Reaction Engines' single-stage-to-orbit Skylon spacecraft took a step closer to reality today as BAE Systems announced that it would buy a 20 percent stake in the company as part of an agreement to help develop Reaction's Synergetic Air-Breathing Rocket Engine (SABRE) hypersonic engine designed to propel the Skylon orbiter.

Under the agreement, BAE will buy £20.6 million (US$32 million) in Reaction Engines share capital and acquire representation on the company's board of directors. In return, Reaction will be able to use BAE's expertise in aerospace technology development and project management. This will allow the partners to expand Reaction's engineering staff and move SABRE away from the demonstration phase into full development, as well as the testing of the completed hypersonic engine.

The SABRE is a scramjet. That is, it reduces the propellant load because it acts as a jet while in the atmosphere and a rocket in space, so it doesn't have to carry as much oxygen to burn the liquid hydrogen fuel. It does so at velocities above Mach 5 (4,500 mph, 7,200 km/h) before flying into space, when it switches to rocket mode to achieve the even faster speeds needed to reach orbit.

"Today’s announcement represents an important landmark in the transition of Reaction Engines from a company that has been focused on the research and testing of enabling technologies for the SABRE engine to one that is now focused on the development and testing of the world’s first SABRE engine," says Mark Thomas, Managing Director, Reaction Engines Limited. "BAE Systems brings industry leading capabilities in program delivery and wider engineering systems integration that will accelerate the development of SABRE as a new engine class and its vehicle applications. This partnership builds on the outstanding technical breakthroughs that Reaction Engines has made and the positive assessments received on the potential of the technology from experts at the European Space Agency and the United States’ Air Force Research Laboratory."

The agreement is still pending approval of Reaction Engines’ shareholders. In the meantime, the British government is expected to provide a £60 million ($92 million) grant for ground testing and seeking applications for Skylon and the SABRE engine.

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