The first sustained flight of a heavier than air aircraft by those Ohio innovators and first aeronautical engineers, Orrville and Wilbur Wright happened on 12-17-1903. Everyone knows the the World War II era reason for the 51 on the Ohio Wing patch but, when I was a cadet we added the first flight date numbers together, like this 12+17+19+3=51. Made for a better story since there is a Wright Flyer on the patch.
I'll add this to the wing files, as I have not come across this interpretation of the number, at least from a cadet perspective. The great riddle I still hope to solve is just exactly who designed the OHWG patch. I much prefer to replace "unknown" with a name.
http://www.ohwg.cap.gov/ohio-wing-world-war-ii-history (http://www.ohwg.cap.gov/ohio-wing-world-war-ii-history)