“D-558-2 is launched from the Navy P2B-1S (Navy designation for the B-29) in this 1950s photograph. The early Douglas and NACA flights of the D-558-2s used only the airplane’s jet engine and took off from the lakebed. This limited the aircraft’s altitude and speed. The solution was to convert the D-558-2 to rocket or combined jet-and-rocket propulsion and to airdrop it from a B-29 converted to the Navy’s P2B-1S configuration.”
(Photo courtesy of http://www.nasa.gov/centers/dryden/multimedia/imagegallery)
This was a separate different program from the more famous X-1 craft which famed pilot Chuck Yeager used to break the sound barrier. But I found this photograph from the archives of NASA to be stunning.