Slats for aircraft wings

Abstract

The present invention relates to a slat (108) for the leading edge of a swept aircraft wing, the slat comprising slat tracks (114) which determine the path of motion of the slat when it moves from a retracted position (FIG. 7) to a fully deployed position (FIG. 15). Each slat track (114) has a shape that follows a spiral path. Thus, the motion of the slat comprises a rotational component about a first axis that may be perpendicular to a flight path (120) and a translational component parallel to the first axis. When viewed from above, the slat may move primarily in a direction parallel to the flight path (120).

Description

Technical Field

[0001] The present disclosure relates to slats for the leading edge of an aircraft wing. More particularly, but not exclusively, the present invention relates to slats for a swept aircraft wing and a swept aircraft wing including such a slat. The present invention also relates to a method of deploying and retracting a slat on a swept aircraft wing. Background Art

[0002] Leading edge slats on swept wings of an aircraft are usually mounted for movement in a direction perpendicular to the leading edge when viewed from above. This is the conventional way of deploying and retracting slats on aircraft wings, but for swept wings with any significant sweep angle, this conventional approach brings certain disadvantages and / or additional complexity. Figure 2 to Figure 5 Some of these disadvantages and / or additional complexities are described.

[0003] The present invention aims to alleviate one or more of the problems associated with slats on swept aircraft wings, wherein the slats are deployed and retracted primarily in a direction perpendicular to the leading edge of the slats. Alternatively or additionally, the present invention aims to provide an alternative and / or improved slat for the leading edge of an aircraft wing and / or a wing comprising the slat. Summary of the invention

[0004] According to a first aspect, a slat for the leading edge of an aircraft wing is provided. The slat comprises two or more slat tracks, which determine the motion path of the slat when the slat moves from the retracted position to the fully extended position when in use. Each slat track has a shape that follows a spiral path. Therefore, in an embodiment of the present invention, the slat can be configured so that it follows a curved path when the slat moves, wherein, when viewed from above, the slat mainly moves in the direction of the flight path, which is superior to the arrangement of the path mainly in the direction perpendicular to the leading edge of the slat when viewed from above in the prior art. Similarly, although the wing and the slat have a swept leading edge (therefore, at an angle perpendicular to the flight path when viewed from above), the shape of the slat and the shape of the surrounding structural parts can have a lateral surface roughly aligned with the flight path (from the perspective of aerodynamics and noise reduction, this is better).

[0005] In other embodiments of the invention, the slat may be configured so that the slat follows a curved path when in motion, and when viewed from above, the slat primarily moves at an acute angle, for example, greater than 5 degrees (and optionally greater than 10 degrees) to the direction perpendicular to the leading edge of the slat, and at an acute angle to the flight path (e.g., also at an acute angle, for example, greater than 2 degrees, optionally greater than 5 degrees, and possibly greater than 10 degrees). The direction of motion of the slat (when viewed from above) may be determined (i.e., by design) by changing the orientation of the axis of the spiral shape that defines the spiral motion and / or the pitch of the spiral shape.

[0006] The spiral path followed by each slat track is roughly the same in shape. In this case, the path of the slat travel can be a path generally following a constant pitch and a constant radius. The spiral path of the shape of each slat track has the same pitch and / or the same radius. The general shape of a slat track is a spiral with a first radius of curvature, while the general shape of another slat track is a spiral with a different second radius of curvature. When provided with more than two slat tracks, the slat tracks that are continuous in the span direction, for example, have a radius of curvature that decreases gradually. In this case, the slat can move in a manner similar to a cone.

[0007] The length of at least one of the slat tracks, such as the length between the start and end of the spiral path of the slat track, corresponds to a rotation around the axis of the spiral shape by at least 15 degrees, possibly greater than 20 degrees and / or less than 60 degrees, optionally less than 50 degrees and possibly equal to or less than 40 degrees.

[0008] The slat can include an airfoil surface supported by two or more slat tracks. The airfoil surface can be substantially supported by at least one of the two or more slat tracks and optionally by all of the two or more slat tracks rigidly. Despite having such a substantially rigid structure, it can be arranged to allow deflection or bending caused by loading during use, such as wing deflection. However, it will be understood that it is preferred to connect (or integrally form) the slat track and the airfoil surface in a manner that does not include complex hinges or ball joints, etc., and if the slat follows a complex motion along an irregular path during its motion, such connection may be required in addition.

