Patent Application
20120132753
This invention refers to an interface arrangement between two components of an aircraft structure having an aerodynamic contour and, more in particular, to an interface arrangement for maintaining the continuity of the aerodynamic contour in the interface.
As is well known, weight is a fundamental aspect in the aeronautic is industry and therefore there is a current trend to use composite materials instead of metallic materials for aircraft structures with an aerodynamic contour such as lifting surfaces and fuselages.
The composite materials that are most used in the aeronautical industry consist of fibers or fiber bundles embedded in a matrix of thermosetting or thermoplastic resin, as a preimpregnated or “prepreg” material. Their main advantages refer to:
The main structure for aircraft lifting surfaces consists of a leading edge, a torsion box, a trailing edge a root joint and a tip. The torsion box consists of several structural elements: upper and lower skins stiffened by stringers on one side; spars and ribs on the other side. Typically, the structural elements forming the torsion box are manufactured separately and are joined with the aid of complicated tooling to achieve the necessary tolerances, which are given by the aerodynamic, assembly and structural requirements.
The interface between those components whose outer surface belongs to the aircraft aerodynamic contour such as a wing skin an a leading edge panel in the case of a lifting surface shall be arranged to comply with the aerodynamic requirements in terms of continuity, smoothness and drag, in the interface area.
In the prior art is well known the use of aerodynamic smoothing sealants covered by a paint layer to seal the gaps involved in said interfaces. These sealants are typically uncured pastes suitable for application by extrusion gun or spatula. They can cure at low temperatures and have a good adhesion to common aircraft substrates. However, when the gaps have certain dimensions the application and maintenance of said sealants raise several problems such as cracking, loosening or even detachment. These problems arise more often when the components joined are composite parts because their joints usually involve bigger gaps than metallic interfaces.
This invention is focused on the solution of this problem.
One objective of the present invention is to provide a smoother interface arrangement between components of an aircraft structure with an aerodynamic contour that assures the continuity of the aerodynamic contour in that interface area as well as an easy maintenance to fill the gap associated to the interface.
Another objective of the present invention is to provide an interface arrangement between components of an aircraft structure with an aerodynamic contour that assures the continuity of the aerodynamic contour in the interface area reducing significantly the amount of aerodynamic smoothing sealant applied to seal the gap associated to the interface.
In one aspect these and other objectives are met by an interface arrangement between a first component and a second component of an aircraft structure having an aerodynamic contour, both components being made of composite material, the first component having a joggle so that it includes a first area which surface belongs to the aircraft aerodynamic contour and a second area where the joint with the second component takes place, the second component having a surface belonging to the aircraft aerodynamic contour, in which an intermediate part suitable shaped for maintaining the continuity of the aircraft aerodynamic contour in the interface area between said components as well as to fill the expected gap between said components, is joined to the first component.
In a preferred embodiment the gap filled with said intermediate part has a width W comprised between 10-15 mm and a height H greater than 3 mm. Hereby it is achieved an interface arrangement applicable to many aircraft structures.
In another preferred embodiment said intermediate part is a wedge-shaped part. Hereby it is achieved a suitable shape for many interface arrangements between components of an aircraft structure with an aerodynamic contour.
In another preferred embodiment, an aerodynamic smoothing sealant is used to fill any remaining gap between said components. Hereby it is achieved an interface arrangement that allows a tolerance margin between the first component, with the intermediate part joined to it, and the second component to help the assembly.
In another preferred embodiment said intermediate part is made of a composite material. Hereby it is achieved an interface arrangement allowing a good superficial finishing in the interface.
In another preferred embodiment said intermediate part is made of a plastic material, preferably polyurethane. Hereby it is achieved an interface arrangement allowing an easy assembly of all the components.
In another aspect, the above-mentioned objectives are met, when the intermediate part is made of a composite material, by a procedure to carry out the aforementioned joint arrangement comprising steps of: a) join the intermediate part to the first component whether by co-curing or by co-bonding); b) join the second component to the first component; c) fill any remaining gap between said components with an aerodynamic smoothing sealant.
In another aspect, the above-mentioned objectives are met, when the intermediate part is made of a plastic material, by a procedure to carry out the aforementioned joint arrangement comprising steps of: a) bond the intermediate part to the first component in the Final Assembly Line; b) fill any remaining gap between said components with an aerodynamic smoothing sealant.
One particular field of application of the present invention is the interface between a skin and a leading edge panel or a trailing edge panel in an aircraft lifting surface such as a wing or a horizontal tail plane.
Another particular field of application of the present invention is the interface between circumferential sections of an aircraft fuselage.
Other characteristics and advantages of the present invention will be clear from the following detailed description of embodiments illustrative of its object in relation to the attached figures.
A detailed description of the invention for an interface arrangement between a wing skin and a leading edge panel follows.
The main structure for aircraft lifting surfaces consists of a leading edge, a torsion box, a trailing edge, a root joint, and a tip. A torsion box structurally consists of spars, ribs and upper and lower skins with several stringers. The upper and lower skins are joined to the leading edge and the trailing edge panels forming the upper and lower wing aerodynamic contour.
This interface arrangement creates a gap 25 of width W and height H which can not be sealed satisfactorily using an aerodynamic smoothing sealant when H is bigger than 10 mm. On the other hand, said sealant raises several maintenance problems due to certain defects (particularly cracking) or to its detachment from the wing skin 21.
According to the present invention, the gap 25 is filled with an intermediate part 31, that in the preferred embodiment shown in
As illustrated in
In a preferred embodiment, the gap 25 filled with said intermediate part 31 has a width W comprised between 10-15 mm and a height H greater than 3 mm.
The procedure to carry out the interface arrangement of the present invention using an intermediate part 31 made of composite material comprises a first step in which the intermediate part 31 is joined to the wing skin 21, whether by a co-curing or by a co-bonding technique, a second step in which the leading edge panel 21 is joined to the wing skin 11 and, if needed, a third step in which any remaining gap 26 between the wing skin 11 and the leading edge panel 21 is filled with an aerodynamic smoothing sealant.
In another preferred embodiment the intermediate part 31 is made of a plastic material, preferably polyurethane. In this case, the intermediate part 31 is bonded to the wing skin 11 in the Final Assembly Line. As in the previous case any remaining gap 26 between the wing skin 11 and the leading edge panel 21 is filled with an aerodynamic smoothing sealant.
The maintenance needs of this union arrangement are minimum because the aerodynamic smoothing sealant is only used to seal a very small gap 26 reducing the risk of cracking, loosening or detachment to the minimum.
On the other hand this interface arrangement allows a more uniform and esthetical superficial finishing of the interface area because of the chemical union between the wing skin 11 and the intermediate part 31 particularly allowing the painting to be applied to them at the same time.
Although the present invention has been fully described in connection with preferred embodiments, it is evident that modifications may be introduced within the scope thereof, not considering this as limited by these embodiments, but by the contents of the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| ES 201031766 | Nov 2010 | ES | national |
