Translating cable device sealing

An aircraft wing assembly, comprising a wing having a fixed leading edge, a slat mounted for movement between a retracted position and an extended position with respect to the fixed leading edge, and a translating cable device for electrically connecting the slat to the wing and having a strut coupled at one end to the slat, the fixed leading edge having an aperture to accommodate the strut, and a seal assembly for sealing between the strut and the aperture.

RELATED APPLICATIONS

The present application is based on, and claims priority from, British Application Number 1121447.5, filed Dec. 14, 2011, the disclosure of which is hereby incorporated by reference herein in its entirety.

FIELD OF THE INVENTION

The present invention relates to an aircraft wing assembly having a leading edge slat, and in particular to a translating cable device for electrically connecting the slat to the wing.

BACKGROUND OF THE INVENTION

Ice protection of aircraft leading edge structures has traditionally been provided on larger commercial fixed wing aircraft through the use of bleed air. More recently, there has been a move to incorporate electrical de-icing systems because of their greater efficiency. The areas of commercial fixed wing aircraft that have particular need for ice protection are the movable leading edge slat structures.

WO2006/027624A describes a coupling arrangement for coupling services between an aircraft wing fixed aerofoil component and a extendable leading edge slat mounted thereto. The coupling arrangement includes a housing for connection to the fixed aerofoil structure, and a hollow telescopic assembly extendable between a retracted and an extended position. A service carrying conduit arrangement carries the services, such as electrical power cables, between the fixed aerofoil component and the leading edge slat, and extends through the hollow telescopic assembly. The service carrying conduit arrangement is flexible and excess thereof is located within the housing when the telescopic assembly is in the retracted position. The telescopic assembly is coupled at one end to the slat, and therefore translates with respect to the fixed aerofoil component as the slat moves. The fixed aerofoil component has an aperture to accommodate the telescopic assembly. The aperture is elongate to permit rotation of the telescopic assembly in a vertical plane as the slat moves.

The aperture in the fixed leading edge structure is covered by the slat when the slat is retracted but faces the oncoming airflow when the slat is deployed for the high-lift (take-off and landing) configurations. The aperture causes aerodynamic drag and undesirable flow disturbances over the wing in the high-lift configurations.

SUMMARY OF THE INVENTION

The invention provides an aircraft wing assembly, comprising a wing having a fixed leading edge, a slat mounted for movement between a retracted position and an extended position with respect to the fixed leading edge, and a translating cable device for electrically connecting the slat to the wing and having a strut coupled at one end to the slat, the fixed leading edge having an aperture to accommodate the strut, and a seal assembly for sealing between the strut and the aperture.

The seal assembly may include a first seal fixed adjacent the aperture, and a second seal fixed to the strut of the translating cable device.

The first and second seals preferably cooperate when the slat is moved to one or more predetermined positions. A plurality of second seals may be provided, each cooperating with the first seal at a respective different slat position.

The translating cable device may have a proximal end mounted to the wing and a distal end coupled to the slat.

The seal assembly may include a flap seal (a first seal) mounted to the fixed leading edge and projecting into the aperture.

The flap seal may include a plurality of flap seal sections with a gap between adjacent sections.

The flap seal may be mounted to a portion of the fixed leading edge substantially surrounding the aperture.

The flap seal may include a first portion mounted to an interior surface of a panel defining the fixed leading edge adjacent an edge of the aperture, and a second portion within the aperture and substantially conformal with an outer surface of the panel.

The flap seal may have a central cut-out.

The translating cable device may include either an articulating mechanism (such as described in WO2009/130473A), or a telescoping mechanism (such as described in US2010/0327111A).

The articulating mechanism may include a first strut pivotally mounted to the wing, and a second strut having a proximal end pivotally connected to the first strut and a distal end coupled to the slat.

The second strut may be curved.

The seal assembly may include a plug seal (a second seal) fixed to the strut at a location remote from the end of the strut which is coupled to the slat.

The plug seal may be arranged to enter the aperture in the fixed leading edge when the slat is fully extended, and to withdraw from the aperture into the wing when the slat is retracted.

