This glider was developed and built in house by NASA Dryden to test the low speed characteristics of a lifting body shape. The M2-F1 was made in tubular steel, plywood and light aircraft parts. The M2-F1 was towed initially by a souped-up 1963 Pontiac Catalina convertible. Later, as we can see here, a more orthodox C-47 was employed.
The “Flying Bathtub” more than vindicated the expense: it proved the lifting body concept and led the way for subsequent, “heavyweight metal” designs.