Aircraft, wing of an aircraft, fixed wing and wing tip device

Abstract

The invention relates to an aircraft (1002) comprising a wing (1001) having a fixed wing (1005) and a wing tip device (1003) movably mounted at an outer end of the fixed wing. The wing tip device (1003) is movable between a flight configuration and a ground configuration. The wing tip device (1003) and the fixed wing (1005) are separated along a tilted main cut plane (1013). The wing tip device (1003) and the fixed wing (1005) meet along an interface cut line (1035). The wing tip device and the fixed wing comprise a wing skin having a thickness and an end face extending across the thickness of the wing skin provides an interface surface corresponding to the interface cut line, wherein the interface surface is tilted in a first orientation towards a front of the wing and in a second, opposite orientation towards a rear of the wing. The invention also relates to a wing of an aircraft, a fixed wing and a wing tip device.

Description

Technical Field

[0001] This invention generally relates to aircraft, aircraft wings, fixed wings and wingtip devices. Background Technology

[0002] There is a trend toward the development of larger passenger aircraft, which necessitates correspondingly larger wingspans. However, the maximum aircraft wingspan is actually limited by airport operating rules that manage the various clearances required for maneuvering around airports (e.g., the wingspan and / or ground clearance needed for gate entrances and safety taxiways).

[0003] To address this problem, various devices have been proposed, including movable wingtip devices specifically designed to reduce wingspan in ground configurations.

[0004] WO2015 / 150835 is an example of the proposed device. In the device of WO2015 / 150835, the wingtip device and the fixed wing are separated along an inclined cutting plane, and the wingtip device is capable of rotating about a rotation axis perpendicular to the cutting plane.

[0005] In the device described in WO2015 / 150835, sealing the interface between the fixed wing and the wingtip device (when the wingtip device is in flight configuration) has been found to be problematic. More specifically, due to the rotation of the wingtip device between flight and ground configurations, relative sliding motion occurs at the interface between the outer end of the fixed wing and the inner end of the wingtip device. While sliding seals can theoretically be used, this solution is suboptimal because sliding seals tend to experience relatively high wear. This can make sliding seals prone to wear and / or damage, and therefore may require frequent inspection and / or replacement.

[0006] GB2551185 discloses an apparatus in which the outer end of a fixed wing and the inner end of a wingtip assembly are joined along an interface cut line separating the outer surface of the fixed wing from the outer surface of the wingtip assembly. The contents of GB2551185 are incorporated herein by reference. In the embodiment described in GB2551185, the interface cut line includes: a first length formed by a cut through the outer surface, but offset from a main cutting plane along a first direction; a second length formed by a cut through the outer surface, but offset from the main cutting plane along a second direction opposite to the first direction; and a transition portion where the interface cut line transitions from the first length to the second length. The wingtip assembly may contact the fixed wing in a sliding contact manner along the transition portion, but the wingtip assembly is separated from the fixed wing along the first and second lengths. In the embodiments mentioned in GB2551185, the first length may be located in a first plane that is parallel to the main cutting plane but offset from the main cutting plane along a first direction, and the second length may be located in a second plane that is parallel to the main cutting plane but offset from the main cutting plane along a second direction.

[0007] Various aspects of the present invention attempt to provide further improvements to the interface between the fixed wing and the wingtip device. Summary of the Invention

[0008] According to a first aspect, an aircraft is provided, including a wing having a fixed wing and a wingtip assembly, the wingtip assembly being movably mounted at the outer end of the fixed wing, the wingtip assembly being movable between: (a) a flight configuration for use during flight; and (b) a ground configuration for use during ground-based operation, in which the wingtip assembly moves away from the flight configuration, causing a reduction in the wingspan of the aircraft's wing, wherein the wingtip assembly and the fixed wing are separated along a principal cutting plane, the principal cutting plane being obliquely oriented, and the wingtip assembly is rotatable between the flight configuration and the ground configuration about a rotation axis normal to the principal cutting plane, and wherein, when the wingtip assembly is in the flight configuration, the outer end of the fixed wing and the inner end of the wingtip assembly are moved along the fixed wing... The outer surface of the fixed wing is connected to the interface cut line that separates from the outer surface of the wingtip device. The interface cut line includes a curved portion that bends about the axis of rotation, extending both at the front and rear of the axis of rotation. The outer end of the fixed wing includes a first interface surface corresponding to the curved portion of the interface cut line, and the inner end of the wingtip device includes a second interface surface corresponding to the curved portion of the interface cut line. When the wingtip device is in flight configuration, at the front position of the axis of rotation, the first interface surface and the second interface surface form a first tilt angle relative to the axis of rotation, and the first interface surface and the second interface surface twist as they travel along the length of the curved portion, such that at the rear position of the axis of rotation, the first interface surface and the second interface surface are oriented at a second tilt angle opposite to the axis of rotation.

[0009] Although the first and second tilt angles are opposite, they do not necessarily have to be equal or opposite. Therefore, the first tilt angle can be larger or smaller than the second tilt angle relative to the axis of rotation. However, the key factor is that the orientation of the tilt angles is reversed. Another way to consider this is to think of the first tilt angle as positive and the second tilt angle as negative when compared with the axis of rotation.

[0010] The first and second interface surfaces can be arranged such that, at all positions along the front of the rotation axis, the first and second interface surfaces are oriented with a first change in orientation relative to the rotation axis. The first and second interface surfaces can also be arranged such that, at all positions along the rear of the rotation axis, the first and second interface surfaces are oriented with a second change in orientation relative to the rotation axis. At the inflection point from the first orientation to the second orientation, the first and second interface surfaces can be oriented parallel to the rotation axis.

[0011] The torsional tilt angles of the first and second interface surfaces imply a localized translational motion away from each other between the first and second interface surfaces as the wingtip device rotates from a flight configuration to a ground configuration. This initial motion is typically a localized translation along mutually perpendicular directions. This provides an improved arrangement in which the movement of the wingtip device from the flight configuration to the ground configuration is easier and less affected by frictional or adhesive forces between the first and second interface surfaces. When the wingtip device is in the flight configuration, an additional sealing surface or element can be provided between the first and second interface surfaces. The sealing surface or element can be arranged along the entire length of the interface cut line. The sealing surface or element can comprise an elastically deformable material such that when the wingtip device is in the flight configuration, the sealing surface or element is compressed between the first and second interface surfaces. The sealing surface or element is used to improve the seal between the fixed wing and the wingtip device when in the flight configuration, thereby improving the aerodynamic performance of the wing. The sealing surface or element can be permanently fixed to one of the first and second interface surfaces.

[0012] The transition from the first tilt angle to the opposite second tilt angle on the first interface surface and the second interface surface can be continuous.

[0013] The fixed wing may include an upper wing skin, the first interface surface of which is the front portion of the upper wing skin facing downwards and the rear portion facing upwards. The wingtip assembly may include an upper wingtip skin, the second interface surface of which is the front portion of the upper wingtip skin facing upwards and the rear portion facing downwards. The upward and downward directions may be defined relative to the conventional vertical Z-axis when the aircraft is on the ground, or locally relative to the wing's orientation.

[0014] The fixed wing may include a lower wing skin, the first interface surface of which is the front portion of the lower wing skin facing the axis of rotation in the downward direction and the rear portion facing the axis of rotation in the upward direction. The wingtip assembly may include a lower wingtip skin, the second interface surface of which is the front portion of the lower wingtip skin facing the axis of rotation in the upward direction and the rear portion facing the axis of rotation in the downward direction.

[0015] The radius of the curved section can increase as the cutting line travels around the axis, for example, the curved section can follow a spiral path around the axis. The radius of the curved section can increase towards the leading edge of the wing, so that the foremost part of the curved section has the largest radius and the rearmost part of the curved section has the smallest radius.

[0016] The wing may include a sealing assembly for sealing between the fixed wing and the wingtip assembly when the wingtip assembly is in flight configuration, and wherein the sealing assembly includes a compression seal for forming / opening a seal in the relative meeting / separation of the fixed wing and the wingtip assembly, the compression seal being associated with a curved portion.