The seal assembly may include a seal boot (a second seal) covering the coupling between the translating cable device and the slat. As well as coopering with a first seal of the seal assembly (such as the flap seal), the seal boot may act as a protective covering to prevent damage to the first seal from protruding elements, such as bolts, for example, of the coupling as it moves through the aperture.

The translating cable device may be passively driven by movement of the slat.

The aircraft wing assembly may further comprise a slat actuation mechanism for driving the slat between its extended and retracted positions.

DETAILED DESCRIPTION OF EMBODIMENT(S)

FIG. 1illustrates a fixed wing commercial aircraft of conventional type having a fuselage1, wings2, under-wing mounted engines3, and horizontal and vertical stabiliser surfaces4,5respectively. However, this invention is not limited to a particular type of aircraft, or aircraft configuration, except insofar as the wings2have movable leading edge slats6.

Accordingly, this invention is applicable to a wide variety of commercial and military aircraft, having a variety of different power plants (e.g. jet, turbo-prop, etc.) mounted in a variety of locations (e.g. fuselage, tail, over-wing, under-wing), wing configurations (e.g. high wing, low wing, blended wing body, etc.), wing planforms (e.g. forward swept, unswept, aft swept, etc.), and a variety of stabiliser surfaces including tail planes, canards etc.

FIG. 2illustrates a partially cut-away view of the wing leading edge region showing the wing2having a fixed leading edge7and one of the slats6fully retracted and stowed against the fixed leading edge7. The slat is movable between a retracted position and a plurality of extended positions (including a take off position, and a landing position) by a slat actuation mechanism. In this embodiment, the slat actuation mechanism includes a slat track8of conventional type. A detailed discussion of the slat track and other components of the slat actuation mechanism will therefore not be repeated here. Of course, it will be appreciated that the slat may be moved by a variety of different slat actuation mechanisms, and this invention is not limited to any particular type of slat actuation mechanism. The slat6is translationally movable with respect to the fixed leading edge7.

Also shown inFIG. 2is a translating cable device9for electrically connecting the slat6to the wing2. The translating cable device9is of an articulating type and includes a first strut10pivotally mounted to the fixed wing structure (e.g. a rib—not shown) by bracket11, and a second strut12having a proximal end13pivotally connected to the first strut10and a distal end14(shown inFIG. 5) coupled to the slat6by a coupling21, e.g. a revolute joint.

The translating cable device9is passively driven by movement of the slat6. The second strut12has a hollow tubular construction which carries a cable (which may be a cable bundle, a single cable, or a plurality of individual cables). The cable is coupled to a cable connector (not shown) mounted on rear of the slat6and is routed through the hollow tubular second strut12, around the pivot joint connecting the first and second struts10,12, and is coupled at its other ends to wiring routes (not shown) within the wing leading edge structure. In the assembly view ofFIG. 2, the (unconnected) cable ends114on the wing side are visible.

Routing of the cables through the articulated translating cable device9may be by means of a cable router such as described in WO2009/130473, the contents of which is incorporated herein by reference. The cable router includes a cable protector adjacent the pivot axis so as to constrain the cable adjacent the pivot and to key the movement of the cable with the respective adjacent struts10,12of the articulating mechanism9. This helps minimise the relative movement between the cable protector and the cable as the mechanism pivots, and thus reduces fretting of the cable.

As the slat6moves between its extended and retracted positions with respect to the wing fixed leading edge7the second strut12, which is coupled to the slat6, moves causing articulation of the translating cable device9.

As can be seen fromFIG. 3, the fixed leading edge has an aperture15to accommodate the strut12. When the slat6is retracted, as shown inFIG. 2, this aperture15is covered by the slat6and is not exposed to the airflow over the wing. The slat6has a high speed bulb seal16for sealing between the slat6and the fixed leading edge7when the aircraft is in the high speed cruise condition. The bulb seal16is disposed just above an upper edge of the aperture15in the sealed condition. The high speed seal16therefore prevents leakage air passing from high pressure regions to low pressure regions around the wing. When the slat6is deployed to its landing position (slat6fully extended), as shown inFIG. 3, the aperture15becomes exposed to the airflow over the wing and, if not sealed, would contribute to aerodynamic drag, noise and undesirable flow disturbances over the upper surface of the wing.