[0009] The slat can be configured so that each slat track has at least two outer surfaces, which are located on opposite sides of the slat track when viewed from a cross section. The two outer surfaces can be straight-grained surfaces. The two outer surfaces can be defined by two surfaces swept out by two imaginary fixed shape lines when moving along a spiral path, for example, when moving along such a path relative to the airfoil surface of the slat. The slat can be configured so that each slat track has two other outer surfaces located on opposite sides of the slat track when viewed in a cross section, wherein the two outer surfaces are defined by two surfaces swept out by two other imaginary fixed shape lines when moving along a spiral path relative to the airfoil surface of the slat. Therefore, there may be four such surfaces: when viewed in a cross section, the four such surfaces define the opposite first and second surfaces that can be regarded as left and right surfaces, and the opposite third and fourth surfaces that can be regarded as top and bottom surfaces.

[0010] Each slat track may have a cross-sectional shape that is substantially the same for a majority of the length of the slat track.The shape of the slat track may have a three-dimensional shape that appears twisted in space.

[0011] The slat may have more than two slat tracks, and may for example have at least four slat tracks. Each of the additional slat tracks may have the features of two or more slat tracks of the invention as described or claimed herein.

[0012] As described or claimed herein, the arrangement of the slat according to the present invention has special benefits when being installed on a swept aircraft wing, for example, a wing with a sweep angle between 20 and 30 degrees (for example, determined by the sweep of the leading edge of the wing in the slat region). Therefore, the present invention also provides a wing, preferably a wing with a swept leading edge and a trailing edge, the wing leading edge comprising a slat according to the present invention as described or claimed herein and / or having a slat located on the leading edge, arranged to travel along a spiral path. The slat may comprise two or more slat tracks. The slat track may be a slat track that determines the motion path of the slat in use. Each slat track may, for example, have a shape that follows a spiral path.

[0013] The axis of the spiral and the pitch of the spiral (the spiral that defines the shape of each slat track or the shape of the spiral that defines the main type of movement of the slat when it is deployed or retracted in some embodiments) can be configured so that the lateral edge of the slat moves substantially parallel to the vertical plane (for example, when the wings are arranged in a direction corresponding to horizontal flight, the wings on the opposite sides of the aircraft are arranged symmetrically about the vertical plane), which is aligned with the flight path of the wing. The axis of the spiral is roughly aligned with the leading edge of the slat. For example, it can be substantially parallel to the leading edge, for example within a range of + / -5 degrees. The axis of the spiral can be at an acute angle of more than 10 degrees relative to a horizontal axis perpendicular to the flight path of the wing.

[0014] The pitch angle of the helix may be approximately the same as the local sweep angle of the leading edge of the wing.

[0015] The movement of each slat track can be guided by one or more guide members, such as rollers. Each slat track can have multiple rollers. For example, there can be two groups of rollers. One group of rollers can be spaced apart from another group of rollers in the direction along the length of the slat track. The rollers can be arranged to constrain the movement of the track in two non-parallel directions (for example, two directions transverse to each other-optionally orthogonal directions), each direction perpendicular to the direction in which the slat track moves through the rollers. At least one roller axis can be oriented approximately perpendicular to the flight line. The axes of all rollers can be oriented approximately perpendicular to the flight line. The axis of one of the rollers, and optionally the axis of each of the rollers in the rollers, is parallel to the direction having zero curvature on the surface of the slat track. The track can have an outer surface with a ruled surface, that is, the outer surface can be formed by sweeping a straight line (imaginary line) along the profile. At least one of the rollers can roll on the (imaginary) line, thereby maintaining a fixed contact line between the outer surface of the roller and the outer surface of the slat track.

[0016] There may be at least two rollers having substantially horizontal axes when the aircraft is in horizontal flight. The aircraft wing may include one or more pairs of track ribs, preferably at least two pairs. Each pair of ribs may be positioned on either side of the slat track. At least one of the guide members / rollers is supported between a pair of such track ribs. Each track rib may extend in a direction aligned with the flight path when viewed in plan view.

[0017] In use, there may be certain types of structural members, which have surfaces that may be fixed, for example, relative to a wing or fuselage of an aircraft, adjacent to a lateral surface of the slat (and for example in close proximity, for example the surface of the structural member and the lateral surface may be directly adjacent to each other). In this case, the movement path of the slat when the slat moves from the retracted position to the deployed position may be such that the minimum spacing between the surface of the structural member and the lateral surface is constant (and preferably relatively small, i.e. small enough to allow contact by the edge seal to provide an aerodynamic seal, for example less than 50 mm).

[0018] The invention also provides an aircraft comprising a swept aircraft wing according to the invention as described or claimed herein.