[0017] The interface cut line may include: (i) a first length formed by a cut through the outer surface, the first length being offset from the main cut plane along a first direction; (ii) a second length formed by a cut through the outer surface, the second length extending in a plane containing the axis of rotation or in a plane parallel to the plane; and (iii) a transition portion, wherein the transition portion is a curved portion centered on the axis of rotation, on which the interface cut line transitions from the first length to the second length. The second length may be formed by a cut through the outer surface, the cut extending in a plane containing the axis of rotation. The plane in which the second length extends may be oriented along the flight path direction. The fixed wing may include a front spar, and the plane in which the second length extends may be oriented perpendicular to the front spar. The first length may be located at the rear of the axis of rotation, and the second length may be located at the front of the axis of rotation.

[0018] The wing may include: an upper surface extending from a leading edge to a trailing edge above the wing; and a lower surface extending from a leading edge to a trailing edge below the wing, wherein a first length extends along the upper surface of the wing, and a second length extends along the upper surface of the wing, through the leading edge, and to the lower surface of the wing. The interface cut line may further include: (iii) a third length located on the lower surface of the wing, formed by a cut through the outer surface, the third length being offset from the main cut plane in a second direction opposite to the first direction; and (iv) another transition portion, on which the interface cut line transitions from the third length to a portion of the second length on the lower surface. The interface cut line may include another transition portion located between the first length and the third length, such that the interface cut line is formed by the first length to the third length, each length transitioning to the adjacent length via a corresponding transition portion. The third length may be located at the rear of the axis of rotation. The first length may be curved and the curvature is formed such that the first length is not located in a single plane. The wing may include a sealing assembly for sealing between the fixed wing and the wingtip assembly when the wingtip assembly is in flight configuration, and wherein the sealing assembly includes a compression seal for forming / opening a seal in the relative meeting / separation of the fixed wing and the wingtip assembly, the compression seal being associated with a first length and a second length.

[0019] It has been found advantageous to divide the interface cut line into a first length and a second length. Since the first length is offset from the main cut plane, sliding contact movement along this length tends to be restricted or nonexistent when the winglet device rotates about its axis of rotation. Conversely, the fixed wing and winglet device tend to separate along the first length with local translational movement. This is advantageous because it allows for non-slip sealing (e.g., compression sealing) along this length. Furthermore, it has been found particularly advantageous to provide a second length formed by a cut through the outer surface, the second length being generally located in a plane containing the axis of rotation, or in a plane parallel to that plane. It has been recognized that by forming the second length in this way, the orientation of the second length of the interface cut line tends to indicate separation of the fixed wing and winglet device in a local vertical direction (along the second length). Therefore, the sealing movement tends to be pure compression. The second length is preferably formed by a cut through the outer surface, the cut extending in a plane containing the axis of rotation or in a plane parallel to the plane, such that the fixed wing and the wingtip device separate in a local vertical direction (along the second length) when the wingtip device moves from the flight configuration toward the ground configuration.

[0020] The second length is preferably formed by a cut through the outer surface, the cut being generally located in a plane containing the axis of rotation. This orientation of the cut allows the fixed wing and wingtip assembly to simultaneously separate along the entire length of the second cut line as the wingtip assembly moves from the flight configuration towards the ground configuration (and vice versa, allowing the fixed wing and wingtip assembly to simultaneously engage along the entire length of the second cut line as the wingtip assembly moves into the flight configuration). The second length is preferably formed by a cut through the outer surface extending in a plane containing the axis of rotation, such that the fixed wing and wingtip assembly separate simultaneously along the entire length of the second cut line as the wingtip assembly moves from the flight configuration towards the ground configuration.

[0021] When the wingtip assembly rotates from the flight configuration to the ground configuration, the wingtip assembly can separate from the fixed wing along a first length and a second length. This separation is preferably a translational movement of the relative portions of the fixed wing and the wingtip assembly away from each other. It will be understood that the wingtip assembly rotates about its axis of rotation; therefore, the separation / translational movement involved is a localized movement near the interface—the wingtip assembly rotates relative to the fixed wing when considered as a whole. Preferably, there is no sliding contact along the second length. Preferably, there is no sliding contact along the first length.

[0022] According to a second aspect of the invention, an aircraft wing can be provided, which serves as a wing according to a first aspect of the invention, the wing having a fixed wing and a wingtip assembly movably mounted on the outer end of the fixed wing, the wingtip assembly being movable between: (a) a flight configuration for use during flight; and (b) a ground configuration for use during ground-based operations, in which the wingtip assembly moves away from the flight configuration, causing a reduction in the wingspan of the aircraft wing, wherein the wingtip assembly and the fixed wing are separated along a principal cutting plane, the principal cutting plane being obliquely oriented, and the wingtip assembly is rotatable between the flight configuration and the ground configuration about a rotation axis normal to the principal cutting plane, and wherein, when the wingtip assembly is in the flight configuration, the outer end of the fixed wing and the wingtip assembly... The inner end of the fixed wing is connected to an interface cutting line that separates the outer surface of the fixed wing from the outer surface of the wingtip device. The interface cutting line includes a curved portion that bends about the axis of rotation, extending both forward and backward along the axis of rotation. The outer end of the fixed wing includes a first interface surface corresponding to the curved portion of the interface cutting line, and the inner end of the wingtip device includes a second interface surface corresponding to the curved portion of the interface cutting line. When the wingtip device is in flight configuration, at a forward position along the axis of rotation, the first and second interface surfaces form a first tilt angle relative to the axis of rotation, and the first and second interface surfaces twist as they travel along the length of the curved portion, such that at a rear position along the axis of rotation, the first and second interface surfaces are oriented at opposite second tilt angles relative to the axis of rotation.

[0023] According to a third aspect of the invention, a fixed wing can be provided, which serves as a fixed wing in either the first or second aspect of the invention, the fixed wing being configured to receive a wingtip device movable between: (a) a flight configuration for use during flight; and (b) a ground configuration for use during ground-based operation, in which the wingtip device moves away from the flight configuration such that the wingspan of the aircraft's wing decreases, wherein the wingtip device and the fixed wing are separated along a principal cutting plane oriented at an angle, and the wingtip device is rotatable between the flight configuration and the ground configuration about a rotation axis oriented normally to the principal cutting plane, and wherein, when the wingtip device is in the flight configuration, the outer end portion of the fixed wing and the inner end portion of the wingtip device are moved along a direction that will... The outer surface of the fixed wing is connected to the interface cut line separating the outer surface of the wingtip device. The interface cut line includes a curved portion that bends about the axis of rotation, extending both forward and backward along the axis of rotation. The outer end of the fixed wing includes a first interface surface corresponding to the curved portion of the interface cut line, and the inner end of the wingtip device includes a second interface surface corresponding to the curved portion of the interface cut line. When the wingtip device is in flight configuration, at the forward position along the axis of rotation, the first and second interface surfaces form a first tilt angle relative to the axis of rotation, and the first and second interface surfaces twist as they travel along the length of the curved portion, such that at the rear position along the axis of rotation, the first and second interface surfaces are oriented at opposite second tilt angles relative to the axis of rotation.

[0024] According to a fourth aspect of the invention, a wingtip device can be provided, which serves as a wingtip device in any of the first, second, or third aspects of the invention, the wingtip device being configured to be received on a fixed wing, the wingtip device being movable between: (a) a flight configuration for use during flight; and (b) a ground configuration for use during ground-based operation, in which the wingtip device moves away from the flight configuration, such that the wingspan of the aircraft's wing decreases, wherein the wingtip device and the fixed wing are separated along a principal cutting plane, and the wingtip device is rotatable between the flight configuration and the ground configuration about a rotation axis oriented normally to the principal cutting plane, and wherein, when the wingtip device is in the flight configuration, the outer end of the fixed wing and the inner end of the wingtip device are aligned along the fixed wing. The outer surface of the fixed wing is connected to the interface cut line separating the outer surface of the wingtip assembly. The interface cut line includes a curved portion that bends about the axis of rotation, extending both forward and backward along the axis of rotation. The outer end of the fixed wing includes a first interface surface corresponding to the curved portion of the interface cut line, and the inner end of the wingtip assembly includes a second interface surface corresponding to the curved portion of the interface cut line. When the wingtip assembly is in flight configuration, at the forward position along the axis of rotation, the first and second interface surfaces form a first tilt angle relative to the axis of rotation, and the first and second interface surfaces twist as they travel along the length of the curved portion, such that at the rear position along the axis of rotation, the first and second interface surfaces are oriented at opposite second tilt angles relative to the axis of rotation.

