Where are vortex generators placed, if any, to minimize high-speed drag separation?

• A. Above the wing
• B. Below the wing
• C. On the fuselage
• D. On the tailplane

Answer: (A)

Vortex generators work by creating small, controlled swirling motions that energize the air in the boundary layer, mixing higher-energy air from above into the near-wall region. This added energy helps the boundary layer resist separating when the wing experiences adverse pressure gradients at high speeds. By placing them on the upper surface, the effect directly targets the area where separation is most likely to occur during fast cruise, keeping the flow attached longer, reducing drag from separated flow, and improving lift distribution. Putting them on the lower surface, fuselage, or tailplane wouldn’t address the wing’s upper-surface separation as effectively and could introduce unnecessary drag or disturbances where they aren’t needed. So, the best placement to minimize high-speed drag separation is on the upper surface of the wing.