Historical Perspective BOEING FRONTIERS
`A step
`to the moon
`DC-X experimental lander set up Boeing for future NASA work
`By Ed MEMi
`You probably remember the Apollo lunar lander from the
`1960s. But did you know that Boeing has more recent expe-
`rience with this type of space vehicle? McDonnell Douglas,
`a Boeing predecessor company, built the Delta Clipper–
`Experimental DC-X, a prototype experimental lander, and the
`more-advanced Clipper Graham DC-XA vehicle. Boeing will
`put that expertise to good use when it competes to build the
`United States’ next lunar lander in 2011 or 2012.
`The DC-X program was an unmanned prototype of a reusable
`single-stage-to-orbit launch vehicle. The one-third-scale DC-X was
`never designed to achieve orbital altitudes or velocity. Instead, it
`was meant to demonstrate various flight concepts, such as verti-
`cal takeoff and landing and responsive operations.
`McDonnell Douglas received its DC-X contract on Aug. 16,
`1991, from the U.S. Department of Defense’s Strategic Defense
`Initiative Office; the contract was taken over by NASA’s Marshall
`Space Flight Center when it became the DC-XA program.
`The cone-shaped 42-foot (12.8-meter) DC-X and DC-XA vehi-
`cles were assembled in Huntington Beach, Calif., with test flights
`taking place at the White Sands Missile Range, N.M. The DC-XA
`was a lighter-weight version of the DC-X that relied on the use of
`more-advanced technologies to provide improved performance.
`The DC-X conducted its first of eight test flights on Aug. 18,
`1993, while another four flights were flown under the DC-XA pro-
`gram. The flights lasted from 59 to 142 seconds, and the highest al-
`titude was 10,300 feet (3,140 meters).
`“Rocket-powered vertical landers are very complex systems, and
`we have a really deep understanding of how those systems work,”
`said James Ball, who was on the original DC-X proposal team and
`eventually went on to lead the DC-XA software team. Ball, now a
`Boeing manager for the flight function at Huntington Beach, noted
`that the lunar lander was a simpler vehicle than the DC-X; for ex-
`ample, the DC-X featured four engines, while previous landers had
`just one.
`The DC-X demonstrated that aircraft-like operations are possible
`using rocket-powered reusable vehicles. “The vehicle flew forward,
`backward, sideways and could hover. Most vehicles don’t do that,”
`said Dan Nowlan, a Boeing technical fellow who was the DC-X
`guidance, navigation and control lead.
`There were also a host of performance requirements for the
`vehicle, which used innovative fuel-tank technologies such as
`lightweight composite tanks, lines and valves. The DC-X pro-
`gram featured new propulsion technologies such
`as gaseous oxygen and hydrogen roll-control
`thrusters. Other innovations included an auton-
`omous checkout to include leak detection and
`isolation. These technologies can be directly
`applied to future lunar lander designs.
`One of the objectives of the test program
`was to demonstrate that the DC-X had a robust,
`adaptive vehicle design. During the fifth test
`flight, a portion of the side of the vehicle was
`damaged, but the design was so robust that the
`vehicle was able to land safely. Lt. Col. Jess
`Sponable, Single Stage Rocket Technology
`program manager for the Ballistic Missile
`Defense Organization, was quoted in a com-
`pany press release saying, “This anomaly
`resulted in successful demonstrations of sev-
`eral important firsts: executing the autoland
`sequence demonstrating an ‘aircraft-like’
`abort mode; landing on the gypsum (des-
`ert ground), demonstrating the ability to
`land future vehicles virtually anywhere;
`and demonstrating the system’s tough-
`ness and robustness, since the DC-X
`continued to fly despite the aeroshell
`During another test flight, a vehicle
`fire destroyed a control flap, but the ve-
`hicle was repaired in time for its next test
`flight. On test flight three, the vehicle sur-
`vived a propellant helium bubble during
`liftoff and autonomously recovered
`the Mcdonnell douglas dc-X blasts off from
`the desert at White Sands Missile range, n.M.
`the dc-X needed only two years from contract
`award to first flight.
`McdonnELL dougLaS photo
`Space Exploration Technologies; NEW PETITION
`Exhibit 1115
`Page 1 of 2


`Historical Perspective BOEING FRONTIERS
` DC-X
`Tale of the tape:
`Height: 42 feet (12.8 meters)
`Diameter: 13 feet 4 inches at base (4.06 meters), conical
`Weight empty: 20,000 pounds (9,072 kilograms)
`Weight with full load of propellants: 41,600 pounds
`(18,869 kilograms)
`Propellants: Liquid oxygen and liquid hydrogen
`Engines: Four RL-lOA5 rocket engines, each
`generating 13,700 pounds (6200 kilograms) thrust.
`Reaction Controls: Four 440-pound-thrust
`(200-kilogram-thrust) gaseous oxygen, gaseous
`hydrogen thrusters
`Workers pose under the dc-X following its
`rollout from the factory floor in huntington
`Beach, calif. the dc-X spacecraft dem-
`onstrated that aircraft-like operations are
`possible using rocket-powered reusable ve-
`hicles and pioneered the use of lightweight
`composite fuel tanks, lines and valves with
`potential for future lunar landers.
`McdonnELL dougLaS photo
`control, demonstrating the equivalent of an
`engine-out capability. “This showed how
`the DC-X’s highly adaptive flight-control
`system could adjust to an unplanned ma-
`neuver and save the vehicle,” Ball said.
`The DC-X was designed for reliability,
`maintainability, supportability and operabil-
`ity. Given the uncertainties of the design, the
`plan was to produce a deliberately simple test
`vehicle and to “fly a little, break a little” to
`gain experience with a fully reusable quick-
`turnaround spacecraft. Demonstration objec-
`tives included a 7-day turnaround between
`flights with a 3-day goal and use of 50 or
`fewer on-vehicle maintenance personnel.
`The program achieved a 26-hour turn-
`around with 10 maintenance personnel.
`“My heroes during the flights were the
`operations and maintenance folks. They
`did amazing things in turning this vehicle
`around in terms of repairs and doing things
`quickly,” Nowlan said. The DC-X program
`flew with a total field-support team of only
`25 engineers and technicians.
`The DC-X used fast-track management
`rules for the $60 million contract. Nowlan
`said one of the reasons for success was
`the reliance on system-level, end-to-
`end testing to spot problems before each
`flight. Independent reviewers were im-
`pressed with the speed with which prob-
`lems were addressed and resolved. “The
`reason DC-X was successful was because
`of our customer commitment to rapid pro-
`totyping principles and our internal pro-
`gram management,” Nowlan said.
`Even with these achievements in flight,
`prototyping and program management, one
`of the program’s most significant techni-
`cal advances was its streamlined software-
`development process. This helped increase
`efficiency over previous systems and great-
`ly cut support-infrastructure requirements
`during test flights. “We literally could turn
`around software in small fractions of what
`it takes to launch current systems,” Ball
`said. Echoed Don Barnes, a Boeing Ares
`I engineer who was a DC-XA stress en-
`gineer for the first use of a composite hy-
`drogen tank in the spacecraft: “We did not
`have much in way of paperwork—which I
`liked, since it was such a fast-paced devel-
`opment program.” n
`Space Exploration Technologies; NEW PETITION
`Exhibit 1115
`Page 2 of 2

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