Fuselage arrangement for airplane

An aircraft fuselage elongated along a longitudinal axis X essentially along a longitudinal axis of the aircraft that determines a direction toward the front along a direction of motion of the aircraft in flight, comprising a section with straight cross sections widening relative to the X axis, with said front section located at the front of the fuselage, with said front section ending in the front of the said fuselage with a fuselage nose and being delimited at the rear by a cross section for joining with a rear section of the fuselage behind the front section, with said front section comprising a cockpit located above a floorboard between a cockpit bulkhead to the rear and a front base at the front, wherein the lower shapes of the front section determine a lower bulge such as a lower profile of the fuselage, in other words a characteristic line of an intersection between a vertical plane of symmetry of the aircraft and an exterior lower surface of the fuselage:

• with simple curvature between the nose of the fuselage and the cockpit bulkhead, and
• with double curvature between the cockpit bulkhead and the joining cross section so that the lower profile has a local extreme at the bottom in a straight intermediate cross section between the said cockpit bulkhead and the said joining cross section,
• and in that the upper shapes of the front section determine an upper profile of the fuselage, in other words a characteristic line of an intersection between the vertical plane of symmetry of the aircraft and an upper exterior surface of the fuselage, that has a simple curvature between the nose of the fuselage and the intermediate cross section, with said upper profile being essentially symmetrical with respect to an axis parallel to the longitudinal X axis and passing through the nose of the fuselage, to the lower profile between the nose of the fuselage (21) and the intermediate cross section, imparting a general ovoid shape to the fuselage in front of the lower bulge.