> In the early 2000s, the plan was to roll out the production model of Y1 by 2015. In 2010, Boeing’s patent became public, revealing a glimpse of the new project: a dream of all low-cost airlines and a bold new step for the industry. The aircraft was supposed to have T-tail and nearly elliptical fuselage cross section with twin-aisle 2-3-2 configuration, but retain drag-per-seat and weight-per-seat ratio comparable to single-aisle competitors. A variety of weight-optimization techniques, utilizing the newest composite structures, was explored. According to Boeing Commercial Airplanes CEO Jim Albaugh, the company was already looking into converting their plants from metal to all-composite manufacturing.
https://www.aerotime.aero/articles/25906-why-can-t-boeing-ju...
> In the early 2000s, the plan was to roll out the production model of Y1 by 2015. In 2010, Boeing’s patent became public, revealing a glimpse of the new project: a dream of all low-cost airlines and a bold new step for the industry. The aircraft was supposed to have T-tail and nearly elliptical fuselage cross section with twin-aisle 2-3-2 configuration, but retain drag-per-seat and weight-per-seat ratio comparable to single-aisle competitors. A variety of weight-optimization techniques, utilizing the newest composite structures, was explored. According to Boeing Commercial Airplanes CEO Jim Albaugh, the company was already looking into converting their plants from metal to all-composite manufacturing.
> But come 2011, the project was shelved.