About the DC-X

The DC-X (Delta Clipper, Experimental) was the first prototype vehicle developed by the BMDO’s (Ballistic Missile Defense Organization, now known as the MDA, Missile Defense Agency) SSRT (Single Stage Rocket Technology) reusable launch vehicle program. The BMDO’s interest in SSRT was to support the goal of the 1991 Missile Defense Act, to "deploy an ABM treaty-compliant anti-ballistic missile system that is capable of providing a highly effective defense of the United States against limited attacks of ballistic missiles". In August of 1991, BMDO contracted McDonnell Douglas Aerospace to design and build the DC-X and possible follow-on programs including the DC-Y Orbital Prototype.

The SSTO program strove to deliver airplane-like operations for rapid turnaround and low per-flight cost. At its heart, the concept involves taking off from Earth, achieving Earth obit and returning to land with the same vehicle. No expendable stages would be required, greatly improving the time to turnaround a vehicle from flight-to-flight, and reducing the cost per flight by not having to replace expended equipment and requiring a radically smaller ground flight control crew and turnaround/maintenance team. Only three people, operating three commercial workstations are required to operate and launch the DC-X. System preparation and maintenance required a team of no more than 25 individuals. Ground testing routinely required only two to three hours to prepare and fire the DC-X. On one occasion the DC-X was actually turned around and fired twice in an eight-hour period, including time to deservice the vehicle, access and reinitialize the systems, alter software limit parameters and reservice the vehicle.

Ground support facilities for the DC-X include the FOCC (Flight Operations Control Center, the mobile 40-foot trailer control center for the DC-X), a launch pedestal, mobile hanger, vehicle transport cart, and a mobile automated propellant servicing system. All critical DC-X support facilities are mobile and transportable. The DC-X can therefore be operated from a variety of dispersed locations without a substantial facility infrastructure. The FOCC itself was designed, developed, fabricated and tested for a total cost of only $1.7 million. At White Sands missile Range, a total of $600,000 of additional permanent facilities were built to support DC-X testing.

Another key point of the SSRT design was to ensure safe abort and return to Earth at any time during launch in case of failure, a capability still lacking in current launch systems. The ultimate goal was to enable safe, low-cost transfer of people and cargo to and from space, dramatically increasing the potential uses of space travel. This non-BMDO spinoff of the technology was referred to as SSTO (Single Stage To Orbit), and was funded by McDonnell Douglas, not BMDO.

The name Delta Clipper comes from two sources. One is the historical impact of the Douglas DC-3 aircraft, known as the Clipper (itself named for the Yankee Clipper ships that opened the sea trade routes more than two centuries before). The DC-3 revolutionized air travel through its high reliability, low operating costs, and sheer high availability. In a matter of years, passenger and cargo air transport became practical and economical to a huge variety of destinations that were unthinkable prior to the DC-3. McDonnell Douglas (now part of Boeing) is the descendent of the original Douglas aircraft company. The Delta part of the DC-X’s name came from the expertise lent by the Thor/Delta rocket program, also from Douglas.

The DC-X was a one-third-size experimental vehicle, built by McDonnell Douglas under a 22-month, $58 million contract. The DC-X prototype’s goals were to verify vertical takeoff and landing, demonstrate subsonic maneuverability, validate airplane-like supportability and maintainability and demonstrate the rapid prototyping development approach. The DC-X suborbital prototype was to be followed by the DC-Y orbital prototype, three times taller, five times heavier (empty) and over twenty-five times heavier fully fueled and loaded. The goal of the orbital Delta Clipper was to put 20,000 pounds of payload into Low Earth orbit (LEO) or 10,000 pounds into polar orbit.

The DC-X and DC-Y designs used Liquid Oxygen (LOX) and Liquid Hydrogen, fueling United Technology/Pratt & Whitney RL10A-5 engines. The RL10A is nearly identical to the engines powering the Centaur upper stage of the Atlas and Titan rockets. It was modified to have a smaller bell, configured for operation at sea level, and gained the ability to throttle between 30% and 100% power. The engine throttling, combined with gimbal mounting, allows for precise attitude control previously unseen in a launch vehicle. The RL10A-5 produces up to 14,560 pounds of thrust and 368 seconds specific impulse in a vacuum. The DC-X utilized four RL10A-5 engines. The DC-X weighed 22,760 pounds dry and empty, and had a gross liftoff weight of 41,630 pounds. The DC-X stands 42-feet tall, and as an experimental prototype has no provisions for any cargo or passengers.

