直升机吊挂飞行耦合分析

从气动导数和运动模态两个层面分析了直升机吊挂飞行中的耦合。首先,建立了直升机/刚性吊索/刚体吊挂物的全耦合飞行动力学模型。然后,计算了配平特性和频响特性,并与飞行试验数据对比验证了模型。最后,通过算例分析了直升机与吊挂系统的耦合。分析表明:直升机上吊挂点处的运动和作用力是形成相互耦合的关键。相互耦合使得直升机姿态对其角运动产生静稳定作用,直升机自身阻尼对整个系统产生作用,同时还增强了吊索摆角对吊索摆动的静稳定性。气动导数的变化削弱了直升机滚转和荷兰滚模态的稳定性,改善了吊挂系统两个单摆模态的动稳定性。直升机和吊挂系统的横航向耦合强于纵向耦合。

Coupling Analysis of Helicopter Flying with Slung Load

Couplings in helicopter flying with a slung load are analyzed via aerodynamic derivatives and natural motional modes. Firstly, a fully coupled flight dynamics model including a helicopter, an inelastic cable, and a rigid body slung load is established. Then, the trim properties and frequency response properties are calculated, and they are compared with flight test data for model validation. Finally, the mutual coupling between the helicopter and the slung load system is analyzed with an example. It shows that, the coupling is mainly caused by the motion of helicopter attachment point and the force acting on it. Because of the coupling, there is a stabilization effect of helicopter attitudes on its angular motion, the damping of helicopter itself has effects on both the helicopter & the slung load system simultaneously, and cable angles have a stronger stabilization ef fect on pendulum motion. As the aerodynamic derivatives change, the helicopter roll and Dutch roll modes are destabilized while two pendulum modes are stabilized. And the lateral-directional coupling is stronger than the longitudinal coupling.