BTW: These full span flaps look very much like those patented 1952 by Youngmann. See more in the following link:
And here is a diagram about what flaps can usually do for the lift coefficient. Using for example type (7) configuration the wing is generating 2.4 time more lift than the wing alone and 1.4 times more than the plain flap (2) alone. The reduction of the wing size (and drag) is proportional to that although the less clean wing adds some drag but we have to remember that most designs can not benefit so much about the cleanness of the wing. /1/
From Loftin, NASA Sp 468, 1985
Typical values of airfoil maximum lift coefficient for various types of high-lift devices: (1) airfoil only, (2) plain flap, (3) split flap, (4) leading-edge slat, (5) single-slotted flap, (6) double-slotted flap, (7) double-slotted flap in combination with a leading-edge slat, (8) addition of boundary-layer suction at the top of the airfoil.
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