Beechcraft X-700 Concept

In the late 1970s, Beechcraft conducted studies on a replacement for the King Air. Called the X-700, the new aircraft would incorporate a cabin with large windows and a round cross section, the latter of which would enable greater pressurization and higher altitude capability. The X-700 was envisioned to evolve into a family of straight-wing turboprops and swept-wing jets utilizing a common fuselage design. Ultimately, Beechcraft canceled the program before any flying examples were built.