In a single-rotor helicopter during forward horizontal flight, how does the angle of attack of the advancing blade compare to that of the retreating blade?

In a single-rotor helicopter, during forward horizontal flight, the advancing blade experiences a greater relative airflow compared to the retreating blade. As the helicopter moves forward, the advancing blade moves into the oncoming wind, which increases its speed relative to the surrounding air. This results in the advancing blade having a higher angle of attack compared to the retreating blade, which effectively sees the airflow as it begins to move away from the oncoming wind.

Conversely, the retreating blade experiences a reduction in relative airflow because it is moving away from the wind created by the forward flight. This reduced speed diminishes the angle of attack for that blade. Thus, the advancing blade has a greater angle of attack.

This principle is essential to understanding helicopter aerodynamics and how lift is generated unevenly on the rotor disc. The advancing blade produces more lift due to the increased airflow, while the retreating blade experiences less lift, which can lead to challenges such as loss of lift if not correctly managed.