Having been a ponderer for 56 years on the two lads from Dayton, Ohio, I keep coming back to their days flying on December 7th, 1903. Even now, many just do not appreciate or fully understand the magnitude of the event or the patient, persistant and, above all else the "Scientific' method they employed to research and then fly their series of gliders and the eventual inevitable product; the Wright Flyer. I still marvel when I study that one photograph taken of the first flight. What these men had constructed was a proper aeroplane in all respects. Just look at the highish aspect ratio mainplanes which resulted from their 1902 gliding trials with lower aspect ratio wings which did not produce the lift and drag results they had anticipated. The low-revving propellers on the Flyer were a marvel and approached the efficiency of fixed-pitch props of today. And they were mounted behind the wings thus minimising drag. I have long suspected that their first engine may have produced a tad more than the stated 12 bhp once the aircraft was on the move and my estimate of the resulting thrust is about 70-90 pounds. The aeroplane was truly controllable in all axis and the lads quickly learned how to manage it. (a jolly sight faster than I did on a Tiger Moth). One grows weary of reading that the first flight lasted only 12 seconds. Quite irrelevant as that was a premature touchdown in the gusty conditions and further flights that day were much longer. The chaps were learning to fly for goodness sake!
Then later when they were really getting into it back in Dayton where the density altitude was much higher than at the coast in winter, they produced aircraft that could go cross-country in true cruising flight, and with a passenger. When other experimenters were hopping along the ground in ungainly devices in Europe, the brothers took a machine there and absolutely stunned and amazed all who saw a true aeroplane for the first time. Some have denigrated the wing-warping roll control, but it was ideal for such low airspeeds and produced minimal adverse drag and yaw. I have long been convinced that once the steady methodical lads had determined to achieve controlled, powered and sustained level (and climbing) flight, their success was assured.
To summarise: Orville and Wilbur didn't merely manage to remain airborne; they designed, produced, test flew and then operated an "AEROPLANE"........
dakota67 rests his (initial) case.