Aircraft fuselage structure and method for its production

1. An aircraft fuselage structure which is constructed from a plurality of shells which are joined together,

each shell forming part of the aircraft fuselage and comprising:

a support structure, and

a skin which is arranged on the support structure and outwardly seals the aircraft fuselage in a compression-proof manner,

wherein the plurality of shells of the aircraft fuselage structure comprises:

an upper and side shell, and

a lower shell,

of which the lower shell has a radius which is, averaged over the circumference, more than 1.2 times the radius, averaged over the circumference, of the upper and side shell,

the upper and side shell and the lower shell being joined together at transition regions extending in the longitudinal direction of the aircraft,

wherein the support structure of the lower shell is designed in terms of the strength of the support structure in such a manner that the support structure is capable of absorbing the internal pressure loading of the lower shell without the use of a main crossmember,

wherein, the aircraft fuselage structure is produced in a hybrid construction with the lower shell being produced from light metal components and the upper and side shell being produced from fiber-reinforced components;

wherein the upper and side shell and the lower shell are connected in the transition regions by a glass-fiber and aluminum composite tab with glass-fiber layers and light metal layers arranged in an alternating manner in a laminate, and

wherein the lower shell has a central region which extends from the center of the aircraft to both sides and has a constant radius and has a smaller radius at the sides in the vicinity of the transition regions, so that the lower shell merges smoothly into the upper and side shell.

2. The aircraft fuselage structure according to claim 1 , wherein the radius in the central region of the lower shell is more than 1.3 times the radius of the upper and side shell.

3. The aircraft fuselage structure according to claim 1 , wherein the radius in the central region of the lower shell is more than twice the radius of the upper and side shell.

4. The aircraft fuselage structure according to claim 1 , wherein the radius in the central region of the lower shell is more than 2.5 times the radius of the upper and side shell.

5. The aircraft fuselage structure according to claim 1 , wherein a lamination is provided on the glass-fiber and aluminum composite tab.

6. The aircraft fuselage structure according to claim 1 or 5 , wherein the connection between the upper and side shell and the lower shell is produced by a multi-row rivet connection.

7. A method for the production of an aircraft fuselage structure which is constructed from a plurality of shells which are joined together,

each shell forming part of the aircraft fuselage and comprising:

a support structure, and

a skin which is arranged on the support structure and outwardly seals the aircraft fuselage in a compression-proof manner,

the plurality of shells of the aircraft fuselage structure comprising:

an upper and side shell, and

a lower shell,

of which the lower shell has a radius which is, averaged over the circumference, more than 1.2 times the radius, averaged over the circumference of the upper and side shell,

the upper and side shell and the lower shell being joined together at transition regions extending in the longitudinal direction of the aircraft, and

the support structure of the lower shell being designed in terms of the strength of the support structure in such a manner that the support structure is capable of absorbing the internal pressure loading of the lower shell without the use of a main crossmember,

wherein production of the upper and side shell from a fiber composite material, including the support structure;

production of the lower shell from an aluminum material, including the support structure;

connection of the upper and side shell to a glass-fiber and aluminum composite tab which contains glass-fiber layers and light metal layers arranged in an alternating manner in a laminate;

fitting the upper and side shell to the lower shell, including the glass-fiber and aluminum composite tab which protrudes on the upper and side shell; and

connection of the glass-fiber and aluminum composite tab to the lower shell.

8. The method according to claim 7 , wherein the production of the upper and side shell from the fiber composite material includes a process of adhesively bonding stringers and frames contained in the support structure and the skin.

9. The method according to claim 7 or 8 , wherein the production of the lower shell from aluminum material comprises production of stringers and frames and skin.

10. The method according to claim 7 or 8 , wherein the connection of the glass-fiber and aluminum composite tab to the upper and side shell and to the lower shell comprises riveting by means of titanium bolts.

11. The method according to one of claim 7 or 8 , wherein the connection of the upper and side shell and the lower shell comprises the provision of a lamination on the glass-fiber and aluminum composite tab.

12. The method according to one of claim 7 or 8 , wherein the method comprises the production of all of the fuselage segments of the fuselage and the joining and connection of the fuselage segments to form the overall fuselage.

13. The method according to one of claim 7 or 8 , wherein the method comprises locking of transverse joints between fuselage sections by means of titanium bolts.