Why Wings Fly
The airfoil — a carefully shaped cross-section — is the fundamental element of flight. By curving the upper surface and angling the wing into the oncoming air, an airfoil creates a pressure difference: lower pressure above, higher pressure below. This pressure imbalance produces lift. The thin airfoil theory, derived by Max Munk in the 1920s, predicts that the lift coefficient grows linearly with angle of attack at a rate of 2π per radian — a remarkably accurate approximation for small angles.
The Drag Budget
Every aircraft designer fights drag. Parasitic drag — the friction and pressure drag from the aircraft's shape — grows with the square of airspeed. Induced drag — the unavoidable penalty of creating lift — actually decreases with speed. The total drag curve has a minimum at some optimum speed, and the corresponding maximum L/D ratio defines the aircraft's best glide performance. This simulation plots both force vectors so you can see how they change with angle and speed.
Stall: The Lift Cliff
As angle of attack increases, a point is reached where the airflow can no longer follow the curved upper surface. The boundary layer separates, turbulence engulfs the wing, and lift collapses while drag spikes. This is stall — the most critical flight condition pilots must understand. The simulation shows the approach to stall by modeling the nonlinear lift curve beyond the critical angle.
From Biplanes to Supercritical Wings
Airfoil design has evolved dramatically. The Wright brothers used thin, cambered profiles based on wind tunnel tests. NACA systematically cataloged airfoil families in the 1930s-40s. Modern supercritical airfoils, designed by Richard Whitcomb at NASA, flatten the upper surface to delay shock wave formation at transonic speeds — enabling jets to cruise faster with less wave drag. Each advance came from deeper understanding of the pressure distributions this simulation helps you explore.