Stability about the vertical axis is commonly referred to as what?

Stability about the vertical axis is commonly referred to as what?

• A. Vertical stability
• B. Lateral stability
• C. Longitudinal stability
• D. Directional stability

Answer: (A)

Stability about the vertical axis is yaw or directional stability. The vertical axis is the yaw axis, and after a disturbance in heading the aircraft’s tendency to maintain or return to its flight path is governed by directional (yaw) stability. This stability is achieved by aerodynamic design features like the vertical tail and the fuselage’s side area, which generate restoring yawing moments when sideslip occurs, damping out yaw changes and helping keep the aircraft on course. The standard term used in aerodynamics for this axis is directional stability (often called yaw stability). The other terms refer to stability about the other axes—lateral stability relates to roll about the longitudinal axis, and longitudinal stability relates to pitch about the lateral axis—while “vertical stability” isn’t the conventional name for this axis.

Stability about the vertical axis is yaw or directional stability. The vertical axis is the yaw axis, and after a disturbance in heading the aircraft’s tendency to maintain or return to its flight path is governed by directional (yaw) stability. This stability is achieved by aerodynamic design features like the vertical tail and the fuselage’s side area, which generate restoring yawing moments when sideslip occurs, damping out yaw changes and helping keep the aircraft on course. The standard term used in aerodynamics for this axis is directional stability (often called yaw stability). The other terms refer to stability about the other axes—lateral stability relates to roll about the longitudinal axis, and longitudinal stability relates to pitch about the lateral axis—while “vertical stability” isn’t the conventional name for this axis.