Wing dihedral contributes most to stability of the airplane about which axis?

Wing dihedral primarily affects an airplane's stability around the longitudinal axis, which is the axis that runs from the nose to the tail of the aircraft. Dihedral refers to the upward angle of the wings relative to the horizontal plane. When an airplane with dihedral is disturbed from level flight, the resulting roll moment caused by a wing dropping will create a force that tends to lift the dropped wing back up. This self-correcting behavior greatly enhances the plane's ability to return to level flight, thereby improving its roll stability about the longitudinal axis.

Although dihedral does not have a significant effect on the vertical or yaw axes, which are more influenced by factors like vertical stabilizers and rudders, its impact on lateral stability is essential. The inherent stability offered by dihedral ensures that any lateral deviations are quickly countered, maintaining the aircraft's desired flight path. This makes dihedral a crucial design feature in enhancing the airplane's overall stability dynamics.