Hypersonic jet travel across the Atlantic has moved a step closer after scientists successfully tested technology to stop jet engines melting at speeds up to 25 times the speed of sound. Researchers at Reaction Engines managed to make a ‘pre cooler’ work at a simulated speed of 3.3 mach or 2,500 mph (4,023kph) – that means large scale hypersonic engines that could be fitted to passenger jets are a step closer to being realised. Their experimental Synergetic Air Breathing Rocket Engine (Sabre) is designed to be fitted to large aircraft to ferry passengers around the world in hours and deliver goods into orbit for less. The ‘pre-cooler’, which lets the aircraft travel at high speed without hot air rushing in and causing the engine to melt was tested at simulated speeds of more than three times the speed of sound. The next stage of tests will see the technology tested at Mach 5.5 (4,200mph / 6,800kph), and could one day lead to flights between London and New York that take less than an hour.