Which force acts perpendicular to the relative wind on an airfoil?

The force that acts perpendicular to the relative wind on an airfoil is lift. Lift is the aerodynamic force that acts at a right angle to the direction of the airflow (relative wind) over the surfaces of the airfoil, such as a wing. This force is generated primarily due to the shape and angle of the airfoil, which causes differences in air pressure above and below the wing.

When air flows over the airfoil, the shape causes the air to travel faster over the top surface than the bottom surface, leading to lower pressure above and higher pressure below. This pressure difference creates lift, allowing the aircraft to rise and maintain altitude. Understanding lift is crucial for pilots, as it directly correlates with the aircraft's ability to fly and maneuver.

The other forces involved in flight—drag, thrust, and weight—serve different functions. Drag opposes the aircraft's forward motion and acts parallel to the relative wind, while thrust propels the aircraft forward. Weight, the force of gravity acting downward, influences the aircraft's altitude but does not act perpendicular to the relative wind.