An aircraft

Abstract

An aircraft (10) comprising: a port swept wing (14B) and a starboard swept wing (14A), each swept wing having an inner wing section (26A) comprising an integrated payload fuselage (20) and an outer wing section (30A) for extending the wingspan, in which each outer wing section has a thickness less than a thickness of the corresponding inner wing section; and in which the sweep angle of each outer wing section is lower than the sweep angle of the corresponding inner wing section; a central region (12) where the port swept wing meets the second swept wing; a port transition region (23A) where the port inner wing section meets the port outer wing section; a starboard transition region (23B) where the starboard inner wing section meets the starboard outer wing section; at least one rear spar on each wing, in which each rear spar is disposed close to a trailing edge (22A) of the wing to carry loads along the respective wing; one or more elevons (34A) or ailerons on each outer wing section; and one or more roll spoilers (32A) on each inner wing section.

Description

[0001] AN AIRCRAFT

[0002] The present invention relates to an aircraft.

[0003] BACKGROUND TO THE INVENTION

[0004] A V-shaped aircraft has been devised previously by the inventor, which has been disclosed in his patent applications (including for example DE102014201040A1 ) and in a number of published papers on the concept. Proof-of-concept prototypes of the V- shaped aircraft have been made. V-shaped aircraft are characterised by a highly-swept inner wing which incorporates a payload fuselage, and an outer wing extending with a lower sweep angle, for extending the wingspan beyond that of the inner wing.

[0005] All aircraft require control surfaces to enable control of the aircraft in flight. These are generally categorised as primary control surfaces, which include ailerons, rudders and elevators, and secondary control surfaces which include flaps, spoilers and slats. Aircraft have three control axes called the yaw, roll and pitch axes. Each primary control surface controls the rotation of the aircraft about one of these axes: a rudder controls the yaw, elevators control the pitch, and ailerons control the roll. Secondary control surfaces are supplemental control surfaces. These can be, for example, spoilers which act as an air brake and reduce or ‘spoil’ the lift on a wing. High lift devices are another example of secondary control surfaces, and include trailing edge flaps, which can be deployed to change the geometry of the aerofoil, and thereby generate more lift.

[0006] Some aircraft are provided with elevons, which combine the functions of ailerons and elevators - they can be operated asymmetrically to control the roll of the aircraft or symmetrically to control the pitch.

[0007] It is also known in some aircraft (particularly in so-called “flying wings” such as the Northrop Grumman B-2 Spirit) to use control surfaces known as split flaps. A split flap comprises an upper flap which deflects upward and a lower flap which deflects downward. When the split flap is deployed, the upper and lower flaps thus split apart, creating a drag force. If a split flap is deployed on one side of the aircraft and not the other, then this will yaw the aircraft towards the side on which the split flap is deployed. It is also possible for the upper and lower surface of the split flap to be deflected together (i.e. both upper and lower surfaces deflect upwards, or both upper and lower surfaces deflect downwards) and in this way they can work as an ordinary aileron or elevator (or elevon). Split flap elevons can therefore in principle by used to control all of the roll (deflect one side upwards and the other side downwards, like ailerons), the pitch (deflect both sides upwards or both sides downwards, like elevators) and the yaw (split apart the split flap on one side but not the other) of an aircraft.

[0008] Current V-shaped aircraft concepts have been envisioned with a number of control surfaces.

[0009] Firstly, elevons can be disposed at a trailing edge of the wing, particularly on the outer wing and in the transition region between the inner and outer wings. V-shaped aircraft are particularly suited to the integration of elevons due to the existence of long sections of straight trailing edge on the outer wing. Additionally, the trailing edge of the outer wing on a V-shaped aircraft is relatively far away from the centre of gravity, in both a lateral and streamwise direction. In other words, the trailing edge of the outer wing is both far aft and outboard of the centre of gravity. Therefore, forces generated at the outer wing trailing edge act with a relatively long lever arm to the center of gravity, increasing the moment each elevon can exert on the aircraft, for both pitch and roll control. This leads to efficiencies in the control surfaces, as smaller forces are required to generate the adequate moments on the aircraft and thereby control it. Additionally, installation of simple hinged control surfaces is comparatively simple on the trailing edge of V-shaped aircraft.

