US Patent 7971832 Wing tip devices

A tip device to act as an outboard continuation of an aircraft wing or other aerodynamic lifting surface has a downward cant angle, a leading edge swept back in relation to the leading edge of the inboard lifting surface, and a chord reducing in the outboard direction of the device. A favourable balance between induced drag reduction and increased wing root bending moment can thereby be achieved. Preferably the device also has an upwardly canted portion at its root end so that the downward cant commences from a relatively elevated spanwise location, thereby alleviating any ground clearance problems.