# Patent

## Title
Wing-fuselage section of an aircraft

## Abstract

A wing-fuselage section of an aircraft, which wing-fuselage section comprises a wing root at which the wing of the aircraft is connected to the fuselage, a fuselage region with fuselage frame elements that extent across the longitudinal direction of the aircraft, and a wing region with spars that extend in the direction of the wingspan. According to the invention, the spars of the wing region and the fuselage frame elements of the fuselage region form part of an integral assembly that extends at least over a middle part of the wing and the fuselage region, including the wing roots.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a national phase entry under 35 U.S.C. §371 of International Application No. PCT/EP2008/054820, filed Apr. 21, 2008, published in English, which claims the benefit of the filing date of German Patent Application No. 10 2007 019 692.1-22 filed 26.04.2007, the disclosure of which application is hereby incorporated herein by reference.
FIELD OF THE INVENTION
The invention relates to a wing-fuselage section of an aircraft according to the precharacterising part of claim 1.
TECHNICAL BACKGROUND
Present-day wing-fuselage connections of aircraft comprise separate components that are joined during assembly. For example, there are wings that are attached on top of, or underneath, the fuselage by means of fittings without curtailing the space in the passenger cabin or in the cargo compartment. Structures are common in which the wing is installed in the form of a two-part, so-called centre-joint solution, or in the form of a three-part solution comprising a centre-section wing box across the cargo compartment. The installation requires connecting elements at the most highly loaded regions of an aircraft.
The various components or assemblies (wings, centre sections of the wings, fuselage), which in some cases may even be developed and produced in different plants before being joined during final assembly, result in very considerable construction and installation expenditure in order to safely master the above-mentioned problematical joining regions. For example, massive fittings are required for the connections whose tolerances are to be met at great expenditure and whose installation requires a great deal of manual work.
It is the object of the present invention to create an improved wing-fuselage section of an aircraft. In particular, a wing-fuselage section is to be created that contributes to a decrease in the overall expenditure of producing an aircraft, as well as contributing to a reduction in weight.
SUMMARY OF THE INVENTION
This object is met by a wing-fuselage section with the characteristics of claim 1.
The invention provides a wing-fuselage section of an aircraft, which wing-fuselage section comprises a wing root at which the wing of the aircraft is connected to the fuselage, a fuselage region with fuselage frame elements that extent across the longitudinal direction of the aircraft, and a wing region with spars that extend in the direction of the wingspan. The invention provides for the spars of the wing region and for the fuselage frame elements of the fuselage region to form parts of an integral assembly that extends at least over a middle part of the wing and the fuselage region, including the wing roots.
Advantageous improvements and embodiments of the wing-fuselage section according to the invention are stated in the subordinate claims.



BRIEF DESCRIPTION OF THE DRAWINGS
Below, an exemplary embodiment of the wing-fuselage section according to the invention is described with reference to the drawing.
The following are shown:
FIG. 1 a perspective view of essential components of an aircraft, in which a wing-fuselage section according to an exemplary embodiment of the invention is realised;
FIG. 2 a perspective view of the wing-fuselage section of the aircraft shown in FIG. 1 according to the exemplary embodiment of the invention comprising an interior stiffening structure made of spars, frame elements and beams, and an outer skin applied thereon;
FIG. 3 a perspective view of the inner stiffening structure of the wing-fuselage section shown in FIG. 2 of the exemplary embodiment of the invention, wherein for improved clarity in addition the engines of the aircraft shown in FIG. 1 are also shown;
FIGS. 4a) to c) in isometric illustrations a front view, a side view and a top view of the inner stiffening structure, shown in FIG. 3, of the wing-fuselage section with a diagrammatic view of a main landing gear and its connection to and accommodation in the wing-fuselage section according to an exemplary embodiment of the invention;
FIGS. 5a) to c) in isometric illustrations a front view, a side view and a top view of the inner stiffening structure, shown in FIG. 3, of the wing-fuselage section with a diagrammatic view of a main landing gear and its connection to and accommodation in the wing-fuselage section according to a further exemplary embodiment of the invention;
FIGS. 6a) and b) a bottom view and a top view of the wing-fuselage section of FIG. 2;
FIG. 7 a diagrammatic top view of the inner stiffening structure of the wing-fuselage section according to the exemplary embodiment, shown in FIG. 3, of the invention;
FIGS. 8 to 11 diagrammatic views to explain a production method relating to the wing-fuselage section according to an exemplary embodiment of the invention;
FIGS. 12 a) and b) diagrammatic views of intersection elements or T-piece elements as can be used according to a further exemplary embodiment of the invention for producing the wing-fuselage section;
FIG. 13 a diagrammatic view of the arrangement of intersection elements as shown in FIG. 12a), for producing the wing-fuselage section according to the further exemplary embodiment of the invention;
FIGS. 14 and 15 diagrammatic views for explaining the production of a wing-fuselage section according to the further exemplary embodiment of the invention with the use of intersection elements and T-piece elements as shown in FIGS. 12 and 13; and
FIG. 16 a diagrammatic view of a structural element comprising intersection elements and T-piece elements as can be produced according to an exemplary embodiment of the invention in an integrated form by means of textile fibre materials.



DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
FIG. 1 shows a perspective view of essential components of a modern aircraft, in which a wing-fuselage section according to an exemplary embodiment of the invention is realised. The aircraft comprises a fuselage 2 and a wing 1 which by means of wing roots 7, 8 is connected to the fuselage 2. On the wing 1, engines 31, 32 are connected by means of carrier elements 37, 38 (pylons). A wing-fuselage section, overall designated by the reference character 40, comprises the wing root 7, 8 by which the wing 1 of the aircraft is connected to the fuselage 2 on both sides, as well as a fuselage region 3 with fuselage frame elements 11-15, 21-25 extending across the longitudinal direction of the aircraft, and on each side a wing region 5, 6 with spars 16-19 which extend in the direction of the wingspan, on one side, and spars 26-29 on the other side of the aircraft.
The wing-fuselage section 40 is realised in the form of an integral assembly comprising the spars 16-19 and 26-29 of the wing regions 5, 6, and the fuselage frame elements 11-15 and 21-25 of the fuselage region 3 as essential structural elements. These structural elements form an integral (i.e. included as part of the whole) inner stiffening structure of the wing-fuselage section, with a fuselage skin 90 and a wing skin 80 also being applied to said stiffening structure.
FIGS. 2 and 3 show the wing-fuselage section, produced in the form of said integral assembly 40, with and without the wing skin 80 and the fuselage skin 90. Together with the wing skin 80 and the fuselage skin 90, which form a further component of the integral assembly 40, the wing-fuselage section is able to absorb and distribute all the static and dynamic loads that occur in this region of the aircraft.
The integrated wing-fuselage section of the exemplary embodiment shown in FIGS. 1 to 3 extends in longitudinal direction of the aircraft from a front interface 104, that is provided for connecting a front fuselage section 4, to a rear interface 109, that is provided for connecting a rear fuselage section 9, as well as in the direction of the wingspan between two interfaces 110 or 120, which in each case are provided for connecting outboard wings 10 and 20, which form the outer parts of the wing 1, to the wing-fuselage section 40. The connections 104, 109 for the front and rear fuselage sections 4, 9 can be designed such that they provide for simple connection of said fuselage sections according to the current state of the art.
As shown in FIG. 3, in the wing region 5, 6 joining regions 131, 132 for connecting the engines 31, 32 are provided. The engines 31, 32 are connected to said joining regions with their respective carrier elements or pylons 37, 38. In the exemplary embodiment shown in FIG. 3 the joining regions 131, 132 provided for connecting the engines 31, 32, and the interfaces 110, 120 provided for connecting the outboard wings 10, 20, are formed by a shared wing connecting element 33, 34 that finishes off and delimits the integral assembly 40 in the direction of the wingspan.
As is shown in the diagrammatic top view of the interior stiffening structure of the integral wing-fuselage section 40 in FIG. 7, in the case of the exemplary embodiment presently described it is provided for the spars 16-19 or 26-29 of the respective wing regions 5, 6 at the wing root 7, 8 to be continued in an integral manner in the fuselage frame elements 11-15 or 21-25 of the fuselage region 3. In other words, as is clearly shown in FIG. 3, on the wing root 7 and 8, the spars 16-19 and 26-29, which extend in the wing plane, form an integral or single-piece transition to the fuselage frame elements 11-15 and 21-25; wherein, in the exemplary embodiment shown, said fuselage frame elements 11-15 and 21-25 extend around the entire circumference of the aircraft fuselage 2 and at the same time form a floor assembly 30 and an intermediate-deck carrier structure 30a of the fuselage region 3 (compare FIGS. 2 and 3).
As is shown in particular in FIGS. 3 and 7, in each case a carrier element 35 and 36 that extends in longitudinal direction of the aircraft is provided at the wing root 7 and 8, wherein the spars 16-18 of one wing region 5, and the spars 26-28 of the other wing region 6, which spars continue in the fuselage frame elements 11-15 and 21-25, extend within the floor assembly 30 in each case to the carrier element 36 and 35 of the respective other side and are connected to said carrier element 36 or 35. In this way the interior stiffening structure of the integral assembly 40 that forms the wing-fuselage section is able to introduce, absorb and distribute all the loads that are experienced in this region, while at the same time being of lightweight construction.
As is further shown in FIG. 7, the spars 16-19 or 26-29 that extend in the direction of the wingspan of the wings or of the wing regions 5, 6 follow the sweep of the wing 1 at an angle to the longitudinal axis of the aircraft, which angle differs from 90°. In the fuselage region 3, where they make a transition to the fuselage frame elements 11-15 or 21-25, or where they form said fuselage frame elements 11-15 or 21-25, they are thus interconnected by intersections as shown in the top view of FIG. 7. As already explained with reference to FIGS. 2 and 3, the fuselage frame elements 11-15 and 21-25 are designed such that they extend over the entire fuselage circumference and at the same time form the floor assembly 30 of the fuselage region 3 and the intermediate-deck carrier structure 30a of the same. Thus each fuselage frame element 11-15, 21-25 per se is provided in the form of an integral unit which comprises said structural components of the floor assembly 30 and of the intermediate-deck carrier structure 30a. 
