aircraft wing

Abstract

In some examples, a wing for an aircraft having a passive variable aeroelastic shape to accommodate efficient flight at a plurality of aircraft speeds comprises a wing skin comprising a composite structure comprising a stack of multiple plies deposited against the wing skin according to a predetermined stack profile, at least one of the multiple plies comprising a continuous nonlinear deposition of material, and the wing skin comprises a stiffness distribution profile defined by the predetermined stack profile.

Description

[Technical Field]

[0001] The present invention relates to a wing for an aircraft. [Background technology]

[0002] The optimum wing sweep for an aircraft, defined as the amount that the wing is angled aft (relative to the aircraft's direction of travel) from its root, for example, varies based on the desired speed capability of the aircraft. For example, at takeoff speeds, wings with little or no sweep are preferred. However, wings with such sweep perform poorly as the aircraft's speed increases, making them unsuitable for use on the aircraft.

[0003] To cover the range of possible aircraft speeds, some aircraft wings can modify the sweep by pivoting the entire wing. While effective, the mechanical systems required to allow such active variation are expensive and heavy, and generally only suitable for aircraft that frequently and rapidly change speed, for example, from subsonic to supersonic.

[0004] Wing twist is a further aerodynamic feature of aircraft wings that allows the distribution of lift along the wing to be tailored.

[0005] With the advent of modern manufacturing processes, aircraft wings can be manufactured to be lighter and stronger using, for example, composite and laminate materials. Such manufacturing techniques can introduce a degree of passive aeroelastic tailoring into the aircraft wing, allowing the degree of wing deflection to vary in response to changing loads (e.g., as the aircraft in question changes speed). Summary of the Invention

[0006] An object of the present disclosure is to provide a wing with passive variable aeroelastic shape to accommodate efficient flight at multiple aircraft speeds.

[0007] These and other objects are achieved by means of the features of the independent claims.

[0008] Further implementations are evident from the dependent claims, the description and the drawings.

[0009] A first aspect of the present disclosure provides a wing for an aircraft, the wing having a passively variable aeroelastic shape for efficient flight at multiple aircraft speeds. The wing comprises a wing skin comprising a composite structure comprising a stack of multiple plies deposited against the wing skin according to a predetermined layup profile, at least one of the multiple plies comprising a continuous nonlinear deposition of material, and the wing skin comprising a stiffness distribution profile defined by the predetermined layup profile. The wing can define a relatively low or high aspect ratio. At least one of the multiple plies can comprise carbon fiber. The nonlinear deposition of material can comprise a continuous track of material. The continuous track of material can comprise at least one bend having a radius of curvature within a range of approximately 40 to 100 mm.

[0010] In implementations of the first aspect, the shape of the continuous track of material can be defined based at least in part on a predetermined layup profile. The continuous track of material can be formed by continuous tow shearing of the material.

[0011] A second aspect of the present disclosure provides a method for fabricating an aircraft wing component, the method comprising depositing a layer of a first material, the layer comprising a nonlinear tow of the first material, the layer being deposited as part of a stack of multiple layers for the component. The nonlinear tow of the first material can define a continuous track including at least one bend having a radius of curvature in the range of approximately 40 to 100 mm.

[0012] In an implementation of the second aspect, the method may further comprise depositing a layer of a first material according to a predetermined layup profile. The nonlinear tow of the first material may be deposited using continuous tow shear. The nonlinear tow of the first material may comprise at least one bend having a radius of curvature within a range of approximately 40 to 100 mm. The method may further comprise depositing a layer of a second material according to a predetermined layup profile, the layer of the second material comprising a nonlinear tow of the second material having at least one bend having a radius of curvature within a range of approximately 40 to 100 mm.

[0013] A third aspect of the present disclosure provides a composite structure for an aircraft wing component, the composite structure comprising a stack of a plurality of plies deposited according to a predetermined stack profile, at least one of the plurality of plies comprising a nonlinear tow of a first material defining a continuous track with at least one bend having a radius of curvature in the range of approximately 40 to 100 mm.

[0014] These and other aspects of the invention will be apparent from and elucidated with respect to the embodiment(s) described hereinafter.

