What does downwash result from?

Downwash is primarily the downward flow of air that occurs as a result of lift generation by rotor blades. In the context of helicopter flight, when a helicopter is in forward flight, the rotor blades create lift, causing air to be pushed downward. This downward movement of air is referred to as downwash.

In forward flight, the rotor blades encounter a change in the airflow due to the forward motion, leading to an increase in the velocity of the airflow over certain sections of the rotor system. This, in turn, intensifies the downwash effect as the helicopter continues to generate lift.

Hovering at high altitudes or having increased speed can influence the flight characteristics, but the fundamental cause of downwash is closely tied to the lift generation process, which is most apparent during forward flight.