[0025] The wingtip device is capable of rotating about an axis of rotation between a flight configuration and a ground configuration. The orientation of the axis is preferably such that the wingspan of the aircraft decreases when the wingtip device rotates about this axis from the flight configuration to the ground configuration.

[0026] The axis of rotation is oriented normally to the main cutting plane. The main cutting plane is preferably inclined. This cutting plane preferably extends through both the upper and lower surfaces of the wing. The distance along the upper surface of the wing from the wing root to the cutting plane (i.e., to the point where the cutting plane intersects the upper surface) can be less than the distance along the lower surface of the wing from the wing root to the cutting plane (i.e., to the point where the cutting plane intersects the lower surface). Therefore, this cutting plane can create an overcut relative to the fixed wing. In other embodiments, the distance along the upper surface of the wing from the wing root to the cutting plane (i.e., to the point where the cutting plane intersects the upper surface) can be greater than the distance along the lower surface of the wing from the wing root to the cutting plane (i.e., to the point where the cutting plane intersects the lower surface). Therefore, the cutting plane can create an undercut relative to the fixed wing.

[0027] The primary cutting plane is preferably an imaginary plane that separates the fixed wing from the wingtip assembly (e.g., a cutting plane produced during the wing design phase). It will be understood that the cutting plane itself does not necessarily appear as a physical planar surface across the entire wing depth. The primary cutting plane will be readily identifiable to those skilled in the art. The primary cutting plane can be the plane in which the wingtip assembly rotates. Some embodiments of the invention may include a support member, such as a slewing ring, for supporting rotation of the wingtip assembly. The support member may be coaxial with the axis of rotation. The primary cutting plane may extend through the thickness of the support member and typically through the middle thickness of the support member (i.e., the middle thickness of the support member is coplanar with the primary cutting plane).

[0028] The axis of rotation can be oriented at an angle relative to the longitudinal direction (i.e., excluding directions parallel or perpendicular to the longitudinal direction). The axis is preferably at an angle relative to the lateral direction (i.e., excluding directions parallel or perpendicular to the lateral direction). The axis is preferably at an angle relative to the vertical direction (i.e., excluding directions parallel or perpendicular to the vertical direction). The vertical, longitudinal, and lateral directions can be perpendicular to each other. In some embodiments, the vertical, longitudinal, and lateral directions can be located in an absolute reference frame (i.e., longitudinal is forward-rear, lateral is port-starboard, and vertical is perpendicular to the ground). The longitudinal direction can be a chord direction, and the lateral direction can be a wingspan direction. In other embodiments, it may be suitable to use the longitudinal, lateral, and vertical directions in a local reference frame of the wing. For example, for a swept wing, the longitudinal direction can be replaced by the length of the wing, and the lateral direction can be the width of the wing (i.e., the width measured perpendicular to the longitudinal direction from the leading edge to the trailing edge). Alternatively or additionally, for a wing with dihedral angles, the vertical direction can be perpendicular to the plane of the wing. In all cases, the cutting plane / axis is oriented such that the wingspan of the wing decreases when the wingtip assembly rotates about the axis. The forward and aft portions of the rotation axis can be determined by reference to a boundary defined by an axis perpendicular to the longitudinal axis of the aircraft and intersecting the rotation axis. All points relative to the boundary toward the forward portion of the aircraft can be considered the forward portion of the rotation axis, and all points relative to the boundary toward the aft portion of the aircraft can be considered the aft portion of the rotation axis. Alternatively, the forward and aft positions can be determined in a local frame of reference for the wing. The boundary can be aligned with and parallel to the leading edge of the wing in a manner intersecting the rotation axis. The aircraft wing may include spars arranged in a generally spanwise direction, and the boundaries of these spars can be aligned with and parallel to the spars in a manner intersecting the rotation axis.

[0029] The orientation of the first interface surface can be arranged such that when the second interface surface partially moves downward as the wingtip device moves from the flight configuration to the ground configuration, the first interface surface points downward. The orientation of the first interface surface can also be arranged such that when the second interface surface partially moves upward as the wingtip device moves from the flight configuration to the ground configuration, the first interface surface points upward. Orienting the interface surfaces such that they partially move apart as the wingtip device moves from the flight configuration to the ground configuration means that the separation is clean and crisp, with little or no friction caused by sliding motion. This arrangement improves the wear characteristics of the interface surfaces. Furthermore, orienting the interface surfaces such that the partial movement of the surfaces toward each other as the wingtip device moves from the ground configuration to the flight configuration allows engagement with and compression of a seal positioned between the first and second interface surfaces.

[0030] The wingtip device is preferably capable of rotating about a single axis of rotation. For example, the rotation of the wingtip device is preferably not the result of a compound rotation (i.e., a net rotation resulting from multiple individual rotations about a separate axis).

[0031] The axis is preferably at an angle of less than 45 degrees to the vertical, and more preferably at an angle of less than 25 degrees to the vertical. The axis may be at an angle of 15 degrees to the vertical axis. It has been found that the orientation of the axis results in a shallow cut plane and the interface area between the fixed wing and the wingtip device may therefore be relatively large, thus the present invention is particularly advantageous in embodiments where the axis is at a relatively small angle to the vertical.

[0032] It has been found that various embodiments of the invention are particularly advantageous when a seal needs to be formed between the fixed wing and the wingtip assembly. The wing may include a sealing assembly for sealing between the fixed wing and the wingtip assembly when the wingtip assembly is in flight configuration.

[0033] The sealing assembly may include a compression seal for forming / opening a seal during the relative rendezvous / separation of the fixed wing and wingtip assembly. The compression seal may be associated with a first length and a second length.

[0034] The wing may include a sealing support structure positioned along a second length. This second sealing support structure may be oriented parallel to a plane containing the second cut line (e.g., along the thickness of the wing skin and coplanar with a plane extending therein along the second length). This can be advantageous because the sealing support structure can support a seal subjected to pure compression (i.e., compression in a direction perpendicular to the plane containing the second line).

[0035] In principle, the slit forming the second length can be oriented in many different directions (as long as the plane in which the second length lies (or is parallel to) also contains the axis of rotation). In some embodiments, the slit forming the second length is oriented along the flight path direction. This arrangement tends to be preferred from an aerodynamic point of view. In some other embodiments, the fixed wing includes a front spar, and the slit forming the second length is oriented perpendicular to the front spar. This arrangement tends to facilitate the integration of wingtip devices with a fixed wing having leading-edge slats in the tip region.

[0036] The first length is preferably located at the rear of the axis of rotation. The second length is preferably located at the front of the axis of rotation.

[0037] The wing may include an upper surface extending from the leading edge to the trailing edge above the wing. The wing may include a lower surface extending from the leading edge to the trailing edge below the wing. A first length may run along the upper surface of the wing. A second length may run along the upper surface of the wing, and may extend beyond the leading edge to the lower surface of the wing. This arrangement is particularly advantageous when the first and second lengths are on opposite sides of the axis of rotation, because the lengths located on the same surface (upper or lower surface) will tend to move in opposite directions as the wingtip assembly rotates. By extending the second cut line in a specific plane, it is possible to make the cut line extend from the upper surface to the lower surface at the leading edge of the wing, because the fixed wing and the wingtip assembly only move away from each other along the cut line and do not require a transition to a different cut line on the lower surface. This arrangement also allows for a single sealing assembly to be positioned along the entire length.

