Originally Posted by
coplatsat
To settle the full weight of the aircraft on the runway which enhances drag, friction, and brake performance. In simple terms, to stop faster.
Flaps allow the aircraft to fly at slower speeds without stalling by increasing lift by increasing the area of the wing. So in landing they are used to be able to continue to fly the plan as slow as possibly safe so that you can land as slow as possible. This then allows the plane to touch down without the danger of snapping of the gear and/or control issues (ie sliding of the runway, cartwheeling down the runway).
Once the plan is on the runway (front gear too), then there is no need for the flaps, and they are retracted to settle the airplane on to the runway. Since clean (no flaps), the speed required to fly is higher than when they are extended.
Are you sure about all your facts there?
I could be wrong, but I don't ever recall seeing flaps being retracted as part of the landing sequence. My recollection is they usually don't start retracting them until they let off the brakes, retract spoilers/slats and disengage(?) thrust reversers, about when they exit the runway.
Them spoilers make the wing stop supplying lift right quick. Much quicker than the relatively slow movement of the flaps.