The Single Stage Rocket Technology (SSRT) program will begin flight testing the DC-X vehicle this summer. Currently, SDIO is not budgeting funds for any other effort other than $5 million in FY94 to complete the DC-X flight testing. SDIO is encouraging other DOD agencies (ARPA and USAF), the Department of Energy (Sandia and Los Alamos National Laboratories), NASA, or a combination of the above to support a joint follow-on ATD program run from SDIO or another agency. This paper recommends a Fast Track ATD program that is well defined and for which independent government cost and schedule estimates exist.
SX-2 Program Definition: The follow-on program would build and fly the SX-2 (Spaceplane Experimental) ATD within three years. The SX-2 uses the same RL-10A5 engines as the DC-X with performance enhancements provided by subcontracts with the Russian rocket engine company Energomash. The vehicle operates out of the same basic facilities and uses the same ground-based crew and control center used to fly the DC-X. Airframe construction will demonstrate the identical composites and unit weights needed for follow-on suborbital and Single Stage to Orbit (SSTO) vehicles. Maximum altitude for the SX-2 is 600,000 feet providing four to five minutes of microgravity time in space. Like its predecessor, the DC-X, the SX-2 will push even further toward demonstrating the feasibility of rocket powered "aircraft-like" operations, support, reliability and associated recurring flight costs in the only credible way -- by doing it. The SX-2 like the DC-X, uses oxygen and hydrogen to support all propulsion and power needs, and offers an environmentally benign exhaust product -- water. With clean exhaust, manageable noise levels and no staging debris, the SX-2 is an environmentally friendly system that can help set the standard for all 21st century launch systems.
Why SX-2: The rationale for funding the SX-2 program centers around five military/commercial "dual use" thrusts: 1) enabling the construction of follow-on suborbital and orbital vehicles providing vastly less expensive commercial spacelift services and fundamentally new strategic and tactical military capabilities, 2) assuring that the American aerospace industry is the first to commercially exploit low cost, highly reliable space access, 3) providing dual use technology spinoffs to the commercial and military sectors, 4) bolstering the aerospace industrial base by opening profitable new commercial opportunities, and 5) developing American-Russian cooperative ventures.
Funding Requirements: The SX-2 program is envisioned as a competitive procurement in which three prime airframe contractors have expressed an interest: Lockheed, McDonnell Douglas and Rockwell International. Total program cost as estimated by both the government and the McDonnell Douglas industry wide team is $450 million. The fiscal year breakout is $75, $185, $180 and $10 million through FY94 through FY97 respectively. The first year of design will focus on reducing the program cost as far as possible towards a self-imposed $300 million Design-to-Cost goal. Just as completing the DC-X significantly reduced the cost and uncertainty of proceeding with the SX-2, the SX-2 program will provide accurate, low risk estimates of the cost of proceeding with follow-on suborbital and orbital vehicles.
A successful SX-2 program will directly enable a family of military, civil and commercial derived vehicles. From cheap suborbital rockets identical to the SX-2 for university and commercial research, to inter- continental ballistic transport vehicles able to deliver cargo globally within minutes, to tommorrow's SSTO launch vehicles, a successful SX-2 program will conclusively show that such vehicles can be built and allow credible estimates of their operating costs and reliabilities. Moreover, if the SX-2 flies as cheaply as the DC-X is designed to operate today, by the turn of the century follow-on vehicles could begin reducing operating costs by up to an order of magnitude over the $10 billion the U.S. spends annually on space launch. Even highly subsidized foreign launch vehicles can't compete with such radicaly reduced operating costs. Beyond space launch, such aerospace vehicles can provide an important complement to tommorrow's military force structure. Their ability to respond globally from central CONUS with the speed of an ICBM and the flexibility of a modern aircraft could form an important pillar of the Air Force's emerging 21st century "Global Reach -- Global Power" strategy.
As far back as the 1986 National Commission on Space, and every national assessment since, the need for fundamentally lower launch costs has consistently been cited as the seminal barrier to the growth of commercial space enterprises. The SX-2 takes a measured step which will quantify the magnitude of potential cost savings and develop a host of commercially useful technologies ready for new dual use military and commercial application.
Technology transfer to the commercial sector can be expedited by a focused program to transition key technologies to American and Russian commercial enterprises. For example, light weight composite materials usable from cryogenic to room temperatures have potential applications ranging from comercial aviation to the automotive industry; high temperature superalloys and composites can enable more efficient engines of all kinds; and hydrogen generation and handling equipment, fuel cells and power units will take a significant step towards a 21st century economy based on hydrogen, electric cars and pollution free hydrogen fueled automobiles. Building the SX-2 in conjunction with an aggressive technology transfer program will allow America to beat the Japanese at their own game -- be the first to spin-off state-of-the-art (but off-the- shelf) technogies to commercial applications.
Beyond technology spin-off, the SX-2 provides a focus for high technology American-Russian cooperation and will bolster the declining American aerospace industry with contracted work in many of the 50 states, but focused in Alabama, California, Colorado, Florida, Missouri and New Mexico. With Russian provided propulsion enhancements it's likely the SX-2 will eventually break the X-15 speed record of Mach 6.7. Once its initial flight test objectives are achieved, the SX-2 can be used for many experiments and high speed technology development for the next century. Low cost, routine access to the hypersonic flight regime can expedite high speed technology development. Experiments flown on the SX-2 can benefit many key technologies including base burning, actively cooled structures, heat pipes, high temperature materials, durable flight controls, hot structures, advanced cryogenic tanks, slush hydrogen, triple point oxygen, advanced avionics and rocket augmented flight. The vision enabled by the SX-2 program can provide a focus for America's youth encouraging higher education and fundamentally new commercial industries on America's space frontier. But the first step unquestionalbly must be development and flight of a proof-of-concept demonstrator like the SX-2..