At a 2° angle of attack, the lift-to-drag (L/D) ratio is approximately the same as that for which other angle of attack?

The lift-to-drag (L/D) ratio is a key performance metric in aviation, representing the efficiency of an aircraft's lift relative to its drag. At different angles of attack, the L/D ratio can change significantly.

At a low angle of attack, such as 2°, the airflow over the wing is smooth and mostly attached, resulting in a good lift-to-drag ratio. As the angle of attack increases, the lift begins to increase significantly, but drag also starts to rise due to increased air friction and possible flow separation. The L/D ratio typically reaches its peak at a specific angle of attack, often referred to as the "design angle of attack," before it gradually diminishes as the angle continues to increase and ultimately leads to stall conditions.

In this context, the statement that the L/D ratio at a 2° angle of attack is approximately the same as that for a 16.5° angle of attack suggests that both angles can yield similar aerodynamic efficiency under specific conditions. This may occur in scenarios involving specific aircraft designs or configurations, where the characteristics of lift and drag might coincide at these two points on the lift curve. This indicates an unusual but significant point of balance between lift generation efficiency and drag penalties at those angles of