Wing
As the flaps are lowered further the air flow breaks up increasing another force, the force of drag. As drag increases the aircraft slows down.

 

 

Modern wings have upturned surfaces at the tip as shown on the left. This prevents turbulence developing as air spills over the edge. Click to see a 300 kb video of the turbulence created by flat wings.

Addition of such wing tips may increase the lift generated by the wing by up to 10%.