作者档案： 斯德克夫兹.000

这 马丁·玛丽埃塔 X-24 was an American experimental aircraft developed from a joint United States Air Force-NASA program named PILOT (1963–1975). It was designed and built to test lifting body concepts, experimenting with the concept of unpowered reentry and landing, later used by the Space Shuttle. Originally built as the X-24A, the aircraft was later rebuilt as the X-24B. The X-24 was drop launched from a modified B-52 Stratofortress at high altitudes before igniting its rocket engine; after expending its rocket fuel, the pilot would glide the X-24 to an unpowered landing.

源： 马丁·玛丽埃塔X-24在维基百科

这 X-38 was an experimental re-entry vehicle designed by NASA to research a possible emergency crew return vehicle (CRV) for the International Space Station (ISS). The 1995–2002 program also developed concepts for a crew return vehicle design that could be modified for other uses, such as a possible joint U.S. and international human spacecraft that could be launched on the French Ariane 5 booster. The program would eventually develop a total of three test prototype flight demonstrators for the proposed Crew Return Vehicle, each having incremental improvements on its predecessor. All three were wingless lifting body vehicles used in drop tests. The X-38 program was cancelled in 2002 due to budget cuts.

源： 美国宇航局X-38在维基百科