Below, with reference to FIGS. 8 to 11 an explanation is provided as to how the wing-fuselage section according to an exemplary embodiment can be produced in the form of said integral assembly 40.
As shown in FIG. 9, the spars 16-19 and 26-29, or the frame elements 11-15 or 21-25 are formed by structural elements 46, 46a, 47, 48, 49 that in the direction of the wingspan continue from one wing region 5 to the other wing region 6, or more precisely expressed from one wing interface 110 to the other wing interface 120, i.e. over the entire extension of the integral wing-fuselage section in its direction of the wingspan. To be able to better distinguish the individual structural elements 46-49, the latter are shown in FIG. 9 in different ways, namely as dashed, dotted or solid lines.
Between two intersections on which the spars or frames 11-15, 16-19, 21-25, 26-29 are interconnected in the fuselage region 3 in the manner described above, said structural elements 46-49 alternately extend at the angle of the respective spar 11, 12, 13, 14, 15 of one side, and at the angle of the respective spar 26, 27, 28, 29 of the respective other side, and at the intersections are connected to the continuous structural elements which in each case form the adjacent or intersecting spars or frame elements which in turn extend between two intersections alternately at the angle of the spar 16-19 of one side, and at the angle of the spar 26-29 of the other side. In FIG. 8 said structural elements 46-49 are shown in the still stretched form.
As is further shown in FIG. 9, in the fuselage region 3 further structural elements 51-58 are provided that form part of the fuselage frame elements 11-15 and 21-25, with the extent of said further structural elements 51-58 being limited to the fuselage region 3. These further structural elements 51-58 are provided in addition to, or as a supplement to, the previously described structural elements 46-49 that continuously extend from one wing region 5 to the other wing region 6.
As shown in FIG. 10, the spars 16-19, 26-29 and some of the frame elements 11-15, 21-25 are interconnected by ribs 61-64, 71-74 that essentially extend in longitudinal direction of the aircraft. In the exemplary embodiment shown, the exterior ribs 64, 74 at the same time form the wing connecting elements 33, 34 at the wing interfaces 110, 120.
The structural elements 46-49, 51-58 can be interconnected by additional intersection elements 41 or T-piece elements 42, or they can be reinforced by said elements, as is shown in FIGS. 14 and 15. Such intersection- and T-piece elements 41 and 42 are shown individually in FIGS. 12(a) and (b), while FIG. 13 shows the position of their arrangement.
The integral assembly 40 that forms the wing-fuselage section can be a metal construction, a fibre-reinforced plastic construction (GFRP, CFRP) or a composite construction. In the last mentioned case, for example the interior stiffening structure shown in FIG. 3 can be a fibre-reinforced plastic construction, while the wing skin 80 and the fuselage skin 90 can be made as a metal construction or as a composite construction combining metal- and fibre-reinforced plastics, which construction being placed onto the interior stiffening structure.
The wing skin 80 and the fuselage skin 90 comprise parallel panels or widths, as shown as an example with reference to the panels 81-83 and 91-93 in FIG. 11.
In fibre-reinforced plastic constructions the structural elements 46-49 and 51-58 that form the spars 16-19, 26-29 and the fuselage frame elements 11-15 and 21-25 can be provided in the form of fibre fabrics or woven fibre fabrics. These fabrics can be sewn together at the intersections and/or reinforced by the intersection elements 41 and T-piece elements 42.
As shown in FIGS. 12a) and b) the structural elements 46-49, 51-58 or the above-mentioned intersection elements 41 or T-piece elements 42 can be made of woven fibre fabrics that are woven together in a corresponding manner. FIG. 16 shows several such intersection elements 41 or T-piece elements 42 woven into a structural element, such as one of the structural elements 46-49, 51-58.
After the wing skin 80 and fuselage skin 90 have been applied, the wing-fuselage section, which is a fibre-reinforced plastic construction, is finished by curing in an autoclave process.
FIGS. 4 and 5 show two exemplary embodiments of the manner in which a main landing gear can be connected to the wing-fuselage section 40 and can be accommodated therein. The exemplary embodiment shown in the isometric views of FIGS. 4a) to c) provides for the main landing gear 400 to be retracted into the fuselage region 3 in a conventional manner. For this purpose a fuselage section 410 is provided that forms a landing gear bay which accommodates the landing gear in its retracted state. It comprises a keel beam 440 that transfers the forces in longitudinal direction of the fuselage in the region of the fuselage sections.
The alternative exemplary embodiment shown in FIGS. 5a) to c) provides for the landing gear 500 to be hinged forward underneath the wing region 5, 6. In this way the structural design of the fuselage 2 can take place in an optimal manner because its structure is not interrupted by a landing gear bay, and there is thus also no need to provide a keel beam. In this concept it is possible to realise a continuous cargo compartment also in the region of the landing gear 500. In this arrangement a fairing (not shown in FIG. 5) that accommodates the landing gear 500 in its retracted state is to be provided.
LIST OF REFERENCE CHARACTERS


