What is a disadvantage of wing-mounted vortex generators?

Wing-mounted vortex generators are devices that are designed to enhance the aerodynamic performance of an aircraft by manipulating airflow over the wings. While they can contribute to increased lift and reduced drag under certain conditions, they also come with some disadvantages.

One significant disadvantage of wing-mounted vortex generators is that they can lead to increased drag at low airspeeds. This is because vortex generators increase turbulence in the boundary layer over the wing, which can be beneficial for delaying flow separation and improving lift at higher angles of attack. However, at lower speeds, this increase in turbulence can result in more drag, as the additional vortex activity can disrupt the smooth airflow needed for optimal performance.

In contrast, the other options typically present benefits rather than disadvantages. For instance, vortex generators are known to decrease drag at high speeds due to their ability to mitigate flow separation, and they can increase lift by enhancing airflow attachment over the wing surface. Weight reduction is generally not a characteristic of vortex generators; instead, they add some weight to the aircraft, which further affirms the correct choice regarding their impact on drag at low speeds.