British Aerospace HOTOL

HOTOL, short for Horizontal Take-Off and Landing, was a British design of the 1980s for an uncrewed, fully reusable single-stage-to-orbit spaceplane. Development was led by a consortium of Rolls-Royce and British Aerospace, and the craft was to be powered by the Rolls-Royce RB545 Swallow, an air-breathing rocket engine that would have used oxygen from the atmosphere in the lower part of the climb to cut the oxidiser carried on board. The final design, HOTOL-K, had a take-off mass of 275 tonnes. Technical problems, uneven government support and little appetite among European partners meant that funding ended in 1989, and engineers from the project then formed Reaction Engines Limited to pursue the Skylon concept.