Flight communications systems were provided by Harris Aerospace, Honeywell supplied inertial navigation, Trimble GPS, radar altimeter and flight control computer avionics. Deutsche Aerospace supplied four extendable pneumatic landing gear units, capable of absorbing up to 6.1 meters per second of velocity during emergency landings. Burt Rutan’s Scaled Composites, Inc built the Aeroshell (external body) of the DC-X. 50,000 lines of Ada code were produced with rapid development tools to operate the onboard Vehicle Management System, the brains of the vehicle responsible for monitoring and control of all systems. The FOCC commands the DC-X, but the DC-X itself actually performs all launch, guidance, navigation and landing operations autonomously, safeguarding the vehicle control in case of loss of communications or other situations. The DC-X flies and lands itself.

About the Test Flight

The first public viewing of the DC-X test launch was held in September of 1993 at the Space Harbor site of the White Sands Missile Range, in south-central New Mexico. Established in July 1945, WSMR encompasses 3200 square miles of mountains and desert. It was home to World War II rocket testing, later V-2 testing, and the Trinity site, home to the Manhattan Project’s first atomic bomb test. WSMR is a landing site for the space shuttle program and is used for training shuttle pilots. Currently it is a test range for missile development and test programs for the Army, Navy, Air Force, NASA and other government agencies and the private sector.

This was not the first launch of the DC-X, in fact this test was part way through the low altitude hover flight series. Tested in this phase were takeoff, vehicle handling, 150-200 foot hover, flight controls, and vertical landing. A second set of longer, higher altitude tests to several thousand feet would test the vehicle characteristics more aggressively including roll maneuvers.

For this flight (and all other DC-X test flights) the vehicle was (remotely) piloted by Charles "Pete" Conrad, Jr. Pete Conrad was a Gemini V pilot in 1965, Gemini XI commander pilot in 1966, Apollo XII commander in 1969, and Skylab astronaut in 1973. He joined McDonnell Douglas in 1976, where he rose to Vice President of new business for McDonnell Douglas Aerospace Space Systems Unit.

About the Video

In the summer of 1993, I was contacted by my friend Andy Mancuso, a noted sci-fi artist (in wood inlay). Through his contacts in the space industry, we learned that the upcoming September test-flight of the DC-X would be open to accredited members of the media, the first time the public would see the DC-X fly. We immediately submitted our credentials as representatives of Painted Desert Enterprises New Product News, a (as-yet-nonexistent) company publication we’d decided Andy’s company ought to create (as it turned out, our publication would later take an unanticipated form). Some weeks passed as we were presumably investigated for any past wrongdoings, and we received notification that our credentials were accepted.

I arranged for time off from my day job (as a sales/tech at an Aurora, Colorado computer store specializing in Amiga computers and desktop video editing applications). Though I didn’t own a video camera of my own, I arranged an inexpensive rental of a quality SVHS camera from a customer of mine whom I'd previously done some free off-hours troubleshooting. My unreliable car at the time would not have made the journey from Denver to southern New Mexico, so I bought a Greyhound ticket to Albuquerque, packed my things, bought a pile of top-grade SVHS video tape, and hopped on a bus.

In Albuquerque I was met by Andy, and we piled our gear into his (equally unreliable) Ford station wagon and headed south through the desert night, bound for Las Cruces, NM, the closest piece of civilization to the White Sands Missile Range. We arrived sometime after midnight and immediately crashed. At 6am the next morning, we signed in at the Las Cruces Hilton (home to the media events), and were taken to the actual test site for an advance viewing of the DC-X and its launch facilities. Being the day before the flight, we were actually able to approach, touch (!) and peer within the body of the DC-X. We returned to the Hilton for many hours of technical briefings and presentations.

