Hypersonic aircraft are those capable of reaching at least Mach 6 - six times the speed of sound, or about 4,000mph. With the US Air Force recently introducing a Mach 6 strike aircraft, preparations are now underway to launch a new, ultra-stealthy bomber. This book covers the many and varied designs created since the 1950s that have sought to attack from very high altitudes. This is a quest that has been made difficult in the face of technical developments in air defence systems. With a host of potential new enemies to address, the US is going high-and-fast, with a class of strike aircraft unreachable by any detection systems. This illustrated book begins with the development of hypersonic projects in the late 1940s/early 1950s and links the changing strategies in war-fighting with advancing technology, some of which provide defensive capabilities for anti-aircraft systems, with some providing an incentive to produce the ultimate super-weapon. The book concludes with a chapter on future concepts not yet within grasp of existing technology and examines the likely future development of trans-atmospheric vehicles that operate at the outer boundaries of the atmosphere.