The X-51A Waverider flew today, and it flew fast.
The scramjet engine in the experimental aircraft burned for a little over three minutes at around 10 a.m. PDT Wednesday in a test range over the Pacific Ocean, pushing the X-51A to the hypersonic speed of Mach 5, or five times the speed of sound. That was the top speed reached by the aircraft in its brief flight, according to Boeing and press reports citing U.S. Air Force officials. (A separate Air Force News Service report says that the X-51 accelerated to Mach 6; we're seeking clarification.)
The 200 seconds of autonomous flight by the U.S. Air Force's X-51A set a duration record for an aircraft powered by a scramjet (short for "supersonic combustion ramjet") engine, though in part that can be chalked up to the rarity of any flights at all at this extreme level. The previous record was set by NASA's X-43A, whose scramjet engine burned for only about 10 to 12 seconds in November 2004, though that aircraft zoomed to Mach 9.8.
It had been expected that the X-51A would fly for as long as 300 seconds (that is, five minutes) and would hit Mach 6. During Wednesday morning's flight, the Waverider suddenly lost acceleration shortly after the 200-second mark for an unexplained reason. "At that point," Boeing's press release says tersely, "the X-51A was terminated as planned." (The Air Force had previously said it had no plans to recover the aircraft.)
Update See video of the launch from the B-52 below:
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