The next morning (Saturday, Sept 11th, 1993) found us on a crowded WSMR bus rattling into the sunrise at 06:30. Photography was prohibited on the WSMR until we actually reached the Space Harbor test site. Upon arrival, we acquired a spot for our tripod and camera, checked out the press hospitality tent (orange juice and yogurt!) and waited while pre-launch preparations were made. As 9:00 am approached, the excitement in the air grew to a perceptible level. Representatives of the major news agencies crowded the front of the viewing area (several miles away from the launch site). We rubbed elbows with politicians, industry leaders, sci-fi authors and others like us, there to witness the coolest thing to happen to space travel since that Moon thing.

As with most rocket launches, it was delayed somewhat, which only served to build the anticipation. Finally, approximately an hour behind schedule, we were notified that the countdown would proceed without further ado. As the seconds unwound, the crowd grew quite muted, no one sure if we would see a spectacular success or failure, all dreading an unspectacular cancellation or extensive delay.

When the time finally came, a wave of jubilation swept the viewing area before the sound of the engine ignition could travel across the intervening desert. Fortunately, the camera’s microphone can hear the cheering and finally the rocket exhaust better than it picks up the deeply reverent profanity that escaped my lips at that moment. There’s nothing like your first rocket launch.

The actual flight can hardly be called uneventful, though by any standards it was. The DC-X did nothing short of exactly what it was supposed to, and did it perfectly. Watching it climb rapidly out of its exhaust plume into the pale sky, and then come to a gentle halt with no visible means of support is nothing short of pure science fiction. The cryogenic hydrogen/oxygen engines burn so cleanly that they produce no visible flame, making the vehicle look like a flying saucer that someone forgot to flatten. It appears to have no business whatsoever just hanging there in the sky. Even more astonishing is when it nonchalantly slides sideways a few hundred feet, stops again for a couple seconds just to prove it can, and then gently descends to the desert floor. The four little pneumatic landing struts that zip out (not quite in synchronization with each other) make it seem all the more likely that a little green man will pop out waving a ray gun as soon as the dust settles.

The crowd went wild. The rest of the morning at the site was filled with people standing in front of podiums telling us what we’d just seen, and why it was so great. The media (the other guys, who actually had an editor who sent them there) interviewed anyone who seemed important. Another bouncy bus ride back to the Hilton, and an afternoon of post-flight briefings followed. For some reason all the presenters seemed much more relaxed and happy. Major Jess Sponable (USAF) even went so far as to hold up a desktop model of the DC-X and joke about how his superiors had mentioned to him that if the test didn’t succeed, well, they pointed out that the model had a sharp pointy end. Later that evening, a noisy reception was held in a hotel conference room where footage of the flight looped on the projectors, and we were able to ask questions of the cast of the show, including pilot Pete Conrad.

The next morning it was back on the road to Albuquerque and thence to Denver. We were riding the peak of exultation, having just seen our wildest sci-fi dreams come to life out on the sands. We talked on the trip back about who would be the first commercial entity to buy their own Delta Clipper (I bet on Fedex) and how were we going to arrange to fly on one someday. We stopped by the side of the road as the sun was fading, to shoot a brief segment zooming back from the stones and grasses, panning up across the horizon and finally up into the sky, zooming back into the clouds.

Back in Denver, I cataloged the hours of conference footage (informative, but as exciting as watching LOX evaporate) and the on-site footage of the launch and the events leading up to it and after it. I decided then that I would try to edit an exciting and interesting video of the event, about five minutes in length. This length came from my desire to use a new piece of equipment we’d just received at the store, the Digital Broadcaster motion-JPEG non-linear digital video editing system with its associated huge high-performance 32-bit SCSI A/V 2-gigabyte hard drive. This was 1993 after all.

With moderate compression, I could just fit five minutes on the 2Gb drive. The system didn’t have working audio capability, so I elected not to produce an informative video with speech and longer informational footage. As it was, the hardware and software was so bleeding edge that I crashed it regularly throughout the editing process, eventually re-editing the video half a dozen times before I learned what to avoid doing long enough to complete the task.

While editing it, I sought a piece of music to use as the background audio for the piece, planning on dubbing the music (hand-synced from audio CD) onto the tape while outputting it from the Digital Broadcaster. I eventually decided that I would edit it to the pace and timing of U2’s song "Where the Streets Have No Name". The lyrics about "high on a desert plain" seemed to fit well, though the actual subject matter of the song doesn’t. I also set about contacting the band’s licensing agency to obtain permission and a royalty arrangement to legally use their music, should I decide to publish the video.