[0038] The interface cut line may further include: (iii) a third length located on the lower surface of the wing, the third length being formed by a cut through the outer surface. The third length may be offset from the main cut plane along a second direction, which is preferably opposite to the first direction. The interface cut line may further include: (iv) another transition portion, on which the interface cut line transitions from the third length to a portion of the second length on the lower surface.

[0039] The wingtip assembly can separate away from the fixed wing along a third length. This separation is preferably a translational movement of the relative components of the fixed wing and the wingtip assembly away from each other.

[0040] In an embodiment where the second length is located in front of the axis of rotation and the first length is located in rear of the axis of rotation, the third length is preferably located in rear of the axis of rotation.

[0041] The interface cut line may include another transition portion located between the first length and the third length. This other transition portion preferably forms the interface cut line from the first length to the third length, with each length transitioning to the adjacent length via a corresponding transition portion. This other transition portion between the first length and the third length may be located near the trailing edge of the wing.

[0042] In principle, the first length can take on a variety of different shapes. For example, according to the apparatus in GB1610108.1, the first length can lie in a first plane that is parallel to the main cutting plane but offset from the main cutting plane along a first direction. In a preferred embodiment, the first length is curved, and the curvature is shaped such that the first length does not lie in a single plane. In other words, the curvature is preferably not formed by the intersection of the plane with the outer surface of the wing. It has been found that giving the first length this curved shape is beneficial for generating relative motion along the interface between the fixed wing and the wingtip device (when the wingtip device rotates about the axis). Furthermore, giving the first length this curved shape allows for a relatively small transition portion between the first and third lengths in the trailing edge region, while still avoiding any possible collisions, since the ends of the first and third lengths can be brought closer together.

[0043] The first length is preferably offset from the main cutting plane along the inner direction.

[0044] In the transition section, the interface cut line transitions from a first length to a second length. The transition section can be relatively short. The transition section can be shorter than both the first and second lengths.

[0045] In principle, the transition portion can take various forms. In a preferred embodiment of the invention, the transition portion is a curved portion centered on the axis of rotation, the radius of which increases continuously as the cutting line travels around the axis. It has been found particularly advantageous to provide an interface with a curved portion, wherein the radius of the curved portion increases continuously around the axis of rotation. In particular, since the radius of the curved portion of the interface cutting line increases, and this curved portion of the interface cutting line is centered on the axis of rotation of the wingtip, this means that when the wingtip device rotates away from the flight configuration, the structure of the wingtip device separates away from the structure of the fixed wing along the interface cutting line.

[0046] The radius of the curved portion preferably increases as the cutting line travels about the axis along the rotational direction that moves the wingtip device from the flight configuration to the ground configuration. Correspondingly, the radius of the curved portion preferably decreases as the cutting line travels about the axis along the rotational direction that moves the wingtip device from the ground configuration to the flight configuration.

[0047] The aforementioned direction is considered from a perspective along the axis of rotation toward the wing surface where the interface cut line is located. For example, in an embodiment where the curved portion of the interface cut line is located on the upper surface of the wing, the direction is considered from a perspective along the axis of rotation toward that upper surface. Generally, unless otherwise stated, it will be understood that when viewing the cut line along the direction along the axis of rotation toward the wing surface where the relevant portion of the interface cut line is located, the shape, radius, or other characteristics of the interface cut line are taken into account. In other words, the characteristics of the curved portion can be considered with reference to its projection onto a plane perpendicular to the axis of rotation.

[0048] In embodiments that include multiple transition sections, it will be understood that any feature described herein with reference to one transition section may equally apply to any or all other transition sections.

[0049] In various embodiments of the invention, the wingtip device can be configured between: (a) a flight configuration for use during flight; and (b) a ground configuration for use during ground-based operations, in which the wingtip device moves away from the flight configuration, causing a reduction in the wingspan of the aircraft's wing. In the flight configuration, the wingspan may exceed airport compatibility limits. In the ground configuration, the wingspan may be reduced such that the wingspan (where the wingtip device is in the ground configuration) is less than or substantially equal to the airport compatibility limits. Airport compatibility limits are wingspan limitations (e.g., related to clearance limitations of buildings, signage, other aircraft). Compatibility limitations are preferably gate limitations.

[0050] The wingtip device can be a wingtip extension; for example, the wingtip device can be a planar wingtip extension. In other embodiments, the wingtip device can include non-planar devices such as winglets, or be composed of non-planar devices such as winglets.

[0051] In the flight configuration, the trailing edge of the wingtip device is preferably a continuation of the trailing edge of the fixed wing. The leading edge of the wingtip device is preferably a continuation of the leading edge of the fixed wing. Preferably, there is a smooth transition from the fixed wing to the wingtip device. It will be understood that a smooth transition may exist even if the sweep or twist at the junction between the fixed wing and the wingtip device changes. However, preferably, there is no discontinuity at the junction between the fixed wing and the wingtip device. The upper and lower surfaces of the wingtip device can be continuations of the upper and lower surfaces of the fixed wing. The wingspan ratio of the fixed wing to the wingtip device can be 70%, 80%, 90%, or greater than the total wingspan of the fixed wing, including the aircraft wing.

[0052] When the wingtip assembly is in a ground configuration, the aircraft combined with the wing may be unsuitable for flight. For example, the wingtip assembly may be aerodynamically and / or structurally unsuitable for flight in a ground configuration. The aircraft is preferably configured such that the wingtip assembly cannot move into a ground configuration during flight. The aircraft may include sensors for sensing when the aircraft is in flight. When the sensors detect that the aircraft is in flight, the control system is preferably arranged to prevent the possibility of the wingtip assembly moving into a ground configuration.

[0053] The aircraft is preferably a passenger aircraft. The passenger aircraft preferably includes a cabin comprising multiple rows and columns of seating units for accommodating multiple passengers. The aircraft has a passenger capacity of at least 20 passengers, more preferably at least 50 passengers, and more preferably more than 50 passengers. The aircraft is preferably a powered aircraft. The aircraft preferably includes an engine for propelling the aircraft. The aircraft may include engines mounted to the wings and preferably under the wings.

[0054] According to another aspect of the invention, an aircraft is provided comprising a wing having a fixed wing and a wingtip assembly movably mounted at the outer end of the fixed wing, the wingtip assembly being movable between: (a) a flight configuration for use during flight; and (b) a ground configuration for use during ground-based operation, in which the wingtip assembly moves away from the flight configuration, causing a reduction in the wingspan of the aircraft's wing. The wingtip assembly is rotatable about an inclined axis of rotation between the flight configuration and the ground configuration, such that the wingtip assembly rotates upward and backward as it moves from the flight configuration to the ground configuration. When the wingtip assembly is in the flight configuration, the outer end of the fixed wing and the inner end of the wingtip assembly are connected along an interface cut line separating the outer surface of the fixed wing from the outer surface of the wingtip assembly. The interface cutting line includes a leading edge portion that extends across the upper surface and reaches the lower surface. This leading edge portion is formed by a cut extending in a plane containing the axis of rotation. The interface cutting line also includes an upper surface portion located on the upper surface and behind the axis of rotation, offset inward from the plane containing the axis of rotation. Furthermore, the interface cutting line includes a lower surface portion located on the lower surface and behind the axis of rotation, offset outward from the plane containing the axis of rotation. The ends of the leading edge portion may abut against corresponding curved portions that connect the leading edge portion to the upper and lower surface portions, respectively. Each curved portion is centered on the axis of rotation, and its radius increases as the cutting line travels around the axis.

[0055] According to another aspect, the present invention may include a method for designing an aircraft or an aircraft wing, as described with reference to the first aspect of the invention or the second aspect of the invention, the method comprising the steps of: designing a first interface surface and a second interface surface, wherein the first interface surface and the second interface surface are positioned along an interface cutting line between a fixed wing and a wingtip device, wherein the orientation of the first interface surface and the second interface surface is twisted from one end of the interface cutting line to the other end of the interface cutting line.

