INDUCED DRAG AND WINGLETS

A simple method is described which allows consideration of the most significant higher order term in the calculation of the induced drag of nonplanar wings. This is the induced lift due to the velocities that the lifting vortices induce on themselves. This induced lift does not change the induced drag. It is positive for positive dihedral and winglets above the wing tip and negative for negative dihedral and winglets below the wing tip. Experiments with small models clearly demonstrate this difference which is neglected in the classical theory. This shows that the higher order effects should be taken into account. The results of several parameter variations are presented.