The DC-X Seeks to "Get The Public Into Space"
Caleb John Clark
(This story was written after I went to see the launch of the DC-X. It appeared on the front page of the Los Alamos Monitor the day after the launch on Sunday, September 11th, 1993. Another version focusing on the AI software appeared in Omni Magazine later that year.)
(Larger version of this photo I was lucky enough to snap.)
The 42 foot, obelisk-shaped Delta Clipper-Experimental launch vehicle (DC-X) lifted off its pad Saturday, spewing out a plume of yellow flame visible from the VIP and news media bleachers 3.5 miles away. The launch, which came at 11:12 a.m. after a delay of two hours and 12 minutes caused by a computer glitch, was the second Clipper flight at White Sands Missile Range in less then a month.
The DC-X, a reusable, suborbital launch vehicle is a 1/3- scale prototype of the proposed DC-Y, and this was the first time the news media and several hundred VIPs had had the chance to witness a test flight. Robert G.H. Carroll III of United Technologies Pratt and Whitney, the company that makes the four main engines used in the DC-X, said that although he's seen launches of the space shuttle, the Atlas, and Delta rockets, he had "never seen anything like this." He added, "this is a major step...in launch operations, and that hasn't happened for a long time."
Rising 300 plus feet straight up, the DC-X did something rockets aren't supposed to do: it stopped in mid-climb, and hovered, absolutely still, for three seconds. It then pitched almost imperceptibly to the left and traveled horizontally for 300-plus feet. The DC-X then stopped and hovered again and started its descent. At about 200 feet above its landing pad, four long landing struts appeared out if its base and as the vehicle neared the Earth, yellow flames flared as it came to a soft landing, 66 seconds after its take off.
The launch of the DC-X marked the second time in history that a launch vehicle had both taken off and landed vertically. The first time was at the first, and private, DC-X test flight Aug. 18. Asked what event in history might parallel this, Flight Manager Pete Conrad, the former Apollo and Gemini commander, cracked a wise smile and said, 'We landed vertically on the moon, and we're landing vertically now, which with the [Earth's] atmosphere is tougher."
The DC-X has broken considerable ground. Its flights mark the first time an oxygen-hydrogen- reaction controls system has flown and controlled a launch vehicle. Its four RL10A-5 engines have been modified with 30 to 100 percent throttle capability, and gimbling. The byproduct of these engines is water, making the DC-X perhaps the world's first "green" launch vehicle. The yellow flame seen during take off and landing is from burning paint and debris on the ground. During flight, only a clear mist-like jet is visible.
This launch also marked the first time a launch vehicle had flown using software written in machine code. And it was also the first time software and avionics where ready before the hardware was.
Integrated Systems of Santa Clara, CA.., developed the MATRIXx software took kit, which consists of 65,000 lines of Ada code, in only 13 months. Gerald Johnson, president of McDonnell Douglas, the company that built the DC-X, said in a news conference, "We have been able to set an extremely fast pace in this program through the use of concurrent engineering and rapid prototyping." He explained that McDonnell Douglas gave its contractors the minimum requirements and then, along with the government, left them alone.
And it worked.
Less them two years after the Ballistic Missile Defense Organization (formally Strategic Defense Initiative Organization) awarded McDonnell Douglas the $58 million contract for phase II of the Single Stage Rocket Technology program (SSRT), the DC-X team completed its second test flight, on time and on budget. The DC-X was launched and flown by a crew of three, headed by Conrad. For comparison, the space shuttle uses a launch crew of about 1,700.
The DC-X team achieved this all using radical methods. Col. Simon Worden, who manages all technology programs at BMDO, said, "The No. 1 objective was a small crew and reusability." The philosophy behind the project? Paul Klevatt, BMDO's director program manager explained it simply: "The rocket had to be designed like an airplane...We didn't want paper, we wanted hardware flying."
Perhaps Klevatt should have said "software and hardware flying" because of the DC-X's reliance on computers. As Conrad explained, "We're called 'flight managers' because we don't fly it." What Conrad does is use a monitor and a mouse. And like the pilot of a modern-day passenger jet, he controls the vehicle's flight mode. If an engine were to fail, he wouldn't compensate with the other three; he would select the appropriate 'engine out' mode.
Bob Dressler of Integrated Systems said the use of this software is the first step in a new direction that he believes will be characterized by "developing tools that people can use, not systems." A good example of this is the fact that Conrad did his flight simulation on exactly the same software he used to fly the DC-X, making the DC-X a flight simulation for itself. The MATRIXx software, which operated in real-time and used off-the-shelf products, can be, and was modified using its own data from the first test flight. For the DC-Y, Dressler said, "They'll just edit the block diagrams to the new vehicle's specs. Everything gets reused."
Chris Rosander, a senior manager at McDonnell Douglas, said the software was completed in one tenth the time and one tenth cost. These facts played a big part in keeping the cost of the vehicle down, he said. While the DC-X can be considered a test bed, primarily for software and operations, the next stage, the one-half scale SX-2 will be, according to Rosander, "a mass/fraction bird." The SX-2 primarily will be testing the strength at higher altitudes of the lightweight, composite material used in the structure and skin of the craft.
McDonnell Douglas' leaders and even the military officials of BMDO, all echoed the same theme for the future of the DC-X and SSRT program: "Get the public into space." As one military official said to the crowd just minutes before launch, "We are at the threshold of a new era, and you [the crowd] are at the doorway. To your front you're seeing the future. You're seeing a spaceport."