X-1 loading pit
the X-1 was stubby-winged, so the cross shaped pit in the Nevada desert fits.
Was the driver Slick, or Chuck?
So, we have the Little Boy loading pit on Tinian and the X-1 loading pit at Edwards.
But it is not over. There is the equation:
B## + P = B## + U = B## + X# = (BIG/P), # is 1 or 2 or 9.
My crack at it is: B29 + P = B29 + U = B29 + X1 = (BIG/P)
I am still in the dark about P and U. The Fat Man bomb was Pu, but Little Boy was U-235. i think that our picture is the Little Boy loading pit. Maybe I am on the wrong track about P and U.