[0010] V-shaped aircraft can also comprise winglets, which are vertical or near vertical extensions near the wingtips of the aircraft, designed to minimise induced drag. Winglets can provide directional stability by providing lateral area away from the centre of gravity, which can be referred to as weathervane stability. Rudders may also be provided on the winglets for yaw control. Additionally, split flaps may be installed on or near the winglets to help control the yaw of the aircraft, by selectively increasing drag on one side or the other. The split flaps may be integrated with the elevons, as described above.

[0011] Despite the above control surfaces, in extreme conditions, for example when landing in high winds or if engine failure occurs, research has shown that the control surfaces in current V-shaped aircraft designs may not provide sufficient control authority to meet certification requirements.

[0012] There are a few clear ways to improve control authority. For example, the size of the outer wings and winglets, and thereby the size of the corresponding control surfaces, could be increased. However, for a given aircraft, an increase in wing size results in an increase in the wetted area of the aircraft, which increases drag and has a negative effect on the aerodynamic performance of the aircraft. Another possible way to improve control would be to increase the approach speed of the aircraft. Control surfaces such as rudders are more efficient at higher speeds, and so smaller deflections are required. However, higher approach speeds are undesirable, especially when landing, due to airport requirements (i.e. higher speeds require longer runways, which limits the airports to which aircraft can fly).

[0013] It is an object of the present invention therefore to reduce or substantially obviate the aforementioned problems and provide a V-shaped aircraft with additional control authority, while maintaining efficiency and performance.

[0014] STATEMENT OF INVENTION

[0015] According to the present invention there is provided an aircraft comprising: a port swept wing and a starboard swept wing, each swept wing having an inner wing section comprising an integrated payload fuselage and an outer wing section for extending the wingspan, in which each outer wing section has a thickness less than a thickness of the corresponding inner wing section, and in which the sweep angle of each outer wing section is lower than the sweep angle of the corresponding inner wing section ; a central region where the port swept wing meets the starboard swept wing; a port transition region where the port inner wing section meets the port outer wing section; a starboard transition region where the starboard inner wing section meets the starboard outer wing section; at least one rear spar on each wing, in which each rear spar is disposed close to a trailing edge of the wing to carry loads along the respective wing; one or more elevons or ailerons on each outer wing section; and one or more roll spoilers on each inner wing section.

[0016] The outer wing section has an absolute thickness significantly less than the inner wing section, since the inner wing section needs to accommodate the payload fuselage, for example a pressurised passenger cabin. The outer wing is made to a thinner more aerodynamic shape. In the transition region, the thickness must taper to join the inner wing section to the outer wing section.

[0017] The presence of the roll spoilers advantageously provides additional control surfaces and enhances the control authority of the aircraft, in particular the roll of the aircraft. Additionally, simultaneous (symmetrical) deployment of the port and starboard spoilers can be used to create additional drag to slow down the aircraft, for example during descent or landing. Furthermore, the spoilers may be designed such that their simultaneous (symmetrical) deployment increases the directional stability of the aircraft. This is called weathervane stability and is generated by the additional lateral surface area that is provided by the extended roll spoilers in a region behind (and to each side of) the centre of gravity.

[0018] The one or more roll spoilers are disposed on each inner wing section. Advantageously, the roll spoilers are provided towards an outer end of each inner wing (i.e. near where the inner wing transitions into the outer wing). The roll spoilers in some embodiments may extend into the transition region. The outboard position of the roll spoilers provides improved directional and roll control, as the distance from the centre of gravity gives them larger moments with respect to the center of gravity, and therefore smaller deployments are necessary to change the roll of the aircraft. Roll spoilers can be integrated with the outer wing shape of the aircraft, and can be designed to not take up significant internal volume in the inner wing, which can be used otherwise, such as for fuel. The roll spoilers may be installed on the upper surface and / or the lower surface of the inner wings.

