Rotor downwash refers to the downward flow of air produced by the rotor blades of a helicopter or other rotary-wing aircraft.

As the blades rotate, they force air downwards, creating lift. This downwash is reinforced by the passage of each successive blade, resulting in an increased downward acceleration of air. The effect is known as Induced Airflow, and it plays a crucial role in the lift and thrust generation of helicopters.

Downwash is affected by several factors, including:

• Rotor Blade Design: The design and configuration of the rotor blades, such as their size and shape, influence the amount of downwash produced.
• Rotor Speed: The speed at which the rotor blades rotate affects the velocity of the downwash.
• Aircraft Weight: Heavier aircraft require more lift, which can increase the downwash.
• Ground Effect: When a helicopter is close to the ground, the downwash interacts with the surface, affecting its characteristics.
• Environmental Conditions: Factors such as wind speed and direction can alter the behaviour of downwash.
• Altitude and Temperature: These can affect air density, which in turn influences downwash.