Wing tip device, aircraft wing, and aircraft and methods of designing and manufacturing the same

Abstract

The invention relates to a wing tip device, to an aircraft wing and to an aircraft as well as to a method for designing and manufacturing an aircraft, the aircraft wing (2) comprising a main wing (3) and a wing tip device (4) at the tip end of the main wing (3), wherein a change in the droop of the leading edge of the wing tip device (4) relative to the extended spanwise position is such that flow separation on the wing tip device (4) first occurs in the outboard region (O) of the wing tip device (4). The droop of the leading edge of the wing tip device (4) can be greatest in the outboard region (O) of the wing tip device.

Description

Technical Field

[0001] This invention relates to aircraft wings with wingtip devices and to the wingtip devices themselves. The invention also relates to aircraft having aircraft wings with wingtip devices. Furthermore, the invention relates to design and manufacturing methods for wingtip devices, aircraft wings, and aircraft. Background Technology

[0002] Wingtip devices primarily improve the efficiency of fixed-wing aircraft by reducing lift-induced drag. While this may increase airfoil drag, the overall lift-to-drag ratio is increased. This improves fuel efficiency, which is particularly important for passenger aircraft.

[0003] Wingtip assemblies are relatively complex structures to design and construct. They are primarily designed to improve high-speed performance. However, wingtip assemblies can provide suboptimal low-speed performance and handling characteristics.

[0004] This invention seeks to solve or mitigate at least some of the problems described above. Alternatively, or in addition, this invention seeks to provide an improved aircraft wing including wingtip devices. Alternatively, or in addition, this invention seeks to provide an improved wingtip device for an aircraft wing. Alternatively, or further, this invention seeks to provide an improved aircraft including a wing with wingtip devices. Alternatively, or further, this invention seeks to provide a method for designing wingtip devices, an aircraft wing with wingtip devices, or an improved aircraft. Alternatively, or further, this invention seeks to provide a method for manufacturing an improved wingtip device, an aircraft wing with wingtip devices, or an improved aircraft. Summary of the Invention

[0005] According to a first aspect of the invention, an aircraft wing is provided comprising a main wing and a wingtip device located at the tip of the main wing, wherein the leading edge of the wingtip device droops and changes relative to its unfolded spanwise position, such that flow separation on the wingtip device first occurs in the outer region of the wingtip device.

[0006] It is advantageous to change the leading edge droop of the wingtip device so that flow separation on the wingtip device first occurs in the outer region of the wingtip device, because this can prolong the time period between the initiation of flow separation and the point where the flow on the wingtip device is completely separated.

[0007] This can result in low-speed drag improvements extending beyond a larger portion of the aircraft's operating flight envelope, while also providing better and more symmetrical handling qualities at low speeds.

[0008] This can also increase the angle of attack at which flow separation begins to occur.

[0009] The references to the “inner” and “outer” regions of the wingtip device are related to the deployment span of the wingtip device. Similarly, the references related to the “inner” and “outer” regions of the wingtip device refer to the inner and outer directions over the deployment span of the wingtip device.

[0010] Technicians will understand the term "unrolled span" in the context of non-planar wingtip devices. It has been confirmed that the unrolled span position is measured as the distance from the leading edge of the wingtip device (from its inner end) when the wingtip device is projected onto a plane parallel to the YZ plane (i.e., a plane parallel to both the Y and Z axes of the aircraft).

[0011] In an embodiment of the invention, the outer region is the outer half of the deployed wingtip device, i.e., the region where 0.5 < η ≤ 1. In this respect, the outer region is the region outside the deployed half-span position, which is located at the middle of the deployed span of the wingtip device.

[0012] The inner region is the inner half of the deployed wingtip device, i.e., the region where 0 ≤ η < 0.5. In this respect, the inner region is the region inside the deployed half-span position.

[0013] In an embodiment of the invention, the change in leading edge droop causes flow separation on the wingtip device to occur first in the outer half of the deployed wingtip device.

[0014] Alternatively, the variation in leading edge droop causes flow separation on the wingtip device to occur first at the tip of the wingtip device or first in the region near the tip of the wingtip device.

[0015] The region near the tip of the wingtip device can be the region of the wingtip device where 0.7≤η≤1, preferably 0.8≤η≤1, more preferably 0.9≤η≤1, and even more preferably 0.95≤η≤1.

[0016] Alternatively, the change in leading edge droop causes flow separation on the wingtip device to occur first at the tip of the wingtip device.

[0017] Optionally, the maximum leading edge droop of the wingtip device occurs at the unfolded spanwise position, such that flow separation first occurs in the outer region of the wingtip device, preferably at or near the tip of the wingtip device.

[0018] Optionally, the leading edge droop of the wingtip device is greatest in the outer region of the wingtip device.

[0019] This is advantageous because it encourages flow separation to occur first in the outer region of the wingtip assembly. In this respect, it encourages flow separation to occur first in the outer region where the leading edge droop is greatest.

[0020] Optionally, the maximum leading edge droop is located at the spanwise position of the unfolded region where η≥0.6.

[0021] In embodiments of the invention, the maximum leading edge droop occurs at the inner side of the tip of the wingtip device. Optionally, the maximum leading edge droop is located at a spanwise position where η ≤ 0.9, preferably η ≤ 0.8. Optionally, the maximum leading edge droop is located at a spanwise position where 0.6 ≤ η ≤ 0.9, preferably 0.6 ≤ η ≤ 0.8.

[0022] Optionally, the leading edge droop decreases outward from its maximum value as it approaches the tip of the wingtip device. Alternatively, the leading edge droop decreases outward from its maximum value at the position of maximum leading edge droop as it approaches the tip of the wingtip device.

[0023] This advantageously allows flow separation to occur first near the tip of the wingtip device.

[0024] Alternatively, the leading edge droop decreases from its maximum value to the tip of the wingtip device.

[0025] In an embodiment of the present invention, the leading edge droop at the tip of the wingtip device is less than the maximum value of the leading edge droop.

[0026] In an embodiment of the invention, the leading edge droop decreases continuously from its maximum value to the tip of the wingtip device.

[0027] Optionally, the leading edge droop at the tip of the wingtip device is the minimum value of the leading edge droop of the wingtip device.

[0028] Optionally, the change in leading edge droop causes the flow separation to move inward as the angle of attack of the airfoil device increases, preferably causing the flow separation to gradually move inward as the angle of attack increases.

[0029] Alternatively, the leading edge droop decreases from its maximum value toward the inner end of the wingtip device.

[0030] In an embodiment of the present invention, the leading edge droop at the inner end of the wingtip device is less than the maximum value of the leading edge droop.

[0031] Optionally, the wingtip device includes a transition region extending from its inner end, in which a leading-edge droop approaches the outer end of the main wing in an inward direction.

