Performance Analysis of the Slowed-Rotor Compound Helicopter Configuration

U.S. Army Research Laboratory, Hampton, VA
Journal of the American Helicopter Society 03/2009; 54(2):22002-1-22002-12. DOI: 10.4050/JAHS.54.022002

ABSTRACT The calculated performance of a slowed-rotor compound aircraft, particularly at high flight speeds, is examined.Correlation of calculated and measured performance is presented for a NASA Langley high advance ratio test to establish the capability to model rotors in such flight conditions. The predicted performance of an isolated rotor and a wing and rotor combination are examined in detail. Three tip speeds and a range of collective pitch settings are investigated. A tip speed of 230 ft/s and zero collective pitch are found to be the best condition to minimize rotor drag over a wide speed range. Detailed rotor and wing performance is examined for both sea level and cruise altitude conditions. Rotor and wing power are found to be primarily from profile drag, except at low speed where the wing is near stall. Increased altitude offloads lift from the rotor to the wing, reducing total power required.

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