Perhaps not at supersonic speeds, but NASA is certainly moving closer to building its piloted experimental aircraft capable of breaking the sound barrier without producing sonic booms. Short for Quiet Supersonic Technology, the first large scale X-59 QueSST aircraft has been cleared for final assembly and integration of systems, the agency announced on December 16, 2019.

The decision to clear NASA’s first large scale, piloted X-plane (or experimental aircraft) in more than three decades, has been made following a major project review, known as Key Decision Point-D (KDP-D), by senior managers of the program.

It was the last hurdle in the X-59 development and construction program before it seeks approval for first flight, currently scheduled in 2021, which the officials will decide upon when they meet again in late 2020.

“With the completion of KDP-D we’ve shown the project is on schedule, it’s well planned and on track,” said Bob Pearce, NASA’s associate administrator for Aeronautics, in an official press release. “We have everything in place to continue this historic research mission for the nation’s air-traveling public.”

Work on the X-59 QueSST, which began on April 2, 2018, is continuing at the Lockheed Martin Aeronautics’ Skunk Works factory in Palmdale, California (U.S.), and is scheduled to run through December 31, 2021.

According to NASA, three major work areas are actively set up for constructing the aircraft’s main fuselage, wing and empennage. Final assembly and integration of the airplane’s systems is targeted for late 2020.

NASA is working to build its first piloted supersonic X-plane in decades – the Low-Boom Flight Demonstration aircraft. 

The idea behind X-59 QueSST

Back in April 2018, Lockheed Martin Aeronautics Company was awarded a $247.5 million cost-plus-incentive-fee contract by NASA to design, build and test a quieter supersonic aircraft.

The X-59 is designed to fly at a maximum speed of Mach 1.5 (990 mph) at a cruising altitude of 55,000 feet and create a sound about “as loud as a car door closing”: that of 75 Perceived Level decibels (PLdB). In fact, NASA wants to eventually beat its own projections and achieve 70 PLdB. For comparison, the Concorde was capable of reaching Mach 2.04 at 60,000 feet with a sonic boom noise level of 105 PLdB. 

“Our airplane should be way below the threshold that people are bothered by, or they may not even hear it,” said David Richwine, NASA deputy project manager for technology on QueSST, as quoted by the Air & Space Magazine.

The technology behind X-59 QueSST is based on decades of research into supersonic flight and design engineering. By carefully designing the aircraft’s shape and overall configuration, engineers believe they have found a way to manipulate the shockwaves coming off an airplane flying at supersonic speeds so they do not produce such intense sonic booms.