HI.. I BUILT MANY YELLOW F-18.. SOME FOR BOB,,GOOD FREIND.. I PUT SLATS ON AN 18 FIRST, FOR BOB.. I THINK THEY MADE TAKE OFF RUNS LONGER..NOT NEEDED.. RD
ORIGINAL: Mike James
No extension is required, if the underlying circular section fits well. That's what prevents a gap.
25 degrees seems to be coincidental with full flap deflection on many fighters, and is what Bob Fiorenze used on his F-18. I've attached an image of the published F-16 deflections in various modes, for comparison.
