I’M EXPECTING AN EARTH-SHATTERING… NOPE, NEVER MIND: NASA X-59 Flies At Mach 1.4 ‘Mission Conditions.’ “The latest flight, the 19th for the Lockheed Martin’s Skunk Works-built aircraft since it took to the air for the first time on Oct. 28, marks a key milestone for the program as it works through the initial phase of envelope expansion flight testing. The aircraft is next due to begin an acoustic validation phase to confirm its slender shape and long nose work as designed to produce a low intensity, sine-wave-shaped sonic boom.”