Part of the difficulty in trying to replicate control surfaces is in knowing exactly how a particular aircraft was designed in the full sized. And, not all 'designs' necessarily stayed with that AC. For example, I believe The F4D Skyray had LE slats-not flaps- were welded shut after it was discovered they popped out at inopportune moments during combat maneuvers, or so I've read. Looking closely at pics of the Su-27, there is something like an inverted 'V' on the interior root of the wing and a ball-shaped protrusion on the flap which would lock its uppermost travel. I could certainly be wrong-never saw one up close- but I think this would preclude the flap from moving upward. Indeed, the flaperons may go into a reflex position I just don't know. Darn, where is Victor Pugachev when I need him! I guess we don' have any Flanker drivers dropping in here. The Su is supposedly a fly-by-wire plane, so the question is what effect LE flaps, by themselves, will have. I just had to have them to add to the scale.