GB2633390A

GB2633390A - Aircraft wing assembly

Info

Publication number: GB2633390A
Application number: GB2313752.4A
Authority: GB
Inventors: Curtis Peter
Original assignee: Aeralis Ltd
Current assignee: Aeralis Ltd
Priority date: 2023-09-08
Filing date: 2023-09-08
Publication date: 2025-03-12
Also published as: WO2025052127A1; GB202313752D0

Abstract

A wing assembly for a modular aircraft 2 comprises a central wing structure 12 having inboard wing sections 20a, 20b which extend laterally on opposing sides of the central wing structure and a plurality of pairs of outboard wing sections 14, 16, 18. Each outboard wing section is arranged to be removably mounted to a respective one of the inboard wing sections such that each pair of outboard wing sections is mountable to the central wing structure to provide a respective alternative wing configuration. The plurality of pairs of outboard wing sections comprises: a first pair having a first outboard sweep angle; and a second pair having a second outboard sweep angle, wherein a leading edge of each second outboard wing section is arranged to extend at a second outboard sweep angle and the second outboard sweep angle is greater than the inboard sweep angle.

Description

Aircraft Wing Assembly

FIELD OF THE INVENTION

The present invention relates to reconfigurable aircraft wing assemblies. In particular the present invention relates to a wing assembly for a modular aircraft, an aircraft comprising a wing assembly, and a method of reconfiguring an aircraft.

BACKGROUND TO THE INVENTION

The present invention relates to aircraft and in particular to reconfigurable military jet aircraft. Military aircraft having particular capabilities are required for particular roles. Accordingly, different aircraft types may have different wing planforms which provide corresponding different aerodynamic properties. For example, aircraft used for intelligence, surveillance and reconnaissance (ISR) may have relatively elongate (high aspect ratio) straight wings to enable greater efficiency and range, whereas combat aircraft may have relatively shorter (low aspect ratio) swept wings or a delta wing, to reduce drag and improve manoeuvrability at higher speeds.

To enable a single aircraft to have different wing planforms, it is known to provide an aircraft with 'variable-sweep' wings (which may be known as 'swing wings'), in which a sweep angle of the wings can be adjusted in flight to vary from a swept wing configuration towards a straighter wing configuration. It is also known to provide a modular aircraft in which different types of wing assemblies can be mounted to a central wing structure in order to provide different wing configurations. Such modular aircraft are disclosed in the present applicant's granted European Patent No. EP 3 411 293 B1.

It is against this background that the present invention is devised. It is an object of the present invention to overcome at least one problem associated with the prior art, whether referred to herein or otherwise. -2 -

SUMMARY OF THE INVENTION

A wing assembly for a modular aircraft, the wing assembly comprising: a central wing structure having inboard wing sections which extend laterally on opposing sides of the central wing structure, a leading edge of each inboard wing section being arranged to extend at an inboard sweep angle with respect to a lateral axis of the aircraft; and a plurality of pairs of outboard wing sections, each outboard wing section being arranged to be removably mounted to a respective one of the inboard wing sections such that each pair of outboard wing sections is mountable to the central wing structure to provide a respective alternative wing configuration; wherein a leading edge of each outboard wing section is arranged to extend at an outboard sweep angle with respect to the lateral axis of the aircraft when the outboard wing section is mounted to a respective inboard wing section; and wherein the plurality of pairs of outboard wing sections comprises: a first pair comprising first outboard wing sections, wherein a leading edge of each first outboard wing section is arranged to extend at a first outboard sweep angle; and a second pair comprising second outboard wing sections, wherein a leading edge of each second outboard wing section is arranged to extend at a second outboard sweep angle and the second outboard sweep angle is greater than the inboard sweep angle.

With this arrangement, the present invention provides a reconfigurable aircraft wing system which enables a single aircraft to be provided with different wing planforms having different aerodynamic properties. The interchangeable outer wing sections allow an aircraft to be reconfigured for different roles, whilst the central wing structure and inboard wing sections are common to (i.e. shared by) each wing configuration of the aircraft, which helps to minimise changes to characteristics (such as aerodynamic properties) of the aircraft between the different wing configurations. The central wing structure may therefore be referred to as a common central wing structure or core wing structure. -3 -

For example, this arrangement may help to minimise the change to the aerodynamic centre of each wing, thus reducing the impact of different wing configurations on control and stability of the aircraft.

Preferably the first outboard sweep angle is less than the inboard sweep angle.

