In 1982, Alan Bond, (who had worked on the Blue Streak rocket and the Daedalus starshp design) began work on air-breathing rocket engines. At around the same time, Robert Parkinson, at British Aerospace, began work on reusable launch vehicles. The next year, Bond patented his engine, known as RB454. The Ministry of Defence classified the design as TOP SECRET. Parkinson and Bond then together created a design for HOTOL (Horizontal Take-Off and Landing ), a revolutionary new space launcher. HOTOL, unlike other rockets, would not take Liquid Oxygen to burn with its fuel. Instead, it extracted oxygen from the air to burn with its fuel. This saved much weight, and allowed HOTOL to be extremely efficient.