There is a simple way to build simulated Fowler Flaps, afterall we are only building models not overweight scale aircraft. On my 80" H9 Piper Cub I used round pin hinges (Robart) install them on the bottom of the wing as in robarts how to hinge flaps, they do move slightly aft , Then downwards. I attached a strip of lexan to the top front of the flap which slides in and out of the wing to fill air gap, bingo your done. and they will slow the piper down so slow at landing there is hardly any roll out. Come on dont argue just share your ideas.