For lateral stability, positive dihedral is designed into the wing. In simple terms, this means that the
wing tips are higher than the wing roots and the aircraft's center of gravity is below the wing's mean
center of pressure. Notice in figure 2.10 that the wing tips for the U-21 and U-6 aircraft are 7 and 2
higher than the wing roots. On the U-21 the tips of the horizontal stabilizer are also higher than the
roots. A definition for dihedral then is: the spanwise inclination of a wing or other surface such as a
stabilizer relative to the horizontal gives the wing or other surface dihedral. This angle is positive if it is
upward and negative if it is downward.
Figure 2.10. Wing Dihedral.