Selection Of A Dynamically Scaled Lift And Thrust-Compounded Helicopter Configuration: Key Insights From Mach-Scaled Wind Tunnel Testing

Abstract

This paper presents a high-speed wind tunnel investigation of compound helicopter aeromechanics, focusing on the effects of various lift and thrust compounding strategies. Six rotorcraft configurations, incorporating various combinations of wings and a pusher propeller, were tested at advance ratios up to 0.7. The comprehensive dataset includes measurements of performance, blade structural loads, and hub vibratory loads. The test data were used to validate the University of Maryland Advanced Rotorcraft Code (UMARC) comprehensive analysis model. Results show that asymmetric half-wing lift compounding is most beneficial for maximizing high-speed lift-to-drag ratio due to a combination of wing-rotor lift sharing and rotor lift offset. Wing lift sharing significantly reduces blade structural and vibratory loads. At high advance ratios, achieving propulsive trim requires substantial propeller power, exceeding that of the main rotor. The objective of this research is to gain insight into the features of compound helicopters that enable efficient high-speed flight to inform future design decisions.