[0032] This is advantageous because it allows the leading-edge droop of the wingtip device to smoothly integrate into the leading-edge droop at the tip of the main wingtip, thus avoiding discontinuities in the leading-edge droop (and therefore avoiding discontinuities in the aerodynamic characteristics at that location).

[0033] Optionally, the leading edge droop at the inner end of the wingtip device is the same as or less than the leading edge droop at the tip of the main wing.

[0034] Optionally, the leading edge droop at the outer end of the transition region is less than the maximum leading edge droop.

[0035] In an embodiment of the invention, the outer end of the transition region is located in the inner region of the wingtip device. Optionally, the outer end of the transition region is located at a spanwise position where 0 < η ≤ 0.3, preferably 0 < η ≤ 0.2.

[0036] Optionally, the wingtip device has an anti-angle that gradually increases in the outward direction.

[0037] Optionally, the wingtip device bends upwards near its tip. Preferably, the wingtip device is a curved, non-planar wingtip device. When used with a curved, non-planar wingtip device, the variation in leading edge droop is particularly advantageous.

[0038] Alternatively, the wingtip device is swept back.

[0039] Alternatively, the leading edge sweep angle of the wingtip device increases in the outward direction, so that the leading edge appears curved when viewed in planar form.

[0040] In an embodiment of the present invention, the region extending from the maximum leading edge downward position to the tip of the wingtip device is the tip region.

[0041] In an embodiment of the present invention, the region of the wingtip device extending from the outer end of the transition region to the position of maximum leading edge droop is the intermediate region.

[0042] Preferably, the intermediate region is the primary region of the wingtip device, while the transition region and the tip region are secondary regions. In this respect, preferably, the intermediate region has a larger deployment span than either the transition region or the tip region.

[0043] Preferably, the ratio of the unfolded span of the intermediate region to the unfolded span of the tip region is greater than or equal to 1.5. Preferably, the ratio of the unfolded span of the intermediate region to the unfolded span of the transition region is greater than or equal to 2.5.

[0044] Preferably, the leading edge sweep angle of the middle region increases in the outward direction, so that (when viewed in planar form) the middle region is curved.

[0045] Preferably, the concave angle of the middle portion increases in the outer direction, causing the middle portion to bend upward.

[0046] Preferably, the tip region is combined to form a tip shape, for example, to form a rounded tip or a Kuchemann tip.

[0047] Preferably, the wingtip device is a winglet. Preferably, the wingtip device is a curved, non-planar winglet.

[0048] Preferably, the wingtip device does not have any movable high-lift device, such as slats or flaps.

[0049] According to a second aspect of the invention, a wingtip device is provided, wherein the leading edge of the wingtip device droops and changes relative to the unfolded spanwise position, such that flow separation on the wingtip device first occurs in the outer region of the wingtip device.

[0050] The wingtip device of the second aspect of the present invention can be used as the wingtip device of the first aspect of the present invention. The wingtip device of the second aspect of the present invention can have any of the features of the wingtip device of the first aspect of the present invention.

[0051] According to a third aspect of the invention, an aircraft wing is provided comprising a main wing and a wingtip device located at the tip of the main wing, wherein the leading edge of the wingtip device droops with respect to its unfolded spanwise position such that the drooping of the leading edge of the wingtip device is maximized in the outer region of the wingtip device.

[0052] The aircraft wing of the third aspect of the present invention may have any of the features of the aircraft wing of the first aspect of the present invention. The wingtip device in the third aspect of the present invention may have any of the features of the wingtip device in the first aspect of the present invention.

[0053] According to a fourth aspect of the invention, a wingtip device is provided, wherein the leading edge of the wingtip device droops differently relative to its unfolded spanwise position, such that the drooping of the leading edge of the wingtip device is maximized in the outer region of the wingtip device.

[0054] The wingtip device of the fourth aspect of the present invention can be used as the wingtip device of the third aspect of the present invention. The wingtip device of the fourth aspect of the present invention can have any of the features of the wingtip device of the first aspect of the present invention.

[0055] According to a fifth aspect of the invention, an aircraft is provided that includes an aircraft wing or wingtip device according to any of the foregoing aspects of the invention.

[0056] In an embodiment of the present invention, the aircraft includes a pair of aircraft wings.

[0057] Preferably, the aircraft is a commercial jet aircraft having a cabin comprising multiple rows or columns of seat units for accommodating multiple passengers, preferably more than 50 passengers. Preferably, the aircraft is a powered aircraft and includes a pair of engines mounted to the wings for propelling the aircraft.

[0058] According to a sixth aspect of the invention, a method is provided for designing a wingtip device used as part of an aircraft wing, wherein the method includes designing the wingtip device such that the leading edge droops relative to the unfolded spanwise position, such that flow separation on the wingtip device first occurs in the outer region of the wingtip device.

[0059] Optionally, the method includes the following steps:

[0060] (i) Design a wingtip device, wherein the leading edge of the wingtip device does not droop over its spread span to meet high-speed design requirements;

[0061] (ii) The design of the wingtip device is to apply a variation in the drooping position of the leading edge relative to the unfolded spanwise position, such that flow separation on the wingtip device first occurs in the outer region of the wingtip device.

[0062] According to a seventh aspect of the invention, a method is provided for designing an aircraft wing including a main wing and a wingtip device located at the tip of the main wing, wherein the method includes designing the wingtip device according to a sixth aspect of the invention.

[0063] According to an eighth aspect of the present invention, a method for designing an aircraft is provided, the method comprising designing an aircraft wing according to a seventh aspect of the present invention.

[0064] According to a ninth aspect of the present invention, a method for manufacturing a wingtip device is provided, the method comprising designing the wingtip device according to a sixth aspect of the present invention and manufacturing the wingtip device according to the design.

[0065] According to a tenth aspect of the present invention, a method for manufacturing an aircraft wing is provided, the method comprising designing an aircraft wing according to a seventh aspect of the present invention and manufacturing the aircraft wing according to the design.

[0066] According to the eleventh aspect of the present invention, a method for manufacturing an aircraft is provided, the method comprising designing an aircraft according to the eighth aspect of the present invention and manufacturing the aircraft according to the design.

[0067] Preferably, the leading edge droop is caused by a parameter. 前缘 Limitations. In this respect, the reference to leading edge droop preferably refers to parametric droop. 前缘 The aforementioned variations in leading edge sag and the relative amount of leading edge sag, preferably referring to parametric sag. 前缘 The corresponding changes and relative quantities.

[0068] The droop at each unfolded position 前缘 The value is the distance the leading edge point is offset from the reference line toward the lower surface, divided by the local chord length. The reference line passes through the trailing edge point and the reference point, which is located on a line perpendicular to the reference line, at the midpoint between the upper and lower surfaces of the local blade section at the reference chord position.