With the above arrangements, the sweep angle of the leading edge of the inboard wing sections is intermediate between the sweep angle of a leading edge of each first outboard wing section, and a sweep angle of a leading edge of each second outboard wing section. In this way, the inboard wing sections are aerodynamically compatible with both the first and second outboard wing sections, to provide a lower sweep wing planform, or a more strongly swept wing planform, respectively. In this way, an aerodynamically stable and efficient wing planform can be provided by the first outboard wing sections, and the wing planform provided by the second outboard wing sections is suitable for relatively high (e.g. transonic) speeds.

The first pair of outboard wing sections may be arranged to provide a mildly or gently swept wing configuration or planform having a relatively low sweep angle. This arrangement may be suitable for an intelligence, surveillance and reconnaissance (ISR) aircraft, for example in which efficiency, aerodynamic stability and/or range are relatively more important than speed and manoeuvrability. In some embodiments, the first outboard wing sections may provide a straight wing configuration.

The second pair of outboard wing sections is arranged to provide a more aggressive (e.g. greater sweep angle) swept wing configuration, in which the outboard wing sections are more strongly swept than the inboard wing sections. These arrangements may be suitable for advanced trainer or combat aircraft in which higher speeds (e.g. transonic speeds) and manoeuvrability are relatively more important than efficiency and/or range. -4 -

The inboard sweep angle may be from 25 to 35 degrees. Preferably the inboard sweep angle is from 28 to 30 degrees. More preferably the inboard sweep angle is from 28.5 to 29.5 degrees. Even more preferably the inboard sweep angle is 29 degrees.

Preferably a trailing edge of each inboard wing section is arranged to extend substantially parallel to the lateral axis of the aircraft. That is, preferably a trailing edge of each inboard wing section extends at a sweep angle of about 0 degrees.

The first outboard sweep angle may be from 8 to 18 degrees, preferably from 10 to 15 degrees. More preferably the first outboard sweep angle is from 12 to 14 degrees, or from 12.5 to 13.5 degrees. Even more preferably the first outboard sweep angle is 13 degrees.

Preferably a trailing edge of each first outboard wing section is arranged to extend substantially parallel to the lateral axis of the aircraft. That is, preferably a trailing edge of each first outboard wing section extends at a sweep angle of about 0 degrees when mounted to a respective inboard wing section. In this way, the trailing edge of each first outboard wing section may extend parallel to, and aligned with, the trailing edge of a respective inboard wing section.

The second outboard sweep angle may be from 35 to 50 degrees. Preferably the second outboard sweep angle is from 40 to 44 degrees. More preferably the second outboard sweep angle is from 41 to 43 degrees, or from 41.5.5 to 42.5 degrees. 25 Even more preferably the second outboard sweep angle is 42 degrees.

Preferably a trailing edge of each second outboard wing section is arranged to extend at a sweep angle which is greater than the inboard sweep angle.

Preferably a trailing edge of each second outboard wing section extends at a sweep angle from 30 degrees to 45 degrees, more preferably from 33 degrees to 35 degrees, or from 33.5 degrees to 34.5 degrees, for example 34 degrees. -5 -

In this way the second outboard wing sections are arranged to provide a wing in which an outboard portion of the wing has a greater sweep angle than an inboard portion of the wing (which may be referred to as a cranked wing).

Preferably the plurality of pairs of outboard wing sections comprises a third pair comprising third outboard wing sections, wherein a leading edge of each third outboard wing section extends at a third outboard sweep angle and preferably the third outboard sweep angle is equal to the inboard sweep angle. Preferably the third outboard sweep angle is intermediate the first outboard sweep angle and the second outboard sweep angle.

The third pair of outboard wing sections may therefore be arranged to provide a moderately swept wing configuration or planform in which the wings comprising the 15 third outboard wing sections have a sweep angle which is intermediate between a sweep angle of wings comprising the first or second outboard wing sections.

The third outboard sweep angle may be from 25 to 35 degrees. Preferably the third outboard sweep angle is from 28 to 30 degrees. More preferably the third outboard sweep angle is from 28.5 to 29.5 degrees. Even more preferably the third outboard sweep angle is 29 degrees. In this way preferably the leading edge of a wing comprising a respective one of the third outboard wing sections has a substantially constant sweep angle. In other embodiments, the third outboard sweep angle may be different to the inboard sweep angle.