[0019] As well as assisting with roll control, deployment of a roll spoiler on one side also creates drag, which adds a yawing moment favourable to turning the aircraft.

[0020] Outboard, as used herein, is used to describe a position located away from the midline of an aircraft, which runs along the approximate ‘axis of symmetry’ of the aircraft, i.e. the longitudinal axis.

[0021] The roll spoilers can also be used for small corrections to the aircraft altitude or direction during cruising flight or other higher speed flight conditions. On the inner wing, in the region where the roll spoilers are, the local lift coefficients are lower due to the larger chord in this region (the larger chord is to accommodate the height of the internal fuselage). Control surface deflections in this region therefore lead to more efficient control of the aircraft in transonic conditions. In contrast, due to the low chord lengths of the outer wing the local lift coefficients in this region are very high and therefore rudder deflections in this region may result in significant drag during manoeuvres in transonic conditions.

[0022] The aircraft may comprise one or more front spars, in which the front spar is disposed close to a leading edge of each wing. The one or more roll spoilers may be attached to or close to a spar of the aircraft (i.e. a front or rear spar). The one or more roll spoilers may be attached to or close to the rear spar. Attaching them close to the spars of the aircraft provides an efficient structural solution for their attachment and makes the attachment light due to the minimal need for additional attachment components.

[0023] Each roll spoiler may have a hinge axis. Each roll spoiler is pivotable about its hinge axis to deploy or return the roll spoiler. The hinge axis of each roll spoiler may be close to a spar of the aircraft. This allows the bulk of the roll spoiler, including the hinge mechanism and attachment components, to be close to the spar.

[0024] An engine may be disposed at the trailing edge of the inner wing section of each wing. Each roll spoiler may be disposed on the wing in a position outward of an engine (i.e. the roll spoiler may be further from the centre line (approximate line of symmetry) of the aircraft than the engine).

[0025] The roll spoilers may be disposed on an upper surface and / or a lower surface of each wing. Therefore, each roll spoiler may not take up significant amounts of interior volume in the trailing edge region of the inner wing and the transition region . This advantageously allows the interior volume to be used otherwise, for example to carry conventional fuel, or to accommodate hydrogen fuel tanks.

[0026] The elevons on the outer section of the wing may comprise split flaps. These may be used as primary control surfaces to control the roll and pitch. The split flaps may be deployed upwards or downwards together to act as elevators. The split flap on one side of the aircraft may be deployed upwards while the split flap on the other side of the aircraft is deployed downwards, to act as ailerons. The split flap on one side may be split apart, where an upper flap of the split flap deploys upwards and a lower flap of the split flap deploys downwards, to increase drag on one side and thereby provide yaw control to the aircraft.

[0027] The elevons on the outer wing portion of the aircraft may not extend into the transition region. Advantageously, this means the roll spoilers can extend into a transition region. It is preferable to have the roll spoilers extend into the transition region as they do not take up significant internal volume and are instead substantially disposed on the outer surface of the aircraft. Therefore, the volume at a rear of the transition region, in particular that close to the trailing edge, can be advantageously used for fuel or aircraft systems. This optimises the use of the outer control surface area, and the interior volume. Additionally, having roll spoilers rather than elevons in this region overcomes problems associated with this region due to the thickness (i.e. the chord) of the transition region since there is a preference to have the hinge of the control surfaces around 80% of the way along the chord to the rear of the aircraft. The significant chord here makes that difficult for the elevons, which take up internal space, as they may clash with the space required for the pressurised cabin.

[0028] A portion of the roll spoiler may be disposed on the transition region. Extending the roll spoilers further outboard (i.e. not only on the inner wing) means that only small deployments are necessary to change the roll of the aircraft, as their deployment has an increased moment on the aircraft, relative to roll spoilers further inboard of the aircraft.

[0029] A deployable fin may be disposed on each transition region. Each fin may be deployable from a flat position, in which the fin forms a substantially continuous surface with the wing, to a deployed position. Each fin may be attached to a surface of the wing.