[0015] Embodiments of the present invention will now be described, by way of example only, with reference to the drawings in which: [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 10 is a schematic diagram illustrating a comparison between tow placement using tow steering and tow shear, according to an example. [Figure 2] 1 illustrates a system for fabricating a wing component for an aircraft, according to an example. [Figure 3] 1 is a schematic diagram of a wing for an aircraft, according to an example. [Figure 4] 1 is a schematic diagram of a wing for an aircraft, according to an example. DETAILED DESCRIPTION OF THE INVENTION

[0017] Illustrative embodiments are described below in sufficient detail to enable those skilled in the art to embody and implement the systems and processes described herein. It is important to understand that embodiments may be provided in many alternative forms and should not be construed as being limited to the examples set forth herein.

[0018] Thus, while the embodiments can be modified in various ways and can take various alternative forms, specific embodiments thereof are shown in the drawings and will be described in detail below by way of example. There is no intention to be limited to the particular forms disclosed. On the contrary, all modifications, equivalents, and alternatives falling within the scope of the appended claims are to be covered. Elements of illustrative embodiments will, where appropriate, be consistently designated by the same reference numerals throughout the drawings and the detailed description.

[0019] The terminology used herein to describe embodiments is not intended to be limiting in scope. The articles "a," "an," and "the" are singular in that they have a single referent; however, the use of the singular herein should not exclude the presence of more than one referent. In other words, elements referred to in the singular can have a number of one or more unless the context clearly dictates otherwise. It should be further understood that the terms "comprises," "comprising," "includes," and / or "including," as used herein, specify the presence of stated features, items, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, items, steps, operations, elements, components, and / or groups thereof.

[0020] Unless otherwise defined, all terms (including technical and scientific terms) used herein should be interpreted as is conventional in the art. Terms in common usage should also be interpreted as is conventional in the relevant art, and should not be interpreted in an idealized or overly formal sense unless expressly defined as such herein.

[0021] By way of example, a wing for an aircraft may comprise a passively variable aeroelastic shape. Such efficient flight may be accommodated at multiple aircraft speeds because the wing may comprise an adaptive compliant wing. For example, efficient flight at multiple different speeds may be achieved without the use of complex, heavy, and expensive active systems directed at varying the angle of wing sweep. Furthermore, wing twist may be implemented to provide a desired lift distribution on the wing.

[0022] Further, in the context of passive systems, an example wing includes a wing skin comprising a composite structure formed using a stack of multiple plies deposited on the wing skin according to a predetermined stack profile, at least one of the multiple plies comprising a nonlinear stack of material, the wing skin having a stiffness distribution profile defined by the stack profile, and the nonlinear stack of material providing an improved passive variable aeroelastic shape.

[0023] Wings enable platforms such as aircraft to have variable airframe geometries, thereby accommodating efficient flight without the need for complex, heavy, and expensive active sweep and / or twist correction structures. In an example, the aircraft may have an elongated fuselage, and the wings, which may be angled wings, may be connected to the fuselage.

[0024] According to an example, the nonlinear deposition of material comprises a continuous track of material. For example, a continuous track of material, which may be carbon fiber, may be formed by continuous tow shearing of the material (e.g., a tow comprising an untwisted bundle or tape of continuous material filaments). Aligning the filaments along the desired structural load path of the wing can significantly improve its performance without increasing its weight. This contrasts with typical automated fiber placement (AFP) techniques, such as tow steering, which impose limitations on the degree to which the tow can be aligned with the desired path, especially when the wing has a relatively low aspect ratio, where a smaller radius of curvature may be advantageous. Furthermore, typical AFP techniques can result in multiple process-induced defects, such as localized fiber wrinkles, buckling, tow gaps, and fiber discontinuities. For example, in AFP techniques such as tow steering, the fibers within the tow are aligned parallel to the nominal tow path due to head rotation, even though the steered tow path is simply shifted along a specific direction. This creates gaps or overlaps in the tows, which in turn can lead to resin-rich areas or localized thickening. Furthermore, the degree to which the tows can be substantially steered before fiber breakage occurs or before the gaps / overlaps become excessive limits their use in creating nonlinear tracks of material.