Preferably a trailing edge of each third outboard wing section extends at a sweep angle (with respect to the lateral axis of the aircraft) greater than 0 degrees, preferably from 10 degrees to 30 degrees, for example about 15 degrees. More preferably a trailing edge of each third outboard wing section extends at a sweep angle from 12 to 14 degrees, even more preferably 13 degrees. In this case the trailing edge of each third outboard wing section is arranged to extend rearwardly from the trailing edge of a respective inboard wing section. -6 -

With this arrangement, the trailing edge of each third outboard wing section is arranged to extend at an angle to the trailing edge of a respective inboard wing section, such that the trailing edge of each wing comprises a kink or crank. In this way an outboard portion of the trailing edge of each wing forms an angle with a respective inboard portion of the trailing edge of the wing.

Preferably a lateral length (e.g. a span, in a direction parallel to the lateral axis of the aircraft) of each outboard wing section is greater than a lateral length of each inboard wing section. Preferably the lateral length of each inboard wing section is at least 15%, or at least 25% of the lateral length of each outboard wing section. In this way preferably each inboard wing section provides at least 25% of the semi-span of each wing.

Preferably a lateral length of each first outboard wing section is at least twice the lateral length of each inboard wing section.

Preferably a lateral length of each third outboard wing section is at least 1.5 times a lateral length of each inboard wing section.

Preferably an aspect ratio of each first outboard wing section is greater than an aspect ratio of each second or third outboard wing section. Preferably an aspect ratio of wings comprising the first outboard wing sections is greater than an aspect ratio of wings comprising the second wing sections. Preferably an aspect ratio of wings comprising the first outboard wing sections is greater than an aspect ratio of wings comprising the third wing sections.

Preferably a planform of each outboard wing section is tapered towards an outboard edge of the respective outboard wing section. In this way each outboard wing 30 section may be tapered towards a tip of a respective wing.

Preferably each outboard wing section is arranged to be mounted to an outboard -7 -edge of a respective one of the inboard wing sections.

Preferably each inboard wing section is provided with an inboard section mounting arrangement for releasably mounting an outboard wing section to the inboard wing section. Preferably each outboard wing section is provided with an outboard section mounting arrangement for engagement with a respective inboard section mounting arrangement, for releasably mounting the outboard wing section to a respective inboard wing section.

Preferable the central wing structure forms part of a common fuselage body of a modular aircraft system.

Also provided is a modular aircraft comprising a wing assembly according to the first aspect of the invention.

Preferably the modular aircraft comprises a pair of engine air intakes, each air intake being disposed above a respective inboard wing section.

Preferably the modular aircraft is a low wing aircraft. Preferably the central wing structure is disposed proximate a lower side of a fuselage body of the aircraft such that the modular aircraft is a low wing aircraft.

Preferably the modular aircraft comprises a propulsion system mounting arrangement for removably suspending a propulsion system of the modular aircraft from a fuselage body of the aircraft and which enables the propulsion system to be removed and replaced with an alternative propulsion system. For example, the propulsion system mounting arrangement may be configured for mounting to the aircraft a first propulsion system or a second propulsion system which is more powerful than the first propulsion system.

According to a second aspect of the invention there is provided a method of reconfiguring an aircraft, the aircraft comprising: -8 -a central wing structure having inboard wing sections which extend laterally on opposing sides of the central wing structure, a leading edge of each inboard wing section being arranged to extend at an inboard sweep angle with respect to a lateral axis of the aircraft; and a plurality of pairs of outboard wing sections, each outboard wing section being arranged to be removably mounted to a respective one of the inboard wing sections such that each pair of outboard wing sections is mountable to the central wing structure to provide a respective alternative wing configuration; wherein a leading edge of each outboard wing section is arranged to extend at an outboard sweep angle with respect to the lateral axis of the aircraft when the outboard wing section is mounted to a respective inboard wing section, the method comprising: removing from the aircraft a first pair of outboard wing sections or a second pair of outboard wing sections; and mounting the other of the first or second pair of outboard wing sections to the central wing structure; wherein a leading edge of each of the second pair of outboard wing sections is arranged to extend at an outboard sweep angle which is greater than the inboard sweep angle.

Preferably a trailing edge of each of the second outboard wing sections is arranged 20 to extend at a sweep angle greater than the inboard sweep angle.