[0030] In another embodiment, deployable fins may be provided on for example a fairing or tank disposed in the transition region, rather than directly on the surface of the wing. In any case, in the non-deployed position, the fins form a substantially continuous surface with the surface to which they are attached, and in the deployed position they extend vertically from the surface to form a fin.

[0031] The deployable fin may be oriented streamwise in the deployed position. The extension mechanism for the deployable fin may be preloaded. In other words, the fins will tend to deploy in the absence of a mechanism to hold them in place in the folded position. It is envisaged that the fins will generally be used only in extreme conditions, for example landing in strong crosswinds or in the event of one engine failing. Deployment of the fins would certainly decrease the performance and efficiency of the aircraft, but would ensure directional stability in these extreme conditions, when it is envisaged that they could deploy automatically as a safety mechanism. The deployable fins also potentially allow the engines to be placed further apart, since the additional yawing moment created by a single engine failure condition when the engines are further apart can be safely counteracted by the deployable fins. Placing the engines further apart has potential advantages for overall aircraft design, and further potential advantages in terms of more room for high-lift devices and / or fuel in the central region, between the engines.

[0032] By having roll spoilers to enhance the roll control of the aircraft, the elevons on the outer wing may not need to be as long and therefore don’t extend into the transition region, which leaves space in the transition region for the deployable fins.

[0033] The sweep angle of each inner wing section may be greater than 60°. The sweep angle of the inner wing section may be greater than the sweep angle of the outer wing section. This advantageously reduces drag.

[0034] The aircraft may comprise at least one extension having an internal volume behind the trailing edge of the wings, the at least one extension being disposed in at least one of the first and second transition region. The aircraft may comprise at least one extension having an internal volume behind the trailing edge of the wings, the at least one extension being disposed in the central region. These extensions may be, or may house, tanks such as those for carrying fuel (including hydrogen fuel).

[0035] Aircrafts with an extension such as the above may have smaller control surface area due to the space required for the extensions. In particular, space required for extensions in the first and second transition region. Therefore, the roll spoilers may be particularly useful in such embodiments to provide additional control surface area.

[0036] The at least one extension may be cylindrical, or cone shaped. The at least one extension may be orientated in a streamwise direction. The cylinder or cone diameter may be substantially similar to a maximum thickness of the swept wings at the central region.

[0037] According to a second aspect of the invention, there is provided an aircraft comprising: a port swept wing and a starboard swept wing, each swept wing having an inner wing section comprising an integrated payload fuselage and an outer wing section for extending the wingspan, in which each outer wing section has a thickness less than a thickness of the corresponding inner wing section , and in which the sweep angle of each outer wing section is lower than the sweep angle of the corresponding inner wing section ; a central region where the port swept wing meets the starboard swept wing; a port transition region where the port inner wing section meets the port outer wing section; a starboard transition region where the starboard inner wing section meets the starboard outer wing section; at least one rear spar on each wing, in which the rear spar is disposed close to a trailing edge of the wing to carry loads along the respective wing; and a deployable fin disposed in each transition region.

[0038] The deployable fin on the transition region of the aircraft can provide increased directional stability to the aircraft. It may be deployed for example in extreme conditions, such as in a cross-wing landing or in the event of a single engine failure.

[0039] Each deployable fin may be deployable from a flat position, in which the fin forms a substantially continuous surface with the surface to which it is attached, to a deployed position. The fin may be substantially vertical in the deployed position The fin can be deployed when necessary and stowed when not needed. It can be deployed in extreme conditions such as a landing in a crosswind or in the case of the failure of one engine. It can be stowed to a flat position to reduce the wetted area associated with the fin, that would otherwise increase the drag acting on the aircraft.

[0040] Each deployable fin may be oriented streamwise in the deployed position. This is to provide lateral surface area, whilst minimising the drag generated by each fin.

[0041] Each fin may be attached to a surface of the wing. Each fin may be attached to an upper and / or lower surface of the wing. In this case, in the non-deployed position the fin forms a continuous surface with the surface of the wing. Alternatively, the fins may be attached to for example a fairing or tank in the transition region.

