At a 4° angle of attack, the L/D ratio is approximately the same as that for which other angle?

The correct answer is that at a 4° angle of attack, the lift-to-drag (L/D) ratio is approximately the same as that for an 8.7° angle of attack due to the behavior of the lift and drag characteristics of the aircraft at varying angles of attack.

At lower angles of attack, the flow over the wing is smooth, reducing drag and maximizing lift, offering a favorable L/D ratio. As the angle of attack increases to certain values, the lift increases while drag also rises but may not outpace the lift proportionally at certain angles, resulting in a specific matching L/D ratio at a higher angle of attack.

In flight dynamics, the relationship between lift and drag is crucial, and the points where the L/D ratios are similar illustrate the aircraft's performance capabilities at those angles. This relationship allows pilots to determine optimal cruising and maneuvering conditions effectively. Thus, the 4° and 8.7° angles of attack fall in a range where they exhibit comparable aerodynamic efficiency, making understanding of this concept essential for a commercial pilot’s training.