Ok, here is a simple explanation on the flap differences on American Planes. 1st off, there are 4 main types of flaps:
1. Plain Flaps
2. Split Flaps
3. Slotted Flaps
4. Fowler Flaps
See attached photo:
ANyways, briefly put,
The Plain Flaps are simply a hinged section of the trailing edge setup to hinge down. This includes the top section of the trailing edge as well. Aircraft with Plain Flaps include the F4u, P-51D, and.
The Split Flaps are setup exactly as they sound, they split away from the upper wing surface, leaving it intact, and hinge downwards. Neither the Spliut or the Plain Flap allow the airflow from the lower wing to go through the flap gap and over the top of the flap. A good example of an aircraft with a split flap being an F-6F, Wildcat, B-17, and AT-6.
Slotted Flaps are a variation of the plain flaps, the difference being that slotted flaps when extended allow a "Slot" to form between the Leading Edge of the Flap and the Trailing Edge of the Wing. The "slot" allows airflow to pass through from underneath the wing and exit over the top of the flap thereby lowering the pressure on top of the flap and increasing it's lift potential. Aircraft with Slotted flaps include the BT-13, Stearman, and BF-109.
Lastly we come to the Fowler Flap, the most effiecient flap design. A Fowler Flap is most distinguishable by it's ability to actually extend the trailing edge of the aircraft it is so attached to. This thereby increases the amount of wing area available for lift, and consequently with the slot formed by the lowering of the flap, increases potential lift. Good examples of fowler type flaps include the P-38, B-25, and A-26.
This is the best explanation that I have of the 4 main flap systems in play today. If you want to read more, there is an excellent article which I took the pic from of flaps on SimHQ.