According to another aspect of the invention there is provided a wing assembly for a modular aircraft, the wing assembly comprising: a central wing structure having inboard wing sections which extend laterally on opposing sides of the central wing structure, a leading edge of each inboard wing section being arranged to extend at an inboard sweep angle with respect to a lateral axis of the aircraft; and a pair of outboard wing sections, each outboard wing section being arranged to be removably mounted to a respective one of the inboard wing sections such that the pair of outboard wing sections is mountable to the central wing structure: wherein a leading edge of each outboard wing section is arranged to extend at an outboard sweep angle with respect to the lateral axis of the aircraft when the -9 -outboard wing section is mounted to a respective inboard wing section; and wherein the outboard sweep angle is greater than the inboard sweep angle.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described by way of example only, with reference to the accompanying drawings, in which like reference numerals indicate like features and in which: Figure 1 is a schematic plan view of a wing assembly according to a preferred embodiment of the invention, showing a central wing structure and a plurality of alternative pairs of outboard wing sections, together with part of an aircraft with 10 which the wing assembly may be used; Figure 2 is a schematic plan view of part of the wing assembly of Figure 1; Figure 3 is a schematic plan view of the wing assembly of Figure 1, showing the outboard wing sections detached from the central wing structure; Figure 4 is a schematic plan view of the wing assembly of Figure 1, showing a first pair of outboard wing sections mounted to the central wing structure; Figure 5 is a schematic plan view of the wing assembly of Figure 1, showing a second pair of outboard wing sections mounted to the central wing structure; and Figure 6 is a schematic plan view of the wing assembly of Figure 1, showing a third pair of outboard wing sections mounted to the central wing structure.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention provides a reconfigurable modular aircraft wing assembly which enables a single aircraft to be provided with a plurality of different wing planforms suitable for different roles.

A wing assembly 10 according to a first embodiment of the invention is shown schematically in plan view in Figures 1, 2 and 3. The wing assembly 10 is arranged to form part of a modular aircraft 2. The wing assembly 10 therefore provides a kit which enables the modular aircraft 2 to be fitted with different wing sections in order to provide the aircraft with alternative wing planforms.

The wing assembly 10 comprises a central wing structure 12, and a plurality of pairs of outboard wing sections 14, 16, 18 which are removably mountable to the central wing structure 12. The central wing structure 12 is arranged on a centre-line X of the aircraft 2 (parallel to a longitudinal axis of the aircraft 2). The central wing structure 12 is arranged to be mounted to, or integral with, a fuselage body 4 of the aircraft 2. The central wing structure 12 comprises a pair of inboard wing sections 20a, 20b. Each inboard wing section 20a, 20b extends laterally away from the centre-line X of the aircraft 2, in a direction generally parallel to a lateral axis Y of the aircraft 2 (i.e. generally perpendicular to the centre-line X of the aircraft 2). Each inboard wing section 20a, 20b extends laterally away from the centre-line X of the aircraft 2 to a lateral edge or outboard edge 22a, 22b of the respective inboard wing section 20a, 20b. In this embodiment, each lateral (outboard) edge 22a, 22b of each inboard wing section 20a, 20b extends generally parallel to the aircraft centre-line X. A forward edge or leading edge 24a, 24b of each inboard wing section 20a, 20b is swept or angled with respect to the lateral axis Y and extends away from the centreline X and in a rearward direction. A rear edge or trailing edge 26a, 26b of each inboard wing section 20a, 20b extends substantially parallel to the lateral axis Y. In this way, each inboard wing section 20a, 20b has a tapered planform. Accordingly, a chord of each inboard wing section 20a, 20b proximate the centre-line X is longer than a chord of the inboard wing section 20a, 20b proximate the lateral edge 22a, 22b. Referring in particular to Figure 2, the leading edge 24a, 24b of each inboard wing section 20a, 20b extends at an angle (referred to herein as an inboard sweep angle A) with respect to the lateral axis Y. The inboard sweep angle A may be from about 25 to about 35 degrees. In this embodiment, the inboard sweep angle A is 29 degrees.

The lateral edge 22a, 22b of each inboard wing section 20a, 20b is provided with an inboard section mounting arrangement (not shown) for releasably mounting an outboard wing section to the inboard wing section 20a, 20b.

Referring also to Figure 3, in the present embodiment, the plurality of outboard wing sections comprises first, second and third pairs (sets) of outboard wing sections 14, 16, 18. Each pair 14, 16, 18 comprises a respective port outboard wing section 14a, 16a, 18a and a respective starboard outboard wing section 14b, 16b, 18b. Figure 1 shows schematically all of these alternative pairs of wing sections 14 (14a, 14b), 16 (16a, 16b), 18 (18a, 18b) together, superimposed, as though mounted to the central wing structure 12. It will be appreciated however that only one pair of wing sections 14, 16, 18 may be mounted to the central wing structure 12 at once. The pairs of outboard wing sections 14, 16, 18 are therefore arranged to provide alternative wing configurations by providing alternative wing planforms. Figure 3 shows the wing assembly 10 as a kit of parts in which the pairs of outboard wing sections 14, 16, 18 are shown detached from the central wing structure 12.

