When NASA tested a plane with a pivoting wing

Not many aircraft can claim to be truly one of a kind, but the NASA AD-1 is undoubtedly one of them. A slim pointed cigar with a single wing that pivoted around a central point, which led to a jarring asymmetry in flight. No other piloted plane has ever been built with a wing that could turn to a lopsided 20 to 2 angle -- but the fascinating story is why it did at all.