How does increasing airspeed affect the propeller angle of attack?

Increasing airspeed generally leads to a decrease in the propeller angle of attack. The angle of attack is defined as the angle between the chord line of the propeller blade and the relative wind. As the airspeed rises, the relative wind becomes more aligned with the plane of the propeller blade. This causes the effective angle at which the air strikes the blades to be reduced if the blade's pitch or orientation remains unchanged.

Maintaining optimal performance relies on managing this angle of attack, which is why it decreases with increased airspeed. This is particularly important for ensuring efficient thrust production and minimizing drag. In contrast, as airspeed decreases, the angle of attack would typically increase for a specific propeller pitch setting, which can lead to efficiency losses if it becomes too high, potentially resulting in stall conditions.

The other options suggest that the angle of attack either remains constant or varies based on thrust without acknowledging the direct relationship between airspeed and angle of attack. Understanding how airspeed impacts this angle is crucial for managing propeller performance in various flight conditions.