Each of the plurality of outboard wing sections 14a, 14b, 16a, 16b, 18a, 18b is generally elongate and extends between an inboard lateral edge and an outboard lateral edge of the outboard wing section 14a, 14b, 16a, 16b, 18a, 18b. An inboard lateral edge of each outboard wing section 14a, 14b, 16a, 16b, 18a, 18b is arranged to abut the outboard lateral edge 22a, 22b of a respective inboard wing section 20a, 20b. An outboard lateral edge of each outboard wing section 14, 16 18 is arranged to provide a tip portion of a respective wing in use. Accordingly, the inboard lateral edge of each outboard wing section 14a, 14b, 16a, 16b, 18a, 18b is arranged to extend substantially parallel to the aircraft centre-line X, and thus parallel to the lateral edge 22a, 22b of the respective inboard wing section 20a, 20b.

Each inboard lateral edge of each outboard wing section 14a, 14b, 16a, 16b, 18a, 18b is provided with a corresponding outboard section mounting arrangement (not shown) configured to engage with the inboard section mounting arrangement of a corresponding inboard wing section 20a, 20b, to mount the outboard wing section 14a, 14b, 16a, 16b, 18a, 18b to the respective inboard wing section 20a, 20b. In this way, the wing assembly 10 comprises a mounting arrangement comprising the inboard section mounting arrangements and the outboard section mounting arrangements. Each inboard section mounting arrangement and a respective outboard section mounting arrangement may be referred to as a wing interface or wing joint. Thus a respective wing when assembled comprises a wing joint at which a respective outboard wing section 14a, 14b, 16a, 16b, 18a, 18b is mounted to a respective inboard wing section 20a, 20b.

Referring additionally to Figure 4, the first pair of outboard wing sections 14 comprises first outboard wing sections 14a, 14b, which in this embodiment are low-sweep wing sections configured to provide a relatively low-sweep or mild sweep wing planform. Each first outboard wing section 14a, 14b comprises a forward edge or leading edge 28a, 28b and a rear edge or trailing edge 30a, 30b spaced apart from the respective leading edge 28a, 28b. The leading edges 28a, 28b and trailing edges 30a, 30b are substantially linear. Each leading edge 28a, 28b extends at an angle to the respective trailing edge 30a, 30b. An inboard lateral edge 32a, 32b extends between the leading edge 28a, 28b and the trailing edge 30a, 30b at an inboard end or base of the wing section 14a, 14b. An outboard lateral edge 34a, 34b extends between the leading edge 28a, 28b and the trailing edge 30a, 30b at an outboard end or tip of the wing section 14a, 14b. The trailing edge 30a, 30b of each first outboard wing section 14a, 14b extends substantially perpendicular to the respective inboard lateral edge 32a, 32b. Each inboard lateral edge 32a, 32b is longer than the respective outboard lateral edge 34a, 34b. In this way, each first outboard wing section 14a, 14b has a tapered planform which tapers towards its outboard lateral edge 34a, 34b. Each outboard lateral edge 32a, 32b extends parallel to the respective inboard lateral edge 30a, 30b.

When each first outboard wing section 14a, 14b is mounted to a respective inboard wing section 20a, 20b (as seen most clearly in Figure 4), each inboard lateral edge 32a, 32b extends parallel to and abuts a respective outboard lateral edge 22a, 22b of the respective inboard wing section 20a, 20b. In this way, the leading edge 28a, 28b of each first outboard wing section 14a, 14b is arranged to extend at an angle (referred to herein as a first outboard sweep angle B) with respect to the lateral axis Y. The trailing edges 30a, 30b are arranged to extend parallel to the lateral axis Y and thus parallel to the trailing edges 26a, 26b of the inboard wing sections 20a, 20b. Each leading edge 28a, 28b thus extends in a direction rearwardly and outboard from the respective inboard lateral edge 32a, 32b.

As can be seen most clearly in Figure 2, the first outboard sweep angle B is less than the inboard sweep angle A. With this arrangement, a leading edge of a respective wing comprising a first outboard wing section 14a, 14b comprises an inboard portion having a greater sweep angle than an outboard portion. The first outboard sweep angle may be from about 8 to about 18 degrees. In this embodiment, the first outboard sweep angle is about 13 degrees. In this way, the first outboard wing sections provide a wing planform in which a sweep angle (such as a leading edge sweep angle or a quarter chord sweep angle) of the wings varies along the wingspan. This arrangement may be referred to as a cranked wing. In particular, an inboard portion of the wing has a larger sweep angle than an outboard portion of the wing.

