1. Chord Line: The chord line is an imaginary straight line drawn from the leading edge to the trailing edge of an airfoil (such as a wing or propeller blade). It represents the reference line for measuring the angle of attack.
2. Relative Airflow: Relative airflow is the direction of the air moving relative to the aircraft. It is the combination of the aircraft's forward motion and the surrounding wind conditions.
3. Angle of Attack: The angle of attack is the angle formed between the chord line of the wing and the direction of the relative airflow. It is typically measured in degrees. A positive angle of attack indicates that the wing is inclined upwards relative to the airflow, while a negative angle of attack indicates a downward inclination.
4. Significance: The angle of attack significantly impacts the lift and drag forces acting on an airplane. Lift is the force that opposes the weight of the aircraft and keeps it in the air. Drag is the force that opposes the forward motion of the aircraft. The angle of attack influences both lift and drag, and it must be carefully controlled to achieve efficient flight.
5. Effects of Angle of Attack:
- Increased Angle of Attack: Increasing the angle of attack generally increases the lift generated by the wing. However, it also increases drag and can lead to a phenomenon called "stall." At high angles of attack, the airflow over the wing becomes turbulent, resulting in a sudden loss of lift and a decrease in controllability.
- Decreased Angle of Attack: Reducing the angle of attack decreases lift but also reduces drag. This is important during low-speed flight or landing when maximum lift is required, but drag must be minimized.
6. Control of Angle of Attack: Pilots control the angle of attack by adjusting the aircraft's control surfaces, such as elevators and ailerons, which change the orientation of the wings and the direction of the lift force.
In summary, the angle of attack is the angle between the wing's chord line and the relative airflow. It affects the lift and drag forces acting on an airplane, and pilots carefully manage it to achieve optimal flight performance and safety.