[0025] By way of example, continuous tracks of material forming nonlinear deposits of material to layers can be deposited using a head that also applies in-plane shear. For example, tows of material can be deposited along a first, reference, direction while being sheared in a second, orthogonal direction, thereby creating serpentine tracks of material. This also eliminates gaps and overlaps in the tows because the fibers within the tows are aligned and thus at a constant angle along the second direction.

[0026] The shearing of the material tow allows curvature to be introduced into the continuous track of material, enabling bends with radii of curvature in the range of approximately 40 to 100 mm. This far exceeds the radii of curvature possible when using, for example, tow steering. Therefore, material deposition can follow a serpentine track according to a predetermined lamination profile, enabling a higher stiffness profile for the wing within at least some regions of the corresponding wing skin. This allows passively variable aeroelastic shapes for the wing to be implemented in situations that would not otherwise be possible (e.g., when using fiber placement with tow steering, which is substantially in-plane bending as opposed to in-plane shear). This allows the lift distribution on the wing to be tailored by depositing one or more tracks using continuous tow shear, for example, to define a desired degree of wing twist.

[0027] 1 is a schematic diagram illustrating a comparison between tow placement using tow steering and tow shear, according to an example. FIG. 1(a) illustrates fibers in a tow aligned in a direction parallel to a reference tow path. FIG. 1(a) also illustrates the presence of tow gaps and tow overlaps due to head rotation. That is, tow gaps and overlaps inevitably occur when the head used to deposit the tow is rotated (as illustrated by the bold line representing the direction of movement of the head tip) such that the steered tow path is simply shifted along a particular direction (the shift direction).

[0028] FIG. 1(b) illustrates the fibers in a tow aligned in a direction parallel to the nominal tow path using tow shear. As can be seen, the orientation of the head tip relative to the nominal tow path remains parallel to the shift direction. Therefore, there are no gaps or overlaps between the tows. That is, the fiber placement head applies in-plane shear deformation to the continuously fed tow material by fixing the head rotation while a single strip of tow material is laid, thereby eliminating gaps and overlaps between the tows because all fibers in the tow are aligned at a constant angle along the shift direction.

[0029] FIG. 2 illustrates a system for fabricating an aircraft wing component, according to an example. A layer 201 of a first material is deposited. The first material may comprise, for example, carbon fiber. In an example, layer 201 may comprise a nonlinear tow of the first material, which may be deposited as part of a stack of multiple layers for the component. The nonlinear tow of the first material defines a continuous track with at least one bend having a radius of curvature within a range of approximately 40-100 mm.

[0030] The layer 201 of first material may be deposited according to a predetermined layup profile 203. The non-linear tows of the first material may be deposited by continuous tow shear using a continuous tow shear device 205. The device 205 may include a head 207. The head 207 may be configured, for example, to receive and deposit the tows of the first material onto a substrate 209. The substrate 209 and the head 207 may be movable relative to one another.

[0031] In an example, the head 207 can be translated in a shift (second) direction relative to a first (reference) direction, where the first (reference) direction defines the direction of travel of the head 207 (e.g., relative to the substrate 209). The second direction can be orthogonal to the first direction to cause shear shearing of the tows of the first material. The layer 201 of the first material can be deposited according to a predetermined layup profile 203. The predetermined layup profile 203 can define the shape of the deposited tows of material for the first layer and can include at least one straight section and a curved section for the deposited material. In an example, the nonlinear tows of the first material can include at least one bend having a radius of curvature in the range of approximately 40-100 mm.

[0032] According to an example, the controller 211 may be used to control the position of the head 207. The controller 211 may implement a predetermined lamination profile 203. For example, the predetermined lamination profile 203 may be provided in the form of machine-readable instructions 213, which may be stored in a computer-readable storage device that can direct the apparatus 205 to operate in a particular mode. For example, the instructions 213 may be provided on a non-transitory computer-readable storage medium 215 encoded with instructions executable by the processor 217 to implement the predetermined lamination profile 203 using the controller 211 to control the position of the head 207 to a second position as the head 207 and substrate 209 move relative to one another in a first direction.

[0033] The term "processor" should be interpreted broadly to include a CPU, processing unit, ASIC, logic unit, or programmable gate set, etc. All methods and modules may be performed by a single processor or may be divided among several processors.

