It would come after repeated setbacks to design of a hypersonic craft. With one short flight, to begin off the coast of Los Angeles, NASA officials say dreams of a commercial airliner that can fly from Los Angeles to Tokyo in two hours instead of 10 is one step closer to reality. NASA officials plan to disclose the date of the test flight at an April 18 news conference at the Dryden Flight Research Center at Edwards Air Force Base, where the plane is being prepared. No one has ever flown an engine like this at the velocity we are talking about. The common turbojet uses turbines inside the engine to compress air, which ignites with kerosene to create combustion and then thrust.
Ramjets are basically a hollow tube with no moving parts, resolving the temperature problem.
They can propel an aircraft past Mach 2, or twice the speed of sound. Air flow into the front of the ramjet is compressed and mixed with fuel. But the ramjet cannot power an aircraft past Mach 5. Although it is mechanically simple, it is vastly more complex aerodynamically than a jet engine. The plane is integrated into the engine and that makes it much more efficient.