British researchers say they\'ve begun tests on a new engine technology meant to lift a spaceplane into orbit from a conventional runway takeoff. The Sabre engine, which breathes air like a jet at lower speeds but switches to an oxygen-fueled rocket mode at high altitudes, is the centerpiece of a proposed orbital vehicle dubbed the Skylon, would operate like an airliner, taking off and landing at a conventional airport runway. Engineers at Reaction Engines Limited say they believe the test will prove the readiness of Sabre\'s key elements. The company hopes to attract investors to raise the $400 million needed to take the project into the final design phase. \"We intend to go to the Farnborough International Air Show in July with a clear message,\" REL Managing Director Alan Bond told the BBC. \"The message is that Britain has the next step beyond the jet engine; that we can reduce the world to four hours -- the maximum time it would take to go anywhere,\" he said. \"And that it also gives us aircraft that can go into space, replacing all the expendable rockets we use today.\"