An airfoil is any surface shaped to generate lift when air flows over it. Wings, propeller blades, and helicopter rotor blades are all airfoils.
How It Works#
An airfoil has a curved upper surface and a flatter lower surface. This shape forces air traveling over the top to move faster than air moving underneath. Faster air creates lower pressure above the wing. That pressure difference pushes the wing upward — and that force is lift.
The front edge of an airfoil is called the leading edge. The rear edge is the trailing edge. The straight line connecting them is the chord line. The amount of curve in the airfoil's shape is called camber. More camber generally means more lift at lower speeds.
The angle between the chord line and the oncoming airflow is called the angle of attack (AOA). Increasing AOA increases lift — up to a point. Push the angle too far, and airflow separates from the upper surface. Lift collapses. This is a stall.
Example in Aviation#
Picture a Cessna 172 on a long final approach. The pilot extends flaps, which changes the camber of the wing's airfoil. The increased camber generates more lift at a slower speed, letting the aircraft descend steeply without gaining excessive airspeed. The shape of the airfoil is doing exactly what it was designed to do.
Why It Matters#
Every aircraft that flies relies on airfoil principles. Understanding how shape, camber, and angle of attack interact helps pilots recognize why speed, flap settings, and aircraft attitude affect lift. It also builds the foundation for understanding stalls, which are among the most critical flight safety concepts.
For student pilots, airfoil theory is not just textbook content. It directly explains what you feel in the controls and what you see on the airspeed indicator during every phase of flight.
Key Takeaways#
- An airfoil generates lift through a pressure difference between its upper and lower surfaces.
- Camber describes the curvature of an airfoil. More camber increases low-speed lift.
- Angle of attack is the angle between the chord line and the oncoming airflow.
- Exceeding the critical angle of attack causes a stall, regardless of airspeed.
- Wings, propellers, and rotor blades all use airfoil shapes to generate aerodynamic force.