NASA’s experimental X-59 completed six test flights during a four-day campaign in late September, setting new programme records for both flight frequency and speed. Operated from the Armstrong Flight Research Center in California, the Lockheed Martin-built aircraft reached Mach 1.53, approximately 1,625 km/h, during one of the flights as it continued preparations for acoustic testing of quieter supersonic flight over land.
The aircraft flew twice on 22 September and twice each on 24 and 25 September. The six-flight total exceeded the previous record of four flights in the same period and brought the X-59’s test-flight count to 38 since testing began in October 2025. NASA has not identified which flight produced the Mach 1.53 record.
The campaign formed part of the programme’s flight-envelope expansion, covering the aircraft’s performance across a broader range of speeds, altitudes and manoeuvres. NASA and Lockheed Martin are developing the X-59 to examine whether supersonic aircraft can generate a substantially reduced sonic boom, with the results intended to support future regulatory and commercial assessments.
Following the campaign, the aircraft entered a scheduled maintenance period expected to last about three weeks, followed by a routine systems review before testing resumes.