Meaning and mechanism
The wings can interact with the surrounding airflow, and can transmit a downward movement. By combining the surface pressure and shear force, we obtain the result of aerodynamic force.
Changes in angle of attack from the same wing result in changes in airflow and the coefficient of lift. A large angle causes airflow separation, leading to a reduction in lift and the formation of stall, characterized by increased drag.
Relationships and conditions
Lift is calculated as L = ½ρv²SCL. When using a small angle approximation CL≈2πα, α must be expressed in radians.
The actual CL (likely referring to Circulation) depends on factors such as wing shape, Reynolds number, and drag coefficient. The assumption that the air passing above and below must meet at the same time is not necessary.
What to observe in the simulation
Beyond stall the lift coefficient decreases; at a fixed angle lift scales with speed squared.
An educational symmetric-airfoil coefficient decays exponentially after 15°. Streamlines illustrate direction. CFD, drag, compressibility and wing-tip effects are omitted.
Key relationships and symbols
L = ½ρv²SCL · CL = 2πα (|α| ≤ 15°)
| Symbol | Meaning | Unit |
|---|---|---|
| CL | Lift coefficient | Dimensionless |
| α | Angle of attack | rad |
| S | Reference wing area | m² |
Worked example
How does the lift coefficient change beyond stall?
It decreases · Beyond stall the lift coefficient decreases; at a fixed angle lift scales with speed squared.
Common misconceptions
- Increasing the flare angle does not mean that the lift will infinitely increase within any range.