What effect does the extension of trailing edge flaps have on an aircraft's glide angle?

The extension of trailing edge flaps alters the aerodynamic characteristics of an aircraft, particularly during descent. Flaps increase lift at lower speeds, which can be beneficial during landing but can negatively impact the glide performance when the aircraft is in a clean, unflapped configuration.

When trailing edge flaps are extended, they increase the drag significantly because they increase the camber of the wing. While more lift can be generated, the corresponding increase in drag often exceeds the benefits of the additional lift, resulting in a reduced glide ratio. The best glide angle, which is the steepest angle and the maximum distance an aircraft can travel relative to its altitude, gets compromised because the added drag can cause the aircraft to descend more steeply and lose altitude more quickly.

Thus, extending the trailing edge flaps degrades the aircraft's best glide angle, leading to a less optimal performance when trying to achieve the best possible glide distance. This understanding is crucial for pilots, especially in scenarios where a controlled descent is necessary, such as during an engine failure or emergency landing.