[0042] The extension mechanism associated with the fins may be preloaded. In other words, the fins may provide a temporary and emergency solution in case of an engine failure (for example by being able to deploy as a one off). The fins may extend, preferably automatically, during an engine failure to improve the directional stability of the aircraft in such a situation. A current concern is that if one engine fails, its outboard placement leads to significant yaw of aircraft, which must currently be counteracted using control surfaces, due to the creation of a large, unbalanced moment. Deployment of fins in case of engine failure would mitigate this risk, and therefore allow the engines to be placed further apart than in conventional V-shaped aircraft concepts. This would in turn increase the available space in and in the central region of the aircraft and to either side of it. Additional space could be used for high-lift devices (see the applicant’s copending application GB2405367.0) or fuel, including for hydrogen fuel tanks (see the applicant’s co-pending application GB2319730.4).

[0043] Control surfaces may be disposed on the outer wing section. The control surfaces on the outer wing section may not extend into the transition region. This enables easy integration of the fins in the transition region.

[0044] One or more roll spoilers may be disposed on each inner wing section.

[0045] In embodiments of the first or second aspects of the invention, a streamwise join can exist in the transition region without intersecting the control surfaces. In other words, there may be a clear space along a streamwise line in the transition region, in which no control surfaces at all are disposed. This means that the outer wing could be constructed separately to the inner wing and joined later.

[0046] The fins may be disposed on an upper surface of the wing and deploy upwards. The fins may be disposed on a lower surface of the wing and deploy downwards. There may be a combination of upper surface fins and lower surface fins.

[0047] Where one or more fins are disposed on the lower surface of the wing and deploy downwards, the fins may be equipped with outrigger gear. Advantageously, this may ensure clearance of the outer wing tips at large bank angles during landing. The outrigger gear may comprise wheels, which can make contact with the ground first if an aircraft lands at an angle and help to stabilise the aircraft during landing. The additional thickness and structural spars in the transition region mean that fins with outriggers can be attached here and bear loads without significant additional reinforcement.

[0048] BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the present invention, and to show more clearly how it may be carried into effect, reference will now be made by way of example only to the accompanying drawings, in which:

[0049] Figure 1 is a perspective view of a first embodiment of an aircraft according to the present invention;

[0050] Figure 2 is a plan view of a second embodiment of an aircraft according to the present invention;

[0051] Figure 3 is a plan view of a third embodiment of an aircraft according to the present invention;

[0052] Figure 4 is a perspective view of a fourth embodiment of an aircraft according to the present invention, with fins in a flat position; and

[0053] Figure 5 is a perspective view of the aircraft of Figure 4, with the fins in a deployed position.

[0054] DESCRIPTION OF PREFERRED EMBODIMENTS

[0055] Referring firstly to Figure 1 , an aircraft is indicated generally at 10. The aircraft comprises a central region 12, a starboard wing indicated at 14A and a port wing indicated at 14B. The wings 14 extend from the central region 12. The wings 14 enclose an integrated payload fuselage indicated at 20. Each wing 14A, 14B has a leading edge 18A, 18B and a trailing edge 22A, 22B.

[0056] For brevity, the starboard wing and not the port wing is described fully. The port wing is symmetrical to the starboard wing and will comprise identical features. Symmetrical / identical features labelled on the starboard wing as xA will be labelled on the port wing as xB.

[0057] It will be appreciated that in embodiments, the aircraft may not be completely symmetrical, for example different equipment may be provided on either side. However most embodiments are likely to be roughly symmetrical in their main features.

