the pitching moment of the airplane should become more negative. And
if the CL should decrease (you guessed it
due to a decrease in AOA) the airplane should develop a nose up pitch attitude.5. FACtoRS InFLuEnCInG DIRECtIonAL AnD LAtERAL StABILIty AnD ContRoL.Directional (or yaw) stability involves an airplaneâs natural tendency to return its nose to the trimmed position when it is momentarily displaced to either the right or left. In other words
directional stability is the natural tendency of the airplane to rotate about its vertical axis and weathervane into the relative wind. Lateral or roll stability
on the other hand
involves the tendency of an airplane to roll when a yaw is induced. When an uncoordinated roll in an airplane with lateral static stability causes a side-slip
the side-slip will in turn cause a rolling moment in a direction which will cause the airplane to reverse its roll. Thus it can be seen that side slips cause both yawing and rolling moments. Most pilots learn this during their first few hours of flight instruction. If the right wing drops while both hands are busy with other duties
a gentle shove on the left rudder pedal will bring it up. âLook Ma! Roll control with no hands!â Generally
airplanes will exhibit greater positive directional stability than lateral stability. Some of the factors that determine the directional (yaw) stability and lateral (roll) stability are listed in Figures 31-10 and 31-11.6. DEGRADAtIon oF AIRPLAnE StABILIty AnD ContRoL.The stability which is designed into an airplane can
unfortunately
be offset by component or system failures or the actions of its operators. Failure of structural components which generate the aerodynamic forces necessary to produce positive static and dynamic stability can create piloting demands which exceed the abilities of even the best of pilots. Where marginal natural stability is augmented by autopilot and/or stability augmentation systems
loss of this assistance can again overload the pilot. Operation of the airplane outside of its approved operating envelope can also present the pilot with requirements which exceed the abilities of any pilot.A. vIoLAtIonS oF CEntER oF GRAvIty LImItS. Both the control-lability and stability of an airplane are affected by changes in the location of an airplaneâs Center of Gravity. Generally speaking an aftward movement of Figure 31-8. Contributions of Various Airplane Components to Static Longitudinal Stability.
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