Which is the correct set of five ways to improve in-flight stability?

Which is the correct set of five ways to improve in-flight stability?

• A. Nose down attitude; Increase weight of sling load; redistribute weight of sling load; install a drag chute; reduce airspeed
• B. Nose up attitude; Decrease weight of sling load; move weight forward; remove drag chute; increase airspeed
• C. Maintain level attitude; Increase airspeed; reduce sling load weight; deploy parachute; accelerate
• D. Use autopilot; adjust rotor speed; modify sling load geometry; use landing gear

Answer: (A)

In-flight stability with a sling load behaves like a pendulum. You improve stability by increasing damping, reducing the energy driving the swing, and aligning the load’s center of gravity with the helicopter’s dynamics. Nose-down attitude helps keep the load line closer to the helicopter’s longitudinal axis, which reduces the tendency of the sling to swing when the aircraft moves or gusts occur. Increasing the sling-load weight adds inertia, making swings slower and easier to damp. Redistributing weight within the sling load, especially moving weight forward toward the helicopter, shifts the load’s center of gravity toward the hook, reducing pendulum torque and making the system less prone to sway. Adding a drag chute provides aerodynamic damping, converting some of the load’s kinetic energy into drag to suppress oscillations. Reducing airspeed lowers the energy imparted to the sling load by gusts and flight maneuvers, contributing to calmer, more stable behavior. Other options either fail to damp sway or worsen it: for example, nose-up attitude tends to increase swing, lighter loads reduce inertia and allow quicker sways, removing drag damping or increasing airspeed raises the energy driving oscillations, and actions like deploying a parachute or altering rotor settings don’t directly address sling-load pendulum stability.

In-flight stability with a sling load behaves like a pendulum. You improve stability by increasing damping, reducing the energy driving the swing, and aligning the load’s center of gravity with the helicopter’s dynamics.

Nose-down attitude helps keep the load line closer to the helicopter’s longitudinal axis, which reduces the tendency of the sling to swing when the aircraft moves or gusts occur. Increasing the sling-load weight adds inertia, making swings slower and easier to damp. Redistributing weight within the sling load, especially moving weight forward toward the helicopter, shifts the load’s center of gravity toward the hook, reducing pendulum torque and making the system less prone to sway. Adding a drag chute provides aerodynamic damping, converting some of the load’s kinetic energy into drag to suppress oscillations. Reducing airspeed lowers the energy imparted to the sling load by gusts and flight maneuvers, contributing to calmer, more stable behavior.

Other options either fail to damp sway or worsen it: for example, nose-up attitude tends to increase swing, lighter loads reduce inertia and allow quicker sways, removing drag damping or increasing airspeed raises the energy driving oscillations, and actions like deploying a parachute or altering rotor settings don’t directly address sling-load pendulum stability.