[0056] It will be understood that any feature described with reference to one aspect of the invention is equally applicable to any other aspect of the invention, and vice versa. For example, features described with reference to the first aspect of the aircraft may also be applied to wings, wingtip devices, and / or methods in other aspects of the invention, and vice versa.

[0057] Unless the context otherwise requires, the term "or" should be interpreted as "and / or". Attached Figure Description

[0058] Embodiments of the invention will now be described by way of example only with reference to the accompanying illustrative drawings, in which:

[0059] Figure 1a and Figure 1b This illustrates a prior art wing with movable wingtip devices;

[0060] Figure 2 It is a top front view of the proposed embodiment in the unpublished application GB1610108.1, which shows the fixed wing / wingtip device interface, interface cutting line and cutting plane;

[0061] Figure 3a A simplified plan view of a wing on an aircraft according to a first embodiment of the present invention is shown, the wing being shown as having wingtip devices that can be in both flight and ground configurations;

[0062] Figure 3b It is a combination of Figure 3a A front view of an aircraft with wings;

[0063] Figure 4 This is a top front view of the wing near the fixed wing / wingtip device interface in the first embodiment of the present invention, and Figure 4 From and Figure 2 The viewpoint used in the video is similar to the viewpoint captured in the video.

[0064] Figure 5a This is another top front view of the wing near the fixed wing / wingtip assembly interface, showing the interface cut line and cut plane;

[0065] Figure 5b It is along Figure 5a A plan view taken along the direction of the rotation axis of the wingtip device;

[0066] Figure 6a and Figure 6b Apart from the fact that the wingtip devices are in a ground configuration rather than a flight configuration, and... Figure 5a and Figure 5b They are the same;

[0067] Figure 7 It is along Figure 6a The front view of arrow A;

[0068] Figure 8 This is another plan view taken along the axis of rotation of the wingtip device;

[0069] Figures 9a to 9c This illustrates the transition region as the wingtip device moves from a flight configuration to a ground configuration. Figure 8 A close-up view of the area circled in the image;

[0070] Figure 10 This is another plan view taken along the axis of rotation of the wingtip device, and Figure 10 The interface cut line located on the lower surface of the wing is shown;

[0071] Figure 11 An end view of a fixed-wing assembly is shown, which includes an exploded section that provides further details related to the interface portion;

[0072] Figure 12 The diagram illustrates the orientation change of the wingtip device from the front to the rear of the rotation axis;

[0073] Figure 13 It shows Figure 11 A separate view of the interface surface of the upper skin of the fixed-wing device shown;

[0074] Figure 14 The invention is shown Figure 11 The image shows a side view of the fixed wing and wingtip assembly in a ground configuration.

[0075] Figure 15 It shows Figure 14 The device, in which the wingtip device is in a ground configuration;

[0076] Figure 16 Shown from a top-down view Figure 15 The device. Detailed Implementation

[0077] Figure 1a This is a perspective view of the fixed wing 1 and wingtip device 3 on the aircraft shown in WO2015 / 150835. Overall, the wingtip device 3 is capable of operating in flight configurations (…). Figure 1a ) and ground configuration ( Figure 1b The wingtip device 3 moves between the leading edge 5' and trailing edge 7' of the fixed wing 1. In the flight configuration, the leading edge 5' and trailing edge 7' of the wingtip device 3 are continuations of the leading edge 5 and trailing edge 7 of the fixed wing 1. Furthermore, the upper and lower surfaces of the wingtip device 3 are continuations of the upper and lower surfaces of the fixed wing 1.

[0078] The wingtip device 3 is arranged in a flight configuration to facilitate flight. Therefore, in the flight configuration, the wingtip device 3 increases the aircraft's wingspan (thus providing beneficial aerodynamic effects, such as reducing the component of induced drag and increasing lift). In principle, it would be desirable to always maintain this larger wingspan and have only a large fixed wing. However, the maximum aircraft wingspan is practically limited by airport operating rules that manage the various clearances required for maneuvering around the airport (e.g., the wingspan and / or ground clearance required for gate entrances and safety taxiways). Therefore, the wingtip device 3 can be moved to a ground configuration for use when on the ground.

[0079] In ground configuration ( Figure 1b In this configuration, the wingtip device 3 is folded from the aforementioned flight configuration by rotating it around the rotation axis 11. By folding the wingtip device 3 in this way, the wingspan of the aircraft 2 is reduced. When the wingtip device 3 is in the ground configuration, the aircraft 2 thus conforms to the aforementioned airport clearance, etc.

[0080] The movement of the wingtip assembly is determined by the type of joint around which the wingtip assembly rotates relative to the fixed wing. To achieve this movement, the wingtip assembly 3 and the fixed wing 5 are separated along an inclined cutting plane 13 passing through the upper and lower surfaces of the wing. The wingtip assembly 3 is capable of rotating about an axis 11 that extends in a direction perpendicular to the inclined cutting plane 13. The axis 11 is oriented at an acute angle relative to all three mutually perpendicular X-axis, Y-axis, and Z-axis (i.e., the chord direction, the wingspan direction, and the vertical direction).

[0081] When a movable wingtip device is in flight configuration, small gaps, steps, or other mismatches at the interface between the outer end of the fixed wing and the inner end of the wingtip device can have adverse aerodynamic consequences (e.g., drag and pressure leakage). In some movable wingtip devices, such as those described above... Figure 1a and Figure 1b In the described movable wingtip devices, it has become difficult to provide interfaces that eliminate these characteristics. For example, in some devices, it has been found that it is difficult to control tolerances near the interface. It has also been found that it is difficult to provide effective sealing devices to suppress leakage flow through the interface.

[0082] Figure 2 It is a top front view of the proposed embodiment in the unpublished application GB1610108.1. Figure 2 The wing 101 is shown near the joint between the fixed wing 105 and the wingtip assembly 103. The wing 101 has an upper surface 131 and a lower surface 133. The fixed wing 105 and the wingtip assembly 103 are separated along an imaginary main cutting plane 113 (the axis of rotation is perpendicular to this imaginary main cutting plane 113).

[0083] Main cutting plane 113 in Figure 2 The plane is represented by a dashed line, at which the main cutting plane 113 intersects the wing. Offset and parallel first plane 113a and second plane 113b (see below) are also present. Figure 2 The planes are also represented by dashed lines, at which they intersect the wing. A portion of the interface cut line 135 extends within these planes, and the interface cut line 135... Figure 2 The solid line represents the area. The outer end of the fixed wing 105 and the inner end of the wingtip assembly 103 are connected along the interface cutting line 135 that separates the outer surface of the fixed wing 105 from the outer surface of the wingtip assembly 103. As will now be described, the interface cutting line 135 is stepped and is formed by a series of different lengths.

[0084] The interface cut line 115 includes a first length 137 that extends from the trailing edge to the starting point of the transition portion 139 in the upper rear quadrant (UA). The first length 137 of the interface cut line lies in a plane 113a that is parallel to the main cut plane 113 but offset in an inward direction.

[0085] The interface cut line 115 also includes a second length 141 that extends from the leading edge to the other end of the transition portion 139 in the upper front quadrant (UF). The second length 141 of the interface cut line also lies in a plane 113b that is parallel to the main cut plane 113 but offset in an outward direction (i.e., in a direction opposite to the other plane 113a).

[0086] As can be understood from the above, the first length 137 and the second length 141 are therefore both located in an inclined plane parallel to the main cutting plane 113, but in a plane offset from the main cutting plane in the opposite direction.

[0087] Between the first length 137 and the second length 141 is a transition portion 139. The transition portion 139 includes: a first portion 139a, which lies in the same plane 113a as the first length 137; and a second portion 139b, at which the interface cut jumps from the first plane 113a to the second plane 113b. The transition portion 139 thus transitions the interface cut line 135 from the first length 137 to the second length 141.

[0088] It has been discovered Figure 2 The device is advantageous, particularly in its ability to seal the interface between the wing and wingtip assembly. However, various embodiments of the invention are considered to offer further improvements, as will be noted below. Figures 3a to 10 It became obvious.