[0069] The reference chord position is selected such that it is located in a portion of the "non-drooping" part of the airfoil, which is sufficiently rearward.

[0070] Preferably, the reference point is located behind the leading edge point at a position greater than or equal to 0.3 times the local chord length (i.e., x / c ≥ 0.3).

[0071] Preferably, the reference point is located at a position 0.3 times the local chord length behind the leading edge point (i.e., at x / c = 0.3).

[0072] Preferably, the drooping of the wingtip device relative to the spanwise position of the deployed position 前缘 The changes cause flow separation on the wingtip device to occur first in the outer region of the wingtip device.

[0073] Alternatively, the drooping relative to the unfolded spanwise position 前缘 The changes cause flow separation on the wingtip device to occur first at the tip of the wingtip device or first in the region near the tip of the wingtip device.

[0074] Alternatively, the drooping relative to the unfolded spanwise position 前缘 The changes cause flow separation on the wingtip device to occur first at the tip of the wingtip device.

[0075] Optionally, the maximum droop of the wingtip device 前缘 It occurs at the spanwise position of the unfolded structure, such that flow separation first occurs in the outer region of the wingtip device, preferably at the tip of the wingtip device or in the region near the tip of the wingtip device.

[0076] Optionally, the drooping of the wingtip device 前缘 It is largest in the outer region of the wingtip device.

[0077] Alternatively, drooping 前缘 The maximum value occurs at the spanning position of the expansion where η≥0.6.

[0078] In an embodiment of the present invention, drooping 前缘 The maximum value occurs at the inner position of the tip of the wingtip device. Optionally, the drooping... 前缘The maximum value occurs at the unfolding position where η ≤ 0.9, preferably at the unfolding position where η ≤ 0.8. Optionally, drooping... 前缘 The maximum value occurs at the unfolding position of 0.6≤η≤0.9, preferably at the unfolding position of 0.6≤η≤0.8.

[0079] Alternatively, drooping 前缘 As the tip of the wingtip device approaches its maximum value, it decreases outwards.

[0080] Alternatively, drooping 前缘 It decreases from its maximum value to the tip of the wingtip device.

[0081] In an embodiment of the present invention, the drooping at the tip of the wingtip device 前缘 The value is less than the droop. 前缘 The maximum value.

[0082] In an embodiment of the present invention, drooping 前缘 It decreases continuously from its maximum value to the tip of the wingtip device.

[0083] Optionally, the drooping at the tip of the wingtip device 前缘 The value is the droop of the wingtip device. 前缘 The minimum value.

[0084] Alternatively, drooping 前缘 The change causes the flow separation to move inward as the angle of attack of the wingtip device increases, preferably causing the flow separation to gradually move inward as the angle of attack increases.

[0085] Alternatively, drooping 前缘 As the inner end of the wingtip device approaches, it decreases from its maximum value towards the inner side.

[0086] In an embodiment of the present invention, the value of the drooping leading edge at the inner end of the wingtip device is less than the drooping... 前缘 The maximum value.

[0087] Optionally, in the transition area, drooping 前缘 The value is close to the droop at the outer tip of the main wing. 前缘 The value of .

[0088] Optionally, the droop at the inner end of the wingtip device 前缘 The value and the droop at the tip of the main wing 前缘 The value is the same as or less than the droop at the tip of the main wing. 前缘 The value of .

[0089] Optionally, the droop at the outer end of the transition region 前缘 The value is less than the droop. 前缘 The maximum value.

[0090] Preferably, hanging 前缘 The maximum value and the droop at the tip 前缘 The ratio of the values ​​is greater than or equal to 2. Optionally, the droop at the tip of the wingtip device... 前缘 The value is less than or equal to 0.02.

[0091] Alternatively, drooping 前缘 The maximum value and the droop at the inner end of the wingtip device 前缘 The ratio of the values ​​is greater than or equal to 1.5.

[0092] In an embodiment of the present invention, the wingtip device is drooping downwards. 前缘 The region where the maximum value extends to the tip of the wingtip device is the tip region. In an embodiment of the invention, the wingtip device extends from the outer end of the transition region to the drooping... 前缘 The region where the maximum value is located is the middle region.

[0093] Preferably, the method of the sixth aspect of the invention includes drooping the wingtip device relative to its spanwise position. 前缘 The design changes are such that flow separation on the wingtip device first occurs in the outer region of the wingtip device.

[0094] Optionally, the method includes the following steps:

[0095] (i) Design a wingtip device, wherein the drooping 前缘 The wingtip device has a zero span of deployment to meet high-speed design requirements;

[0096] (ii) The downward position relative to the unfolded span 前缘 The changes applied to the design of the wingtip device cause flow separation on the wingtip device to occur first in the outer region of the wingtip device.

[0097] Alternatively, or otherwise, the leading edge droop can be determined by parameter Y5. 上 Limitations. In this regard, the reference for leading edge drooping preferably refers to parameter Y5. 上 The variation and amount of leading edge droop defined above, preferably referring to parameter Y5. 上 The corresponding changes and quantities.

[0098] Y5 at each deployed spanwise position on the wingtip device 上 The value is the distance from the upper surface of the local wing section to the local chord along the following line divided by the local chord length: this line is normal to the chord and intersects the chord at a position 0.05 times the local chord length behind the leading edge (i.e., at x / c = 0.05).

[0099] Preferably, the wingtip device Y5上 The change in spanwise position relative to the unfolded configuration causes flow separation on the wingtip device to occur first in the outer region of the wingtip device.

[0100] Optionally, Y5 上 The changes cause flow separation on the wingtip device to occur first at the tip of the wingtip device or first in the region near the tip of the wingtip device.

[0101] Optionally, Y5 relative to the unfolded spanwise position 上 The changes cause flow separation on the wingtip device to occur first at the tip of the wingtip device.

[0102] Optionally, the maximum Y5 of the wingtip device 上 It occurs at the spanwise position of the unfolded structure, such that flow separation first occurs in the outer region of the wingtip device, preferably at the tip of the wingtip device or in the region near the tip of the wingtip device.

[0103] Optionally, the Y5 wingtip device 上 It is largest in the outer region of the wingtip device.

[0104] Optionally, Y5 上 The maximum value occurs at the spanning position of the expansion where η≥0.6.

[0105] In an embodiment of the present invention, Y5 上 The maximum value occurs at the inner side of the tip of the wingtip device. Optionally, Y5 上 The maximum value is located at the unfolding position where η≤0.9, preferably at the unfolding direction where η≤0.8. Optionally, Y5 上 The maximum value is located at the unfolding position of 0.6≤η≤0.9, preferably at 0.6≤η≤0.8.

