What is the angle of attack in aerodynamics?

• A. The angle between the wing chord line and the relative wind.
• B. The angle between the wing span and the relative wind.
• C. The angle between the fuselage axis and the relative wind.
• D. The angle between the leading edge and the trailing edge of the wing.

Answer: (A)

The angle of attack is the angle between the wing’s chord line and the relative wind. The chord line is the straight line from the wing’s leading edge to its trailing edge, and the relative wind is the airflow the aircraft experiences as it moves through the air. This angle is what governs lift: increasing the angle of attack generally increases lift up to a critical point, after which the airflow separates and the wing can stall.

It’s not about how wide the wing is or about the fuselage’s orientation in space, which is why angles defined relative to the wing’s span or to the fuselage axis aren’t the correct description. The angle between the leading edge and trailing edge describes the wing’s geometry, not its flight-angle to the air.