[0089] Figure 3a A plan view of the wing 1001 on the aircraft 1002 according to the first embodiment of the present invention is shown. Figure 3b The aircraft is shown in the image. Figure 3a In the diagram, wing 1001 is shown with wingtip devices 1003 that can be in both flight and ground configurations. The flight configuration is shown in shaded form and is self-evident. Figure 3a This illustrates the reduction in wingspan that occurs when the wingtip device 1003 is rotated to a ground configuration. Due to... Figure 3a For the purposes of this study, the interface cut line between the fixed wing and the wingtip device is shown in a simplified form, the actual shape of which is shown in the following figures with further reference below.

[0090] Overall, the wingtip device 1003 of the first embodiment is capable of... Figures 1a to 1b as well as Figure 2 Rotation occurs in a similar manner to that shown. In other words, the wingtip assembly 1003 is capable of rotating about an axis 1011 oriented to the direction of a hypothetical principal inclined cutting plane 1013 that separates the outer end of the fixed wing 1005 from the inner end of the wingtip assembly 1003 (see...). Figure 4 The axis 1011 forms an acute angle with respect to all three mutually perpendicular X-axis, Y-axis, and Z-axis (i.e., chord direction, span direction, and vertical direction). The wing includes an annular slewing bearing (not shown) for guiding rotation and reacting loads to the fixed wing. An imaginary main cutting plane 1013 passes through the middle of this slewing bearing.

[0091] As in Figure 7 China and when Figure 5a and Figure 6aWhen compared, it is evident that the nature of the motion is such that when the wingtip device 1003 rotates about axis 1011, the upper and lower surfaces of the wingtip device located in front of axis 1011 move downward, while the upper and lower surfaces of the wingtip device located in rear of axis 1011 move upward.

[0092] A particular aspect of the invention lies in the shape of the interface cutting line between the fixed wing and the wingtip device, and will now be referred to... Figures 4 to 10 To describe it in more detail.

[0093] First refer to Figure 4 , Figure 5a and Figure 5b These figures show views of the area surrounding the fixed-wing / wingtip assembly interface. The wingtip assembly 1003 is a planar wingtip extension (its distal end is not visible in these figures). To be compatible with... Figure 2 In a similar manner, the wing 1001 has an upper surface 1031 and a lower surface 1033. The outer end of the fixed wing 1005 and the inner end of the wingtip assembly 1003 are connected along an interface cutting line 1035 that separates the outer surface of the fixed wing 1005 from the outer surface of the wingtip assembly 1003. The interface cutting line 1035 is arranged such that a specific type of relative motion occurs between the outer end of the fixed wing 1005 and the inner end of the wingtip assembly 1003 when the wingtip assembly 1003 rotates from a flight configuration to a ground configuration. The interface cutting line 1035 is formed by a series of different lengths, which will be described in more detail below.

[0094] The fixed wing 1005 and the wingtip assembly 1003 are separated along an imaginary main cutting plane 1013 (the axis of rotation is perpendicular to this imaginary main cutting plane 1013). The main cutting plane 1013 is... Figure 4 The dashed line indicates that the main cutting plane 1013 intersects the wing at this point, but the main cutting plane 1013 itself does not appear as a physical cut in the wing skin. Instead, and with... Figure 2 Similar to the device in the diagram, the interface cutting line 1035 includes a first length 1037 located in the upper rear quadrant and offset from the main cutting plane 1013. However, with Figure 2 Compared to the device in the previous example, the first length is not located in a parallel plane; instead, it is curved, so that it does not lie in any single plane. It has been found that giving the first length this curved shape is advantageous in terms of relative movement along the interface between the fixed wing and the wingtip device (when the wingtip device rotates about its axis). Furthermore, giving the first length this curved shape allows for a relatively small transition section between the first length 1037 and the third length 1045 in the trailing edge region, as it allows the ends of these lengths to be brought relatively close together.

[0095] The interface cut line 1035 also includes a second length 1041 that is in front of the axis of rotation 1011. As compared with the Figure 2 device in, this second length does not offset outward. Instead, this second length 1041 extends along the upper surface 1031 of the wing, passes through the leading edge, and extends onto the lower surface 1033 of the wing. The second length 1041 is located within a plane P (schematically indicated by a dashed line in some of the figures in the drawings) that includes the axis of rotation 1011, and this plane is also substantially perpendicular to the front spar of the wing. This is best illustrated in Figure 5b , Figure 6b and Figure 7 .

[0096] It has been found that it is particularly beneficial to provide the second length 1041 within the plane that includes the axis of rotation 1011. It has been recognized that by forming the second length in this way, when the wing tip device 1003 moves from the flight configuration towards the ground configuration, the fixed wing 1005 and the wing tip device 1003 separate simultaneously along the entire length of the second cut line 1041. In addition, the orientation of the second length 1041 of the interface cut line 1035 tends to mean that the fixed wing 1005 and the wing tip device 1003 separate in a locally perpendicular direction (along the second length 1041). Therefore, the sealing movement tends to be pure compression.

[0097] In other embodiments (not shown), the second length may not necessarily be located within the plane that includes the axis of rotation, but the second length may be located within a plane parallel to this plane. Such an arrangement does not necessarily cause simultaneous separation between the fixed wing and the wing tip device, but such an arrangement still tends to present a perpendicular relative movement between the two sides of the interface cut line, which is beneficial in terms of sealing.

[0098] Another advantageous feature of the first embodiment of the present invention is the shape of the transition portion 1039 between the first length 1037 and the second length 1041. In the first embodiment of the present invention, the transition portion 1039 is substantially in a spiral form, as now described with reference to Figure 8 and Figures 9a to 9c .

[0099] Figure 8 is a view observed from above the wing along the axis of rotation 1011 of the wing tip device 1003 and towards the upper surface 1031 of the wing, where the interface cut line 1035 is located on the upper surface 1031 of the wing. Superimposed on Figure 8 are some radii R1 to R4 from the axis 1011 to the interface cut line 1035.

[0100] The radius of the curved portion 1039 varies as the cut line 1035 rotates about the axis 1011 in the direction that causes the wing tip device to move from the flight configuration to the ground configuration (by Figure 8The direction of rotation (indicated by the curved arrow) increases continuously. Therefore, when moving from the rear position adjacent to the first length 1037 of the cutting line to the front position adjacent to the second length 1141 of the cutting line, the radius behaves such that: R1 <R2<R3<R4。

[0101] It has been found particularly advantageous to provide an interface cut line with a curved portion 1039, in which the radius of the curved portion 1039 continuously increases about the rotation axis 1011. Specifically, since the radius of the curved portion 1039 of the interface cut line 1035 increases and since this curved portion of the interface cut line is centered on the rotation axis 1011 of the wingtip, this means that as the wingtip device 1003 rotates away from the flight configuration, the structure of the wingtip device 1003 separates from the structure of the fixed wing 1005 along this portion of the interface cut line 1039. (Refer to...) Figures 9a to 9c The best diagram shows, Figures 9a to 9c It is at the wingtip from the flight configuration ( Figure 9a ) to ground configuration ( Figure 9b When moving Figure 8 A close-up view of the area within the dashed circle.

[0102] Point P in the curved portion 1039 along the interface cut line 1035 wt Located on the side of the wingtip device 1003 and at a position radius R1 away from the axis of rotation. When the wingtip device is in flight configuration, the corresponding point P of the cutting line 1039 on the fixed wing 1005 side. fw It will be located at a position approximately equidistant from the axis by a radius (R1), see [reference]. Figure 9a When the wingtip device 1003 rotates away from the flight configuration by an angle α, point P on the wingtip device 1003... wt It will rotate about the axis, see Figure 9b Point P fw It is still located at a position with a radius R1 from axis 1011 (because of this point P) fw Located on the wingtip device 1003), but because the radius of the cutting line 1039 increases as the cutting line 1039 moves around the axis, the radially outward point P on the wingtip device... fw α (It is located at P) fwThe new position (at the same angle α around the axis) will be located at a radius (R2) further away from the axis due to the characteristics of the curved portion 1039. Therefore, the wingtip device 1003 and the fixed wing 1005 will necessarily move and separate along the interface 1039 when the wingtip device 1003 moves away from the flight configuration (and vice versa, the wingtip device 1003 and the fixed wing 1005 will move toward each other when the wingtip device 1003 moves into the flight configuration). A similar characteristic continues to occur when the wingtip device 1003 rotates further to an angle θ, see [reference]. Figure 9c This movement is beneficial because it tends to avoid relative sliding motion at interface 1039.