[0106] Optionally, Y5 上 As the tip of the wingtip device approaches from Y5 上 The maximum value decreases outwards.

[0107] Optionally, Y5 上 It decreases from its maximum value to the tip of the wingtip device.

[0108] In an embodiment of the present invention, Y5 at the tip of the wingtip device 上 The value is less than Y5 上 The maximum value.

[0109] In an embodiment of the present invention, Y5 上 It decreases continuously from its maximum value to the tip of the wingtip device.

[0110] Optionally, the Y5 at the tip of the wingtip device 上 The value is Y5 of the wingtip device. 上 The minimum value.

[0111] Optionally, Y5 上 The change causes the flow separation to move inward as the angle of attack of the airfoil increases, preferably causing the flow separation to gradually move inward as the angle of attack increases.

[0112] Optionally, Y5 上 From Y5, near the inner end of the wingtip device 上 The maximum value decreases towards the inside.

[0113] In an embodiment of the present invention, Y5 at the inner end of the wingtip device 上 The value is less than Y5 上 The maximum value.

[0114] Optionally, in the transition region, Y5 上 The value of Y5 is close to the outer tip of the main wing. 上 The value of .

[0115] Optionally, Y5 at the inner end of the wingtip device 上 The value of Y5 at the tip of the main wing 上 The value is the same as or less than Y5 at the tip of the main wing. 上 The value of .

[0116] Optionally, Y5 at the outer end of the transition region 上 The value is less than Y5 上 The maximum value.

[0117] Preferably, Y5 上 The maximum value and Y5 at the tip 上 The ratio of the values ​​is greater than or equal to 1.3.

[0118] Optionally, Y5 上 The maximum value of Y5 at the inner end of the wingtip device 上 The ratio of the values ​​is greater than or equal to 1.3.

[0119] Optionally, the Y5 at the tip of the wingtip device 上 The value is less than or equal to 0.04.

[0120] Optionally, Y5 上 The maximum value of Y5 at the outer end of the transition region 上 The ratio of the values ​​is greater than or equal to 1.1.

[0121] In an embodiment of the present invention, the wingtip device is from Y5 上The region where the maximum value extends to the tip of the wingtip device is the tip region. In an embodiment of the invention, the wingtip device extends from the outer end of the transition region to Y5. 上 The region where the maximum value is located is the middle region.

[0122] Preferably, the method of the sixth aspect of the invention includes adjusting the Y5 of the wingtip device relative to the deployed spanwise position. 上 The design changes are such that flow separation on the wingtip device first occurs in the outer region of the wingtip device.

[0123] Optionally, the method includes the following steps:

[0124] (i) Design a wingtip device, wherein Y5 上 The value is such that the wingtip device does not have a drooping leading edge over its deployment span, in order to meet the high-speed design requirements;

[0125] (ii) By applying Y5 上 The change in the leading edge drooping relative to the spanwise position of the unfolded wingtip device is applied to the design of the wingtip device, so that flow separation on the wingtip device first occurs in the outer region of the wingtip device.

[0126] Preferably, the leading edge droop is caused by a parameter. 前缘 and Y5 上 The combination of limitations. In this regard, the reference to leading edge droop preferably refers to parametric droop. 前缘 and Y5 上 In addition to the changes in leading edge droop and the relative amount of leading edge droop as defined above, preferably referring to parametric droop. 前缘 and Y5 上 The corresponding changes and relative quantities of the two.

[0127] Preferably, the drooping of the wingtip device relative to the spanwise position of the deployed position 前缘 and Y5 上 The changes cause flow separation on the wingtip device to occur first in the outer region of the wingtip device.

[0128] Alternatively, the drooping relative to the unfolded spanwise position 前缘 and Y5 上 The changes cause flow separation on the wingtip device to occur first at or near the tip of the wingtip device.

[0129] Alternatively, the drooping relative to the unfolded spanwise position 前缘 and Y5 上 The changes cause flow separation on the wingtip device to occur first at the tip of the wingtip device.

[0130] Optionally, the maximum droop of the wingtip device 前缘 and Y5 上 It occurs at the spanwise position of the unfolded structure, such that flow separation first occurs in the outer region of the wingtip device, preferably at or near the tip of the wingtip device.

[0131] Optionally, the drooping of the wingtip device 前缘 and Y5 上 It is largest in the outer region of the wingtip device.

[0132] Preferably, the method of the sixth aspect of the invention includes drooping the wingtip device relative to its spanwise position. 前缘 and Y5 Upper The design changes are such that flow separation on the wingtip device first occurs in the outer region of the wingtip device.

[0133] Optionally, the method includes the following steps:

[0134] (i) Design a wingtip device, wherein the drooping 前缘 The wingtip device has a zero span in its unfolding range, and Y5 上 The value is such that the wingtip device does not have a drooping leading edge over its deployment span, in order to meet the high-speed design requirements;

[0135] (ii) The downward position relative to the unfolded span 前缘 and Y5 上 The changes applied to the design of the wingtip device cause flow separation on the wingtip device to occur first in the outer region of the wingtip device.

[0136] Any of the above aspects of the invention may include any of the features of the other aspects of the invention. For example, the method of any of the above aspects may include features of the aircraft wing or wingtip device of any other aspect of the invention, and vice versa.

[0137] Other preferred and advantageous features of the invention will become apparent from the following description. Attached Figure Description

[0138] Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings:

[0139] Figure 1 This is a front view of an aircraft according to an embodiment of the present invention;

[0140] Figure 2 yes Figure 1 A plan view of the aircraft shown from above;

[0141] Figure 3It is viewed from above. Figure 1 and Figure 2 The diagram shows the plan view of the starboard winglet of the aircraft.

[0142] Figure 4 yes Figure 3 Rear view of the winglet shown;

[0143] Figure 5 yes Figure 3 and Figure 4 A perspective view of the winglet shown (with example partial winglets shown in dashed lines);

[0144] Figure 6 It shows Figures 3 to 5 The diagram shows a partial winglet of the winglet to illustrate the parameters used to limit the drooping of the winglet's leading edge;

[0145] Figure 7 The leading edge sag parameter is shown relative to the spanwise position (η) of the unfolded shape. 前缘 and Y5 上 Along the changes in the winglets; and

[0146] Figure 8 This is a flowchart illustrating the steps of a design and manufacturing method for an aircraft wing according to another embodiment of the present invention. Detailed Implementation

[0147] Figure 1 An aircraft 1 according to an embodiment of the present invention is shown. Aircraft 1 is a commercial jet aircraft comprising a pair of wings 2. Aircraft 1 is a passenger-carrying aircraft having a passenger cabin comprising multiple rows or columns of seat units for accommodating multiple passengers, in this case more than 50 passengers. Aircraft 1 is a powered aircraft and includes a pair of engines mounted below the wings 2 for propelling aircraft 1.

