How does angle of attack affect lift?

Lift increases with angle of attack up to a critical point, after which it decreases sharply due to stall.

Is angle of attack the same as attitude?

No, attitude is the aircraft's orientation to the horizon, while angle of attack is relative to airflow.

What happens beyond the critical angle of attack?

The wing stalls and lift decreases rapidly.

Angle of Attack

Q: What is angle of attack (alpha)?

It is the angle between an aerofoil's chord line and the direction of the relative airflow.

Q: What is angle of incidence?

It is the fixed angle between the aircraft's longitudinal axis and the wing root chord line.

Easy4 min readPrinciple of Flight (A)

Moderately Examined

The angle of attack (alpha, α) is a fundamental aerodynamic concept describing the angle between an aerofoil's chord line and the direction of the oncoming airflow. This angle directly influences how much lift a wing produces and plays a critical role in flight dynamics, including stall behavior. Understanding angle of attack is essential for safe and efficient aircraft operation, as it differs from both aircraft attitude and angle of incidence.

In depth

Explanation

Definition of Angle of Attack

Angle of attack (α) is the angle between the chord line of an aerofoil (a straight line from leading to trailing edge) and the direction of the relative airflow. For a complete aircraft, it is typically referenced as the angle between the longitudinal axis and the relative wind, but for exam purposes, always use the chord line as the reference.

Angle of Incidence vs. Angle of Attack

Angle of incidence is the fixed angle between the aircraft's longitudinal axis and the wing root chord line, set during manufacturing and not changed in flight. Do not confuse this with angle of attack, which varies continuously during flight as the aircraft's orientation and airflow change.

Influence on Lift

As angle of attack increases, lift also increases—up to a point. Beyond a certain critical angle (the stall angle), further increases cause a rapid loss of lift as the airflow separates from the wing.

The CL-Alpha Graph

This graph plots the coefficient of lift (CL) against angle of attack (α). Key points include:

Where the curve crosses the horizontal axis (zero lift): This is the angle where no lift is generated.
Where the curve crosses the vertical axis (α = 0): Shows the lift at zero angle of attack (not always zero for cambered aerofoils).
The peak of the curve (CLMAX): The maximum lift before stall occurs.

Angle of Attack vs. Attitude

Attitude is the aircraft's orientation relative to the horizon, while angle of attack is always relative to the airflow. An aircraft can have a low nose attitude but a high angle of attack, especially in unusual flight situations or during a stall. Always distinguish these concepts in exam questions.

The essentials

Key Points

Angle of attack (α) is the angle between the chord line and the relative airflow.

Angle of incidence is fixed and set between the fuselage axis and wing root chord.

Lift increases with angle of attack up to the stall angle (critical α).

Beyond the critical angle of attack, lift rapidly decreases (stall).

The CL-alpha graph shows how lift coefficient varies with angle of attack.

Attitude is not the same as angle of attack; attitude is relative to the horizon.

Watch out

Common Exam Traps

Confusing angle of attack with angle of incidence—incidence is fixed, alpha varies.

Mixing up attitude (aircraft nose position) with angle of attack (relative to airflow).

Assuming zero angle of attack always means zero lift (not true for cambered wings).

Believing increasing angle of attack always increases lift (not true past stall).

Test yourself

Example Exam Questions

Question 1Easy

What is the angle of attack (α) in relation to an aerofoil?

Question 2Easy

Which statement about angle of incidence is correct?

Question 3Medium

On a CL-alpha graph, what does the point of maximum CL (CLMAX) represent?

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