Which of the following can affect the angle of attack?

The angle of attack refers to the angle between the chord line of the airfoil (or rotor blade in this case) and the direction of the oncoming air (or relative wind). This angle is crucial for the performance of rotorcraft, as it directly influences lift generation and stability.

Blade flexing and collective pitch controls are significant factors affecting the angle of attack. Blade flexing occurs due to aerodynamic forces acting on the rotor blades during flight; as the blades flex, they change their angle relative to the oncoming airflow. This flexibility allows the blades to adjust their angle of attack dynamically, which is essential for optimizing lift and ensuring efficient flight.

Collective pitch control, on the other hand, alters the angle of attack for all rotor blades simultaneously. By changing the pitch of the blades collectively, the pilot can increase or decrease the angle of attack, which in turn promotes changes in lift depending on flight requirements, such as climbing or descending.

While other options may influence aspects of flight, they do not directly impact the angle of attack in the same manner that blade flexing and collective pitch controls do. Weather conditions can affect overall aircraft performance, and weight distribution can influence stability and handling, but neither specifically alters the geometrical relationship crucial for the angle