May 8, 1996 16:37:23.11
WITH GROUND TESTS COMPLETE, DC-XA TO RESUME FLIGHTS THIS MONTH
The Delta Clipper-Experimental Advanced (DC-XA), a
single stage rocket developed by NASA and McDonnell Douglas
Aerospace, yesterday completed a series of ground tests at
the U.S. Army White Sands Missile Range, New Mexico, and now
is being readied for flight.
The DC-XA will undergo a series of five flight tests
beginning no earlier than May 17. The date for the first
test will be determined later this week.
“Flight testing the DC-XA will provide information about
the performance of composite materials and other advanced
technologies in the launch vehicle as it encounters the
conditions of flight, such as temperature, pressure and
noise. This information will be very valuable for the X-33
technology demonstrator NASA and an industry partner will
develop in the future,” said Dan Dumbacher, NASA’s DC-XA
program manager at the Marshall Space Flight Center,
Huntsville, AL. Marshall is the host center for NASA’s
Reusable Launch Vehicle Technology Program. The U.S. Air
Force’s Phillips Laboratory at Kirtland Air Force Base, New
Mexico, will manage flight test operations.
The DC-XA evolved from the DC-X, which the U.S. Air
Force flew eight times between August 1993 and July 1995.
The 43-foot-high existing airframe was extensively modified
by replacing existing systems with a composite hydrogen tank;
a Russian-built aluminum-lithium alloy liquid oxygen tank; a
composite intertank to connect the hydrogen and oxygen tanks;
and an auxiliary propulsion system which includes a composite
liquid hydrogen feedline, a composite liquid hydrogen valve,
a liquid-to-gas conversion system reaction control system,
and a Russian auxiliary power unit providing redundant
hydraulic power for flight control.
“When DC-XA lifts off from its launch stand, it will be
the first time a rocket has flown with a composite hydrogen
tank. This innovation and the many other technology
enhancements included in the vehicle will make its flight
testing very challenging,” said Dumbacher.
Ground testing of the DC-XA exercised all of the vehicle
subsystems and showed the vehicle is ready for flight,
Dumbacher said. It included three firings of DC-XA’s main
propulsion system, between three and 20 seconds in duration,
and up to 95 percent thrust level.
McDonnell Douglas is supported in the preparation of DC-
XA for flight by Aerojet, prime developer of the auxiliary
propulsion system; Lockheed Martin Corporation, developer of
the ground propellant system, and by Rockwell International,
which provided an acoustic structural health monitoring
system for the hydrogen tank.
The DC-XA, X-34 and X-33, and related long term
technology development efforts, comprise NASA’s Reusable
Launch Vehicle Technology Program, a partnership among NASA,
the Air Force and private industry to develop a new
generation of single-stage-to-orbit launch vehicles. The X-
34, a small technology demonstrator, will undergo test flight
in 1998 while the X-33 large technology demonstrator is
planned for test flight in 1999. Success of the X-33 could
lead to a national, industry-led decision to develop a
commercial reusable launch vehicle early next century. Such
a vehicle would dramatically reduce the cost of launching
payloads into space.
Space Access Update #64 5/18/96
DC-XA’s First Flight Completed
Vehicle Takes Minor Damage In Post-Flight Fire
copyright 1996 by Space Access Society
Saturday, May 18th, 1996 – The DC-XA single-stage rocket experimental
vehicle flew this morning for the first time since its handover to NASA
last year and major rebuild over the winter. The test took place at the
same White Sands Missile Range, New Mexico site the original DC-X made
its eight flights from. This first post-rebuild flight had originally
been scheduled for Friday, but was delayed 24 hours by a faulty sensor
on one of the vehicle’s four RL-10-a5 rocket engines. This morning’s
flight was a minimal test-hop, 800 feet up from the launch stand, then
350 feet sideways to over the landing pad, then a vertical descent and
landing, total flight time of about a minute.
The flight went as planned until the final landing phase, when the DC-XA
descended the last few feet onto the concrete landing pad more slowly
than expected. This final descent phase has been the object of ongoing
tweaking dating back to the last several flights of the original DC-X.
The target touchdown velocity is around four feet per second; previous
touchdowns have varied from two feet per second to as high as fourteen
feet per second – that last due to an invalid data problem with a radar
altimeter rather than the landing control software, however.
The problem with slow landings is that the vehicle sits in the backwash
from the rocket engines too long, and the base of the vehicle can suffer
heat damage. There is some thought being given to landing the potential
followon to DC-XA (if McDonnell-Douglas wins the X-33 competition) on an
open grid of some sort to reduce backwash, but meanwhile DC-XA lands on
a plain concrete slab, and slow landings can cause problems.
This morning’s slow landing apparently started a small fire on the
exterior of the vehicle. According to McDonnell-Douglas sources, the
fire was promptly extinguished, and the vehicle has been de-fuelled and
moved back to its launch stand in the normal manner. One of the
vehicle’s four body-flaps (hinged square control surfaces, one on each
side of the conical vehicle near its base) was damaged and will have to
be replaced. We’re told there is no other obvious damage, but the
structure around that body flap will be carefully inspected for possible
heat damage. The DC-XA engineering/flight-test team will be looking
into that and into why this landing was slow over the next few days,
then implementing fixes.
