Which came first, paper airplanes or real ones?
Prior to the invention of the flying machine, did people fold paper into the traditional paper airplane shape and let 'er fly? Or did the airplane inspire the invention of the paper airplane?
One of your more piquant questions, ain't it? Presumably you didn't have model railroads until you had railroads. But not only did model (including paper) airplanes precede airplanes, the former were an essential step in the development of the latter, and the histories of the two are inextricably linked.
Unfortunately, that's about all we can definitively say about paper airplanes, a subject shrouded in obscurity. Credit for the first paper airplane is generally given to Leonardo da Vinci, prompting Scientific American magazine to name the prize awarded in its 1967-68 paper airplane contest the Leonardo. But while Cecil doesn't want to take anything away from the ultimate Renaissance man, close examination suggests he may not deserve the honor.
Leonardo was interested in flight and designed a parachute (square, perversely enough) and a primitive helicopter. (One of his model choppers, using feathers for rotors, is thought to have gotten airborne, although scoffers say it was simply based on a then-popular kid's toy.) He made reference in one of his notebooks to building a model airplane out of parchment, the paper of the day. There's a tradition, undoubtedly false, that he actually flew. But it's debatable whether Leonardo had any clue about airfoils, which of course are the heart and soul of paper airplanes and indeed of virtually all heavier-than-air craft. Paper airplane aficionados, no doubt hoping to drag in a big name and thus lend a cloak of respectability to their art, say Leonardo did understand airfoils and so may legitimately be said to be the father of the fold-'em-and-fly-'em school of aeronautics. But his notes and drawings make it pretty obvious that flying as he understood it was a brute force proposition — you stayed aloft by flapping your wings, forcing air down, and clawing your way into the sky. This has little to do with the paper airplanes of today, whose charm lies in their ability to stay aloft simply by gliding, with minimal exertion on the part of the thrower.
One can argue that the true father of the paper airplane — at least the one true father of whom we have any detailed knowledge — was an English squire named George Cayley, who built gliders around 1800. Cayley constructed several of these from kites (linen rather than paper, but close enough) fastened to poles, which he flung like a javelin from a hillside near his home. After a little fine-tuning he found he could get up considerable distance, and a new form of recreation for sixth-grade recess was born.
Experimentalists by that time had a rough knowledge of airfoils, based in part on efforts to improve the efficiency of windmills. Cayley greatly expanded on this during his own research. Later he wrote a detailed and fairly accurate treatise on aircraft design. It attracted little notice, but it's not Cayley's fault if he was surrounded by dopes.
As for who designed the classic paper "dart" known to every school child, we don't know for sure. We do know that in 1867 J.W. Butler and E. Edwards of Great Britain proposed a human-sized dart that was virtually identical in design to the modern paper variety. (The propellant was not to have been a giant hand, however, but rather a solid fuel.) The plane was never built and it was a long time before practical delta-winged aircraft emerged. But some bored grade schooler either ripped off Butler-Edwards or had a remarkably similar inspiration, because the design has been the foundation of 90 percent of paper aircraft constructed since.