Define effective translational lift.

Define effective translational lift.

• A. When the rotor completely outruns the recirculation of old vortices and begins to work in relatively undisturbed air
• B. A decrease in rotor efficiency due to recirculation
• C. The rotor's lift is equal to weight
• D. A condition where rotor speed is reduced to zero

Answer: (A)

Effective translational lift is the boost in rotor lift and the drop in power required that happens when the helicopter moves forward into air that isn’t disturbed by the rotor’s own wake. As forward speed increases, air flows through the rotor disc that has less of the previous downwash, so the induced velocity through the rotor decreases. With the rotor operating in this fresher air, it can produce more thrust at the same rotor RPM. The option that states the rotor completely outruns the recirculation of old vortices and starts working in relatively undisturbed air directly captures this improvement in air quality through the rotor and the resulting increase in lift. The other descriptions refer to recirculation losses, lift balancing weight, or a non-rotating condition, none of which define effective translational lift.

Effective translational lift is the boost in rotor lift and the drop in power required that happens when the helicopter moves forward into air that isn’t disturbed by the rotor’s own wake. As forward speed increases, air flows through the rotor disc that has less of the previous downwash, so the induced velocity through the rotor decreases. With the rotor operating in this fresher air, it can produce more thrust at the same rotor RPM. The option that states the rotor completely outruns the recirculation of old vortices and starts working in relatively undisturbed air directly captures this improvement in air quality through the rotor and the resulting increase in lift. The other descriptions refer to recirculation losses, lift balancing weight, or a non-rotating condition, none of which define effective translational lift.