[0148] Reference Figure 1 and Figure 2 The aircraft 1 has a longitudinal (roll) axis (X), a lateral (pitch) axis (Y), and a normal (yaw) axis (Z). The longitudinal (roll) axis (X) has its origin at the center of gravity of the aircraft and is parallel to the center line (CL) of the fuselage of the aircraft 1, pointing forward. The lateral (pitch) axis (Y) also has its origin at the center of gravity and is parallel to the line drawn from one wingtip of the aircraft 1 to the other (i.e., parallel to the spanwise direction), pointing to the right side of the aircraft 1 (pointing to the right chord). The normal (yaw) axis (Z) also has its origin at the center of gravity and is perpendicular to both the longitudinal axis (X) and the lateral axis (Y), pointing to the bottom of the aircraft 1.

[0149] Each wing 2 includes a main wing 3 and a wingtip assembly in the form of a winglet 4 attached to the outer tip 6 of the main wing 3. Each wing 2 is identical, and therefore only one wing of the wing 2 (the starboard wing) will be described below. It will be understood that the description of this wing 2 also applies to the other wing 2 (the port wing).

[0150] The aircraft 1 has a total wingspan (b) and each wing 2 has a half wingspan (s).

[0151] For each wing 2, the main wing 3 extends outward in the spanwise direction from the root 5 located at the intersection with the aircraft fuselage to the tip 6 (see...). Figure 2 The main wing 3 is tapered and swept back. In this respect, the main wing 3 has a leading edge 31 and a trailing edge 32 that are swept back, wherein the degree of sweeping back of the trailing edge 32 is slightly less than that of the leading edge 31.

[0152] Reference Figures 3 to 5 Each winglet 4 extends outward from the inner end 7 of the outer tip 6 attached to the main wing 3 to the tip 8. The winglet 4 also extends chordally from the leading edge 9 to the trailing edge 10.

[0153] Winglet 4 is non-planar and curves upward as it extends outward toward the tip 8. The curvature of the local dihedral increases from a low angle or approximately zero angle at or near the outer tip of the main wing 3 and increases in the outward direction. The tip 8 of winglet 4 is almost vertical, but tilted at a small angle relative to the vertical plane.

[0154] Winglet 4 is swept back. In this respect, the leading edge 9 of winglet 4 is curved, and the sweep angle of the leading edge of winglet 4 increases as winglet 4 extends outward in the spanwise direction. The trailing edge 10 of winglet 4 is also slightly curved, and the sweep angle of the trailing edge 10 of winglet 4 increases slightly as winglet 4 extends outward in the spanwise direction.

[0155] The leading edge 9 and trailing edge 10 of winglet 4 are continuous portions of the leading edge 31 and trailing edge 32 of main wing 3. Furthermore, the upper surface 19 and lower surface 20 of winglet 4 (see below) are continuous portions of the upper and lower surfaces of main wing 3. Therefore, there is a smooth transition from main wing 3 to winglet 4.

[0156] It will be understood that even if the sweep or twist changes at the connection between the main wing 3 and the winglet 4, a smooth transition can still exist. However, it is preferable that there is no discontinuity at the connection between the main wing 3 and the winglet 4.

[0157] The use of winglets 4 reduces lift-induced drag on wing 2, resulting in improved fuel efficiency and reduced carbon emissions. In the currently described embodiment, winglets 4 are fixed relative to the main wing 3.

[0158] The winglet 4 includes an upper surface 19 and a lower surface 20 forming the winglet 4 (see...). Figure 4 The upper and lower skins of the aircraft. The upper surface 19 and the lower surface 20 are the upper and lower aerodynamic surfaces exposed to airflow during flight.

[0159] The dimensionless parameter "η" will be used to define the spanwise position of the deployed winglet 4. In this respect,

[0160] η = y w / s w

[0161] in:

[0162] y w = The distance from the inner end of the winglet's leading edge to the leading edge when the leading edge is projected onto a plane parallel to the YZ plane (i.e., a plane parallel to both the Y and Z axes of the aircraft); and

[0163] s w = The total length from end to end of the projection of the leading edge of the winglet onto a plane parallel to the YZ plane.

[0164] In this regard, "s w "y" refers to the winglet's "spreading span," which is the span of the winglet when it is spread out into a plane, and "y" w "η" is the distance in the winglet's spread span. In addition, "η" is the ratio of the spread span in the outward direction (η = 0 corresponds to the inner end 7 of the winglet 4, η = 1 corresponds to the tip end 8 of the winglet 4).

[0165] In this respect, η corresponds to the spanwise position of the deployed winglet 4.

[0166] What will be understood is that y w and s w They have the same distance unit (and can have any distance unit, as long as the distance units are the same), such that η is a dimensionless parameter.

[0167] It will also be understood that if the winglet is (actually) flat, then its "spread" span is the actual span of the winglet.

[0168] The winglet 4 includes the inner region (in...) Figure 3 The middle area is marked with "I") and the outer area (in Figure 3 (Marked as "O" in the middle). The references to the "inner" and "outer" regions are related to the deployment span of winglet 5. Similarly, the references related to the "inner" and "outer" of winglet 4 refer to the inner and outer directions over the deployment span of winglet 4.

[0169] The inner region (I) is the inner part of the half-span position (M) of the deployed winglet 4, which is located at the midpoint of the deployed span of the winglet 4. In this respect, the inner region (I) is the inner half of the deployed winglet 4, i.e., the region where 0 ≤ η < 0.5. The outer region (O) is the outer part of the region at the half-span position (M). In this respect, the outer region (O) is the outer half of the deployed winglet 4, i.e., the region where 0.5 < η ≤ 1.

[0170] Reference Figure 3 The winglet 4 includes a transition region 21, a middle region 22, and a tip region 23. The transition region 21 extends outward from the inner end 7 of the winglet 4 (located at the spread spanwise position A on the winglet 4) to the outer end located at the spread spanwise position B on the winglet 4. In the transition region, the winglet 4 is integrated into the tip 6 of the main wing 3.

[0171] The intermediate region 22 extends outward from the outer end of the transition region 21 to the outer end located at the outward spanwise position C of the winglet 4.

[0172] The tip region 23 extends outward from the outer end of the middle region 22 to the outer end of the tip 8 of the winglet 4 (located at the spread-out position D of the winglet 4).

[0173] In the currently described embodiment, the outer end of the transition region 21 (the unfolded spanning position B) is located at η = 0.2 and the outer end of the intermediate region 22 (the unfolded spanning position C) is located at η = 0.7.

[0174] The various parameters used to define the shape of winglet 4, and in particular the variation of the leading edge droop of winglet 4 with the spanwise position as it unfolds, will now be described.

