In a vortex ring state condition, the rotor tip vortices recirculate through the rotor disk and what happens to the induced flow into the main rotor?

In a vortex ring state condition, the rotor tip vortices recirculate through the rotor disk and what happens to the induced flow into the main rotor?

• A. Increase
• B. Decrease
• C. No change
• D. Fluctuate

Answer: (A)

In a vortex ring state, the rotor’s downwash is recirculated back through the rotor disk, so more air is drawn through the rotor from below. This increases the induced velocity (the downward flow through the rotor). The higher induced flow reduces lift efficiency, making the helicopter harder to control and prone to a rapid descent. So the best choice is that the induced flow into the main rotor increases.

In a vortex ring state, the rotor’s downwash is recirculated back through the rotor disk, so more air is drawn through the rotor from below. This increases the induced velocity (the downward flow through the rotor). The higher induced flow reduces lift efficiency, making the helicopter harder to control and prone to a rapid descent. So the best choice is that the induced flow into the main rotor increases.