[0058] The starboard wing 14A is disposed extending from the central region 12. The wing 14A extends substantially horizontally. The wing 14A comprises an inner wing section 26A that attaches to the central region 12. The wing 14 comprises an outer wing section 30A which extends from the inner wing section 26A. The inner wing section 26A has a positive sweep angle. Preferably, the inner wing section 26A has a sweep angle of over 50 degrees. The outer wing section 30A also has a positive sweep angle. The sweep angle of the outer wing section 30A is less than the sweep angle of the inner wing section 26A. The wing 14A comprises a transition region 23A where the inner wing 26A is joined to the outer wing 30A. I.e. the transition region 23A is the area of wing close to the “kink” (the change in sweep angle). In the transition region, the thickness of the wing will also taper from the relatively thick inner wing section 26A to the thin outer wing section 30A.

[0059] Each wing section 26A, 30A has a leading edge. In this embodiment the leading edge 18A extends along the inner wing section 26A and the outer wing section 30A. The leading edge 18A runs in a straight line along the front of the inner wing section 26A. There is then a discontinuity in the transition region 23A where the leading edge 18A transitions to a significantly smaller sweep angle in the outer wing section 30A. The outer wing section 30A provides an increased wingspan of the aircraft. In this embodiment, it is the inner wing section 26A which integrates the payload fuselage 20. The outer wing section 30A is much thinner, more akin to the wing of a conventional aircraft.

[0060] The payload fuselage 20 is integrated into a front part of the inner wing section 26A. In other words, the payload fuselage 20 is integrated near to the leading edge 18A, and part of the wing extends behind the payload fuselage 20 (i.e. aft and towards the centreline of the aircraft) to the trailing edge 22A. The payload fuselage 20 runs broadly parallel to the leading edge of the wing. The payload fuselage 20 is integrated into the inner wing section 26A for more even weight distribution and therefore reduced bending moments. The payload fuselage 20 may be pressurised for accommodation of passengers.

[0061] Engine 46A is provided on the trailing edge of the wing 14A, approximately halfway along the inner wing section 26A. The engine may be semi-buried, i.e. may have an intake at the boundary layer close to the wing.

[0062] A winglet 36A is provided on the outer wing portion 30A at the distal end of each wing (i.e. furthest from the central region 12). The winglet 36A is substantially perpendicular to the outer section of the wing 30A for reducing drag. The winglet 36A is oriented substantially vertically. A rudder 56A is disposed at the rear of the winglet 36A. The rudder 56A is a control surface that can be used to control the yaw of the aircraft 56A. Roll spoiler 32A is disposed on the wing 14A. The roll spoiler 32A is disposed on the inner wing section 26A. Roll spoiler 32A is disposed behind engine 46A (i.e. further along the wing towards the end of the wing than the engine 46A). Roll spoiler 32A has a hinge axis 54A around which it can rotate. Hinge axis 54A is disposed proximate to a rear spar of the wing. Therefore, the roll spoiler 32A can be attached to the aircraft without the need for additional heavy attachment components.

[0063] The roll spoiler 32A extends from a region aft of the engine 46A, to and into the transition region 23A. The roll spoiler 32A can extend into the transition region 23A as elevon 34A (described in detail below) can be slightly shorter than in previous designs, given the increased roll control provided by the roll spoiler 32A. Additionally the roll spoiler 32A advantageously does not take up significant internal volume in the inner wing section, leaving space for payload, fuel, or other aircraft equipment.

[0064] The roll spoiler 32A is advantageously disposed behind the pressurised cabin region 20 (i.e. towards the trailing edge of the wing from the pressurised cabin region) . The pressurised cabin 20 is near a leading edge 18A of the aircraft and may be substantially cylindrical in cross section for maximum strength. The inner wing section 26A however must be an aerodynamic aerofoil shape. This means a rear fairing extends behind the pressurised cabin 20, that is used for storage of aircraft systems or fuel. The roll spoiler 32A is advantageously disposed on this rear fairing, as it requires very little internal volume, so makes best use of the available surface area of the aircraft in this region , whilst leaving the maximum volume available from the rear fairing for storage. The available storage can therefore be used for fuel, such as hydrogen fuel.

[0065] Control surfaces, specifically elevons 34A, are disposed on the outer wing section 30A. The elevons 34A are disposed at a trailing edge 22A of the outer wing section 30A. Three elevons 34A are disposed along the outer wing section 30A.

