NASA has selected Lockheed Martin to build an X-plane to demonstrate that sonic boom noise can be reduced to a level low enough to lift bans on commercial supersonic flight over US land.

NASA believes the low-boom demonstrator—its first clean-sheet manned X-plane in decades—will pave the way for development of quiet supersonic transports by US industry once the overland flight ban has been lifted and replaced by sound-based certification rules.

The Low Boom Flight Demonstrator is scheduled to fly in 2021 and will be used to gather community-response data to enable FAA and ICAO to develop sound-based rules for supersonic flight over land.

Lockheed’s Skunk Works had produced a preliminary design for the demonstrator under a previous contract from NASA and was the sole bidder to build the X-plane, NASA Integrated Aviation Systems Program director Ed Waggoner said April 4.

Under the $247.5 million contract, Lockheed will complete design and fabrication of the single-seat, single-engine demonstrator, which is expected to receive its X-plane designation this summer.

The aircraft is shaped to reduce sonic boom and designed to mimic the shockwave signature of a quiet supersonic airliner, generating a maximum boom loudness of 75 PLdB flying at Mach 1.4 and 55,000 ft. This compares with 105-110 PLdB for the Concorde.

The aircraft the Skunk Works will build is essentially unchanged from the preliminary design produced for NASA, Lockheed Low Boom Flight Demonstrator program manager Peter Iosifidis said.

The next step is a “delta” preliminary design review in July, leading to a critical design review in September 2019.

Following a first flight in summer 2021, the X-plane will go through flight clearance at NASA Armstrong Flight Research Center in California, followed by an acoustic validation phase to ensure it produces the desired boom signature, NASA Commercial Supersonic Technology program manager Peter Coen said.

Immediately after the completion of those phases in September 2022, Coen said, NASA plans to conduct its first public-response test campaign over a community in the southwest US that, unlike Armstrong, is not routinely exposed to sonic booms.

“We plan to conduct two community-response tests a year for a total of four to six,” he said.

Flights to gather data from noise measurements and public surveys will be conducted over communities ranging from large cities to small town and rural areas.

To meet the requirements of the regulators, “the data will be representative of the diversity of communities exposed [to booms],” Waggoner said. NASA is working with the international aviation community to define the data required, he said.

The planned three-year period of community-response flight testing, from 2023-25, “meshes with key international meetings to which we will provide the data, so it is important we stay on schedule,” Waggoner said. ICAO’s Committee on Aviation Environmental Protection is scheduled to establish the sonic boom standard at its 13th meeting in 2025.

Among those pursuing a future supersonic commercial airliner are Denver-based Boom Technology founder and CEO Blake Scholl, who believes the company’s first supersonic passenger aircraft can enter commercial service as soon as 2023 and that there is a market for as many as 1,000 supersonic airliners to be delivered by 2035.

Graham Warwick