Performance Analysis of the Slowed-Rotor Compound Helicopter Configuration

Abstract

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 and the McDonnell XV-1 demonstrator to establish the capability to model rotors in such flight conditions. The predicted performance of a slowed-rotor vehicle model based on the CarterCopter Technology Demonstrator is examined in detail. An isolated rotor model and a model of a rotor and wing are considered. Three tip speeds and a range of collective pitch settings are investigated. A tip Mach number of 0.2 and zero collective pitch are found to be the optimum condition to minimize rotor drag. Performance is examined for both sea level and cruise altitude conditions.