Referring again to Figure 3, and additionally to Figure 5, the second pair of outboard wing sections 16 comprises second outboard wing sections 16a, 16b which in this embodiment are high-sweep wing sections configured to provide a relatively high-sweep or aggressive sweep wing planform. Each second outboard wing section 16a, 16b comprises a forward edge or leading edge 36a, 36b and a rear edge or trailing edge 38a, 38b spaced apart from the leading edge 36a, 36b. An inboard lateral edge 40a, 40b extends between the leading edge 36a, 36b and the trailing edge 38a, 38b at an inboard end or base of each wing section 16a, 16b. Each trailing edge 38a, 38b is substantially linear. Each leading edge 36a, 36b comprises a linear, inboard portion 37a, 37b and a curved outboard portion 39a, 39b. Each linear inboard portion 37a, 37b extends between the inboard lateral edge 40a, 40b and the curved outboard portion 39a, 39b. Each curved outboard portion 39a, 39b curves rearwardly from the linear portion 37, 37b to meet the trailing edge 38a, 38b at a rearwardly pointing tapered tip. Each curved portion 39a, 39b thus provides an outboard lateral edge 42a, 42b of the wing section 16a, 16b. Each linear portion 37a, 37b and each trailing edge 38a, 38b extends at an acute angle to the inboard lateral edge 40a, 40b. Each linear portion 37a, 37b begins to converge with its respective trailing edge 38a, 38b towards the outboard end of the wing section 16a, 16b. In this way, each second outboard wing section 16a, 16b has a tapered planform which tapers towards the outboard lateral edge 42a, 42b.

When each second outboard wing section 16a, 16b is mounted to a respective inboard wing section 20a, 20b, the leading edge 36a, 36b of the each second outboard wing section 16a, 16b is arranged to extend rearwardly at an angle to the lateral axis Y and the trailing edge 38a, 38b is arranged to extend rearwardly at an angle to the lateral axis Y. In particular, the linear portion 37a, 37b of each leading edge of each second outboard wing section 16a, 16b is arranged to extend at an angle (referred to herein as a second outboard sweep angle C) with respect to the lateral axis Y. The second outboard sweep angle C is greater than the inboard sweep angle A (as seen most clearly in Figure 2). The second outboard sweep angle C may be from about 35 to about 50 degrees. In this embodiment, the second outboard sweep angle C is about 42 degrees. With this arrangement, a leading edge of a respective wing comprising a second outboard wing section 16a, 16b comprises an outboard portion having a greater sweep angle than an inboard portion. The second outboard wing sections 16a, 16b thus provide a wing planform in which a sweep angle (such as a leading edge sweep angle or a quarter chord sweep angle) of the wings varies along the wingspan. In particular, an outboard portion of the wing has a larger sweep angle than an inboard portion of the wing.

The trailing edge 38a, 38b of each second outboard wing section 16a, 16b is arranged to extend rearwardly from the trailing edge 26a, 26b of the respective inboard wing section 20a, 20b. In this embodiment, the trailing edge 38a, 38b of each second outboard wing section 16a, 16b is arranged to extend at a sweep angle (with respect to the lateral axis Y) about 34 degrees.

The second pair of outboard wing sections 16a, 16b therefore provide a cranked wing. The second pair of outboard wing sections 16a, 16b provide an aggressively-swept wing planform suitable for a tactical or combat aircraft which may operate at transonic speeds.

Referring again to Figure 3, and additionally to Figure 6, the third pair of outboard wing sections comprises third outboard wing sections 18a, 18b, which in this embodiment are moderate-sweep wing sections configured to provide a relatively moderate-sweep wing planform. Each third outboard wing section 18a, 18b comprises a forward edge or leading edge 44a, 44b and a rear edge or trailing edge 46a, 46b spaced apart from the leading edge 44a, 44b. An inboard lateral edge 48a, 48b extends between the leading edge 44a, 44b and the trailing edge 46a, 46b at an inboard end or base of each wing section 18a, 18b. Each trailing edge 46a, 46b is substantially linear. Each leading edge 44a, 44b comprises a linear, inboard portion 47a, 47b and a curved outboard portion 49a, 49b. Each linear inboard portion 47a, 47b extends between the inboard lateral edge 48a, 48b and the curved outboard portion 49a, 49b. Each curved outboard portion 49a, 49b curves rearwardly from the linear portion 47, 47b to meet the trailing edge 46a, 46b at a rearwardly pointing tapered tip. Each curved portion 49a, 49b thus provides an outboard lateral edge 50a, 50b of a respective wing section 16a, 16b. Each linear portion 47a, 47b and each trailing edge 46a, 46b extends at an acute angle to the inboard lateral edge 48a, 48b. Each linear portion 47a, 47b begins to converge with its respective trailing edge 46a, 46b towards the outboard end of the wing section 16a, 16b. In this way, each second outboard wing section 16a, 16b has a tapered planform which tapers towards the outboard lateral edge 50a, 50b.

