Which CG location generally allows the greatest elevator control authority?

Which CG location generally allows the greatest elevator control authority?

• A. Forward CG
• B. Aft CG
• C. Neutral CG
• D. Mid-range CG

Answer: (A)

Elevator control authority comes from the tail’s ability to create a pitching moment about the aircraft’s center of gravity. The stronger the moment you can produce for a given elevator deflection, the greater the control authority. When the CG sits forward, the distance from the CG to the tail is larger. That longer lever arm means the same downward (tail-down) or upward (tail-up) force at the tail generates a larger moment about the CG. In other words, a given tail force from the elevator deflection has more leverage to raise or lower the nose, so elevator control authority is greater. However, forward CG also makes the aircraft more statically stable, so you may feel a stronger resistance to pitch changes, which can require more input to achieve the same maneuver. Moving the CG aft shortens that lever arm, reducing the moment for a given tail force and thus reducing elevator control authority, while reducing stability. Mid-range or neutral CG would yield intermediate results.

Elevator control authority comes from the tail’s ability to create a pitching moment about the aircraft’s center of gravity. The stronger the moment you can produce for a given elevator deflection, the greater the control authority.

When the CG sits forward, the distance from the CG to the tail is larger. That longer lever arm means the same downward (tail-down) or upward (tail-up) force at the tail generates a larger moment about the CG. In other words, a given tail force from the elevator deflection has more leverage to raise or lower the nose, so elevator control authority is greater.

However, forward CG also makes the aircraft more statically stable, so you may feel a stronger resistance to pitch changes, which can require more input to achieve the same maneuver. Moving the CG aft shortens that lever arm, reducing the moment for a given tail force and thus reducing elevator control authority, while reducing stability. Mid-range or neutral CG would yield intermediate results.