German space researchers reboot effort to launch hypersonic space plane

The Deutsches Zentrum für Luft- und Raumfahrt (DLR), Germany's aerospace research center, has renewed decade-old plans for a suborbital passenger space plane that could fly from Europe to Australia in under 90 minutes. The rocket-powered SpaceLiner, originally conceptualized as a 50-passenger hypersonic airliner, has now been given new urgency and direction with a roadmap for flights within the next 20 years, SpaceLiner project lead Martin Sippel told Aviation Week at last month's American Institute of Aerodynamics and Astronautics' Space Planes and Hypersonics Conference in Glasgow. Sippel spoke at the conference, presenting on SpaceLiner's technical progress and the program's mission definition—which now includes potentially delivering satellites and other payloads to space.

In addition to providing a fairly exclusive passenger service—which would target an extremely small percentage of the international travel market—the goal of the program is to spur large-scale production of reusable rocket engines and booster vehicles that would reduce the cost of other space missions. “The point-to-point passenger market already exists and is growing," Sippel told Aviation Week. "We have several hundred million passengers traveling intercontinental distances each year. But even if the share will only be 0.2 percent... from a space perspective that’s a potentially huge impact. We could increase hundredfold the number of launches and, as it is a reusable vehicle designed for between 150 and 300 flights, you have serial production of engines. If you have 11 engines per vehicle then you would build 2,000 engines per year or so. That’s a huge production run, and that was the motivation.”

The DLR SpaceLiner would launch upright with the assistance of an external booster, in a fashion similar to NASA's now-retired Space Shuttle. The booster stage, equipped with its own wings, would be captured after use by a tow aircraft and then be released for an autonomous landing. The main vehicle would glide in a low orbit trajectory and then land like a normal aircraft at its destination, reaching a maximum speed of 4.3 miles per second. The goal size of the space plane is a 100-passenger vehicle, with the passenger compartment capable of ejection and flight on its own as an emergency measure. The reusable booster stage could also be used to ferry other vehicles to space, including launch systems for satellites to be placed in higher orbit.