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The DC-X, short for Delta Clipper
or Delta Clipper Experimental, was an unmanned prototype of a reusable
single-stage-to-orbit launch vehicle built by McDonnell Douglas in conjunction
with the United States Department of Defense's Strategic Defense Initiative
Organization (SDIO) from 1991 to 1993. Starting 1994 until 1995, testing
continued through funding of the US civil space agency NASA. In 1996,
the DC-X technology was completely transferred to NASA, which upgraded
the design for improved performance to create the DC-XA.
Built as a 1/3rd scale prototype, the DC-X was never designed to achieve
orbital altitudes or velocity, but instead to demonstrate the concept
of vertical take off and landing. It would take off vertically like standard
rockets, but also land vertically with the nose up. This design used attitude
control thrusters and retro rockets to control the descent, allowing the
craft to begin atmospheric entry nose-first, but then roll around and
touch down on landing struts at its base. The craft could be refueled
where it landed, and take off again from exactly the same position.
Construction of the DC-X started in 1991 at McDonnell Douglas' Huntington
Beach facility. The aeroshell was custom-constructed by Scaled Composites,
but the majority of the spacecraft was built from commercial off-the-shelf
parts, including the engines and flight control systems.
NASA agreed to take on the program after the last (of eight) DC-X flight
in 1995. In contrast to the original concept of the DC-X demonstrator,
NASA applied a series of major upgrades to test new technologies. In particular,
the oxygen tank was replaced by a lightweight (alloy 1460 equivalent of
alloy 2219) aluminium-lithium alloy tank, and the fuel tank by a newer
composite design.The control system was likewise "improved". The upgraded
vehicle DC-XA, and resumed flight in 1996. The fourth flight proved to
be its last. During testing, one of the LOX tanks had been cracked. When
a landing strut failed to extend due to a disconnected hydraulic line,
the DC-XA fell over and the tank leaked. The LOX from the leaking tank
fed a fire which severely burned the DC-XA, causing such extensive damage
that repairs were impractical.
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| Delta
Clipper-Experimental (DC-X) Test Program |
|
Event
|
Launch Date
|
Altitude
(m) |
Duration
(sec) |
Result
|
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Flight
#1
|
1993 |
August
18
|
46 |
59 |
Success
|
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Flight
#2
|
September
11
|
92 |
66 |
|
Flight
#3
|
September
30
|
370 |
72 |
|
Flight
#4
|
1994 |
June 20
|
870 |
136 |
|
Flight
#5
|
June 27
|
790 |
78 |
Flight abort after
hydrogen explosion |
|
Flight
#6
|
1995 |
May 16
|
1,330 |
124 |
Success
|
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Flight
#7
|
June 12
|
1,740 |
132 |
|
Flihgt
#8
|
July 07
|
2,500 |
124 |
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| Delta
Clipper-Experimental Advanced (DC-XA) Test Program |
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Event
|
Launch Date
|
Altitude
(m) |
Duration
(sec) |
Result
|
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Flight
#1
|
1996
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May 18
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244 |
62 |
Success
|
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Flight
#2
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June 07
|
590 |
64 |
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Flight
#3
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June 08
|
3,140 |
142 |
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Flight
#4
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July 31
|
1,250 |
140 |
destroyed
after landing |
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