Roll Plane (Y-Z) Maneuver (Aileron-Induced)
The aileron-induced motion generates the roll maneuver with angular velocity, p, about the X-axis, in addition to velocities in the Y-Z plane. Aircraft structures designed to the pitch-plane loading are the most critical; therefore, roll-plane loading is not discussed herein.
5.3.2 Yaw Plane (Z-X) Maneuver (Rudder-Induced)
The rudder-induced motion generates the yaw (coupled with the roll) maneuver with angular velocity, r, about the Z-axis, in addition to linear velocities in the Z-X plane. Aerodynamic loading of an aircraft due to yaw is also necessary for structural design.
5.3 Aircraft Loads
An aircraft is subject to load at any time. The simplest case is an aircraft stationary on the ground experiencing its own weight. Under heavy landing, an aircraft can experience severe loading, and there have been cases of structural collapse. Most of these accidents showed failure of the undercarriage, but breaking of the fuselage also has occurred. In flight, aircraft loading varies with maneuvers and/or when gusts are encountered. Early designs resulted in many structural failures in flight.