When each third outboard wing section 18a, 18b is mounted to a respective inboard 30 wing section 20a, 20b, the leading edge 44a, 44b of each third outboard wing section 18a, 18b is arranged to extend rearwardly, at an angle to the lateral axis Y and the trailing edge is arranged to extend rearwardly and at an angle to the lateral axis. In particular, the linear portion 47a, 47b of each leading edge 44a, 44b is arranged to extend at an angle (referred to herein as a third outboard sweep angle D) with respect to the lateral axis Y. The third outboard sweep angle D is substantially equal to the inboard sweep angle A (as seen most clearly in Figure 2). In this embodiment therefore, the third outboard sweep angle is about 29 degrees. In this embodiment therefore the third outboard sweep angle D is less than the second outboard sweep angle C. With this arrangement, a linear portion of a leading edge of each wing comprising a third outboard wing section 18a, 18b has a substantially constant sweep angle. In some embodiments the third outboard sweep angle may be from about 25 to about 35 degrees.

The trailing edge 46a, 46b of each third outboard wing section 18a, 18b is arranged to extend rearwardly from the trailing edge 26a, 26b of the respective inboard wing section 20a, 20b. In this embodiment, the trailing edge 26a, 26b of each third outboard wing section 18a, 18b is arranged to extend at a sweep angle of about 13 degrees with respect to the lateral axis Y. As mentioned above, each outboard wing section is mountable to a respective inboard wing section at a wing joint. The mounting arrangements which provide the wing joints are not described in detail in the present embodiment. However, preferably, the outboard section mounting arrangements of each of the first, second and third outboard wing sections are substantially similar and attach to the inboard section mounting arrangements in substantially the same way. In this way, the different outboard wing sections are conveniently interchangeable to allow the wing assembly to be reconfigured. In the embodiments described above, the central wing structure and outboard wing sections are preferably constructed with internal frame structures (spars, ribs, stringers and the like) covered by an external skin (such as a stressed skin structure).

Using the same inboard wing sections for each alternative wing configuration helps to minimise some aerodynamic changes (such as the position of the aerodynamic centre) associated with changing the wing planform. In the present invention, the inboard wing sections provide a significant component of the wing length and planform area, and thus contribute substantially to the aerodynamic performance of the wings. In particular, in preferred embodiments each inboard wing section provides at least about 25% of the length (semi-span) of each wing.

With the arrangements described above, the present invention provides a reconfigurable wing assembly which enables a single aircraft to be provided with different wing configurations. Each outboard wing section is arranged to be releasably mounted to a respective inboard wing section so that a wing planform of the aircraft can be reconfigured for different roles or operations. In particular, the present invention enables the same single aircraft to be configured with a low sweep angle wing or a high sweep angle wing, whilst using the same inboard wing sections. In particular, the present invention enables a modular aircraft to be configured as a tactical or combat aircraft with strongly swept outboard wing portions, whilst inboard portions of the wings have a smaller sweep angle than found in prior art combat aircraft which have a single, strongly swept wing configuration.

Further modifications and variations not explicitly described above can also be contemplated without departing from the scope of the invention as defined in the appended claims.

