Propeller Wash - Fixed Wing Interactions

As urban air mobility (UAM) develops, future vehicles must become more fuel-efficient, quieter, and capable of very short takeoffs. While fixed-wing aircraft offer improved fuel efficiency through passive lift, they require long takeoff rolls, compared to rotor-type aircraft, which limits their effectiveness in urban settings. To shorten ground roll distances, organizations such as NASA have proposed using propeller wash to enhance lift during takeoff and landing, which can exhibit significant lift gains. We hypothesize that the lift augmentation can be optimized through strategic placement of the propeller within the streamwise-vertical plane (relative to the wing). We used a low-speed, open-circuit wind tunnel to measure the performance of a NACA 4412 airfoil (AR = 3.27) placed downstream of a variably located three-blade propeller (chord/ blade diameter = 1). The performance with and without propeller-induced flow was evaluated across a Reynolds number range up to 180,000 and an advance ratio range up to 0.5. Propeller positions ranged from +0.3c to +1.0c horizontally and ±0.5c vertically, relative to the leading edge, in increments of 0.1c. edge. Initial results show the largest lift coefficient increases occurred at low incoming flow velocities (high thrust coefficient, lower efficiency) when the propeller was positioned above the wing chord line, approximately 0.4c ahead of the leading edge. This trend shifted at higher incoming speeds (lower thrust coefficient, higher efficiency) with the peak lift enhancement when the propeller was below the wing chord line and 0.5c upstream. The presentation will cover further aerodynamic characterization, including a dual-rotor configuration.