重型直升机-吊挂耦合系统闭环飞行品质分析

以CH-53A/D直升机为对象，研究重型直升机在增稳控制系统工作条件下外挂载荷运输飞行任务中的飞行品质问题。基于单质点吊挂假设和控制系统模型，建立了直升机-吊挂耦合闭环系统的非线性动力学模型。在该假设下，吊挂物引入了额外的自由度和约束，使方程增加为13阶的微分方程组。针对闭环状态下的耦合系统，进行了小扰动线性化处理，在此基础上进行了吊挂飞行操纵响应的时域特性和频域特性分析，参照军用旋翼飞行器驾驶品质要求（ADS-33E）的品质指标分析了吊挂物质量、吊挂绳长和直升机前飞速度对耦合系统飞行品质的影响。结果表明，吊挂物质量、吊挂绳长和前飞速度对于系统的时域特性以及各项操纵品质有不同程度的影响。 

Heavy helicopter-slung-load coupling system flying qualities in closed-loop state

Flying qualities of a heavy helicopter augmented with an automatic flight control system (AFCS) and flying with externally slung loads are investigated using the mathematical model of the CH-53A/D helicopter. A nonlinear dynamical model of helicopter-slung-load in closed-loop state was built based on single mass-point hypothesis and a control system model. Under this hypothesis, extra degrees of freedom and constraints were brought in by the consideration of the slung-load, which made the set of equations of motion increased to a 13-order one. The coupling system in closed-loop state was linearized under small-perturbed conditions. After this, the slung-load flight control response characteristics in both time and frequency domain were analyzed. The effect of slung-load mass, slung-load rope length and helicopter velocity on coupling system's flight quality was analyzed according to the handling qualities requirements for military rotorcraft indicated by ADS-33E. The final results show that the slung-load mass, slung-load rope length and helicopter velocity have varying degrees of impact on the time domain features and handling qualities of the coupling system.