NASA and Boeing have effectively cancelled the X-66 Transonic Truss-Braced Wing ... X-66 transonic demonstrator plane shelved By David Szondy. April 28, 2025 Facebook; Twitter; ...

Boeing and NASA will pause work on the X-66 Sustainable Flight Demonstrator, an experimental plane design featuring long, thin wings meant to make the plane more fuel efficient.

Boeing and NASA will pause work on a new, experimental aircraft design meant to deliver more sustainable options for the future of aviation. The aircraft project — called the X-66A Sustainable ...