The news that the U.S Air Force and Boeing are preparing for the first flight test of the X-37B unmanned military space plane gives hope to proponents of reusable vehicles for sub-orbital cargo or passenger space transportation.
With the end of the Space Shuttle looming on the horizon, and little previous talk of a fixed-wing replacement, consultants like William Grahame have begun to push for increased awareness of the need to keep open this avenue to both space and hypersonic long-distance travel. Having been associated for several years with California-based Kelly Space & Technology, Grahame’s concept uses a similar towed assist first-stage launch.
Dubbed the Spacemaster, Grahame’s concept sees the initial take-off behind a modified Boeing 747. “During take-off, the first stage would be powered by turbojet engines which serve to reduce drag force on the tow cable and subsequently to provide thrust for flight back to base and landing,” says Grahame. “Upon reaching an altitude between 30,000 and 40,000 ft., the first and second stage (which sits atop the first stage) flies under first-stage rocket thrust to Mach 4-5 whereupon scramjet (supersonic combustion ramjet) engine thrust is initiated at approximately 100,000 ft.”
At this point, the second stage separates from the first stage and continues under rocket power to perform sub-orbital and orbital space transportation missions as well as missions to the International Space Station. The second stage then cruises under turbojet power for flight back to a runway landing.
For more on Grahame’s ideas, you can e-mail him at: email@example.com