Towards an effective nonplanar wing design strategy

Abstract

This study investigates the potential of nonplanar wings with a reduced projected span to perform better than planar wings with the same planform area. Existing research appears contradictory regarding if and how a reduced-span constant area configuration could increase the aerodynamic efficiency of the wing. This inconclusiveness could stem from the lack of design standardization between research studies. A standardized design methodology has been developed to help focus future nonplanar research. Vortex-lattice method analyses of nonplanar planforms using a modified version of Tornado helped identify trends in pressure distribution and induced drag at specific lift coefficients. The numerical results indicated that wings with a downward spanwise camber can be more efficient than planar wings or wings with an upward camber. The amount of wing that is planar, designated the planar fraction, was found to influence the tip dihedral angle necessary to reduce a wing’s induced drag. Five wings that were predicted to be aerodynamically comparable were analyzed with NASA Langley’s unstructured Navier-Stokes solver USM3D. These numerical results verified the predictive capabilities of Tornado within certain error bounds. This methodology can yield nonplanar wings with effective spans greater than their projected spans, and can also yield a set of wings that are all aerodynamically comparable.