最大巡航速度和最大平飞速度是共轴刚性旋翼高速直升机最重要的性能指标之一，其特殊的构型和工作方式导致其旋翼桨毂载荷问题突出。高速飞行俯仰姿态、平尾安装角、横向周期变距差动和旋翼转速等配平状态和设计参数对需用功率、桨毂载荷和操稳特性等具有显著的非线性交叉耦合影响，本文在考虑飞行品质相关要求下开展了高速飞行配平策略优化设计方法研究，为获得飞行性能和桨毂载荷综合最优配平策略提供设计手段。首先，基于共轴刚性旋翼高速直升机非线性飞行动力学模型，分析了不同配平策略设计参数对配平特性、稳定性和操纵性等影响规律。在此基础上，将配平策略设计问题描述为数学优化问题。最后，为提高优化计算效率和降低优化失败风险，基于Kriging代理模型开展配平策略优化设计研究。优化结果表明：在最大巡航速度和最大飞行速度下，相比基准配平策略，在最优功率配平策略下需用功率分别降低5.7%和6.9%；在最优桨毂力矩配平策略下桨毂力矩载荷分别降低55.6%和55.2%；在需用功率和桨毂力矩综合最优策略下需用功率分别降低1.8%和3.1%，桨毂力矩载荷分别降低49.4%和46.2%，验证了本文提出的配平策略优化设计方法的有效性。
Maximum cruise speed and maximum level flight speed are among the most important performance indexes for coaxial rigid rotor high-speed helicopters, whose special configuration and operating mechanism lead to serious rotor hub loading problems. The trim strategy design parameters, such as high-speed flight pitch attitude, horizontal tail installation angle, differential lateral cyclic pitch, and rotor speed, induce significant cross-coupling effects on the required power, rotor hub loads, controllability, and stability. In this paper, the optimal design method of the trim strategy for high speed flight is con-ducted under the handling qualities requirements. The aim is to provide a methodology for achieving the optimal trim strategy that achieves the best trade-off between flight performance and rotor hub loads. Firstly, based on the nonlinear flight dynamics model of the coaxial rigid rotor high-speed helicopter, the impact of design parameters of different trim strategies on the trim characteristics, stability, and controllability was analyzed. Subsequently, the trim strategy design problem was described as a mathematical optimization problem. Lastly, in order to improve optimization computational efficiency and reduce the risk of optimization failure, the trim strategy optimization design was conducted based on the Kriging surrogate model. The optimization results indicate that, at the maximum cruise speed and maximum flight speed, the required power is reduced by 5.7% and 6.9% under the optimal power trim strategy compared to the baseline strategy; the rotor hub moment is reduced by 55.6% and 55.2% under the optimal rotor hub moment trim strategy; the required power is reduced by 1.8% and 3.1%, and the hub moment load is reduced by 49.4% and 46.2% under the trim strategy that trade-off between power and hub moment. These results validate the effectiveness of the proposed optimization de-sign method for trim strategy.
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