The German X-4 was a small World War II air-to-air missile that could be fired at heavily armed Allied bombers from a distance. To prevent jamming, guidance was trasmitted by wires running between the missile and launch aircraft. Slated for use on the Me 262 jet fighter, the X-4 could also have been fired from such piston-engine aircraft as the Ju 88, Ju 388, and Fw 190, all of which launched test missiles beginning in August 1944.
A BMW 109-548 liquid-fuel rocket engine powered the missile. Ruhrstahl produced 1,000 X-4 airframes in late 1944, but an Allied air raid destroyed the engines and production lines, a blow from which the program never recovered. Nothing is known about the origins of the Smithsonian's artifact except that it came to the NASM in 1971 as part of a U.S. Navy gift of early German and American experimental missiles and glide bombs.
Transferred from the U.S. Navy, Naval Supply Center, Cheatham Annex, Williamsburg, Va.