During flight 4 on July 31, 1997, landing strut 2 failed to extend, causing the unbalanced vehicle to tip over on its landing pad. The LOX tank exploded and there were indications of secondary explosions in the LH2 tank as well. The ensuing fire damaged large sections of the DC-XA. An investigation board was convened to determine the cause of the accident, which was later determined to be an unconnected helium pressurant line that supplied hydraulic pressure to extend the landing strut.

The conclusion of the program was summed up well by the Reusable Launch Vehicle program director, Gary Payton. He stated, "The way the budget is now, we cannot afford to rebuild the Clipper Graham and will not be able to continue with that takeoff and landing technique, so we will declare victory with the DC-XA."

Like any good experimental vehicle, the DC-XA flew until it was destroyed. We will always be impressed by the lessons this little rocket taught us about the right way to travel to the heavens...

The DC-X Program:

The Delta Clipper Experimental was constructed in 1991-93 at McDonnell Douglas' Huntington Beach facility. It was intended as a one-third scale model of a proposed SDIO single-stage launch vehicle. It first flew in August 1993 and had completed three flights when SDIO terminated the Delta Clipper program. After additional funding was procured, the vehicle flew five more flights before being returned to Huntington Beach for conversion into the DC-XA.

Delta Clipper-Experimental (DC-X) Test Program
Rollout		April 3, 1993
Flight	Launch Date	Time (MDT)	Duration (sec)	Altitude (m)	Description
1	August 18, 1993	1643	59	46	Verified flight control systems and vertical landing capabilities.
2	September 11, 1993	1112	66	92	Ascent and landing mode control and ground effects survey.
3	September 30, 1993	1030	72	370	180 degree roll; aerostability data.
4	June 20, 1994	0842	136	870	Full propellent load; radar altimeter in control loop.
5	June 27, 1994	0837	78	790	In-flight abort after gaseous hydrogen explosion; vehicle demonstrated autoland capabilities.
6	May 16, 1995	0940	124	1330	Continued expansion of flight envelope; constant angle of attack.
7	June 12, 1995	0838	132	1740	First use of reaction control system thrusters; AOA from 0 to 70.
8	July 7, 1995	0702	124	2500	Final flight; demonstrated turnaround maneuver; aeroshell cracked during 14 ft/s landing.

The DC-XA Program:

The Delta Clipper Experimental Advanced was a modified version of the DC-X. It had a lightweight graphite-epoxy liquid hydrogen tank and an advanced graphite/aluminum honeycomb intertank built by McDonnell Douglas; an aluminum-lithium liquid oxygen tank built by Energia; and an improved reaction control system from Aerojet. These improvements reduced dry vehicle mass by 620 kilograms. The DC-XA was operated by NASA and the Department of Defense under the Reusable Launch Vehicle program. The flight vehicle was tested at White Sands during the summer of 1996, and demonstrated a 26-hour turnaround between its second and third flights, a first for any rocket. After the fourth flight, however, the DC-XA suffered severe damage and the program ended due to lack of funding.

Delta Clipper-Experimental Advanced (DC-XA) Test Program
Rollout		March 15, 1996
Arrival at White Sands		March 22, 1996
Engine Test 1		May 4, 1996
Engine Test 2		May 7, 1996
Flight	Launch Date	Time (MDT)	Duration (sec)	Altitude (m)	Description
1	May 18, 1996	0814	62	244	First flight of the DC-XA; aeroshell caught fire during slow landing.
2	June 7, 1996	1015	64	590	Maximum structural stresses with 50% full LOX tank.
3	June 8, 1996	1217	142	3140	26-hour rapid turnaround demostration; new altitude and duration record.
4	July 31, 1996	1315	140	1250	Landing strut 2 failed to extend; vehicle tipped over and LOX tank exploded; vehicle destroyed.