The US Air Force on Wednesday test launched a hypersonic cruise missile, with the vehicle accelerating to Mach 6 before splashing down in the Pacific Ocean, officials said. The Air Force said the test flight of the X-15A Waverider lasted more than 200 seconds, the longest ever hypersonic flight powered by scramjet propulsion. The previous record was 12 seconds in a NASA X-43 vehicle. "We are ecstatic to have accomplished most of our test points on the X-51A's very first hypersonic mission," Charlie Brink, program manager with the Air Force Research Laboratory at Wright-Patterson Air Force Base in Ohio. "We...