[0019] The present invention also provides a method for deploying or retracting a slat on a swept aircraft wing. The method may utilize a swept aircraft wing according to the present invention as described or claimed herein. The motion of the slat during movement between the fully deployed position and the fully retracted position may include a rotational component around a first axis. The first axis may be fixed relative to the wing in space. The first axis may be spaced apart from an imaginary envelope relative to the wing, wherein the slat moves within the imaginary envelope during movement. The motion of the slat may include, for example, a component of translational motion substantially parallel to the first axis. The velocity component corresponding to the translational motion may be proportional to the rotational velocity component corresponding to the rotation around the first axis. The motion of the slat may include a torsional motion component around a second axis. The motion of the slat may be described as including only a rotation around the first axis and a component of translational motion parallel to the first axis.

[0020] The aircraft may be a passenger aircraft, for example a commercial passenger aircraft configured to carry more than 50 passengers, for example more than 100 passengers. The aircraft may be an aircraft having a maximum take-off weight of at least 20 tons, possibly more than 40 tons.

[0021] Of course, it will be appreciated that features described in relation to one aspect of the invention may be incorporated into other aspects of the invention. For example, the method of the invention may incorporate any of the features described with reference to the arrangement of the invention, and vice versa. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings, in which:

[0023] Figure 1 The aircraft is shown in plan view;

[0024] Figures 2 to 5Schematically illustrates arrangements with which embodiments may be compared and contrasted;

[0025] Figures 6 to 17 shows the slat according to the first embodiment viewed from different stages and different viewing angles when the slat according to the first embodiment moves from a retracted position to a deployed position;

[0026] Fig.18 and 19 Similar to Figures 2 to 5 The arrangement of the first embodiment is schematically shown in the illustrated manner to facilitate comparison; and

[0027] Fig. 20 is a schematic flow chart showing the steps involved in a method of moving a slat on a swept wing of an aircraft according to a second embodiment. DETAILED DESCRIPTION

[0028] Figure 1 An aircraft 100 according to a first embodiment of the invention is schematically shown. The aircraft has two swept wings 102 with a sweep angle of about 27 degrees. Each wing 102 carries an engine 104 supported via an engine pylon 106. The wing includes a plurality of slats 108 located on the leading edge of the wing. Figure 1 The shape and arrangement of the slats shown in FIG. 1 are schematically shown. ) Figure 2 5 show in highly schematic form an enlarged view of a slat arrangement not according to the invention. Figure 2 and Figure 3 An arrangement on a swept wing with a slat 108 is presented, the slat 108 being retracted in a conventional manner in a direction perpendicular to the leading edge from a retracted position of the slat 108 ( Figure 2 ) moves to the deployed position of the slat 108 ( Figure 3 ). Without any special means, there is a gap 110 between the lateral edge of the slat and the edge of the pylon when it is deployed. Figure 4 and Figure 5 An arrangement is presented in which the hanger 106 incorporates a protrusion 112 to mitigate the effects of the clearance gap (i.e., Figure 3 The effect of the presence of a gap 110 of the type shown in FIG. Figure 4 The slat 108 is shown in its stowed position, and Figure 5 The slat 108 is shown in a deployed position. Other solutions for filling the gap include adding additional moving parts to fill the gap when the slat is deployed.

[0029] Figures 6 to 17A portion of an aircraft wing 102 and a slat 108 of a first embodiment are shown in different perspective views. Figures 6 to 9 shows the slat in its fully retracted position (viewed from different angles), Figures 10 to 13 The slats are shown in a partially deployed position (seen from different angles of the same set of slats), Figures 14 to 17 The slats are shown in a fully deployed position (again, from a different angle of the same set of slats). Figure 6 , Fig.10 14 shows the slats from the rear (ie viewed in the direction of the flight path). Figure 7 , Fig.11 and Fig.15 This is a view from above. Figure 8 , Fig.12 and Fig.16 is a view from one side and above, while Fig. 9 , Fig.13 and Fig.17 is a view from the other side and below. The slat is shown to include two slat tracks 114, which have a cross-section that is generally square in shape (although in reality the cross-sectional shape in the cross-section may be more complex, such as having a cross-sectional shape similar to that currently used in slat tracks of the prior art). Each slat track has a shape that follows a spiral path along the length of the slat track. In this example, the shape can be described as a shape defined by a constant cross-section (shown as a square in the figure) following a spiral path in space. The shape of the slat track appears to be twisted in space (for example, compare Figure 6 , Fig.10 and Fig.14 ). The spiral defined by the path defined by the center point of each slat track has the same, constant radius, and the same, constant pitch.

