Agency aims to use QUESST aircraft to demonstrate that supersonic travel need not create disruptive sonic booms.
NASA’s X-59 QUESST supersonic demonstrator broke the sound barrier for the first time on 5 June, a milestone ahead of the agency’s plan to complete a series of flights to evaluate design features intended to soften sonic booms.
Developed for NASA by Lockheed Martin’s Skunk Works unit, the 81min flight involved the X-59 taking off from Edwards AFB in California and reaching Mach 1.1 at 43,400ft, according to NASA.
“In the coming days, we expect to take the next step and push to Mach 1.4,” says NASA administrator Jared Isaacman.
The supersonic sortie comes roughly seven months after the X-59 completed its maiden flight, on 28 October. Powered by a single 22,000lb-thrust (98kN) GE Aerospace F414-GE-100 engine, the aircraft has now flown 16 times, settling into “a steady test rhythm”, Isaacson adds.
The X-59 is central to NASA’s Quiet Supersonic Technology (QUESST) project to demonstrate that supersonic aircraft can be made quiet enough to justify lifting the USA’s overland ban on civilian supersonic flight.
That ban is in place due to sonic booms – shockwaves generated by aircraft breaking the sound barrier – causing disruption to people on the ground.
But the X-59’s long and slender fuselage and other exterior features help minimise those waves and effect how they come off the aircraft. An “aft deck” under the engine nozzle, for instance, directs waves up, not down, NASA says.
It has estimated the X-59’s sonic signature, measured on the ground, will not exceed 75 perceived dB – “a quiet thump”, as the agency describes it. By comparison, Concorde’s boom came in at 105 perceived dB.
A NASA McDonnell Douglas F-15 trailed the X-59 during the 5 June supersonic sortie. “The loud sonic booms from the F-15 obscured any sound made by the X-59,” the agency says.
NASA expects within days to put the X-59 through a “mission conditions” test flight that will involve accelerating to M1.4 at 55.000ft – roughly the parameters at which the agency intends to fly the X-59 during a series of planned “community” flights.
That phase of the programme will involve overflying populated areas, measuring the sonic signature and surveying people about their perception of the noise. ”X-59 is getting ready for its quiet supersonic debut,” says Isaacman.
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