SpaceLiner's European project planners say their reliance upon proven rocket technology could allow their vehicle to fly sooner rather than later. They plan to use liquid oxygen and hydrogen rocket propellants so that the rocket engines leave only water vapor and hydrogen in the atmosphere. (Video: How DARPA's HTV-2 Hypersonic Bomber Test Works)
"We will not try to improve the performance of the engine but would like to have it more reusable," Sippel told TechNewsDaily.
The empty rocket stage from SpaceLiner would return to Earth immediately after launch in preparation for reuse. An aircraft could grab the rocket stage in midair, tow it toward an airfield and release it for an autonomous gliding landing.
Chances of Survival
But big challenges remain before SpaceLiner can take off. Researchers first must finalize a design shape capable of surviving the intense heat created by gliding at hypersonic speeds through the upper atmosphere. New cooling technologies and improved heat shielding for SpaceLiner's wing "leading edge" could help in that case.
Launching like a rocket rather than taking off like an aircraft means SpaceLiner would remain restricted to suitable launch sites with uninhabited areas down range. The SpaceLiner also would need a careful flight path during its final landing approach - the "sonic boom" shock that accompanies aircraft traveling faster than the speed of sound can damage buildings on the ground at low altitudes.
"The profile of the vehicle is very similar to a rocket-propelled vehicle," Sippel explained. "We only have a small corridor in which we can fly safely and economically."
SpaceLiner's design will make use of study results from a FAST20XX (Future High-Altitude High-Speed Transport 20XX) project funded by the European Union and backed by researchers from Germany, Austria, Spain, Switzerland, Italy, Belgium, the Netherlands, France and Sweden. It can also draw lessons from upcoming efforts such as Project ALPHA by Aerospace Innovation GmbH - a space plane that aims to launch in midair from an Airbus A330 aircraft.
But future success ultimately depends upon the success of space tourism efforts by companies such as Virgin Galactic. If enough people prove willing to pay top dollar for suborbital flights as part of their travels around the world, Sippel envisions a fleet of SpaceLiners eventually making 10 to 15 flights per day.
This article originally appeared on TechNewsDaily.
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