To seal the aperture15, a seal assembly is provided which includes a plurality of discrete seal elements, which will now be described in detail.

FIG. 4illustrates a flap seal17(a “first seal”) fixed adjacent the aperture15. The flap seal17includes a plurality of flap seal portions and in the embodiment depicted inFIGS. 4 and 5the flap seal17includes four flap seal portions including two upper flap seal portions17a,17band two lower flap seal portions17cand17d. The flap seal portions17a-dare discrete seal elements individually fastened to the interior surface of a D-nose panel18defining the fixed leading edge profile. The flap seal portions17a-dare arranged so as to provide a clearance gap19between each adjacent flap seal section17a-d.

The flap seal17has a stepped configuration including a mounting portion17esurrounding substantially the entire circumference of the generally elliptical aperture15(save for the gaps19) and which mounting portion17eis fastened to the reverse face of the D-nose panel18. The flap seal17further includes a free portion17fprojecting into the aperture15. The free portion17fis arranged substantially flush with the outer surface of the D-nose panel18. Finally, the flap seal17includes an intermediate portion17gconnecting the free portion17fto the mounting portion17ewhich traverses the wall thickness of the D-nose panel18around the circumferential edge of the aperture15.

The free portion17fof the flap seal is configured to deflect as the strut12of the translating cable device9moves between its extended and refracted positions driven passively by movement of the slat6. By providing the flap seal17as a plurality of discrete flap seal portions17a-dwith gaps19between adjacent portions the free portion17fof the flap seal is permitted greater freedom for deflecting as the strut12moves through the aperture15. The flap seal portions17a-dare arranged to seal a respective quadrant of the generally elliptical aperture15, although the upper seal sections17a, bare larger than the lower seal sections17c, d.

The flap seal17further defines a cut-out20located generally centrally within the flap seal17. The cut-out20is sized larger than the outer diameter of the strut12but smaller than a maximum “diameter” of the coupling21used to connect the distal end14of the strut12to the slat6. As shown inFIGS. 4 and 5, coupling21extends either side of the flap seal17when the slat6is retracted for the cruise condition.

When slat6is moved to its partially extended take off position, the slat trailing edge22remains in contact with the outer surface of the D-nose panel18defining the fixed leading edge7. The flap seal17is therefore not exposed to the oncoming airflow over the wing surface. However, the flap seal17is exposed to the cove region behind the partially extended slat6and so the flap seal17is required to provide adequate sealing to prevent excessive airflow through the aperture15which may result in a generally spanwise cross-flow through the inside of the wing immediately behind the fixed leading edge7.

When slat6is moved to its fully extended landing position, as shown inFIG. 3, the aperture15and therefore the flap seal17becomes exposed to the airflow over the wing and so the seal assembly includes a “second seal” fixed to the strut12of the translating cable device9such that the first and second seals cooperate to provide an enhanced sealing effect. The second seal is a plug seal23, best shown inFIGS. 6 and 7.

The plug seal23is arranged to enter the aperture15in the D-nose panel18defining the fixed leading edge when the slat is fully extended (i.e. to its landing position), and to withdraw from the aperture15into the wing leading edge region behind the D-nose panel18when the slat is retracted. The plug seal23includes a mounting portion23aformed generally as a sleeve for fixing to the tubular strut12at its proximal end13. The plug seal23further comprises a generally elliptical sealing face23bshaped to generally correspond with the shape of the elliptical aperture15but sized smaller than the edges of the aperture15. The sealing face23bis set at an oblique angle to the longitudinal axis of the strut12and is supported by a conical form23cso as to blend into the sleeve section23a. The plug seal23is generally rigid as compared with the flap seal17. The plug seal23may be generally solid, or alternatively for weight saving the plug seal23may include internal voids.

As can best be seen fromFIG. 7, when the slat6is moved to its fully extended (landing) position the translating cable device9becomes fully extended such that the plug seal23enters the aperture15. It is to be noted that the flap seal17has been removed from around the aperture15inFIG. 7for clarity. The sealing face23bcontacts the interior surface of the free portion17fof the flap seal17so as to provide an improved sealing effect. In particular, the plug seal23has the effect of preventing any significant inward deflection of the flap seal quadrants17a-ddue to the oncoming airflow, to seal the gaps19between the flap seal quadrants17a-d, and also to fill the cut-out20in the flap seal17. In this way, the flap seal17and the plug seal23provide an excellent sealing effect so as to substantially aerodynamically seal the aperture15in the fixed leading edge7when the slat6is fully deployed to its landing position.

