Minimum drag wing configuration for aircraft operating at transonic speeds

摘要

A tip fin or wing extension is disclosed wherein the tip fin is mountable to a conventional aircraft wing to form a nonplanar wing configuration which minimizes induced drag during both low speed and high speed operation of the aircraft. The tip fin is of generally trapezoidal geometry extending streamwise along the end of the aircraft wing and projecting vertically upward therefrom. The height of the tip fin and its cross sectional geometry are established to provide a substantial reduction in induced drag relative to that exhibited by the aircraft wing alone. Further, the tip fin is joined to the wing by a smoothly contoured upwardly extending arcuate region and the maximum thickness ratio of the tip fin airfoil section is established to minimize interference drag caused by the interaction of the tip fin within the wing flow field. In addition, the tip fin is twisted such that the angle of incidence between the tip fin chordal plane and the free-stream direction varies as a function of position along the tip fin height. This twist distribution is established to provide near optimal loading of the wing.