This paper describes the effects of a composite coupled blade spar on the performance of a slowed RPM helicopter rotor in high speed edgewise flight. This study expands upon previous work that showed that antisymmetric composite coupling in the spar of a UH-60A-like rotor can provide a significant increase in the lift to drag ratio of a rotor when the RPM is reduced. The current analysis was performed using a full 3-D FEA based aeroelastic computational structural dynamics (CSD) solver, X3D, now with the inclusion of a freewake aerodynamics model. This was validated using extant UH-60A test data for high advance ratios. The current analysis shows that a blade with composite coupling can provide a maximum increase of in the lift to drag ratio of approximately 1.5 at 85% of the nominal RPM (NR) of 27 rad/s. However, close study of the strain in the rotor showed that the coupled rotor would unlikely be feasible at 27 rad/s as the axial strains felt by the rotor around the azimuth often exceed the allowable tensile strain of 6000 με. The details of what can be done to reduce the axial strain at all rotational speeds is part of an ongoing investigation.
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机译：本文介绍了复合材料耦合翼梁对高速RPM直升机转子在高速侧向飞行中的性能的影响。这项研究扩展了以前的工作，该工作表明，当降低RPM时，UH-60A型转子翼梁中的反对称复合耦合可显着提高转子的升阻比。当前的分析是使用基于完整3D FEA的气动弹性计算结构动力学（CSD）求解器X3D进行的，现在包含了自由苏醒的气动模型。使用现有的UH-60A测试数据对高进给比进行了验证。当前的分析表明，具有复合联轴器的叶片可以在27 rad / s的额定RPM（NR）的85％时，最大提升升阻比约1.5。但是，对转子中应变的仔细研究表明，耦合转子在27 rad / s时不太可行，因为转子在方位角周围感受到的轴向应变通常超过了6000με的允许拉伸应变。在所有转速下如何减小轴向应变的细节是正在进行的研究的一部分。
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