What does blowback cause in a rotor system?

What does blowback cause in a rotor system?

• A. It increases airspeed without altering rotor orientation.
• B. It decreases rotor RPM uniformly with no change in lift direction.
• C. It causes a change in the rotor attitude and, therefore, changes the direction of the total lift vector.
• D. It has no effect on the lift vector.

Answer: (C)

Blowback is a disturbance that tilts the rotor disk because the rotor’s downwash and wake interact with the airframe. When the rotor disk tilts, the thrust direction no longer points straight up. Since lift acts perpendicular to the rotor disk, tilting the disk also tilts the overall lift vector. That change in the lift vector direction produces pitching or rolling tendencies in the aircraft and must be corrected with the flight controls.

Blowback is a disturbance that tilts the rotor disk because the rotor’s downwash and wake interact with the airframe. When the rotor disk tilts, the thrust direction no longer points straight up. Since lift acts perpendicular to the rotor disk, tilting the disk also tilts the overall lift vector. That change in the lift vector direction produces pitching or rolling tendencies in the aircraft and must be corrected with the flight controls.