临近空间太阳能飞行器横航向稳定性

临近空间太阳能飞行器的横航向气动导数和质量特性与常规飞行器存在显著差异,其横航向模态具有不同于常规飞行器的特点。理论分析表明,临近空间太阳能飞行器滚转交感动导数较大,偏航阻尼动导数较小,导致螺旋模态发散;航向气动阻尼力矩和惯性力矩之比较大,因而荷兰滚模态阻尼比较大。为解决常规线性化动力学模型无法体现风场影响的问题,以地速在机体坐标系中的投影作为状态变量,建立了考虑风场影响、适用于地速为0 m/s状态的线性化横航向动力学模型。利用此模型分析了临近空间太阳能飞行器在水平风和垂直风中的横航向稳定性。分析结果表明,稳定风场对横航向模态特征根无影响,但会导致横航向模态特征矢量发生改变。建立的动力学模型可用于此类飞行器的动力学分析和仿真。

Lateral-directional stability of near-space solar-powered aircraft

The lateral-directional aerodynamic derivatives and mass characteristics of the near-space solar-powered aircraft are very different from conventional aircraft. The characteristics of its lateral-directional modes differ from conventional aircraft. Theoretic analysis shows that the large rolling-moment-due-to-yaw-rate derivative and small yawing-moment-due-to-yaw-rate derivative of the near-space solar-powered aircraft result in the divergent spiral mode. Moreover, the ratio of aerodynamic damping moment to inertia moment is large, causing the high damping ratio of the Dutch roll mode. In order to solve the problem that the impact of wind could not be represented in conventional linear dynamic model, a linear lateral-directional dynamic model, which considers the impact of wind and is applied to the 0 m/s ground speed state, is established by employing the projection of ground speed onto body coordinate system as the state variable. The lateral-directional stabilities of the near-space solar-powered aircraft in horizontal and vertical wind are analyzed using the model. The analysis indicates that stable wind field has no impact on eigenvalues of lateral-directional modes, while it leads to different eigenvectors. The established dynamic model could be used for dynamic analysis and simulation of this kind of aircraft.