直升机低速回避区计算分析

Prediction for Helicopter Low-Speed Height-Velocity Diagram

在可实现安全自转着陆的条件下,基于最小化回避区面积的思想分析预测了直升机低速高度——速度曲线。将直升机自转着陆表示成非线性最优控制问题,其状态方程使用发动机失效后增广的纵向三维刚体飞行动力学模型。采用直接转换和非线性规划的方法求解非线性最优控制问题。以UH-60直升机为例,计算了考虑1s操纵延迟的单发失效的低速高度-速度曲线,并给出了高悬停点、拐点和低悬停点的最优自转着陆过程,发现这些最优着陆过程与驾驶员的实际操纵程序一致。

The low-speed height-velocity （HV） diagram of a helicopter is analytically predicted based on the idea of minimizing the unsafe region of the HV diagram under the condition of realistic autorotation landing. The autorotation landing of the helicopter is formulated as a nonlinear optimal control problem. The state equations are described by an augmented longitudinal three-dimensional rigid-body flight dy- namic model. The nonlinear optimal control problem is solved by using direct transcription and nonlin- ear programming. For UH-60 helicopter, the analytical methodology is used to develop a reasonable es- timation of the one-engine-inoperative （OEI） low-speed HV diagram with 1 s pilot delay. The OEI auto- rotation landing procedures from the high hover point, knee point and low hover point are presented. The results show that the autorotation landings can be made by using normal pilot procedures.