Here's the arrangement I'll be using on my sport jet for the leading edge flaps.

To make this work, I've made a male mold, from which I mold the round interior piece... the "leading edge within a leading edge. (second photo)


Bob Violett has 'em on his F-100. Bob Fiorenze put them on an F-18, and Larry Wolfe has put them on several aircraft. The camber change does make a difference, at larger-than-park flyer size.