What is the downward deflection of the airstream as it passes over the wing and past the trailing edge?

• A. Angle of attack
• B. Relative wind
• C. Upwash
• D. Downwash

Answer: (D)

The downward deflection of the airstream behind the wing is downwash. When the wing generates lift, it pushes air downward as it flows over and off the trailing edge. This creates a downward component in the wake, which is the downwash. This is different from upwash, which is the slight upward deflection of air in front of the wing, and from the relative wind, which is the overall direction opposite the airplane’s motion, while the angle of attack is the angle between the wing’s chord line and that relative wind. So the term that describes the airflow bending downward after passing the trailing edge is downwash.