Boeing's X-66 Sustainable Flight Demonstrator has completed its first wind tunnel tests, marking a key step in validating its design. The aircraft, developed in collaboration with NASA, features a transonic truss-braced wing design aimed at improving aerodynamic efficiency and sustainability.

Testing included a low-speed wind tunnel assessment at NASA's Langley Research Center in Virginia, where a nearly 6-foot wingspan model was evaluated for lift, drag, and other aerodynamic forces. A semi-span model was then tested at NASA's Ames Research Center in California to simulate high-speed flight conditions and provide data for design refinements and flight simulators.

The results will guide further design adjustments before additional testing. A full-span model is now undergoing high-speed wind tunnel testing, and modifications to an MD-90 aircraft to create the full-scale X-66 prototype are ongoing. Ground and flight testing is expected to begin in 2028.