cold fjord writes "It looks like another milestone for hypersonic flight has been reached. From the story: 'The final flight of the X-51A Waverider test program has accomplished a breakthrough in the development of flight reaching Mach 5.1 over the Pacific Ocean . . ."It was a full mission success," said Charlie Brink, X-51A program manager for the Air Force Research Laboratory Aerospace Systems Directorate. The cruiser traveled over 230 nautical miles in just over six minutes over the Point Mugu Naval Air Warfare Center Sea Range. It was the longest of the four X-51A test flights and the longest air-breathing hypersonic flight ever. . . This was the last of four test vehicles originally conceived when the $300 million technology demonstration program began in 2004. The program objective was to prove the viability of air-breathing, high-speed scramjet propulsion. The X-51A is unique primarily due to its use of a hydrocarbon fuel in its supersonic combustion ramjet, or Scramjet, engine. ... The use of logistically supportable hydrocarbon fuel is widely considered vital for the practical application of hypersonic flight.'"