There is one other major Item to keep in mind. Flaps also increase drag as much as they do lift. 10 to 15 degrees of flap seem to produce the best lift to drag coefficient. The higher degrees of flap used the higher the drag, the lower the increase of lift. the use of full Flaps is to help in landing your plane at a steeper angle of attack with out gaining air speed. For an example say you had a very tall tree at the end of your runway. With out flaps at the steeper angle of attack needed to land you would over shoot or end up in the grass at the other end of the runway. With Full Flaps deployed while coming in for the landing at the same high angle of attack needed to land on the runway can be accomplished by the drag caused by the flaps and little to no increase in air speed.
jerrysu29 Call Sign Wild Man