[0034] By way of example, a layer of a second material can be deposited. The second material can be the same as or different from the first material. The second material can be deposited according to a predetermined layering profile and can include a nonlinear tow of the second material. The nonlinear tow of the second material can include at least one bend having a radius of curvature in the range of about 40 to 100 mm.

[0035] Figure 3 is a schematic diagram of a wing for an aircraft, according to an example. In the example of Figure 3, wing 301 has a passively variable aeroelastic shape for efficient flight at multiple aircraft speeds and includes wing skin 303 comprising a composite structure including a stack of multiple layers deposited on the wing skin according to a predetermined layup profile. At least one of the multiple layers comprises a continuous nonlinear deposition of material. Wing skin 303 includes a stiffness distribution profile defined by the layup profile. Thus, for example, at least one of the wing's twist or pitch can be adjusted according to the layup profile by varying the stiffness distribution of the wing skin.

[0036] 3 illustrates an example (not to scale and highly simplified) of a continuous nonlinear deposition of material 305. The nonlinear deposition of material 305 comprises a continuous track of material, which in the example of FIG. 3 is serpentine, extending generally from the root 307 of the wing 301 (where the wing is attached to the fuselage) to the tip 309, although the beginning and end locations of such a track may be at any point on the wing skin.

[0037] In the example of Figure 3, the curvature of the track decreases in the direction from root 307 to tip 309. That is, the radius of curvature of the bend in the track increases in the direction along the track from root 307 to tip 309. This may be gradual, e.g., continuous decrease, stepwise decrease, or a combination thereof. Considering that the start and end locations of such a track may be at any point on the wing skin, the curvature of the track may remain the same or may increase or decrease in any direction relative to the orientation of the wing skin. For example, the track may be stacked laterally across the wing skin.

[0038] A laminate profile can comprise multiple such tracks, which can be offset or translated from one another in any one or more directions within the plane of the wing skin. In the context of tracks deposited using tow shear, as the shear angle (e.g., at the curvature of the track) increases, the lateral movement of the tow fibers relative to one another reduces the tow / tape width and increases the thickness. Therefore, the thickness of the track increases locally at these points without a corresponding increase in the number of plies in the laminate.

[0039] Figure 4 is a schematic diagram of a wing for an aircraft, according to an example. In the example of Figure 4, the wing 401 has a passively variable aeroelastic shape to accommodate efficient flight at multiple aircraft speeds and includes a wing skin 403 comprising a composite structure comprising a stack of multiple layers deposited against the wing skin according to a predetermined layup profile. The example of Figure 4 illustrates an alternative implementation of a continuous track of material. More specifically, a continuous track of material extends laterally across the wing skin 403, with multiple such laterally extending continuous tracks of material 411 being provided across the length of the wing skin from its root 407 to its tip 409. The continuous track may extend across one or both of the top and bottom sides of the wing skin.

[0040] In an example, the density of the continuous track of material can vary along the length of the wing skin. For example, the density of the continuous track of material in the root region 407 of the wing is higher (darker) than the density at the tip (lighter) of the wing (409), as illustrated by the gradation in Figure 4. In an example, the continuous track of material can decrease in density and / or degree of curvature in a direction from root to tip of the wing.

[0041] In the case of Figures 3 or 4, the stiffness of the wing skin 303, 403 will be higher at the root of the wing than at the tip of the wing as a result of differences in the thickness of one or more tracks resulting from the degree of curvature implemented by the layup profile. That is, as explained above, as the shear angle (e.g., the curvature of the track) increases, the lateral movement of the tow fibers relative to one another reduces the tow / tape width and increases the thickness. Therefore, the track thickness increases locally at these points without a corresponding increase in the number of plies in the layup. Thus, variations in the stiffness distribution profile defined by the layup profile can be achieved. That is, the stiffness of the wing skin can be varied by modifying at least one of the track density, the degree of curvature of one or more tracks, and the number of plies. It should be recognized that although the degrees of curvature of the tracks in regions 407 and 409 of Figure 4 are illustrated as being the same, they may be different and / or individual, tracks within a region may have different degrees of curvature relative to others in the same region, etc.

