When the lift of an airfoil increases, what happens to the drag?

When the lift of an airfoil increases, the drag typically increases as well. This is primarily due to the relationship between lift and drag, which is described by the lift-to-drag ratio. As the angle of attack of the airfoil increases to produce more lift, the airfoil also experiences an increase in induced drag, which is a component of drag that arises from the creation of lift.

As lift increases, the airfoil generates stronger vortices at the wingtips, resulting in higher induced drag. Additionally, other forms of drag, such as form drag and skin friction, can be affected by the increased airflow and turbulence around the airfoil at higher lift conditions. Therefore, the overall drag on the airfoil tends to increase as lift is generated, confirming that the correct answer is that drag increases with an increase in lift.