NASA’s X-66A is a Boeing-built experimental aircraft intended to demonstrate a transonic truss-braced wing for quieter, lower-emission commercial aviation. The full-scale demonstrator uses very long thin wings stabilized by diagonal struts; NASA and Boeing paused the flight-demonstrator work while continuing thin-wing research, so the aircraft remains a development-stage research asset rather than an operational airliner.
Future launches and major activity directly linked to this vehicle family.