Many years ago when I was finishing my senior thesis in college writing about the development of jet powered airliners, I was digging through the "stacks" in the library looking for aerodynamic textbooks from the 1930s and 1940s. Winglets, ring wings, box wings - you name it. All documented barely 20 years after the Wrights made their first flight. It's taken 80 years to refine them, but it's amazing to me that the concepts have been around that long.