Returning toFIG. 5, it can be seen that when the slat6is fully retracted, the coupling21between the distal end14of the strut12and the slat6extends either side of the flap seal17and includes several relatively sharp projecting surfaces, such as exposed bolts etc. The seal assembly therefore includes a further seal element, in the form of a seal boot24shown inFIG. 8. The seal boot24is considered to be another “second seal” since, in addition to providing a protective cover over the coupling21for protecting the flap seal17, the seal boot24is arranged to cooperate with the flap seal17so as to provide an improved sealing effect when the slat6is in its fully retracted (cruise) position. By substantially sealing the aperture15with the flap seal17and the seal boot24in the cruise configuration, it becomes possible to minimise spanwise airflow along the interior of the wing immediately behind the fixed leading edge7.

As can be seen, the seal assembly includes a plurality of “second seals” (the plug seal23and the boot seal24) each adapted to cooperate with the “first seal” (the flap seal17) at respective different positions of the slat6.

The seals may include various seal materials, and each of the seals may be constructed differently. The seals17,23,24are exposed to cold temperature environments. The flap seal17may be sufficiently flexible yet sufficiently abrasion resistant to accommodate movement of the strut. The boot seal24may also be flexible yet abrasion resistant. The plug seal23may be less flexible than the flap seal17.

Suitable seal materials for the flap seal17may include, for example, a reinforced silicone rubber or other elastomer. A fluoro-silicone material may be preferable. The reinforcement may include a fabric, such as a woven or knitted fibre layer. The fibres may be of polyester, cotton or any other suitable material. The outer surface of the flap seal17may include an environmental protection layer, such as a polyurethane coating. The flap seal17may be moulded or otherwise formed. Similar materials may also be used for the seal boot23.

The plug seal24may be stiffer than the flap seal17. The plug seal24is also exposed to cold temperature environments, but generally has lower abrasion and flexibility requirements than the flap seal17. The plug seal24may therefore be constructed of a variety of materials, such as a phenolic resin with a woven fabric (e.g. Tufnol), a soft elastomer, an aluminum composite, or a combination of these.

Depending on the location of the various seals to the aircraft engines, the seal materials may need to be fire retardant to a particular level.

As shown inFIG. 8, the boot seal24encapsulates the coupling21and is formed generally as a sheath having a proximal end24awrapped around the distal end14of the strut12, and a distal end24bfor sealing against the aft face of the slat6. The seal boot24provides protection to the edges of the cut-out20in the flap seal17from protruding relatively sharp edges of the coupling21. The boot seal24also occupies the cut-out20in the flap seal17when the slat6is fully retracted so as to provide an improved sealing effect when the slat6is fully retracted. In addition, the seal boot24provides a more aerodynamic surface around the coupling21so as to reduce aerodynamic drag and noise created when the distal end14of the strut12is projected into the airflow within the cove region immediately behind the slat6when the slat is partially or fully deployed for the take off or landing high lift configurations.

It will be appreciated that whilst in the above described embodiment the translating cable device is of the articulating type, other translating cable devices are known in the art such as the telescopic arrangement described in US2010/0327111A.FIG. 9shows a telescopic translating cable device25arranged to provide a similar function of electrically connecting the slat6to the wing2. The telescopic translating cable device includes a strut in three sections, which move telescopically as the slat6moves between its retracted and extended positions. As can be seen, the aircraft wing assembly shown inFIG. 9also includes the flap seal17in the fixed leading edge7, the plug seal23fixed to the outside of the strut, and the seal boot24around the coupling21between a distal end of the telescopic translating cable device25and the slat6. The flap seal17, the plug seal23and the seal boot24are arranged and function substantially identically to the embodiment described above. The plug seal23is fixed to the middle one of the three telescopic strut sections, adjacent a distal end thereof nearest the slat6. Of course, the telescopic strut can have greater or fewer sections than three.