And I was an English Lit major LONG ago. I did some fairly extensive research into winglets a while back and was surprised also that the first concepts were actually well before first flight. Also the design of a winglet is specific in that it is targeted for a specific regime (ie m 0.80M) for its BEST performance. And as noted before, adding a winglet means essentially completely re-designing the wing but part of the equation is already fixed.. thus complicating the process. And a fair amount of the stuff out there is just that.. stuff.

The thing that amazes me is the same guy, Whitcomb, is the one who came up with the area rule fuselage. He said he spent time each day just pondering and one day's pondering was on bird wings. That gave him the idea for the winglets and he then his homework, did some extensive research (prior to the internet), found old papers and began the process. First tests on the KC-135 where actual savings exceeded estimates.

Aviation Partners has moved beyond the 'simple' winglet and is exploring the 'spiroid' which is a tip that continues into a full closed curve.