There’s no telling at this point whether this will push back the next
planned flight dates of June 7th and 8th, but our first guess would be
that those will slip by a week or two. We’ll likely know more in a few
days, though.
A quick bit of editorializing: Discovering and fixing this sort of
problem is exactly why we test-fly experimental vehicles. Fly a little,
see what breaks, figure out why, fix it, fly a little more. We look
forward to the DC-XA crew discovering, and solving, more problems as
this summer’s test series continues.
DC-XA COMPLETES SECOND TEST FLIGHT
A McDONNELL DOUGLAS NEWS RELEASE
WHITE SANDS MISSILE RANGE, N.M. – An experimental rocket today
successfully completed its second test flight, providing data to evaluate
advanced technology materials and components under flight conditions.
The cone-shaped reusable launch vehicle, formerly known as the Delta
Clipper-Experimental Advanced (DC-XA), made its first flight renamed as the
Clipper Graham.
The Clipper Graham climbed vertically at 170 feet per second to an altitude
of approximately 2,000 feet, then flew laterally for 550 feet up range before
throttling back its engines and descending tail first onto the desert floor.
Duration of the flight was 63.6 seconds.
Today’s 10:15 a.m. MDT test flight was the second since advanced technology
materials and components were integrated into the launch vehicle.
“The test flights are providing data to evaluate the performance of new
lightweight components, which include a graphite composite liquid hydrogen
tank, graphite composite intertank and aluminum-lithium liquid oxygen tank,”
said Dave Schweikle, McDonnell Douglas’ DC-XA program manager.
“Each time the Clipper Graham flies, we are increasing our knowledge of the
strength and durability of these lightweight materials, which have been
exposed to cryogenic temperatures,” he explained.
“The goal of the program is to demonstrate SSTO technology that will lead
to the development of operational reusable launch vehicles,” Schweikle said.
“These launch vehicles will dramatically reduce the cost of placing payloads
into space.”
Today’s flight provided the first test of a differential global positioning
system (DGPS) which provides data to the Clipper Graham’s navigational system.
Signals from satellites of the Global Positioning System and a ground
station were used to precisely determine the position of the reusable rocket.
Under a cooperative agreement with NASA, McDonnell Douglas extensively
modified the launch vehicle by replacing original systems with a McDonnell
Douglas-built graphite composite liquid hydrogen tank and intertank and a
Russian-built aluminum-lithium liquid oxygen tank. The U.S. Air Force’s
Phillips Laboratory is providing flight management support to the flight test
program.
In addition, Clipper Graham is flying with a graphite composite liquid
hydrogen feedline and valve, a liquid-to-gas conversion system to fuel the
reaction control thrusters, and a Russian auxiliary power unit to provide
redundant hydraulic power for flight control.
Data from the DC-X and the DC-XA is being supplied to the reusable launch
vehicle government-industry team. The X-33 is a large, reusable technology
demonstration vehicle which is planned to fly in 1999. Success of the X-33
could lead to a national, industry-led decision to develop a commercial
reusable launch vehicle early in the next century.
The McDonnell Douglas entry in the X-33 competition is a vertical
takeoff/vertical landing rocket based on the configuration of the Clipper
Graham. NASA is expected to announce a decision on the X-33 in July.
STATUS REPORT: FOURTH TEST FLIGHT OF CLIPPER GRAHAM
A McDonnell Douglas news release
WHITE SANDS MISSILE RANGE, N.M., July 31, 1996 – The experimental
NASA-McDonnell Douglas Clipper Graham rocket flew today, but a problem during
landing caused the vehicle to tip over and catch fire.
The Clipper Graham began its 2-minute, 20-second test flight at 1:15 p.m. MDT. It was the fourth flight in a test series that began in May.
Program managers Dan Dumbacher of NASA and Dave Schweikle of McDonnell Douglas
said the vehicle performed its flight maneuvers extremely well. It completed
its planned test profile, which included an arc-like sweeping maneuver from a
near upright position, before descending base-first from the 4,100-foot maximum
altitude. All of the vehicle’s components appeared to function normally.
However, approximately 200 feet above the landing pad one of four landing gear
failed to deploy. The Clipper Graham touched down on the three deployed
landing gear, shut off its engines, then fell on its side because it lacked the
support of the fourth landing gear.
A committee will be established to investigate the cause of the incident. The
committee will gather flight and landing data to determine what caused the
problem. Engineers and technicians will not be able to examine the severely
damaged vehicle for at least 24 hours because of safety considerations.
Dumbacher and Schweikle said the Clipper Graham is an experimental, high-risk
technology program. The Clipper Graham is a follow-on of the Delta
Clipper-Experimental vertical-takeoff, vertical-landing rocket that
successfully completed a series of eight flight tests.
Dumbacher and Schweikle said each of the tests in the program has been more
demanding, demonstrating the behavior of the experimental vehicle under a
variety of dynamic flight conditions.