Development of hypersonic vehicles and weapons progresses

Economist : Since the 1950s, researchers have been trying to develop hypersonic vehicles that aren’t rockets, meaning that don’t carry their own oxygen. Instead, they use various techniques to take oxygen from the atmosphere. The extreme speeds at which hypersonic vehicles travelâmdash;faster than five times the speed of soundâmdash;don’t allow for moving parts such as the spinning blades in turbofan and turbojet engines. Instead, most designs are based on supersonic combustion ramjets (scramjets), which use the speed of the vehicle to initiate and control the combustion. However, the technology is still very experimental. The first successful test didn’t occur until the 1990s, and since then, only a handful of other tests have been successfully carried out. In 2002 a collaboration between the UK and Australia achieved an uncontrolled scramjet flight of Mach 7.6 for 6 s by firing the vehicle downward after it was first lifted by a rocket. NASA has successfully tested two different controlled scramjet vehicles, both launched from carrier aircraft: One reached a record speed of Mach 9.68, and the other sustained Mach 5.1 for 4 minutesâmdash;the longest recorded hypersonic flight at that speed. The US Air Force and DARPA are working on a nonscramjet hypersonic missile that will be launched by rocket nearly to space and then glide down at Mach 16, much the way the space shuttle returned to Earth.