Angle of Attack
The angle of attack (AoA) is the acute angle between the chord line of an aerofoil (or the longitudinal axis of a body) and the direction of the oncoming airflow (relative wind). It is one of the most critical parameters in aerodynamics, directly controlling the magnitude of lift and drag generated by a wing; increasing AoA raises lift up to a critical value beyond which the flow separates and the wing stalls. Pilots continuously manage angle of attack to balance lift against weight during all phases of flight.
Effect of Angle of Attack on Lift and Drag for a Typical Cambered Aerofoil
| AoA (°) | C_L (approx.) | C_D (approx.) | L/D Ratio | Flight Condition |
|---|---|---|---|---|
| -4 | -0.1 | 0.015 | −6.7 | Inverted flight / pushover |
| 0 | 0.25 | 0.013 | 19.2 | Level cruise (low speed) |
| 4 | 0.65 | 0.020 | 32.5 | Efficient climb |
| 8 | 1.00 | 0.040 | 25.0 | High-lift approach |
| 12 | 1.30 | 0.090 | 14.4 | Near stall |
| 16 | 0.90 | 0.200 | 4.5 | Post-stall (separated flow) |
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Related Terms
Aerodynamic Lift
Aerodynamic lift is the component of the net aerodynamic force acting perpendicular to the direction of the oncoming airflow, enabling aircraft, wings, and aerofoils to overcome gravity. It arises primarily from the pressure difference between the upper and lower surfaces of a wing, explained by Bernoulli's principle and the Kutta-Joukowski theorem. Lift is fundamental to fixed-wing flight and is carefully optimised in aircraft design through wing shape, angle of attack, and airspeed.
Aerodynamic Stall
An aerodynamic stall occurs when the angle of attack of a wing exceeds the critical angle, causing boundary layer separation over most of the upper surface and a sudden, dramatic reduction in lift accompanied by a large increase in drag. It is not related to engine failure but is a purely aerodynamic phenomenon that can occur at any airspeed and any attitude. Recovery requires reducing angle of attack by lowering the nose, applying full power, and levelling wings — making stall recognition and recovery a core pilot training requirement.
Aerodynamics
Aerodynamics is the branch of fluid mechanics that studies the motion of air and other gases, and the forces they exert on solid bodies moving through them. It forms the scientific foundation for the design of aircraft, rockets, automobiles, and buildings, governing phenomena such as lift, drag, and pressure distribution. Understanding aerodynamic principles is essential for optimising vehicle performance, fuel efficiency, and structural stability at various speeds and altitudes.
From French angle d'attaque, used in 18th-century ballistics to describe the angle at which a projectile met a surface. Adopted into aeronautics in the early 20th century to describe the aerofoil's incidence to the airstream.