[0175] Reference Figure 5 The local winglet 40' at each spanwise position is defined as the cross-sectional shape produced by the intersection of the winglet 4 and the following plane: this plane intersects the quarter chord (i.e., at x / c = 0.25; see...). Figure 5 The local direction of the projection of the dashed line marked with x / c = 0.25 onto a plane parallel to the YZ plane (i.e., a plane parallel to both the Y and Z axes of the aircraft) is perpendicular.

[0176] The combination of all the partial winglets 40' defines the external shape of the winglet 4.

[0177] Figure 6 A schematic diagram of a portion of the winglet 40' (at a hypothetical spanwise position of deployment) is shown. It will be understood that... Figure 6 It is a schematic diagram and not to scale.

[0178] Each local winglet 40' has a leading edge point 9', a trailing edge point 10', and a local chord (c). If there exists a unique trailing edge point 10', then the trailing edge point 10' is defined as the trailing edge point 10'; otherwise, if there is no such unique point, the trailing edge point 10' is defined as the centroid of all trailing edges. The leading edge point 9' is defined as the point on the local winglet 40' farthest from the trailing edge point 10'. The local chord (c') is the straight line connecting the leading edge point 9' and the trailing edge point 10'. The local chord length (c) is the length of the local chord (c') (i.e., the length between the leading edge point 9' and the trailing edge point 10').

[0179] For example Figure 6 As shown, the maximum local wing thickness t max It is defined as the maximum distance normal to the chord (c) between the upper surface 19' and the lower surface 20' of the local wing 40'.

[0180] In the currently described embodiment, the angle of attack of winglet 4 is the angle between the flight direction (F) of winglet 4 and the root chord (c). 根部 The angle (α) between (see) Figure 5 However, it will be understood that any suitable reference line on the winglet 4 can be used.

[0181] The droop of the leading edge of the winglet 4 relative to its unfolded spanwise position varies along the winglet 4, causing flow separation on the winglet 4 to first occur in the region of the tip 8 of the winglet 4.

[0182] Wing 4 does not have any movable high-lift devices, such as slats or flaps.

[0183] Figure 6 Various parameters for defining and quantifying leading edge sag are also shown. In the embodiment described herein, leading edge sag is sag by parameters. 前缘 and Y5 上 Limitations and quantification.

[0184] The parameter droop at each spanwise position on the winglet 4 前缘 It refers to the distance (Dr) that the leading edge point 9' is offset from the reference line (e) toward the lower surface 20' divided by the local chord length (c). The reference line (e) passes through the trailing edge point 10' and the reference point G, which is located on a line perpendicular to the reference line (e) between the upper surface 19' and the lower surface 20' of the local blade section at the reference chord direction.

[0185] The reference chord position is chosen such that it is located sufficiently aft of the airfoil, within a portion of the "non-drooping" portion of the airfoil. In the embodiment described herein, the reference point G is located 0.3c behind the leading edge point 9' (i.e., 0.3 times the local chord length (c). This position is defined as x / c = 0.3, where x is the distance from the leading edge point 9' along the chord (c') (towards the trailing edge point 10'), and c is the local chord length).

[0186] The reference chord position can be located at any chord position sufficiently rearward from the leading edge point 9', such that the reference chord position is within the "non-drooping" portion of the airfoil. Preferably, the reference point G is located at a position greater than or equal to 0.3 times the local chord length behind the leading edge point 9' (i.e., x / c ≥ 0.3). More preferably, the reference point G is located at a position equal to 0.3 times the local chord length behind the leading edge point 9' (i.e., x / c = 0.3).

[0187] Refer again Figure 6 Parameter Y5 上 It is the distance from the upper surface 19' of the local blade section 40' to the chord line (c) on the following line divided by the local chord length (c): the line is normal to the chord line (c) and intersects the chord line (c) at a position 0.05c behind the leading edge point 9' (i.e., x / c = 0.05).

[0188] exist Figure 7 Middle, lower line (marked as "drooping") 前缘 The text appears to be a series of symbols and symbols, possibly indicating a downward droop. A direct translation isn't possible without further context 前缘 The variation along winglet 4 relative to the spanwise position (η) after deployment. x-axis (i.e., droop) 前缘 =0 indicates drooping. 前缘 The value at the zero leading edge droop.

[0189] Top line (marked as "Y5") 上 The text appears to be a mix of Chinese characters and symbols, possibly related to Y5. A direct translation wouldn't be meaningful without further context 上 The variation along winglet 4 relative to the spanwise position (η) after deployment. The horizontal dashed line N represents Y5. 上 The value at the zero leading edge droop.

[0190] The drooping is shown at the spanning positions of the expansions for η=0, η=0.2, η=0.7, and η=1. 前缘 and Y5 上 The values ​​are shown. Straight lines connecting these points are also illustrated to show the general variation between these values. However, it will be understood that the values ​​between these points may not lie on these straight lines.

[0191] As leading-edge droop increases, the nose radius of the airfoil increases to accommodate the droop.

[0192] The droop of the leading edge of winglet 4 relative to its deployed spanwise position (η) changes, causing flow separation on winglet 4 to occur first in the outer region (O) of winglet 4. In this respect, the droop of winglet 4 relative to its deployed spanwise position (η) 前缘 and Y5 上 The change causes flow separation on winglet 4 to first occur in the outer region (O) of winglet 4.

[0193] In the embodiment described herein, the drooping of the leading edge relative to the deployed spanwise position (η) causes flow separation on the winglet 4 to first occur in the region near the tip 8 of the winglet. In this respect, in the embodiment described herein, flow separation first occurs at the spanwise position (T) where η = 0.95.

[0194] The drooping variation of the leading edge relative to its spanwise position results in the greatest drooping of the leading edge in the outer region (O) of the winglet 4, near the tip 8 of the winglet 4. In this respect, the drooping... 前缘 and Y5 上 The value is largest in the outer region (O) of winglet 4.

[0195] More specifically, in the current embodiment, the leading edge droop is greatest at the spanwise position (C) where η = 0.7. In this respect, as Figure 7 As shown, drooping 前缘 The maximum value (P1) occurs at η = 0.7. Y5 上 The maximum value (P1') also occurs at η = 0.7. In the currently described embodiment, the drooping... 前缘 The maximum value (P1) is 0.041 and Y5 上 The maximum value (P1') is 0.048.

[0196] The drooping of the forewing is most pronounced in the outer region (O) of the winglet 4, which is advantageous because this feature promotes flow separation to occur primarily in the outer region (O) of the winglet 4. At this point, this feature promotes flow separation to occur primarily in the region outside the location of the greatest leading-edge droop.

