In this paper, recent developments in quasi-3D aerodynamic methods are presented. At their core, these methods are based on the lifting-line theory and vortex lattice method, but with a relaxed set of hypotheses, while also considering the effect of viscosity (to a certain degree) by introducing a strong non-linear coupling with two-dimensional viscous aerofoil aerodynamics. These methods can provide more accurate results compared with their inviscid classical counterparts and have an extended range of applicability with respect to the lifting surface geometry. Verification results are presented for both steady-state and unsteady flows, as well as case studies related to their integration into aerodynamic shape optimisation tools. The good accuracy achieved using relatively low computational time makes such quasi-3D methods a solid choice for conducting conceptual-level design and optimisation of lifting surfaces.
