Final answer:
A stall in aircraft dynamics occurs when the wing exceeds its critical angle of attack, leading to disrupted airflow and a significant loss of lift. The principles of Bernoulli and Newton's third law help explain how lift is generated by differences in air pressure and velocity around the wing.
Step-by-step explanation:
A stall occurs when the smooth airflow over the unmanned aircraft's wing is disrupted, resulting in a rapid reduction in lift. This happens when the wing exceeds its critical angle of attack. This critical angle is the point at which the airflow can no longer follow the contour of the wing due to excessive angle, leading to separation of the flow and a stall. The other options provided, such as exceeding maximum allowable operating weight or maximum speed, do not directly cause a stall but may contribute to the conditions where a stall could occur more easily.
Bernoulli's principle is often applied to explain how lift is generated on a wing. The wing is typically angled so the air flowing over the top surface has to travel a longer path and therefore speeds up, reducing pressure and creating lift. This difference in velocity above and below the wing generates lift according to Bernoulli's principle, while Newton's third law also explains lift through the action of the wing pushing the air down, resulting in an equal and opposite reaction that pushes the wing up.