The Influence of a Tip Propeller’s Vertical Offset on a Trailing Wing with Fixed Lift

Wingtip-mounted tractor propeller configurations are receiving attention across the aerospace industry for their aerodynamic benefits. However, results showing variations in spanwise lift and drag due to changes in the propeller-wing vertical offset for such configurations are scarce in the literature. In previous work, we presented computational results showing changes in the spanwise distributions of lift and drag coefficients for a trailing rectangular wing when the vertical offset of its wingtip propeller is varied for a fixed angle of attack. Since changing the vertical offset also changes the wing's integrated lift, this paper examines how the results compare when the wing's inclination is simultaneously modified to maintain a target lift. For this, we perform steady Reynolds-averaged Navier--Stokes computational fluid dynamics simulations using the open-source flow solver ADflow with the Spalart--Allmaras turbulence model and an actuator-disk approach. Ensuring that the wing generates the same integrated lift in each case adds complexity to the problem compared to fixed-angle-of-attack simulations because the wing's inclination must be adjusted. To accomplish this, we use a gradient-based optimizer and a free-form deformation approach with mesh warping. We present results for a fixed angle of attack of 4 deg and for a target lift coefficient of 0.3, over a range of propeller-wing vertical offsets for both inboard-up and outboard-up propeller rotations. We include plots of spanwise distributions of lift and drag coefficients, integrated lift and drag coefficients, and lift-to-drag ratios.