SIFT Army Aviation Practice Test 2025 – Complete Exam Prep

Profile drag refers to the aerodynamic drag that arises from the shape of the rotor blades or wings and how they interact with the air as they move through it. The correct answer indicates that profile drag is influenced by two primary factors: the inclined rotor disk and the angle of attack.

When rotor blades are inclined, the angle at which they meet the oncoming airflow affects how efficiently they can generate lift and how much drag they create. The angle of attack is the angle between the chord line of the blade and the oncoming wind; as this angle increases, the lift increases up to a certain point, but it also increases the drag. Therefore, by understanding that profile drag is directly related to the orientation and angle of the rotor disks, one can see why this combination is significant in aviation and rotorcraft performance.

The other options do not correctly encapsulate the concept of profile drag. While skin friction and surface imperfections contribute to overall drag, they are not specific to the profile drag component associated with rotor blades or wings. Likewise, while induced drag is a real phenomenon related to lift generation, it does not combine factors to result in profile drag, and angular momentum is not a contributing factor in this context.