Hypersonic speed is five times the speed of sound. Scientists measure speeds this fast with a Mach number, named for Austrian physicist Ernst Mach. Sound has a speed of Mach 1 and anything Mach 5 or above is considered hypersonic. While the speed of sound changes depending on temperature and...
Despite intriguing designs like the Hiller XHOE-1 Hornet helicopter, the proposed Republic XF-103 bomber interceptor and the short-lived Lockheed D-21B unmanned reconnaissance drone, ramjet aircraft languished until the 1964 debut of the Lockheed SR-71 Blackbird. The fastest manned aircraft until it...
Lockheed’s Skunk Works is another organization with a reputation for breaking with tradition. In addition to the U-2 and the Mach 3 SR-71 Blackbird, the Skunk Works was responsible for the first stealth attack fighter: The F-117, without a single curve in its exterior surface, had to b...
Flying faster than Mach 5 is an old idea. During the 1950s and 1960s US hypersonic flight research programs such as the X-15 rocket plane were the first to test the concept. Intercontinental Ballistic Missiles, which re-enter the atmosphere at hypersonic speeds were also developed ar...