An aircraft has greater longitudinal stability when?

An aircraft has greater longitudinal stability when?

• A. The C of G is well forward of the centre of pressure
• B. The C of G is at the midpoint of the wing
• C. The C of G is at the aft limit
• D. The center of pressure is behind the C of G

Answer: (A)

Longitudinal stability in an aircraft refers to its ability to maintain a consistent pitch attitude and return to equilibrium after being disturbed. An aircraft has greater longitudinal stability when the center of gravity (C of G) is positioned well forward of the center of pressure (CP). When the C of G is forward of the CP, any disturbance that causes the nose to pitch up results in a shift in the aerodynamic forces that helps the aircraft return to its original pitch attitude. The aerodynamic center produces a moment that pushes the nose down, counteracting the initial disturbance. This configuration creates a restoring moment that enhances stability. Positioning the C of G too far aft, in contrast, decreases longitudinal stability because any pitching moment caused by disturbance will produce a tendency for the nose to pitch further upward, rather than returning to stable equilibrium. Therefore, maintaining the C of G forward of the center of pressure is crucial for ensuring that the aircraft responds to disturbances in a manner that promotes stability.

Longitudinal stability in an aircraft refers to its ability to maintain a consistent pitch attitude and return to equilibrium after being disturbed. An aircraft has greater longitudinal stability when the center of gravity (C of G) is positioned well forward of the center of pressure (CP).

When the C of G is forward of the CP, any disturbance that causes the nose to pitch up results in a shift in the aerodynamic forces that helps the aircraft return to its original pitch attitude. The aerodynamic center produces a moment that pushes the nose down, counteracting the initial disturbance. This configuration creates a restoring moment that enhances stability.

Positioning the C of G too far aft, in contrast, decreases longitudinal stability because any pitching moment caused by disturbance will produce a tendency for the nose to pitch further upward, rather than returning to stable equilibrium. Therefore, maintaining the C of G forward of the center of pressure is crucial for ensuring that the aircraft responds to disturbances in a manner that promotes stability.