Hyper-X aircraft. Computer-aided design graphic of the Hyper-X, the first jet aircraft designed to fly at more than 5 times the speed of sound (Mach 5, or 5760 kilometres per hour at sea level). The aerodynamic pressures exerted on the Hyper-X and the air around it in flight are colour-coded from red (high pressure), through yellow & green to dark blue (low pressure). Around the aircraft is a high-pressure shock wave. The unpiloted, 4-metre- long Hyper-X burns hydrogen fuel to fly at hyper- sonic speeds of up to Mach 10. It uses atmospheric oxygen for combustion, rather than having its own supply like a rocket. This increases its payload & range. The first flights are due in 1999.