Figures 1 and 2 depict the same airplane with a forward center of gravity and one in which the CG is further aft, closer to the center of lift. The CG acts on the airplane via the red arrow while lift—shown here opposing CG, actually works at a right angle to the relative wind. In both instances, some tail down force must be generated, as represented by the green arrow at each tail. That tail down force imposes an increase in the aerodynamic weight the wings must support, requiring the wings to generate greater lift than demanded by the airplane’s weight. When greater lift must be generated, the wing’s induced drag increases. Tail down force and the wing’s induced drag are greater when the distance between CG and CL is greater.