[0030] The slat track 114 is attached roughly rigidly (but allows some flexure to attach, see below) to the structure of the airfoil surface 116 supporting the slat 110. The slat track is each arranged to pass through the roller 118 of the fixed axis when the slat moves between the stowed position and the deployed position of the slat. The roller is arranged between the slat track ribs 124 arranged in parallel, and the slat track ribs 124 extend in the direction roughly aligned with the flight line. Each slat track is provided with two groups of rollers, each group has four rollers, and each side of the cross-sectional shape of the slat track corresponds to a roller. Thus, when the slat track moves through the roller, there is a set path of travel of the slat track. The path of this setting is spiral due to the geometry of the spiral slat track. When the slat moves from one position to another, the spiral shape of the set path has a constant pitch, a constant radius and an axis of the spiral shape fixed relative to the wing in space. The slats rotate about 30 degrees around the axis of the spiral shape between the stowed position of the slats and the deployed position of the slats. Therefore, it will be appreciated that the radius of the spiral shape is relatively large and is located significantly below and spaced from the leading edge of the wing compared to the distance the slats move between the stowed position of the slats and the fully deployed position of the slats. During the slat and slat track movement, the slat and slat track do not intersect the axis of the spiral shape at any point.

[0031] The movement of the slat through space when the slat moves from its fully stowed position to its fully deployed position follows a spiral path. The axis of the spiral shape (limiting the spiral path adopted) is roughly parallel to the leading edge of the slat, and the radius and pitch of the spiral shape make the slat appear to be parallel to the flight path movement of the wing when viewed from above. When the slat moves, the leading edge of the slat and the leading edge of the wing area extended from it remain roughly parallel. Regardless of any deflection in the components, the movement of the track through space makes the position of the cross-sectional shape of the slat track at a given fixed distance from the roller remain roughly accurate (conceptually similar to the material shape produced by being extruded as the material passes through an extrusion die with a twisted channel).

[0032] Reference Figure 7 , Fig.11 and Fig.15 , the lateral edges of the slats will be observed to move generally parallel to the flight path of the wing 102 (indicated by arrow 120 ). Fig.18 (Plan view with slats retracted) and Fig.19(a plan view of the slat when partially deployed) schematically illustrates the benefits of such an arrangement. It will be seen that the engine pylon 106 can have a conventional shape with an edge aligned with the flight path, the lateral edge portions of the slat 108 can be generally aligned with the flight path, and the movement of the slat - generally in the flight path when viewed from above - is also in the direction of the flight path. Therefore, no gaps are created when the slat moves from one position to another (compared to the Figures 2 to 5 During the movement of the slat between its fully stowed position and its fully extended position, the spacing between a lateral edge of the slat and a corresponding lateral edge of the pylon, when viewed in plan view, remains substantially the same. Additionally, during the movement of the slat between its fully stowed position and its fully extended position, the spacing between another lateral edge of the slat and a corresponding surface of the fuselage remains substantially the same.

[0033] Fig. 20 FIG25 is a schematic flow chart 250 showing the steps of a method of moving a slat on a swept wing of an aircraft according to a second embodiment. At step 260, the slat is in the fully extended position of the slat. Step 262 represents the movement of the slat from the extended position to the retracted position. As part of this step, the slat moves only with two main motion components, which are Fig.18 The two boxes 264 and 266 shown in the figure represent the first component (box 264) including the rotation around the first axis and representing the main component of the motion of the slat. Thus, the motion of the slat as a first approximation can be described as an arc motion with the first axis as the rotation center. When the slat moves from the deployed position to the retracted position, the range of the arc through which the slat moves around the first axis is less than 50 degrees. The first axis is approximately flush with the horizontal line (for example, within the range of + / -20 degrees) and is located below the wing and spaced apart from the wing. The first axis is also roughly parallel to the leading edge of the slat (for example, within the range of + / -5 degrees when viewed from above). There is an imaginary envelope, which can be considered to be fixed in place and shaped relative to the wing, and during the movement, the slat moves in the imaginary envelope. The radius of curvature of the motion around the first axis is large enough so that the first axis is spaced apart from the imaginary envelope in which the slat moves. The second component (box 266) includes a translation motion parallel to the first axis. The amount of motion of the second component is proportional to the amount of motion of the first component, so the speed of the translational motion of the second component is proportional to the speed of the rotation about the first axis.

[0034] Although the present invention has been described and illustrated with reference to specific embodiments, it will be appreciated by those skilled in the art that the invention lends itself to many different variations not specifically described herein. Some possible variations will now be described by way of example only.

