Physics for Aviation
What is the difference between an airfoil's angle of incidence and its angle of attack?
Answer
Angle of incidence is the angle between the chord line and the airplane's longitudinal axis; angle of attack is the angle between the chord line and the relative wind
The angle between the chord line and the longitudinal axis of the airplane is the angle of incidence, a rigging value built into the airframe. The angle between the chord line and the relative wind is the angle of attack, which changes in flight; as angle of attack increases, lift increases until the airflow separates and the wing stalls.
Source: FAA-H-8083-30B, Ch. 5 p. 5-38 — 'Airfoil — angle of incidence / Angle of Attack'
Not the answer
- Angle of incidence is measured in flight and angle of attack is measured on the ground
- Both describe the angle between the chord line and the relative wind, measured at the root and the tip respectively
- Angle of incidence is the angle between the chord line and the relative wind; angle of attack is the angle between the chord line and the longitudinal axis
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