[0042] Modifying the stiffness profile of the wing allows the degree of change in the angle of deflection, twist, and / or sweep of the wing to vary depending on, for example, the speed of the aircraft to which the wing is attached. For example, at relatively higher speeds, a wing such as that illustrated in FIGS. 3 or 4 , which is relatively stiffer at the root compared to the tip of the wing, will therefore exhibit more elastic properties toward the tip. For example, the stiffness profiles described above with reference to FIGS. 3 and 4 can be varied to accommodate different scenarios and use cases. For example, an opposite profile to that illustrated with reference to FIGS. 3 and 4 can be implemented, for example, to reduce twist or deflection at the tip of the wing while minimizing the weight of the wing skin (e.g., because relatively less material can be used toward the root of the wing skin). It should be appreciated that there are several different shapes and combinations of one or more tracks that can be implemented to provide a wing skin with a desired stiffness profile, and the above is not intended to be limiting, but is illustrative and intended to help explain how toe shear of material can be used in the present context, for example, for wings having relatively high or low aspect ratios.

[0043] By way of example, a composite structure for an aircraft wing component may be provided using, for example, the process described above with reference to Figure 2. To that end, a stack of multiple layers may be deposited according to a predetermined stack profile, and at least one of the multiple layers may comprise a non-linear tow of a first material defining a continuous track with at least one bend having a radius of curvature in the range of about 40 to 100 mm.

[0044] The preceding description is provided to enable those skilled in the art to best utilize various aspects of the exemplary embodiments disclosed herein. This illustrative description is not intended to be exhaustive or to be limited to any precise form disclosed. Many modifications and variations are possible without departing from the spirit and scope of the present disclosure. The embodiments disclosed herein should be considered in all respects as illustrative and not restrictive. In determining the scope of the present disclosure, reference should be made to the appended claims and their equivalents.

Claims

1. 1. A wing for an aircraft, the wing having a passively variable aeroelastic shape for efficient flight at multiple aircraft speeds, the wing comprising:

1. A wing comprising a wing skin comprising a composite structure comprising a stack of a plurality of plies deposited against the wing skin according to a predetermined layup profile, at least one of the plurality of plies comprising a continuous nonlinear deposition of material, the wing skin comprising a stiffness distribution profile defined by the predetermined layup profile.

2. The wing of claim 1 , wherein the wing defines a relatively low aspect ratio.

3. The wing of claim 1 , wherein the wing defines a relatively high aspect ratio.

4. The airfoil of any one of claims 1 to 3, wherein at least one of the layers comprises carbon fiber.

5. An airfoil according to any preceding claim, wherein the continuous non-linear deposition of material comprises a continuous track of material.

6. The airfoil of claim 5 , wherein the continuous track of material comprises at least one bend having a radius of curvature in the range of about 40 to 100 mm.

7. 7. The airfoil of claim 5 or 6, wherein the shape of the continuous track of material is defined based at least in part on the predetermined layup profile.

8. An airfoil according to any one of claims 5 to 7, wherein the continuous track of material is formed by continuous tow shearing of the material.

9. 1. A method for making a wing component for an aircraft, the method comprising:

1. A method comprising: depositing a layer of a first material, the layer comprising a nonlinear tow of the first material, the layer of first material being deposited as part of a stack of multiple layers for the component.

10. 10. The method of claim 9, wherein the nonlinear tow of the first material defines a continuous track with at least one bend having a radius of curvature in the range of about 40 to 100 mm.

11. depositing a layer of said first material according to a predetermined deposition profile; The method of claim 9 or 10, further comprising:

12. depositing the nonlinear tow of the first material using continuous tow shear; The method of any one of claims 9 to 11, further comprising:

13. 13. The method of any one of claims 9 to 12, wherein the nonlinear tow of the first material comprises at least one bend having a radius of curvature in the range of about 40 to 100 mm.

14. depositing a layer of a second material according to the predetermined deposition profile.

14. The method of claim 9, further comprising: wherein the layer of second material comprises a non-linear tow of the second material comprising at least one bend having a radius of curvature in a range of about 40 to 100 mm.

15. 1. A composite structure for a wing component for an aircraft, said composite structure comprising: A stack of multiple layers deposited according to a predetermined stacking profile wherein at least one of the plurality of layers comprises a non-linear tow of a first material defining a continuous track with at least one bend having a radius of curvature in the range of about 40 to 100 mm.

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