Hi! A little late to this, but the "bombing circle" was made sometime between 1953 and 1955 and complete sometime between '55 and '59 (one complete circle and two 3/4 circles). It might've been a type of bombing ring, but not WWII era. Perhaps rudimentary photo recon imaging for EAFB or photo bombing ring? In '59 there's a house just 1/2 mi NE of the bomb center so if there was any live bombing, it had to have stopped by then.