[0197] The leading edge droop decreases outward from its maximum value at the position where the leading edge droop is greatest toward the tip 8 of the winglet 4. This can advantageously promote flow separation to occur first near the tip 8 of the winglet 4.

[0198] In this respect, the leading edge droop at the tip 8 of the winglet 4 is less than the maximum value of the leading edge droop, and the leading edge droop continuously decreases from the maximum value at the position where the leading edge droop is the largest to the tip 8 of the winglet 4.

[0199] like Figure 7 As shown, drooping 前缘The value decreases continuously from its maximum value (P1) at the position where the leading edge droops the most to the tip 8 of the winglet 4. Similarly, Y5 上 The value decreases continuously from its maximum value (P1') at the position where the leading edge droops the most to the tip 8 of the winglet 4.

[0200] The drooping of the leading edge of winglet 4 at its tip 8 is the minimum value of the leading edge drooping of winglet 4. In this respect, such as Figure 7 As shown, drooping 前缘 and Y5 上 The droop is smallest at the tip of winglet 4 (point 8). 前缘 The value is 0.017, and Y5 上 The value is 0.036.

[0201] Preferably, hanging 前缘 The maximum value and the droop at the tip 8 前缘 The ratio of the values ​​is greater than or equal to 2. Preferably, Y5 上 The maximum value and Y5 at the tip 8 上 The ratio of the values ​​is greater than or equal to 1.3.

[0202] The drooping of the leading edge relative to the spanwise position of the unfolded airfoil causes the flow separation to gradually move inward from the position (T) where flow separation first occurs as the angle of attack (α) of the winglet 4 increases.

[0203] What will be understood is that "gradually moving inward" means that, in contrast to the instantaneous occurrence of flow separation at a remote location where flow separation occurs (e.g., in contrast to the instantaneous occurrence of flow separation over the entire span of the wingtip device), flow separation propagates from the location (T) where flow separation first occurs.

[0204] In this respect, the leading edge droop decreases inward from its maximum value at the spread span (C) toward the inner end 7 of the winglet 4 (located at the spread span (A)).

[0205] In this respect, the leading edge droop at the inner end 7 of winglet 4 is less than the maximum leading edge droop. In this respect, the droop at the inner end 7... 前缘 and Y5 上 The value is less than its maximum value.

[0206] In the current embodiment, the drooping at the inner end 7 of the winglet 4 前缘 The value is 0.028.

[0207] In the current embodiment, Y5 at the inner end 7 of the winglet 4 上 The value is 0.038.

[0208] The outer end (B) of transition region 21 is located at a spanwise position where η = 0.2. In transition region 21, the leading edge droops along the inward direction near the tip 6 of the main wing 3. In this respect, the droop... 前缘 and Y5 上 The value is close to the droop at the tip 6 of the main wing 3. 前缘 and Y5 上 The value of is advantageous because it allows the leading-edge droop of the winglet 4 to smoothly integrate into the leading-edge droop at the tip 6 of the main wing 3, thus avoiding discontinuities in the leading-edge droop (and therefore avoiding discontinuities in aerodynamic performance at that position).

[0209] In the currently described embodiment, the leading edge droop at the inner end 7 of the winglet 4 is the same as the leading edge droop at the tip 6 of the main wing 3. Alternatively, the leading edge droop at the inner end 7 of the winglet 4 may be less than the leading edge droop at the tip 6 of the main wing 3.

[0210] The droop at the outer end of the transition region is less than the maximum droop at the outer edge. In this respect, the droop at the outer end of the transition region... 前缘 The value is less than the droop. 前缘 The maximum value of Y5. Furthermore, Y5 at the outer end of the transition region. 上 The value is less than Y5 上 The maximum value. In the current embodiment, the droop at the outer end (B) of the transition region 21. 前缘 The value (P2) is 0.03. (Drooping) 前缘 The maximum value and the droop at the outer end (B) of the transition region 21 前缘 The ratio of the values ​​is 1.37. Preferably, the drooping... 前缘 The maximum value and the droop at the outer end (B) of the transition region 21 前缘 The ratio of the values ​​is greater than or equal to 1.3. In the current embodiment, Y5 at the outer end (B) of the transition region 21 上 The value (P2') is 0.041. Y5 上 The maximum value of Y5 at the outer end (B) of the transition region 21 上 The ratio of the values ​​is 1.17. Preferably, Y5 上 The maximum value of Y5 at the outer end (B) of the transition region 21 上 The ratio of the values ​​is greater than or equal to 1.1.

[0211] According to another embodiment of the present invention, a method 105 for designing an aircraft wing 2 (i.e., the aircraft wing 2 of the above-described embodiment of the present invention) is provided. The method includes designing a winglet 4 according to another embodiment of the present invention. The method includes designing a winglet 4 whose leading edge droops differently relative to its unfolded spanwise position, such that flow separation on the winglet 4 first occurs in the outer region (O) of the winglet 4.

[0212] In this regard, refer to Figure 8 The method includes the following steps:

[0213] (i) Design a wingtip device that does not have a leading edge droop over its deployment span to meet high-speed design requirements (step 101);

[0214] (ii) The variation of the drooping of the leading edge relative to the unfolded spanwise position is applied to the design of the wingtip device, such that flow separation on the wingtip device first occurs in the outer region of the wingtip device (step 102).

[0215] High-speed requirements can, for example, provide some reduction in lift-induced drag at the operating cruise speed of aircraft 1.

[0216] The method for manufacturing the aircraft wing 2 (106) includes designing the aircraft wing according to the above method (105) and manufacturing the aircraft wing according to the design (step 103). It will be understood that the method for manufacturing the winglet 4 includes designing the winglet according to the above method and manufacturing the winglet according to the design.

[0217] A method for designing an aircraft 1 according to another embodiment of the present invention includes designing an aircraft wing according to the method (105) described above, wherein the aircraft wing is part of the aircraft design.

[0218] A method for manufacturing an aircraft 1 according to another embodiment of the present invention includes designing an aircraft according to the above method and manufacturing the aircraft according to the design.

[0219] In summary, in the embodiments of the present invention, the drooping of the leading edge of the winglet 4 relative to its unfolded spanwise position causes flow separation on the winglet 4 to first occur in the outer region of the winglet, especially near the tip of the winglet 4.

[0220] The development and progression of inward stall are delayed. This improves the low-speed characteristics of the winglet. In this respect, it increases both the aircraft angle of attack at which the upflow begins to separate on the winglet and the time interval between the start of upflow separation on the winglet and the point of complete separation. This results in a lower-speed drag improvement that extends beyond a larger portion of the aircraft's operating flight envelope, while also providing more benign and symmetrical handling qualities.

[0221] Therefore, this provides improved low-speed handling characteristics without significantly affecting the performance of the winglet 4 at high speeds (e.g., at operating cruise speeds).

