Boeing ready to build next generation X-plane for NASA

PO1 William "Chip" Nagel
..."Boeing signed a contract with NASA in February, agreeing to build a more fuel-efficient airliner. The company aims to modify an MD-90 airplane, a common single-aisle passenger plane that NASA says contributes to almost half of airline emissions worldwide. The model's fuselage will be shortened, and its wings will get much longer and will be partially supported by trusses underneath. Boeing's design for this is the "Transonic Truss-Braced Wing." It is estimated that it could reduce fuel consumption by 30%.

The x-plane designation (for experimental aircraft) places the X-66A in a special field, reserved for major advances in aerospace. Some are developed publicly, and others are top secret. The X-1, for example, was the first aircraft to break the sound barrier in 1947."