[0066] Each of the elevons 34A may be in the form of a split flap. The split flap may comprise upper and lower flaps. The upper and lower flaps may be deflected together, upwards or downwards, to work as an elevon, or the upper flap may be deflected upward and the lower flap deflected downward, to increase drag and create a yawing moment.

[0067] Figure 1 illustrates an example scenario. Elevons 34A are extended (ie. deployed to a position in which the elevons 34A is angled upwards) to generate a rolling moment for the aircraft 10 to enter a right turn. The port elevons 34B are extended downward. The roll spoiler 32A on the starboard wing 14A is also extended. The roll spoiler 32A can thereby add to the rolling moment by reducing the lift generated on the outboard side of the inner wing section 26A of the starboard wing 14A. The roll spoiler 32B on the port wing 14B is not deployed and is flat, keeping the lift unchanged on the inner section 26B of the port wing 14B. The additional rolling moment generated by the deployment of the roll spoiler 32A provides more control authority for the roll and turn manoeuvre. Additionally, the roll spoiler 32A on the starboard wing 14A creates drag, thereby creating a yawing moment favourable for entering the right turn.

[0068] Figure 2 is a plan view of a different embodiment of the invention, that is substantially identical to the one shown in Figure 1 . However, instead of three elevons 34A, there are two elevons 134A (which may also be split flaps) on the outer wing section 130A.

[0069] Features already described in the previous embodiment, that are substantially identical in this embodiment, shall be labelled sequentially, i.e. a feature labelled in the first embodiment (Figure 1 ) as 20A will be labelled as 120A in the next embodiment (Figure 2) and as 220A in the next embodiment (Figure 3).

[0070] It is apparent from Figure 2 that the elevons 134A do not extend far into the transition region, leaving space for roll spoiler 132A. Figure 2 also shows that a streamwise join can exist in the transition region without cutting through any of the control surfaces. This means that the inner and outer wing can be manufactured separately, and joined at a streamwise join later.

[0071] Figure 3 shows an alternative embodiment of the present invention. In this embodiment, tanks 244, 238 for additional storage volume, such as that used for fuel, are disposed on the aircraft 210.

[0072] A central tank 244 is disposed in the central region 212 of the aircraft 210. The central tank 244 is oriented such that the long axis of its cone is substantially aligned with a streamwise direction. The central tank 244 has a root diameter similar to the maximum thickness of the wing profile. As in previous embodiments, the wing 214A comprises a transition region 223A where the inner wing 226A is joined to the outer wing 230A. Starboard outer tank 238A is disposed proximate to transition region 223A. Similarly, port outer tank 238B is disposed proximate to the transition region 223B of the portside wing 214B.

[0073] The tanks 238A, 238B, 244 are similar in function. The tanks 238A, 238B, 244 are used to accommodate fuel. The tanks 238A, 238B, 244 can accommodate a pressurized volume. The pressurised fuel tanks can be used to store liquid hydrogen. A vertical fin 240 may be provided on top of the outer tanks 238, for additional lateral stability. This fin is known from prior designs, and increases stability but at a cost of decreased aerodynamic performance and efficiency.

[0074] Additional control surfaces, which may be elevons 234A and also split flaps, are disposed on the outer wing section 230A. These elevons 234A are disposed near, and substantially parallel to the trailing edge 222A. An elevon 234A extends from near the winglet 236A to the edge of the extension 238A.

[0075] Aircrafts with tanks 238, 244 may have less surface area available for elevons 234A, due to the space required for the tanks. Therefore, roll spoilers 232A may be particularly useful in such embodiments to provide more control surface area placed away from the tanks 238, 244.

[0076] Figure 4 shows another embodiment. As in previous embodiments, roll spoilers 332A are provided on the inner wing section 326A, and elevons 334A are provided on the outer wing section 330A. However, in this embodiment, a deployable fin 350A is provided on the wing 314A.The deployable fin 350A is moveable from a flat position to a vertical position. Figure 4 shows the deployable fin 350A in the flat position, in which it forms a substantially continuous surface with the upper surface of the wing 314A.

