阶小扰动运动线化方程,计算了农林飞机近地作业飞行的模态特性,并运用特征矢量研究了各模态中起主要作用的运动变量;利用Routh判据对农林飞机近地作业飞行的纵向动稳定性进行了分析,通过简化推导了存在地面效应时保证飞机动稳定性其重心的位置要求.研究结果表明,农林飞机近地作业飞行时地面效应对其纵向气动特性及稳定性的影响不可忽略.

The longitudinal aerodynamics of agriculture aircraft during low-altitude flight operation was analyzed. And the longitudinal static stability criterion in ground effect was discussed, including the effects of major aerodynamic derivatives on longitudinal static stability. By the five-order small-disturbance linear equation in ground effect, the influence on the mode properties of agriculture aircraft during low-altitude flight operation was computed. And the approach of mode vectors was used to investigate the dynamic stability, which is useful to understand the major variables acting in different modes. The longitudinal dynamic stability was analyzed by Routh＇s criteria. To ensure dynamic stability, the favorable position of the center of gravity was deduced by approximations. The results show that the longitudinal aerodynamics and stability influenced by ground effect should not be ignored for the agriculture aircraft during low-altitude flight operation.