A verified model for prediction of helicopter performance is used to investigate the effect of individual blade pitch control on the flight performance of helicopters. The influence of the harmonic number, amplitude, and phase angle of the pitch control on the rotor power required and lift to drag ratio of the UH-60A helicopter is analyzed. The distribution of the angle of attack and drag coefficient over the rotor disk are shown to analyze the physical mechanism of performance improvement by individual blade pitch control. The results indicate that the second-and third-order harmonic individual blade pitch control can reduce the power required and increase the helicopter lift to drag ratio in high speed flight, but the effect is relatively limited. For the helicopter with larger take-off weight, the effect can be enhanced. The performance improvement achieved by the second-order harmonic coupled with the third-order harmonic individual blade pitch control is better than that by a single harmonic input, and the maximum power reduction is 4.5%. The fourth-order harmonic individual blade pitch control does not exhibit the potential in performance improvement. In high speed flight, the blade pitch control can reduce the angle of attack in the retreating side and delay the stall, and then the drag coefficient and rotor power required can be reduced to improve the flight performance of the helicopter.
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