Flap deflection angle of a wing on lift to drag ratio?

[barca12345]

How does the flap angle affect lift to drag ratio of a wing?

 

[.Scott]

As flaps are extended, the wings will generate more lift and much more drag. The lift to drag ratio goes way down.

As you may know, flaps are used primarily during the landing sequence and sometimes on takeoff as well. They allow the wings to generate more lift at slower speeds. They can also enhance ground effect, especially on low-wing planes.