Which factor mainly affects the amount of lift and drag produced by an airfoil?

The angle of attack is crucial in determining the amount of lift and drag produced by an airfoil. It refers to the angle between the chord line of the airfoil and the direction of the oncoming airflow. As this angle changes, it directly influences the aerodynamics of the airfoil, affecting both lift and drag.

When the angle of attack increases, the airflow over the wing changes, leading to an increase in lift up to a certain point known as the critical angle. Beyond this angle, lift can begin to decrease, causing stall conditions where the airfoil cannot generate sufficient lift. The relationship between angle of attack, lift, and drag is fundamental to flight mechanics, making it the primary factor impacting how efficiently the airfoil can operate under various flight conditions.

While other factors such as speed, blade material, and altitude do play roles in overall aerodynamic performance, they are not as directly impactful on lift and drag as the angle of attack itself. Speed affects how much air flows over the wings, but the interaction between speed and angle of attack is what fundamentally dictates the airfoil's performance.