Hypersonic flight explored as military game-changer

The sleek aircraft, really more rocket than plane, dropped from the wing of a B-52 before shooting through the sky above Point Mugu Sea Range off the California coast, leaving a long, white contrail in its wake.

The unmanned X-51A hit Mach 4.8, almost five times the speed of sound, with help from a solid rocket booster. Then the Boeing Co. aircraft jettisoned the booster and its experimental scramjet engine took over, sucking in highly compressed air to propel the vehicle even faster — to a hypersonic speed of about 3,400 mph, or Mach 5.1.

The aircraft relied on that scramjet for only 3½ minutes during the 2013 test flight, but researchers say reliable technology that propels aircraft to hypersonic speeds of Mach 5 or higher could be functional within 10 years, initially for use in missiles. The stakes are high. The Pentagon sees hypersonic weaponry as a potential game-changer that could give it — or an opponent — the kind of edge that stealth aircraft or smart bombs did in decades past. Hypersonic missiles would be extremely difficult to shoot down, arriving with little to no warning and maneuvering to avoid defenses.

Russia and China are also developing hypersonic missiles, and in November, there were reports China had started building the world’s fastest wind tunnel to test hypersonic aircraft and weapons.

“I am also deeply concerned about China’s heavy investments into the next wave of military technologies, including hypersonic missiles,” Adm. Harry Harris Jr., head of the Navy’s U.S. Pacific Command, said this month before a House Armed Services Committee. “If the U.S. does not keep pace, (U.S. Pacific Command) will struggle to compete with the People’s Liberation Army on future battlefields.”