Interest in the coaxial compound helicopter (CCH) has been increasing in the civil aviation and engineering community for its high-speed and high-maneuverability features, and is likely to continue to do so for the foreseeable future. Since the control in CCH is totally different from the conventional helicopter, the redundant control strategy design is one of the biggest challenges. In this study, the CCH model based on XH-59A is built to investigate the impact of the propeller and the elevator on the flight performance. Four trim strategies with different objectives are proposed and then compared to find the optimal control allocation. A heuristic descent search method is applied to search the optimal velocity at which the propeller and the elevator are engaged. A significant improvement of power required at medium- and high-speed with acceptable rotor airloads increment was found by using the Hybrid Trim strategy in the speed range of 0–100 m/s, with regard to a pre-configured pitch angle schedule. The corresponding control variables obtained located in a reasonable control range, with a maximum power reduced of 13% at 100 m/s, which showcase the potential of the Hybrid Trim strategy.

民用航空和工程界对同轴复合直升机 (CCH) 的兴趣一直在增加，因为它具有高速和高机动性的特点，并且在可预见的未来很可能会继续这样做。由于CCH中的控制与传统直升机完全不同，冗余控制策略设计是最大的挑战之一。本研究建立基于XH-59A的CCH模型，研究螺旋桨和升降舵对飞行性能的影响。提出了四种不同目标的修剪策略，然后进行比较以找到最佳控制分配。采用启发式下降搜索方法搜索螺旋桨和电梯啮合的最佳速度。通过在 0-100 m/s 的速度范围内使用混合配平策略，在预配置的俯仰角计划中，发现在中速和高速时所需的功率显着提高，并且转子空载增量可接受。得到的相应控制变量位于合理的控制范围内，最大功率在 100 m/s 时降低了 13%，展示了 Hybrid Trim 策略的潜力。