    1 Wing
    2 Fuselage
    3 Fuselage region
    4 Front fuselage section
    5 Wing region
    6 Wing region
    7 Wing root
    8 Wing root
    9 Rear fuselage section
    10 Outboard wing
    11 Fuselage frame element
    12 Fuselage frame element
    13 Fuselage frame element
    14 Fuselage frame element
    15 Fuselage frame element
    16 Spar
    17 Spar
    18 Spar
    19 Spar
    20 Outboard wing
    21 Fuselage frame element
    22 Fuselage frame element
    23 Fuselage frame element
    24 Fuselage frame element
    25 Fuselage frame element
    26 Spar
    27 Spar
    28 Spar
    29 Spar
    30 Floor assembly
    30a Intermediate-deck carrier structure
    31 Engine
    32 Engine
    33 Wing connecting element
    34 Wing connecting element
    35 Carrier element
    36 Carrier element
    37 Pylon
    38 Pylon
    39 Engine bracket
    40 Integral assembly
    41 Intersection element
    42 T-piece element
    46 Continuous structural element
    46a Continuous structural element
    47 Continuous structural element
    48 Continuous structural element
    49 Continuous structural element
    50 Further structural element
    51 Further structural element
    52 Further structural element
    53 Further structural element
    54 Further structural element
    55 Further structural element
    56 Further structural element
    57 Further structural element
    61 Ribs
    62 Ribs
    63 Ribs
    64 Ribs
    71 Ribs
    72 Ribs
    73 Ribs
    74 Ribs
    80 Wing skin
    81 Skin panel
    82 Skin panel
    83 Skin panel
    90 Fuselage skin
    91 Skin panel
    92 Skin panel
    93 Skin panel
    104 Front interface
    109 Rear interface
    110 Wing interface
    120 Joining regions
    131 Joining regions
    132 Joining regions
    400 Landing gear
    410 Fuselage section
    440 Keel beam
    500 Landing gear

