螺旋桨飞机近地飞行时的纵向稳定性

Longitudinal Stability of Jet-Propeller Aircraft During Low-Altitude Flight

根据某型飞机气动试验数据,分析了地面效应和螺旋桨滑流增量对飞机静稳定性的影响;根据小扰动线性化方程,计算了不同飞行条件下的飞机模态特性,分析了地面效应和螺旋桨滑流对飞机动稳定性的影响。结果表明：地面效应将使飞机纵向运动频率增加,而阻尼比降低;地效区内滑流增量使短周期震荡频率和阻尼比均增加,也使长周期阻尼比增加,而对长周期模态频率的影响不大;无地效时,滑流将使长短周期两种模态的频率均降低,而阻尼比增加。

The aerodynamics of propeller plane during low-altitude flight was analyzed. And the effect of ground and propeller airflow to the static stability and aerodynamics derivatives was discussed. Through the small-disturbance linear equation, the mode properties with ground effect and propeller airflow was computed, meanwhile the effect of ground and propeller airflow to the mode properties was analyzed. The result shows that the ground effect will increase the frequency of the period movement, and decrease the damp. In the effect of ground the propeller airflow will increase the damp and the frequency of the short-time mode. In the same time, the propeller airflow in the effect of ground will increase the damping of the long-time mode, and change the frequency of it slightly. Without the ground effect the airflow will decrease the frequency and increase the damping in both of the two modes