Almost 60 years ago, the sound barrier was thought impossible to pass. Yet soon after the X-1’s success, programs were already in the works to take us beyond Mach 1 and into supersonic flight (Mach 1- Mach 5). However, to cross the next barrier of hypersonic flight (any speed greater than Mach 5), drastic problems would have to be over come in design, propulsion, and construction materials that were currently unavailable. With years of research and testing, these obstacles were finally overcome with the recent success of Mach 9.8 flight achieved in November of 2004. Powered by the Scramjet (Supersonic combustion ramjet), NASA’s X-43A test vehicle touched a realm of flight rarely found by air-breathing airplanes, hypersonic flight. With the X-43’s amazing thrust potential being produced by an engine that has no compressors or moving parts, scientists and countries alike are intrigued to see how this technology can be applied towards future goals and projects.
Scramjets are not a new idea. Although the most exciting developments and successes have taken place most recently, the concept has been actively pursued since the 1940’s. With government supersonic flight programs like the F-80 Shooting Star, Republic XF- 103 and the X-15, valuable information was gained about ramjet/scramjets performance. Their advances in studying hydrocarbon-fueled engines alone have helped scramjet technology to reach its current developmental state.
Scramjet engines are a far departure from the conventional turbine jet engine. Air enters both engines and is compressed. Fuel is added to the compressed air, ignited, and forced out the back of the engines. This is basically the only thing the two engines have in common. However, if hypersonic flight is to be achieved comparisons need to be drawn against this and other a power plants to see why the scramjet is the answer for hypersonic propulsion.
With the successful demonstration of these engines by the United States and other countries, many possibilities are now attainable. From precision guided missiles to Mach 10 flight, and the proposed X-43B, the technology is here to stay. If funding can be secured, new generations of long range bombers, fast-reaction cruise missiles, and a space launch system that could cut the costs associated with propelling astronauts and payload into space to one-hundredth of today’s prices, could be realized. Civilization continues to strive for faster and more efficient means of transportation and with scramjet-powered vehicles, the hypersonic barrier now does not seem impossible. With promise, scramjets powered vehicles might one day live up to the aggressive political goals stated by President Reagan in 1986 in regards to the National Aerospace Plane, “To provide travel from New York to Tokyo in two hours.” However talk is cheap, and one thing scramjets have definitely proved, low cost scramjet research and development doesn’t exist.