SIFT Army Aviation Information Practice Test

The correct answer highlights a critical aspect of rotor dynamics in helicopter flight. On the advancing side of the rotor blade, lift dynamics increase primarily due to a larger angle of attack. As the rotor blade moves forward through the air, the advancing blade encounters increased airflow and, often, an increased angle of attack relative to the incoming wind. This combination enhances lift production because a higher angle of attack generally leads to a larger lift coefficient, provided it does not exceed the critical angle where stall may occur.

Additionally, as the rotor blade progresses through its rotation, the advancing side benefits from the rotational speed combined with the forward speed of the helicopter. This effectively increases the relative velocity and accelerates airflow over the airfoil, contributing to a higher lift generation compared to other areas of the rotor disk.

In contrast, the other options do not accurately capture the dynamics at play on the advancing side. The centripetal force does not directly cause a decrease in lift on this side, and lift is not constant across the rotor disk due to varying angles of attack and airflow conditions. Finally, the retreating blades experience different dynamics, predominantly characterized by a decrease in lift due to adverse pressure gradients and lower effective angles of attack, which are distinct from the characteristics of the advancing blades