[0103] In the first embodiment, the curved portion 1039 is formed by means of a spline curve generated by a plurality of radii, such that the curved portion generally follows a spiral shape. In other embodiments (not shown), it will be understood that the bend can be a precise spiral shape, or it can be other shapes exhibiting an increasing radius about the axis of rotation. In an alternative embodiment of the invention, the bend can be a regular arc shape. The inclination of the end face of the fixed wing and the end face of the wingtip device is such that the rotational movement of the wingtip device causes a translational movement of the interface surfaces away from each other, without any sliding movement.

[0104] It will be understood that the spiral shape of the curved portion 1039 is formed with reference to a view taken from above and along the axis of rotation (i.e., with reference to the projection of the curved portion 1039 onto a plane perpendicular to the axis of rotation 1011). In practice, the shape of the curved portion 1039 may also extend beyond this plane due to the curved nature of the outer surface of the wing. However, aspects of the invention recognize that the curvature about the axis of rotation of the wingtip assembly is particularly important in allowing the fixed wing and the wingtip assembly to separate effectively, and therefore the characteristics of the curved shape are particularly important from this perspective.

[0105] about Figures 4 to 9c The interface cut line in the text mainly refers to the interface cut line 1035 on the upper surface 131 of the wing. However, the corresponding feature also exists on the lower surface 1033, and in this respect, now refer to Figure 10 . Figure 10 This is a view taken from above the axis of rotation 1011, but Figure 10 The portion 1035' of the interface cut line 1035 on the lower surface 1033 is shown in dashed lines.

[0106] The lower portion 1035’ of the interface cut line includes a third length 1045 that extends over the lower rear quadrant and that is connected via a transition 1047 at the trailing edge to a first length 1037 that lies over the upper surface rear quadrant. The third length 1045 is curved such that it minimizes the length of the transition portion 1047 but still avoids collisions (e.g., with the upper surface of the wing) when the wingtip device rotates towards the ground configuration.

[0107] The interface cut line also includes a curved generally spiral second portion 1039’ that lies on the lower surface and connects the third length 1045 to the end of a second length 1041 on the lower surface 1033. The second curved portion 1039’ also has a radius that increases as the cut line moves from a rear position on the lower surface to a front position about axis 1011 (shown in Figure 10 dashed lines where R1 < R2 < R3 < R4), where at the rear position the second portion 1039’ joins the third length 1045 and at the front position the second portion 1039’ joins the second length 1041. Thus, as the wingtip device moves away from the flight configuration, the fixed wing and the wingtip device also move apart along this interface cut line 1035’.

[0108] Although radii R1 to R4 have been shown in Figure 10 it will be understood that the radii need not have the same magnitude / precise characteristics as the radii on the upper surface spiral portion 1039.

[0109] Figure 11 and Figures 13 to 15Cutting line 1039 is shown in more detail. The outer end of the fixed wing 1005 includes an upper wing skin 1100 of thickness T located in the region of cut line 1039. At cut line 1039, the upper wing skin 1100 includes a first interface surface 1102. The wingtip assembly 1003 also includes a lower wing skin 1104 of thickness T' located in the region of cut line 1039. At cut line 1039, the lower wing skin 1104 of the wingtip assembly 1003 includes a second interface surface 1106. When the wingtip assembly 1003 is in flight configuration, the first interface surface 1102 and the second interface surface 1106 are brought very close together and / or in direct or indirect contact with each other, such that a compressive sealing force is applied between the first interface surface 1102 and the second interface surface 1106. One or both of the first interface surface 1102 and the second interface surface 1106 may include a compressible seal for further enhancing the sealing effect when the wingtip device 1003 is in flight configuration. To provide a good seal between the first interface surface 1102 and the second interface surface 1106, each surface is inclined at the contact point in the same plane when the wingtip device 1003 is in flight configuration. Since the interface cut line 1039 (and therefore, the first interface surface 1102 and the second interface surface 1106) follows a curve from the front to the rear of the rotation axis 1011, the plane containing the first interface surface 1102 and the second interface surface 1106 is also twisted such that, in the front of the rotation axis 1011, the end surface defined by the first interface surface points downward and the end surface defined by the second interface surface points upward; and in the rear of the rotation axis 1011, the end surface defined by the first interface surface 1102 points upward and the end surface defined by the second interface surface 1106 points downward. This change in orientation can Figure 12 As seen in more detail below. The upward and downward directions are determined relative to the Z-axis of the aircraft when it is on the ground, and for a downward-pointing end surface, it is not necessary for that end surface to be completely downward, and for an upward-pointing end surface, it is not necessary for that end surface to be completely upward. Alternatively, the upward and downward directions can be defined as the local orientation of the wing.

[0110] As explained above, when in Figure 7 When observing and when Figure 5a and Figure 6aIn comparison, the nature of the motion is such that when the wingtip device 1003 rotates about axis 1011, the upper and lower surfaces of the wingtip device located at the front of axis 1011 move downwards, while the upper and lower surfaces of the wingtip device located at the rear of axis 1011 move upwards. By providing the torsion described for the first interface surface 1102 and the second interface surface 1106, the first interface surface 1102 and the second interface surface 1106 initially move perpendicularly away from each other when the wingtip device 1003 moves away from the flight configuration and during rotational motion. This prevents adhesion or friction during the rotation of the wingtip device 1003, thereby improving ease of movement and reducing wear. Furthermore, when the wingtip device 1003 moves back into the flight configuration, the first interface surface 1102 and the second interface surface 1106 move toward each other, causing the two surfaces to come into contact under the compressive force between the two surfaces, thereby improving the seal between the two surfaces when the wingtip device 1003 is in the flight configuration.

[0111] In this invention, the wingtip device is moved such that the distal end of the wingtip device sweeps upward and backward when the wingtip device is in a ground configuration. Those skilled in the art will appreciate that these movements can be altered so that the distal end of the wingtip device can sweep forward and / or downward when in a ground configuration, and the orientations of the first and second interface surfaces can be changed accordingly. However, the surfaces along the interface cut line will still exhibit torsion, causing the orientations of the first and second interface surfaces relative to the axis of rotation of the wingtip device to change along the interface cut line. The orientations of the first and second interface surfaces will depend on the localized movements of these surfaces relative to each other as the wingtip device moves between flight and ground configurations.

[0112] Figure 12 The diagram illustrates how the orientation of the interface surface twists from a first inclined front portion of the axis of rotation (AoR) to a second inclined rear portion opposite to the axis of rotation, wherein the continuous twist angles of the orientation provide inflection points parallel to the axis of rotation. The dashed line shows the top surface of the upper wing skin. Although the above description primarily concerns the interface cut lines in the upper wing skin, those skilled in the art will understand that a corresponding configuration can exist in, and preferably does exist in, the lower wing skin of the aircraft. This arrangement allows for easy separation of the lower wing skin during movement from a flight configuration to a ground configuration and also allows for improved sealing arrangements during movement from a ground configuration to a flight configuration.

[0113] Although the invention has been described and illustrated with reference to specific embodiments, those skilled in the art will understand that the invention is applicable to many different variations not specifically shown herein.

[0114] In the foregoing description, the elements or components mentioned have known, obvious, or foreseeable equivalents, which are then 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 covering any such equivalents. The reader will also understand that the elements or features of the invention described as preferred, advantageous, convenient, etc., are optional and do not limit the scope of the independent claims. Furthermore, it should be understood that these optional elements or features, which may be beneficial in some embodiments of the invention, may be undesirable and therefore may not be present in other embodiments.

