At about what airspeed does the helicopter go through effective translational lift (ETL)?

At about what airspeed does the helicopter go through effective translational lift (ETL)?

• A. 12-16 knots
• B. 16-24 knots
• C. 24-28 knots
• D. 28-32 knots

Answer: (B)

Effective translational lift begins when forward airspeed introduces translational flow through the rotor disk, reducing rotor downwash effects and making the rotor more efficient. As you pick up speed, the rotor sees more air moving opposite to the blade and less blind hover downwash, so the same rotor RPM produces more lift with less power. This transition happens in the mid-speed range, typically around 16 to 24 knots indicated airspeed, where the helicopter shifts from hover-dominant lift to translational lift. You’ll notice the aircraft needing less power to maintain altitude and gaining better forward performance as you pass this onset range.

Effective translational lift begins when forward airspeed introduces translational flow through the rotor disk, reducing rotor downwash effects and making the rotor more efficient. As you pick up speed, the rotor sees more air moving opposite to the blade and less blind hover downwash, so the same rotor RPM produces more lift with less power. This transition happens in the mid-speed range, typically around 16 to 24 knots indicated airspeed, where the helicopter shifts from hover-dominant lift to translational lift. You’ll notice the aircraft needing less power to maintain altitude and gaining better forward performance as you pass this onset range.