Between 1993 and 1996, the McDonnell Douglas DC-X, also known as the "Delta Clipper", conducted twelve low-altitude suborbital test launches to verify the configuration and handling of the uncrewed single-stage-to-orbit Delta Clipper design, which was proposed to the United States Department of Defense and the National Aeronautics and Space Administration (NASA) for use as a reuseable launch vehicle.[1] Claimed as the first rocket to conduct a vertical landing on Earth, the DC-X was a one-third scale demonstrator for the proposed operational Delta Clipper vehicle.[2]
After the first three flights Strategic Defense Initiative Organization funding for the test project was cancelled;[3] the remaining test program was conducted by NASA and the Advanced Research Projects Agency.[4] Following the eighth test flight, the vehicle was transferred fully to NASA and the vehicle was modified to DC-XA configuration,[5] also known as "Clipper Graham" after General Daniel O. Graham who had died in 1995 after supporting the Delta Clipper project.[6]
Of the overall test program, ten of the vehicle's launches were fully successful; the fifth test flight was aborted early in the flight following an on-board explosion but the vehicle was successfully recovered. The twelfth and final flight saw one of the vehicle's landing legs fail to extend; on landing, when the vehicle tipped over onto its unsupported corner, a liquid oxygen tank ruptured and exploded, the ensuing fire destroying the modified DC-XA vehicle and ending the program. Despite the loss the program was considered overall to have been a success.[1]
Flight No. | Date and time of takeoff (UTC) | Vehicle | Launch site | Suborbital apogee | Outcome | Duration | Reference |
---|---|---|---|---|---|---|---|
1 | 18 August 1993 23:43 | DC-X | White Sands Space Harbor | 59 sec | |||
Control system and vertical landing capability test.[7] Demonstrated hovering ability and horizontal translation. | |||||||
2 | 11 September 1993 18:12 | DC-X | White Sands Space Harbor | 66 sec | |||
Ground effects and ascent-and-landing mode control test. | |||||||
3 | 30 September 1993 17:30 | DC-X | White Sands Space Harbor | 72 sec | |||
Aerostability test; vehicle conducted 180° roll. | |||||||
4 | 20 June 1994 15:42 | DC-X | White Sands Space Harbor | 2 min 16 sec | |||
First flight with fully loaded propellant tanks and operational radar altimeter. | |||||||
5 | 27 June 1994 15:37 | DC-X | White Sands Space Harbor | 78 sec | |||
Flight aborted after hydrogen explosion on launch; autoland capabilities demonstrated. | |||||||
6 | 16 May 1995 16:40 | DC-X | White Sands Space Harbor | 2 min 4 sec | |||
Flight envelope expansion test. | |||||||
7 | 12 June 1995 15:38 | DC-X | White Sands Space Harbor | 2 min 12 sec | |||
AOA envelope expansion, first reaction control system usage. | |||||||
8 | 7 July 1995 14:02 | DC-X | White Sands Space Harbor | 2 min 4 sec | |||
Turnaround maneuver demonstrated; hard landing resulted in damage to the aeroshell. | |||||||
9 | 18 May 1996 15:14 | DC-XA | White Sands Space Harbor | 62 sec | |||
First flight following modification to DC-XA configuration; slow landing resulted in aeroshell fire. | |||||||
10 | 7 June 1996 17:15 | DC-XA | White Sands Space Harbor | 64 sec | |||
Maximum structural stress test. | |||||||
11 | 8 June 1996 19:17 | DC-XA | White Sands Space Harbor | 2 min 22 sec | |||
Demonstration of 26-hour rapid turnaround; altitude and duration record set. | |||||||
12 | 31 July 1996 20:15 | DC-XA | White Sands Space Harbor | 2 min 20 sec | |||
Successful maneuvering test; vehicle destroyed on landing when landing strut failed to extend and LOX tank exploded.[8] |