Single butt line keel and roof beam

An aircraft fuselage, comprising:

• two keel beams, each keel beam formed as a single component having no joints, each keel beam comprising 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, wherein the second portion is positioned at an angle relative to the first portion;
• two roof beams, each roof beam coupled to the second portion of a corresponding keel beam at a point remote from the first portion, wherein each roof beam and a corresponding keel beam are positioned along a single butt line relative to an aircraft fuselage centerline;
• and a plurality of frame members, each frame member coupled to both keel beams and both roof beams, wherein the roof beams are coplanar with the first portion and the second portion of each corresponding keel beam, wherein the at least two roof beams are parallel with one another and disposed proximate upper corners of the fuselage, and wherein the keel beams and the roof beams extend to one or more tail wings mounted on the fuselage, and are coupled together using a slip joint that allows for angular and lateral and/or longitudinal alignment between the roof beam and the keel beam.