Analysis on induced drag characteristics of forward swept wings

Forward swept wing is one of the plane forms of aircraft configuaration. For aerodynamic characteristics of induced drag of forward swept wings，the existing papers have provided confusing understandings. In order to clarify the mechanism of induced drag of forward swept wings，the induced drag characteristics are calculated and analyzed for different wing plane forms. The forward swept wings，aft-swept wings and straight wings are considered and compared with nonlinear vortex lattice method， lifting-line theory，and high-order Euler equations numerical methods. The advantages of forward swept wings are also briefly summarized. The results show that conventional perception that the induced drag of forward swept wings is smaller than that of aft-swept wings is a misunderstanding. Even within the framework of potential flow theory and based on numerical results with Navier-Stokes equations，the induced drag of forward swept wings is greater than that of aft-swept wings.