WASHINGTON -- NASA and Boeing announced the aircraft produced through the agency's Sustainable Flight Demonstrator project has been designated by the U.S. Air Force as the X-66A.

The new X-plane seeks to inform a potential new generation of more sustainable single-aisle aircraft - the workhorse of passenger airlines around the world. Working with NASA, Boeing will build, test, and fly a full-scale demonstrator aircraft with extra-long, thin wings stabilized by diagonal struts, known as a Transonic Truss-Braced Wing concept.

The X-66A is the X-plane specifically aimed at helping the United States achieve the goal of net-zero greenhouse gas emissions by 2050. To build the X-66A, Boeing will work with NASA to modify an MD-90 aircraft, shortening the fuselage and replacing its wings and engines. The resulting demonstrator aircraft will have long, thin wings with engines mounted underneath and a set of aerodynamic trusses for support. The design, which Boeing submitted for NASA’s Sustainable Flight Demonstrator project, is known as a Transonic Truss-Braced Wing.

The X-66A is the first X-plane specifically focused on helping the United States achieve the goal of net-zero aviation greenhouse gas emissions, which was articulated in the White House's U.S. Aviation Climate Action Plan.

NASA and Boeing sought the X-plane designation shortly after the agency announced the Sustainable Flight Demonstrator project award earlier this year. The Air Force confers X-plane status for development programs that set out to create revolutionary experimental aircraft configurations. The designation is for research aircraft. With few exceptions, X-planes are intended to test designs and technologies that can be adopted into other aircraft designs, not serve as prototypes for full production.

For the X-66A, the Air Force provided the designation for an aircraft that validates technologies for a Transonic Truss-Braced Wing configuration that, when combined with other advancements in propulsion systems, materials, and systems architecture, could result in up to 30% less fuel consumption and reduced emissions when compared with today's best-in-class aircraft.

Due to their heavy usage, single-aisle aircraft today account for nearly half of worldwide aviation emissions. Creating designs and technologies for a more sustainable version of this type of aircraft has the potential for profound impact on emissions.