What is the phenomenon where the rotor disk tilts aft during transition due to unequal airflow?

• A. Blowback
• B. Blade Twist
• C. Center of Gravity
• D. Center of Pressure

Answer: (A)

During the hover-to-forward-flight transition, the rotor’s downwash no longer encounters air in a purely symmetric way because the helicopter is moving forward. The air interacting with the rotor is deflected by the airframe in a way that creates an uneven flow across the rotor disk, producing a rearward pitching moment. This causes the rotor disk to tilt aft—that phenomenon is called blowback. Blade twist, center of gravity, and center of pressure describe other aspects of rotor or aircraft performance and stability, not this dynamic interaction of rotor downwash with the airframe during transition.