Experimental Investigation of Propeller–Wing Interactions during Dynamic Tiltrotor Conversion Maneuver

The aerodynamics of propeller--wing interactions during a dynamic tiltrotor conversion maneuver were experimentally studied. This investigation builds upon previous work studying the conversion maneuver as a series of discrete tilt angles. This study varied the freestream velocity, rotational frequency, number of proprotors, proprotor spacing, and conversion time period. Wing loads, surface pressures, and particle image velocimetry were used to investigate tiltrotor aerodynamics. For the multi-proprotor configuration, as the conversion period decreased, wing performance increasingly deviated from quasi-static measurements. Dynamic effects decreased as the freestream velocity increased. Minimal dynamic effects were observed when only one proprotor was used. The greatest dynamic wing performance effects resulted from proprotor-proprotor interactions in proximity to the wing. Several nondimensional parameters including the Transition Number and reduced frequency were evaluated to assess how the dynamic effects observed in the wind tunnel may scale to full-size aircraft.