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Rival spaceplanes attract interest abroad

Paul Sutherland, Feature writer
Jan 14, 2014, 8:00 UTC

Sen—Two very different spaceplanes being developed in Europe and the United States have each won the interest of parties on the opposite sides of the Atlantic.

The UK’s design for Skylon - and in particular its revolutionary SABRE hybrid engine - is to be studied and assessed by the US Air Force to see if the technology has potential to power its hypersonic vehicles.

And the European Space Agency (ESA) has agreed to work with Sierra Nevada Corporation (SNC) to find areas where they can work together to develop the American company’s Dream Chaser spacecraft.

Yesterday Reaction Engines Ltd (REL) in the UK announced its first formal link-up with the US government. The company, based at Abingdon, near Oxford, has entered into a Cooperative Research and Development Agreement (CRADA) with the Air Force Research Laboratory’s Aerospace Systems Directorate.

The US interest is the latest major success for REL. Last year the British government pledged £60 million investment to continue development of the Skylon project. And that came after experts from ESA concluded a study by agreeing that the technology behind SABRE - it stands for Synergistic Air-Breathing Rocket Engine - had proved itself.

Validation of this technology clearly caught the eye of the Americans too. They will have been impressed at how SABRE will switch in flight from air-breathing mode which takes it to Mach 5.5 - twice as fast as a jet - to that of a rocket engine, reaching Mach 25, or 7.5 km per second. The engine’s hybrid nature will allow a spacecraft to take off from a runway and fly directly into orbit.

Its secret is heat exchanger technology that can can cool air entering the engine from 1,000°C to minus 150°C in just one hundredth of a second whilst preventing ice from forming within the unit. And it is all done using equipment that weighs less than a standard car to transfer as much heat - 450MW - as generated by an electricity power station.

The engines will be able to power Skylon to become a reusable replacement for the Space Shuttle, carrying cargo and crews to space stations from any airport with a long enough and strong enough runway, and with a speedy turnaround time between missions.

But the SABRE engine also has the potential to power other vehicles, and could fly passengers at hypersonic speed from one side of the Earth to the other - e.g. London to Sydney - in less than four hours.

Dream Chaser

An artist's impression of Dream Chaser landing on a runway. Credit: Sierra Nevada Corporation

REL’s managing director Alan Bond, the inventor behind Skylon and SABRE, said: “The signing of this agreement with AFRL builds on an extraordinary period for Reaction Engines Ltd which has seen the successful demonstration of SABRE’s ultra-lightweight high performance heat exchanger technology and a UK Government commitment of £60 million ($100m) towards the next phase of development of the SABRE engine.”

Barry Hellman, for AFRL, said: “This CRADA opens the door for joint development and testing to help AFRL understand the SABRE engine’s technical details, and whether it may offer unique performance and vehicle integration advantages when compared to traditional hypersonic vehicle concepts. We look forward to exploring the engine and its lightweight heat exchangers which have the potential to enable hypersonic air-breathing rocket propulsion.”

Meanwhile, Sierra Nevada’s new deal with ESA could be seen as a bid to broaden the potential market for their mini-shuttle Dream Chaser. This reusable vehicle is still undergoing early flight tests while rival commercial companies have flown successful missions to the International Space Station.

SNC believe the strength of their vehicle is that, once hoisted by a conventional rocket, it will be able to return to a runway landing just as the Shuttles did. In their view, it could therefore lift astronauts and cargo into low-Earth orbit but also serve as a platform for technology demonstrations, construction and repair in space, as well as crewed and un-crewed scientific missions.

ESA will work with Sierra Nevada Corporation to identify how European hardware, software and expertise can be used to further develop the Dream Chaser with a view to it being used to fly European missions. A passenger vehicle is missing from Europe’s own range of spacecraft. Its Automated Transfer Vehicle (ATV) has proved itself as a vey capable cargo-carrier but, sadly, it was not designed for crews and ends its missions by being destroyed in the atmosphere.

A new and advanced docking system for the ISS will also be explored. After an initial evaluation and planning phase by ESA and SNC this year, the organisations expect to continue the relationship through a long-term agreement leading to actual flights by Dream Chaser into orbit.

Gallery: Sierra Nevada Corporation Dream Chaser