X-4 BantamSTS079-358-027 (16-26 September 1996) --- Astronaut William F. Readdy looks over a checklist at the commander's station on the Space...ISS005-E-17402 (13 October 2002) --- Cosmonauts Valery G. Korzun (left), Expedition Five mission commander, Sergei Y. Treschev and astronaut Peggy...The X-4's design allowed it to be separated into two parts, aft of the engines, for servicing and instrumentation work.In this 1952 photograph NACA test pilot Joe Walker (on left) is seen discussing tests points to be flown on...The NACA High-Speed Flight Research Station X-4 research aircraft is seen in this 1950s in-flight close-up photograph.