[0222] Although the invention has been described and illustrated with reference to specific embodiments, it will be understood by those skilled in the art that the invention itself is applicable to many different variations not specifically shown herein.

[0223] In the currently described embodiment, the leading edge droop is parametrically drooping. 前缘 and Y5 上 The combination of these parameters determines the degree of drooping. Leading edge drooping can be determined by only one of these parameters; for example, leading edge drooping can be determined by only drooping. 前缘 Limited to or exclusively by Y5 上 Limited. However, preferably, the leading edge droop is determined by a parameter. 前缘 and Y5 上 Combination restrictions.

[0224] In the currently described embodiment, the variation in droop of the leading edge relative to its unfolded spanwise position along the winglet 4 causes flow separation on the winglet 4 to occur first in the region of the tip 8 of the winglet 4. Alternatively, or additionally, the variation in leading edge droop can cause flow separation on the winglet 4 to occur first at any location in the outer region (O) of the winglet 4. However, preferably, flow separation occurs first in the region of the tip 8 of the winglet 4.

[0225] In the currently described embodiment, the wingtip device is a curved, non-planar winglet. However, the wingtip device can be another type of winglet or wingtip device, such as a cantilever wingtip.

[0226] In the currently described embodiment, the winglet 4 is fixed relative to the main wing 3. Alternatively, the winglet 4 may be movable relative to the main wing 3. In this respect, the winglet 4 may be rotatable relative to the main wing 3 between the flight configuration used during flight and the ground configuration used during land-based operations, in which the span of the wing 2 is reduced.

[0227] The aircraft can be any type of aircraft, including any flying vehicle, such as a manned aircraft or a UAV. However, the aircraft is preferably a passenger aircraft.

[0228] Where “or” is used in the preceding description, it is used to mean “and / or”.

[0229] In the foregoing description, references have been made to elements or components having known, obvious, or foreseeable equivalents, which are incorporated herein as if separately described. Reference should be made to the claims, which define the true scope of the invention, and the claims should be interpreted to include any such equivalents. The reader will also understand that 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 while such elements or features may be beneficial in some embodiments of the invention, they may be undesirable and therefore absent in other embodiments.

Claims

1. An aircraft wing, the aircraft wing comprising a wingtip device located at the tip of a main wing, wherein, The wingtip device is a winglet, wherein the wingtip device includes an upper skin forming an upper surface and a lower skin forming a lower surface, each skin spanning between the leading and trailing edges of the wingtip device and defining a plurality of partial winglets, wherein the wingtip device has a parameter-dependent drooping shape. 前缘 The leading edge droop is defined, wherein the droop at each spread spanwise position on the winglet is defined. 前缘 It is the distance the leading edge point is offset from the reference line passing through the trailing edge point and the reference point toward the lower surface divided by the local chord length, the reference point being located on a line perpendicular to the reference line at the midpoint between the upper and lower surfaces of the local airfoil section at the reference chordal position, and wherein the wingtip device has a variation in leading edge droop relative to the deployed spanwise position, wherein the leading edge droop of the wingtip device is maximum in the outer half of the deployed wingtip device, and wherein the leading edge droop decreases from its maximum value outwards as it approaches the tip of the wingtip device, such that flow separation on the wingtip device first occurs in the outer region of the wingtip device.

2. The aircraft wing according to claim 1, wherein, The change in leading edge droop causes flow separation on the wingtip device to occur first at the tip of the wingtip device or first in the region near the tip of the wingtip device.

3. The aircraft wing according to claim 1 or 2, wherein, The change in leading edge droop causes the flow separation to move inward as the angle of attack of the wingtip device increases.

4. The aircraft wing according to claim 3, wherein, The leading edge droop decreases from its maximum value toward the inner end near the wingtip device.

5. The aircraft wing according to claim 1 or 2, wherein, The wingtip assembly includes a transition region extending from the inner end of the wingtip assembly, wherein the leading edge droop is approximately equal to the value of the leading edge droop at the outer end of the main wing in the inward direction.

6. The aircraft wing according to claim 5, wherein, The leading edge droop at the outer end of the transition region is less than the maximum leading edge droop.

7. The aircraft wing according to claim 1 or 2, wherein, The wingtip device has a dihedral angle that gradually increases outwards.

8. The aircraft wing according to claim 1 or 2, wherein, The wingtip device is swept back.

9. The aircraft wing according to claim 8, wherein, The leading edge sweep angle of the wingtip device increases along the outer direction, so that the leading edge appears curved when viewed in planar form.

10. An aircraft comprising an aircraft wing according to any one of claims 1 to 9.

11. A method for designing a wingtip device for use as part of an aircraft wing, wherein, The method includes designing the wingtip device as a winglet, wherein the wingtip device includes an upper skin forming an upper surface and a lower skin forming a lower surface, each skin spanning between the leading and trailing edges of the wingtip device and defining a plurality of local flaps, wherein the wingtip device has a parametrically drooping shape. 前缘 The leading edge droop is defined, wherein the droop at each spread spanwise position on the winglet is defined. 前缘 It is the distance the leading edge point is offset from the reference line passing through the trailing edge point and the reference point toward the lower surface divided by the local chord length, the reference point being located on a line perpendicular to the reference line at the midpoint between the upper and lower surfaces of the local airfoil section at the reference chordal position, and wherein the wingtip device has a variation in leading edge droop relative to the deployed spanwise position, wherein the leading edge droop of the wingtip device is maximum in the outer half of the deployed wingtip device, and wherein the leading edge droop decreases from its maximum value outwards as it approaches the tip of the wingtip device, such that flow separation on the wingtip device first occurs in the outer region of the wingtip device.

12. The method according to claim 11, wherein, The method includes the following steps: (i) Design a wingtip device, wherein the leading edge of the wingtip device does not droop over its spread span to meet high-speed design requirements; (ii) The design of the wingtip device is to apply a variation in the drooping of the leading edge relative to the unfolded spanwise position, such that flow separation on the wingtip device first occurs in the outer region of the wingtip device.

13. A method for designing an aircraft wing comprising a main wing and a wingtip assembly located at the tip of said main wing, wherein, The method includes designing the wingtip device according to any one of claims 11 or 12.

14. A method for designing an aircraft, the method comprising designing an aircraft wing according to claim 13.

15. A method of manufacturing a wingtip device, the method comprising designing the wingtip device according to any one of claims 11 or 12 and manufacturing the wingtip device according to said design.

16. A method of manufacturing an aircraft wing, the method comprising designing an aircraft wing according to claim 13 and manufacturing the aircraft wing according to the design.

17. A method of manufacturing an aircraft, the method comprising designing the aircraft according to claim 14 and manufacturing the aircraft according to the design.

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