Claims

CLAIMS1. A wing assembly for a modular aircraft, the wing assembly comprising: a central wing structure having inboard wing sections which extend laterally on opposing sides of the central wing structure, a leading edge of each inboard wing section being arranged to extend at an inboard sweep angle with respect to a lateral axis of the aircraft; and a plurality of pairs of outboard wing sections, each outboard wing section being arranged to be removably mounted to a respective one of the inboard wing sections such that each pair of outboard wing sections is mountable to the central wing structure to provide a respective alternative wing configuration; wherein a leading edge of each outboard wing section is arranged to extend at an outboard sweep angle with respect to the lateral axis of the aircraft when the outboard wing section is mounted to a respective inboard wing section; and wherein the plurality of pairs of outboard wing sections comprises: a first pair comprising first outboard wing sections, wherein a leading edge of each first outboard wing section is arranged to extend at a first outboard sweep angle; and a second pair comprising second outboard wing sections, wherein a leading edge of each second outboard wing section is arranged to extend at a second outboard sweep angle and the second outboard sweep angle is greater than the inboard sweep angle.
2. A wing assembly according to Claim 1, in which the first outboard sweep angle is less than the inboard sweep angle
3. A wing assembly according to Claim 1 or Claim 2, in which the inboard sweep angle is from 28 to 30 degrees.
4. A wing assembly according to any preceding claim, in which a trailing edge of each inboard wing section extends substantially parallel to the lateral axis of the aircraft.-20 -
5. A wing assembly according to any preceding claim, in which the first outboard sweep angle is from 12 to 14 degrees.
6. A wing assembly according to any preceding claim, in which a trailing edge of each first outboard wing section is arranged to extend substantially parallel to the lateral axis of the aircraft.
7. A wing assembly according to any preceding claim, in which the second outboard sweep angle is from 41 to 43 degrees.
8. A wing assembly according to any preceding claim, in which a trailing edge of each second outboard wing section is arranged to extend at a sweep angle which is greater than the inboard sweep angle.
9. A wing assembly according to Claim 8, in which a trailing edge of each second outboard wing section extends at a sweep angle from 33 to 35 degrees.
10. A wing assembly according to any preceding claim, in which the plurality of pairs of outboard wing sections comprises a third pair comprising third outboard wing sections, wherein a leading edge of each third outboard wing section extends at a third outboard sweep angle and the third outboard sweep angle is equal to the inboard sweep angle.
11. A wing assembly according to Claim 10, in which the third outboard sweep angle is from 28 to 30 degrees.
12. A wing assembly according to Claim 10 or Claim 11, in which a trailing edge of each third outboard wing section is arranged to extend rearwardly from the trailing edge of a respective inboard wing section.
13. A wing assembly according to any of Claims 10 to 12, in which a trailing edge -21 -of each third outboard wing section extends at a sweep angle from 10 degrees to 30 degrees.
14. A wing assembly according to any preceding claim, in which the lateral length of each inboard wing section is at least 25% of the lateral length of each outboard wing section.
15. A wing assembly according to any preceding claim, in which a lateral length of each first outboard wing section is at least twice the lateral length of each inboard wing section.
16. A wing assembly according to Claim 10 or any of Claims 11 to 15 when dependent on Claim 10, in which a lateral length of each third outboard wing section is at least 1.5 times a lateral length of each inboard wing section.
17. A wing assembly according to any preceding claim, in which an aspect ratio of wings comprising the first outboard wing sections is greater than an aspect ratio of wings comprising the second or third outboard wing sections.
18. A wing assembly according to any preceding claim, in which a planform of each outboard wing section is tapered towards an outboard edge of the respective wing section.
19. A wing assembly according to any preceding claim, in which the central wing structure forms part of a common fuselage body of a modular aircraft system.
20. A modular aircraft comprising a wing assembly according to any preceding claim.
21. A modular aircraft according to Claim 20, comprising a pair of engine air intakes, each air intake being disposed above a respective inboard wing section.-22 -
22. A modular aircraft according to Claim 20, or Claim 21, in which the central wing structure is disposed proximate a lower side of a fuselage body of the aircraft such that the modular aircraft is a low wing aircraft.
23. A modular aircraft according to any of Claims 20 to 22, comprising a propulsion system mounting arrangement for removably suspending a propulsion system of the modular aircraft from a fuselage body of the aircraft and which enables the propulsion system to be removed and replaced with an alternative propulsion system.
24. A method of reconfiguring an aircraft, the aircraft comprising: a central wing structure having inboard wing sections which extend laterally on opposing sides of the central wing structure, a leading edge of each inboard wing section being arranged to extend at an inboard sweep angle with respect to a lateral axis of the aircraft; and a plurality of pairs of outboard wing sections, each outboard wing section being arranged to be removably mounted to a respective one of the inboard wing sections such that each pair of outboard wing sections is mountable to the central wing structure to provide a respective alternative wing configuration; wherein a 20 leading edge of each outboard wing section is arranged to extend at an outboard sweep angle with respect to the lateral axis of the aircraft when the outboard wing section is mounted to a respective inboard wing section, the method comprising: removing from the aircraft a first pair of outboard wing sections or a second pair of outboard wing sections; and mounting the other of the first or second pair of outboard wing sections to the central wing structure; wherein a leading edge of each of the second pair of outboard wing sections is arranged to extend at an outboard sweep angle which is greater than the inboard sweep angle.
25. The method of Claim 24, in which a trailing edge of each of the second outboard wing sections is arranged to extend at a sweep angle greater than the inboard sweep angle.