Question

Which type of drag increases as an aircraft increases its angle of attack to produce more lift?

Accepted Answer

The type of drag that increases as an aircraft increases its angle of attack is induced drag. Induced drag is an unavoidable byproduct of generating lift. To produce lift, an airfoil deflects air downward, which creates a pressure difference between the upper and lower surfaces of the wing. This pressure difference causes air to flow around the wingtips from the high-pressure area underneath to the low-pressure area above, resulting in rotating masses of air known as wingtip vortices. These vortices create a downward component of airflow behind the wing called downwash, which tilts the total aerodynamic force vector rearward. Because drag is defined as the component of the total aerodynamic force acting parallel to the relative wind, this rearward tilt creates drag. As the angle of attack increases, the pressure differential between the top and bottom of the wing becomes greater to produce more lift, which strengthens the wingtip vortices and increases the magnitude of induced drag. This relationship is inverse to speed, meaning that at slower flight speeds, where a higher angle of attack is required to maintain level flight, induced drag becomes the dominant form of drag.

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Which type of drag increases as an aircraft increases its angle of attack to produce more lift?