Claims

1. An aircraft comprising a wing having a fixed wing and a wingtip assembly, the wingtip assembly being movably mounted at the outer end of the fixed wing, the wingtip assembly being movable between: (a) a flight configuration intended for use during flight; and (b) A ground configuration for use during ground-based operations, in which the wingtip devices move away from the flight configuration, thereby reducing the wingspan of the aircraft's wing. in, The wingtip assembly and the fixed wing are separated along a main cutting plane, which is oriented at an angle, and the wingtip assembly is capable of rotating about a rotation axis normal to the main cutting plane between the flight configuration and the ground configuration. And among them, When the wingtip device is in the flight configuration, the outer end of the fixed wing and the inner end of the wingtip device are connected along an interface cutting line, which separates the outer surface of the fixed wing from the outer surface of the wingtip device. The interface cutting line includes: The curved portion bends about the axis of rotation, extending both at the front and rear of the axis of rotation; and wherein, The outer end of the fixed wing includes a first interface surface corresponding to the curved portion of the interface cutting line. The inner end of the wingtip device includes a second interface surface corresponding to the curved portion of the interface cutting line. Furthermore, when the wingtip device is in the flight configuration, at the forward position of the rotation axis, the first interface surface and the second interface surface form a first tilt angle relative to the rotation axis, and the first interface surface and the second interface surface twist as they travel along the length of the curved portion, such that at the rear position of the rotation axis, the first interface surface and the second interface surface are oriented at a second tilt angle opposite to the rotation axis.

2. The aircraft according to claim 1, wherein, The transition from the first tilt angle to the opposite second tilt angle on the first interface surface and the second interface surface is continuous.

3. The aircraft according to claim 1 or claim 2, wherein, The fixed wing includes an upper wing skin, and the first interface surface is the end face of the upper wing skin that faces the front portion of the rotation axis in a downward direction and the rear portion of the rotation axis in an upward direction.

4. The aircraft according to claim 1 or claim 2, wherein, The wingtip device includes an upper wingtip skin, and the second interface surface is the end face of the upper wingtip skin that faces the front portion of the rotation axis in an upward direction and the rear portion of the rotation axis in a downward direction.

5. The aircraft according to claim 1 or claim 2, wherein, The fixed wing includes a lower wing skin, and the first interface surface is the end face of the lower wing skin that faces the front portion of the rotation axis in a downward direction and the rear portion of the rotation axis in an upward direction.

6. The aircraft according to claim 1 or claim 2, wherein, The wingtip device includes a lower wingtip skin, and the second interface surface is the end face of the lower wingtip skin that faces the front portion of the rotation axis in an upward direction and the rear portion of the rotation axis in a downward direction.

7. The aircraft according to claim 1 or claim 2, wherein, The radius of the curved portion increases continuously as the cutting line travels around the axis.

8. The aircraft according to claim 1 or claim 2, wherein, The wing includes a sealing assembly for sealing between the fixed wing and the wingtip assembly when the wingtip assembly is in the flight configuration, and wherein the sealing assembly includes a compression seal for forming / opening a seal in the relative meeting / separation of the fixed wing and the wingtip assembly, the compression seal being associated with the curved portion.

9. The aircraft according to claim 1 or claim 2, wherein, The interface cutting line includes: (i) A first length, formed by a cut through the outer surface, the first length being offset from the main cutting plane along a first direction; (ii) a second length, formed by a cut through the outer surface, the second length extending in a plane containing the axis of rotation or in a plane parallel to that plane; and (iii) A transition portion, wherein the transition portion is the curved portion centered on the axis of rotation, and on the transition portion, the interface cutting line transitions from the first length to the second length.

10. The aircraft according to claim 9, wherein, The second length is formed by a cut through the outer surface, the cut extending in the plane containing the axis of rotation.

11. The aircraft according to claim 9, wherein, The plane extending within the second length is oriented along the flight path.

12. The aircraft according to claim 9, wherein, The fixed wing includes a front wing sparsity, and the plane extending therein of the second length is oriented perpendicular to the front wing sparsity.

13. The aircraft according to claim 9, wherein, The first length is located at the rear of the rotation axis, and the second length is located at the front of the rotation axis.

14. A wing of an aircraft having a fixed wing and a wingtip assembly, the wingtip assembly being movably mounted at the outer end of the fixed wing and movable between the two: (a) a flight configuration intended for use during flight; and (b) A ground configuration for use during ground-based operations, in which the wingtip devices move away from the flight configuration, thereby reducing the wingspan of the aircraft's wing. in, The wingtip assembly and the fixed wing are separated along a main cutting plane, which is oriented at an angle, and the wingtip assembly is capable of rotating about a rotation axis normal to the main cutting plane between the flight configuration and the ground configuration. And among them, When the wingtip device is in the flight configuration, the outer end of the fixed wing and the inner end of the wingtip device are connected along an interface cutting line, which separates the outer surface of the fixed wing from the outer surface of the wingtip device. The interface cutting line includes: The curved portion bends about the axis of rotation, extending both at the front and rear of the axis of rotation; and wherein, The outer end of the fixed wing includes a first interface surface corresponding to the curved portion of the interface cutting line. The inner end of the wingtip device includes a second interface surface corresponding to the curved portion of the interface cutting line. Furthermore, when the wingtip device is in the flight configuration, at the forward position of the rotation axis, the first interface surface and the second interface surface form a first tilt angle relative to the rotation axis, and the first interface surface and the second interface surface twist as they travel along the length of the curved portion, such that at the rear position of the rotation axis, the first interface surface and the second interface surface are oriented at a second tilt angle opposite to the rotation axis.

15. A fixed wing configured to receive a wingtip device, the wingtip device being movable between: (a) a flight configuration intended for use during flight; and (b) A ground configuration for use during ground-based operations, in which the wingtip devices move away from the flight configuration, resulting in a reduction in the wingspan of the aircraft's wing. in, The wingtip assembly and the fixed wing are separated along a main cutting plane, which is oriented at an angle, and the wingtip assembly is capable of rotating about a rotation axis normal to the main cutting plane between the flight configuration and the ground configuration. And among them, When the wingtip device is in the flight configuration, the outer end of the fixed wing and the inner end of the wingtip device are connected along an interface cutting line, which separates the outer surface of the fixed wing from the outer surface of the wingtip device. The interface cutting line includes: The curved portion bends about the axis of rotation, extending both at the front and rear of the axis of rotation; and wherein, The outer end of the fixed wing includes a first interface surface corresponding to the curved portion of the interface cutting line. Wherein, at the front position of the rotation axis, the first interface surface forms a first tilt angle relative to the rotation axis, and the first interface surface twists as it travels along the length of the curved portion, such that at the rear position of the rotation axis, the first interface surface is oriented at a second tilt angle opposite to the rotation axis.

16. A wingtip device configured to be received on a fixed wing, the wingtip device being movable between: (a) a flight configuration intended for use during flight; and (b) A ground configuration for use during ground-based operations, in which the wingtip devices move away from the flight configuration, resulting in a reduction in the wingspan of the aircraft's wing. in, The wingtip assembly and the fixed wing are separated along a main cutting plane, which is oriented at an angle, and the wingtip assembly is capable of rotating about a rotation axis normal to the main cutting plane between the flight configuration and the ground configuration. And among them, When the wingtip device is in the flight configuration, the outer end of the fixed wing and the inner end of the wingtip device are connected along an interface cutting line, which separates the outer surface of the fixed wing from the outer surface of the wingtip device. The interface cutting line includes: The curved portion bends about the axis of rotation, extending both at the front and rear of the axis of rotation; and wherein, The inner end of the wingtip device includes a second interface surface corresponding to the curved portion of the interface cutting line. Furthermore, when the wingtip device is in the flight configuration, at the forward position of the rotation axis, the second interface surface forms a first tilt angle relative to the rotation axis, and the second interface surface twists as it travels along the length of the curved portion, such that at the rear position of the rotation axis, the second interface surface is oriented at a second tilt angle opposite to the rotation axis.

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