After the video was done, I finally heard back directly from U2’s agents. They apparently found the BMDO’s participation in the DC-X project to be abhorrent (being emphatically anti-war themselves), and refused any sort of arrangement whereby I could redistribute their music with my video. I guess I can see their perspective, but I think the situation was misunderstood.

If you’d like to experience the video as it was originally intended to be seen, and you own a copy of Where the Streets Have No Name, start the track at the same moment you start the video.

About the Past and Future of the DC-X

BMDO budgeted $5 million in FY94 to complete the planned DC-X program and transfer the DC-X to follow-on programs. Follow-on flight demonstration programs were estimated to take 3 years and require an additional $300 million in budget, to work towards the DC-Y Delta Clipper and a useful launch vehicle capable of carrying cargo and/or passengers. The Delta Clipper was foreseen as being self-piloting, controlled by either a ground crew (in the case of unmanned cargo flights) or by a pilot onboard.

Funding was not as forthcoming, and the DC-X program staggered through the final phases of its flight tests underfunded and overworked. At one point, only $1 million in last-minute emergency funding from NASA saved the program from stopping unfinished in its tracks. During its final flight tests, an overworked ground crew is believed to have failed to properly connect a pneumatic hose to one of the four extendable landing legs. At the completion of the following flight (which was itself perfect) only three of the four legs deployed. The DC-X set down gently and solidly on its three legs and shut down its engines, having determined it was now touching the ground. With the thrust stabilization shut off, the rocket gently toppled over, causing an explosion of the remaining onboard fuel and the complete destruction of the vehicle.

After this event, even more attention was focused away from the proven DC-X technology in favor of more ‘exciting’ launch systems like to the X-30 or National Aerospace Plane, all of which were depending heavily on undeveloped and unproven technologies such as the promising but tricky Aerospike engine, and lifting-body wing/hull designs. The DC-X received no further development, funding or even much attention. Even before the crash, McDonnell Douglas did not feel it could carry on the development of the non-BMDO Delta Clipper project without support from the government. BMDO itself apparently found other more important things to occupy its time and budget.

Within the last few years, budget overruns and technological difficulties have forced the cancellation of all of the programs that the DC-X was passed over in favor of. Some of these programs overran their budgets by amounts greater than the entire proposed DC-Y development budget.

Pete Conrad, one of the original Gemini and Apollo astronauts and the pilot of the DC-X, was killed while riding his motorcycle recreationally in California. He was the embodiment of the astronaut, died living on the edge.

What is the future of SSTO? It looks quite bleak today, almost ten years later. Despite numerous calls for a Space Shuttle replacement, the government and aerospace industry has failed to come up with a viable solution. Our expensive International Space Station cannot operate at a full crew complement, because we have no vehicle available to rescue more than three crewmembers on short notice. (The Russian Soyuz capsule which stays docked with the ISS, holds only three, and the Shuttle cannot be launched on anything resembling short notice.) The most exciting things happening in space launch today are systems launched from floating offshore oil platforms, from balloons, from conventional aircraft, and from the backyards of amateur Rocket Scientists around the world seeking the fame and fortune of the X-Prize.

Almost a decade ago, we were within a good hard stone’s throw of achieving SSTO with reductions in turnaround time and payload cost-per-pound that promised to revolutionize the business of moving stuff from Down Here to Up There. I hate to impinge upon the reputations of the great people we saw pushing the DC-X project there in the desert, but it seems clear now that it’s not in the economic interests of the aerospace industry to destroy their current business models of expensive complicated space launch by undermining their own monopoly. I suspect it will require an outsider with nothing to lose to upset the house of cards and deal a new hand.

About the Author

Chris ‘Xenon Hanson is one of the co-founder of 3D Nature, LLC (Arvada, CO), which produces 3D-landscape visualization applications (World Construction Set and Visual Nature Studio) for personal computers. Before 3D Nature, Chris worked (in reverse chronological order) at a research station in Antarctica; for an Amiga/Desktop Video retail computer store (The Computer Room, Aurora, CO); and for a small Amiga software publisher (Progressive Peripherals, Denver, CO). While working at The Computer Room, he produced the DC-X video, and Home Cookin’ 1993. He lives in the mountains of Colorado, and wishes he had his own VTOL rocket.


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