This P-61 was donated to the National Air Museum (as it was then known) as early as 1950, after five years of test work. However, NACA soon asked to borrow it for high-altitude experimental work. After about 50 flights as a mothership, dropping recoverable swept-wing test bodies, it was returned in 1954 to museum storage. Some 52 years later, it was unveiled for display in original test markings