Embodiments are directed to an aircraft fuselage comprises two keel beams and two roof beams. Each keel beam is formed as a single component having no joints. Each keel beam comprises a first portion that is configured to define a floor of an aircraft and a second portion that is configured to define a tail section of an aircraft. The second portion is positioned at an angle relative to the first portion. Each roof beam is coupled to the second portion of a corresponding keel beam at a point remote from the first portion. Each roof beam and a corresponding keel beam are positioned along a single butt line relative to an aircraft fuselage centerline. Frame members are coupled to both keel beams and both roof beams.