[0035] In alternative embodiments, the slat may have three slat tracks, and may have four slat tracks, and may have more slat tracks. One or more of the tracks may be driven, but there may be undriven driven tracks. At least some of the rollers may be resiliently mounted to provide flexing of the tracks relative to each other during loading, or to allow wing flexing.

[0036] The motion of the slat need not be such that all parts of the slat have the same main (helical) axis of rotation. Successive slat trajectories may describe a helical path with a progressively increasing radius in the spanwise direction (each helix involved having a constant radius). The slat trajectory may describe a path that may be described as helical but still not completely aligned with a mathematically ideal helical shape.

[0037] It will be appreciated that the angle through which the slat rotates about the axis of the helical shape between its fully stowed position and its fully extended position will vary depending on the aircraft requirements and may be as low as 15 degrees or less and potentially as high as 40 degrees, or more.

[0038] In the foregoing description, reference is made to wholes or elements with known, obvious or foreseeable equivalents, and these equivalents are incorporated herein as if set forth separately. The true scope of the invention should be determined with reference to the claims, which should be interpreted as including any such equivalents. The reader will also understand that wholes or features described as preferred, beneficial, convenient or similar of the invention are optional and do not limit the scope of the independent claims. In addition, it will be understood that such optional wholes or features, although they may be beneficial in certain embodiments of the invention, may not be desirable in other embodiments and therefore may not exist in other embodiments.

[0039] Unless the context requires otherwise, the term "or" should be construed as "and / or".

Claims

1. A slat for a leading edge of an aircraft wing, the slat comprising two or more slat tracks which, when in use, determine the path of movement of the slat when the slat moves from a retracted position to a fully extended position, each slat track having a shape following a spiral path, wherein: The slat includes an airfoil surface supported by the two or more slat tracks, and wherein the airfoil surface and the two or more slat tracks are configured to move along the spiral path when the airfoil surface and the two or more slat tracks are deployed forward of the leading edge of the aircraft wing, The slats are configured such that each slat track has at least two outer surfaces located on opposite sides of the slat track when viewed in cross section, and wherein, The two outer surfaces are defined by two surfaces swept out by two imaginary fixed shape lines when moving along the helical path relative to the airfoil surface of the slat.

2. The slat according to claim 1, wherein: Each slat track has a uniform cross-sectional shape over the length of the slat track.

3. The slat according to claim 1, wherein: The spiral path corresponding to one of the slat tracks is a spiral shape having a first radius, and the spiral path corresponding to the other of the slat tracks is a spiral shape having a second, different radius.

4. The slat according to claim 1, wherein: The airfoil surface is rigidly supported by at least one slat track of the two or more slat tracks.

5. A swept aircraft wing comprising a slat for a leading edge of an aircraft wing according to any one of claims 1-4.

6. The swept aircraft wing of claim 5, wherein: The axis of the helical path and the pitch of the helical path are configured such that the lateral edge of the slat moves parallel to a vertical plane aligned with the flight path of the wing.

7. A swept aircraft wing according to claim 5 or 6, wherein: An axis of the helical shape corresponding to the helical path is aligned with the leading edge of the slat.

8. A swept aircraft wing according to claim 5 or 6, wherein: The movement of each slat track is guided by two sets of rollers, one set of rollers being spaced apart from the other set of rollers in a direction along the length of the slat track, each set of rollers constraining the movement of the slat track in two orthogonal directions, the two orthogonal directions being perpendicular to the direction in which the slat track moves through the set of rollers.

9. A swept aircraft wing according to claim 8, comprising at least two pairs of track ribs, wherein: Each pair of track ribs is positioned on both sides of the slat track, At least one roller in each set of rollers is supported between a pair of track ribs, and When viewed in plan, each track rib extends in a direction aligned with the flight path.

10. A swept aircraft wing according to claim 5 or 6, wherein: There is a fixed surface adjacent to a lateral surface of the slat, the path of movement of the slat as the slat moves from a retracted position to a deployed position being such that a minimum spacing between the fixed surface and the lateral surface is constant.

11. A swept aircraft wing according to claim 5 or 6, wherein: The sweep angle of the wing is between 20 degrees and 30 degrees.

12. An aircraft comprising a swept aircraft wing according to any one of claims 5 to 11.

13. A method for deploying or retracting a slat on a swept aircraft wing according to any one of claims 5 to 11, wherein: The movement of the slat during movement between the fully extended position and the fully retracted position includes: a component of rotation about a first axis that is fixed in space relative to the wing and spaced from an imaginary envelope relative to the wing, wherein the slat moves within the imaginary envelope during movement, and A translational motion component parallel to the first axis, the speed of the translational motion being proportional to the speed of the rotation about the first axis.

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