The ULY factor which occurs while the aircraft decelerates through translational lift results in increased power required to establish a hover is called:

The ULY factor which occurs while the aircraft decelerates through translational lift results in increased power required to establish a hover is called:

• A. LOSS OF TRANSLATIONAL LIFT
• B. WEATHERCOOK STABILITY
• C. COLLECTIVE INDUCED YAW
• D. MAIN ROTOR / TAIL ROTOR INTERACTION

Answer: (A)

Translational lift is the extra lift the rotor generates as the helicopter moves forward, because the rotor interacts with air that has already been accelerated by the rotor itself, reducing the induced flow and the power needed in hover. When you decelerate through that translational lift region back toward a hover, you lose that added lift. The rotor then has to produce the same weight support with less favorable inflow, so more thrust (and thus more power) is required to establish or return to a hover. This is a transient effect during the transition, not a steady-state condition. Other phenomena described by the other choices relate to yaw or rotor interactions, not this specific loss of translational lift during deceleration.

Translational lift is the extra lift the rotor generates as the helicopter moves forward, because the rotor interacts with air that has already been accelerated by the rotor itself, reducing the induced flow and the power needed in hover. When you decelerate through that translational lift region back toward a hover, you lose that added lift. The rotor then has to produce the same weight support with less favorable inflow, so more thrust (and thus more power) is required to establish or return to a hover. This is a transient effect during the transition, not a steady-state condition. Other phenomena described by the other choices relate to yaw or rotor interactions, not this specific loss of translational lift during deceleration.