Wind Tunnel Test of Optimal Rotor Blade Tip for a Winged Compound Helicopter at High Advance Ratio

Aerodynamic characteristics of optimized blade tip geometries for flight at high advance ratio are identified by wind tunnel tests conducted in October 2020. Several types of high-speed compound helicopters are in the development process today after the successful technology demonstrations. JAXA has been studying a high-speed compound helicopter for emergency medical service since it is expected to help save lives significantly in Japan. In this study, optimized blade shapes are invented, whose high-speed performance is twice as high as a conventional blade shape while maintaining hovering performance. In this paper, an optimized rotor blade with a swept-back angle is evaluated highest among optimized rotors and UH-60A rotor in the items of hover performance, high-speed performance, reduction effect of rotor drive power, control hydraulic system output reduction effect, and static aerodynamic stability. Thus, it is concluded that an optimized rotor blade with a swept-back angle is the most practical from the viewpoint of the aerodynamic characteristics of the rotor blade tips.