Though 2025 is ticking away, NASA still aims to complete the first flight this year of its X-59 Quesst quiet-supersonic demonstrator, saying the team is progressing into high-speed taxi tests and plotting out the jet’s planned maiden sortie.
“The X-59 has completed low-speed taxi testing, has nearly completed medium-speed [tests] and is headed into high-speed [tests],” NASA tells FlightGlobal. “The X-59 is set to fly in 2025.”
It says the X-59 ground-taxi tests “started with manoeuvres like slow taxiing at just a few miles per hour and have advanced to speeds that will be seen during take-off runs”. The activity is being conducted at Palmdale, California.
“The bulk of the test points have been braking and steering related, but all subsystems and flight disciplines are using the tests to gain as much knowledge as they can prior to first flight,” the agency adds in a recent post on its website.
NASA and Lockheed Martin Skunk Works, which designed and developed the single-pilot X-59, have already delayed first flight several times.
The partners initially expected the aircraft to be airborne in 2021 but that date has progressively shifted; more recently the target was set for early 2025.
The project falls under NASA’s Low-Boom Flight Demonstrator programme. The partners gave the X-59 external features intended to prevent it from producing a typical sonic boom, but to instead generate a “quiet thump”.
NASA and Lockheed are now “mapping every step” of the planned first flight, saying that sortie will involve the aircraft completing “a lower-altitude loop” at 217kt (402km/h) for the purpose of systems-integration evaluations. Only during later tests will the team push the X-59’s speed into the supersonic realm.
“We record 60 different streams of data with over 20,000 parameters onboard,” says NASA X-59 instrumentation engineer Shedrick Bessent. “Before we even take off, it’s reassuring to know the system has already seen more than 200 days of work.”
The X-59 is powered by a single 22,000lb-thrust (98kN) GE Aerospace F414-GE-100 turbine. It has fly-by-wire controls and is expected to hit speeds of about Mach 1.4.
NASA says it has equipped the jet with numerous safety features, including batteries that “back up the X-59’s hydraulic and electrical systems” and a hydrazine-based emergency engine restart system.
“In the unlikely event of a loss of power, the hydrazine system would restart the engine in flight. The system would help restore power so the pilot could stabilise or recover the aircraft,” says the agency.
NASA lead test pilot Nils Larson is scheduled to be at X-59’s controls during first flight.
The jet carries a pilot-oxygen system as it is expected to cruise at 59,000ft and an ejection seat and canopy derived from equipment on US Air Force Northrop Grumman T-38 training jets.
NASA eventually intends to conduct a series of “community overflight testing” using X-59. It will measure the jet’s sound and conduct public surveys to understand how people perceive its ’sonic thump’. NASA hopes the findings will lead US authorities to lift a civilian supersonic overland flight ban in place since 1973.
