THE COMMERCIAL EQUATION

If an existing aeroplane is fitted with winglets, the increased bending loads compel some strengthening of the mainplane, adding weight, and there is a reduction in load carrying capacity. This may be compensated by the increased efficiency so that some fuel is saved. Clearly, whether the aircraft should or should not have winglets is finally determined not by aerodynamic considerations alone but by commercial factors such as the cost of the materials and the investment in design and the wind tunnel testing time, and the price of fuel. That the winglets do work as their inventors claim is not doubted, but this does not imply they should necessarily be fitted to every commercial aeroplane.

flight direction