Boeing and NASA say they’ll collaborate with Seattle-based Alaska Airlines and four other major airlines on the Sustainable Flight Demonstrator project, which aims to put Boeing’s innovative X-66 braced-wing aircraft design through flight tests in the 2028-2029 time frame. The X-66A makes use of a concept known as the Transonic Truss-Braced Wing, or TTBW, which features ultra-long, ultra-thin, drag-reducing wings that are stabilized by diagonal struts. The demonstrator aircraft will also incorpo