Which characteristic is true of critical angle of attack?

The characteristic of the critical angle of attack being variable with aircraft design is accurate because each aircraft is engineered with specific aerodynamic properties that dictate its behavior in flight. The critical angle of attack is the angle at which the airflow begins to separate from the wing's upper surface, leading to a stall. This angle can differ significantly based on various design factors, including wing shape, aspect ratio, and overall aircraft configuration.

Aerodynamic features such as wing shape (e.g., high-lift devices), camber, and aspect ratio influence how and when airflow remains attached to the wing. Consequently, different aircraft types—be it gliders, fighter jets, or commercial airliners—exhibit unique critical angles of attack suited to their operational needs and performance characteristics.

While it's true that the critical angle of attack cannot be exceeded without risking a stall, this is fundamentally about the consequences of exceeding it rather than its inherent characteristics. The claim that it remains constant across all conditions or is independent of weight does not hold since various flight conditions, such as speed, altitude, and environmental factors, can also influence the effective critical angle of attack experienced by the aircraft. Hence, acknowledging that this angle varies with aircraft design provides a clear understanding of its significance in aerodynamic performance.