Hypersonic Travel Moves Closer to Reality

X-51A Scramjet Engine Completes Ground Tests
Aviation Week

A year from now, over the Pacific Ocean off California in airspace cleared of all civilian traffic, hypersonics could take a step closer to reality. In the same skies where five years earlier the X-43A Hyper-X flew for 10 sec. at Mach 9.6, powered by a supersonic-combustion ramjet, the X-51A WaveRider is planned to fly on scramjet power for 5 min., accelerating from Mach 4.7 to beyond Mach 6 and demonstrating that sustained hypersonic flight is practical.

Boeing’s X-51A and its Pratt & Whitney Rocketdyne (PWR) scramjet can trace their roots back 20 years to the X-30 National AeroSpace Plane, an overambitious and unsuccessful attempt to build a Mach 30 single-stage-to-orbit technology demonstrator. The X-51A’s goals are far more modest, but it could lead directly to development of a hypersonic long-range strike missile. It would also be a step closer to an eventual air-breathing space access vehicle.