Why does the back of the wing on a commercial airliner extend out during landing procedures? What effect does it have on the aircraft?

Question

Why does the back of the wing on a commercial airliner extend out during landing procedures? What effect does it have on the aircraft?

In: Engineering

Answer 1

Its takes a lot to stop a plane so the slower you can land, the better. Enter flaps. By changing the shape of the wing, the plane can fly much slowly but it becomes more unstable. You would never want to fly with flaps down unless there was some reason you needed to be so slow you needed them.

So before where the plane needed to be moving at 140mph to stay in the air, now it can do it at 105 and can slow down much easier when it touches down.

Same when you need to take off. A little bit of flaps lets you get off the ground sooner since the speed you lift off will be lower now.