## Claims

1. A wing-fuselage section of an aircraft, said wing-fuselage section comprising:
a wing root at which a wing of the aircraft is connected to a fuselage;
a fuselage region comprising a plurality of fuselage frame elements extending across a longitudinal direction of the aircraft; and
a wing region comprising a plurality of spars that extend in a direction of the wingspan,
wherein the spars of the wing region at the wing root continue as a single piece transition in an integral manner in the fuselage frame elements of the fuselage region forming part of an integral assembly that extends at least over a middle part of the wing and the fuselage region, including the wing root, and wherein the spars that extend in the direction of the wingspan of the wing region generally follow a sweep of the wing extending at a non-perpendicular angle to the longitudinal direction of the aircraft, and
wherein at least one of the fuselage frame elements intersect with at least one other fuselage frame element in the fuselage region.

2. The wing-fuselage section of claim 1, wherein the integral assembly extends in the longitudinal direction of the aircraft from a front interface that is provided for connecting a front fuselage section to a rear interface that is provided for connecting a rear fuselage section.

3. The wing-fuselage section of claim 1, wherein the integral assembly extends in the direction of the wingspan and comprises at least one interface for connecting an outboard wing to the wing-fuselage section.

4. The wing-fuselage section of claim 1, wherein the integral assembly in the wing region comprises at least one joining region for connecting at least one engine.

5. The wing-fuselage section of claim 4, wherein the joining region for connecting the at least one engine and the interface for connecting the outboard wing are formed by a shared wing connecting element that delimits the integral assembly in the direction of the wingspan.

6. The wing-fuselage structure of claim 1, further comprising at least one carrier element that extends in the longitudinal direction of the aircraft is provided at the wing root, and wherein the spars of the wing region, which spars continue in the fuselage frame elements, on one side extend to the carrier element or on the other side and are connected to said carrier element.

7. The wing-fuselage section of claim 1, wherein the fuselage frame elements form a floor assembly of the fuselage region.

8. The wing-fuselage section of claim 1, wherein the fuselage frame elements form an intermediate-deck carrier structure.

9. The wing-fuselage section of claim 1, wherein the fuselage region defines a circumference, and wherein the fuselage frame elements are configured such that they extend over the entire fuselage circumference.

10. The wing-fuselage section of claim 7, wherein the fuselage frame elements form a unit that integrally comprises the floor assembly and an intermediate-deck carrier structure.

11. The wing-fuselage section of claim 1, wherein the spars or frame elements are formed by a first plurality of continuous structural elements extending in the direction of the wingspan from a first wing region to a second wing region, which structural elements extend between two intersections alternately at the angle of the spar of one side, and at the angle of the spar of the other side, and at the intersections are connected to the continuous structural elements which in each case form the adjacent spars or frame elements which in turn extend between two intersections alternately at the angle of the spar of one side, and at the angle of the spar of the other side, respectively.

12. The wing-fuselage section of claim 11 further comprising in the fuselage region a second plurality of structural elements that supplement the first plurality of structural elements and form part of the fuselage frame elements and that in their extent are limited to the fuselage region.

13. The wing-fuselage section of claim 11, wherein the structural elements are interconnected by a plurality of intersection elements or T-piece elements.

14. The wing-fuselage section of claim 1, wherein at least one of adjacent spars and frame elements are interconnected by ribs that extend in the longitudinal direction of the aircraft.

15. The wing-fuselage section of claim 1, wherein on the spars and frame elements or ribs an outer skin is arranged which, firmly connected to the aforesaid, forms part of the integral assembly.

16. The wing-fuselage section of claim 1, wherein the wing-fuselage section is a metal construction.

17. The wing-fuselage section of claim 1, wherein the wing-fuselage section is a fibre-reinforced plastic construction.

18. The wing-fuselage section of claim 1, wherein the wing-fuselage section is a composite construction.

19. The wing-fuselage section of claim 15, wherein the structural elements comprise fibre fabrics or woven fibre fabrics sewn together at the intersections.

20. The wing-fuselage section of claim 19, wherein the structural elements are reinforced at the intersections by a plurality of intersection elements or T-piece elements.

21. The wing-fuselage section of claim 15, wherein the structural elements comprise fibre fabrics or woven fibre fabrics woven together at the intersections.

22. The wing-fuselage section of claim 21, wherein the structural elements are reinforced at the intersections by a plurality of intersection elements or T-piece elements.