The X-4 was a small, wire-guided, air-to-air missile designed as a standoff weapon against Allied bombers. It was slated for use with the Me 262 jet fighter, but could also have been fired from a number of piston-engine aircraft such as the Ju 88, Ju 388 and Fw 190, which test-launched test missiles beginning in August 1944.
This wire bobbin would have been placed in one of two of the missile's four wing tips, from which the control wires paid out until they reached the breaking point. Nothing is presently known about its origins, but the U.S. Navy transferred it to the Smithsonian in a shipment of missile artifacts in 1948.
Transferred from the U.S. Navy Bureau of Aeronautics