A Parametric Computational Fluid Dynamics Investigation of Classical Aircraft Winglet Performance

This paper presents a high-fidelity parametric optimization of classical winglet geometry for transonic transport aircraft using Reynolds-Averaged Navier-Stokes (RANS) simulations validated against the NASA Common Research Model. A design space defined by winglet length, cant, and sweep was explored through 125 unique configurations. The main contribution of the paper is the use of Chebyshev polynomial sampling to create an interpolated 3-parameter aerodynamic efficiency map with minimal boundary interpolation error. For all cases the total wing span is kept fixed by truncating based on the winglet cant angle. For the modified geometries we utilize an aerodynamic trim compensation based on the reduction in lift from the truncated baseline wing and its CL vs AoA slope. Crucially, the results reveal a "Design Trap" where over 65% of the design space degrades performance. Results show maximum aerodynamic efficiency at high sweep angles 50-60 deg and cant angles 70-90 deg, providing a robust framework for rapid preliminary winglet design while highlighting sensitive geometric regions.