[0077] The deployable fin 350A has a hinge axis 352A. The deployed fin is oriented in a substantially streamwise direction. The hinge axis 352A is also oriented in a streamwise direction. The hinge axis 352A meets a kink at the trailing edge 322A, where the trailing edge of the outer wing 330A meets the trailing edge 322A of the inner wing 326A.

[0078] The deployable fin 350A is disposed at the transition region 323A. The deployable fin 350A extends from the transition region 323A towards or into the outer wing section 330A when in a flat position, as shown in Figure 4. The deployable fin 350A is disposed close to a trailing edge 322A of the outer wing section 330A. A front edge of the deployable fin 350A joins with a front edge of elevon 334A.

[0079] A rudder 356A is disposed on the winglet 336A, which can be used to control the yaw of the aircraft 310, as in previous embodiments.

[0080] Figure 5 shows the deployable fin 350A in the deployed, vertical position. Arrows show the direction in which the fins move from the flat to vertical position. Roll spoiler as used herein describe spoilers that can be used asymmetrically as flight control surfaces to provide roll control. Spoiler is used to mean a device which intentionally reduces the lift component of an aerofoil in a controlled way.

[0081] The embodiments described above are provided by way of example only, and various changes and modifications will be apparent to persons skilled in the art without departing from the scope of the present invention as defined by the appended claims.

Claims

CLAIMS1 . An aircraft comprising: a port swept wing and a starboard swept wing, each swept wing having an inner wing section comprising an integrated payload fuselage and an outer wing section for extending the wingspan, in which each outer wing section has a thickness less than a thickness of the corresponding inner wing section, and in which the sweep angle of each outer wing section is lower than the sweep angle of the corresponding inner wing section; a central region where the port swept wing meets the starboard swept wing; a port transition region where the port inner wing section meets the port outer wing section; a starboard transition region where the starboard inner wing section meets the starboard outer wing section; at least one rear spar, on each wing, in which each rear spar is disposed close to a trailing edge of the wing to carry loads along the respective wing; one or more elevons or ailerons on each outer wing section; and one or more roll spoilers on each inner wing section.

2. An aircraft as claimed in any previous claim, comprising one or more front spars, in which the front spar is disposed close to a leading edge of each wing.

3. An aircraft as claimed in any previous claim, in which the one or more roll spoilers are attached to or close to a spar of the aircraft.

4. An aircraft as claimed in any previous claim, in which the one or more roll spoilers are attached to or close to the rear spar.

5. An aircraft as claimed in any previous claim, in which each roll spoiler has a hinge axis, and the hinge axis of each roll spoiler is close to a spar of the aircraft.

6. An aircraft as claimed in any previous claim, further comprising an engine disposed at the trailing edge of the inner wing section of each wing.

7. An aircraft as claimed in any previous claim, in which each roll spoiler is disposed on the wing in a position outward of an engine.

8. An aircraft as claimed in any previous claim, in which the roll spoilers are disposed on an upper surface and / or a lower surface of each wing.

9. An aircraft as claimed in any previous claim, in which the elevons or ailerons on the outer wing portion of the aircraft do not extend into the transition region.

10. An aircraft as claimed in any previous claim, in which the elevons or ailerons comprise split flaps.1 1 . An aircraft as claimed in any previous claim, in which a portion of the one or more roll spoilers are disposed on the transition region.

12. An aircraft as claimed in any previous claim, in which a deployable fin is disposed on each transition region.

13. An aircraft as claimed in claim 12, in which each deployable fin is deployable from a flat position, in which the fin forms a substantially continuous surface with the wing, to a deployed position.

14. An aircraft as claimed in claim 12 or claim 13, in which each deployable fin is oriented streamwise in the deployed position.

15. An aircraft as claimed in any previous claim, in which the sweep angle of each inner wing section is greater than 60°.

16. An aircraft as claimed in any previous claim, in which the aircraft comprises at least one extension having an internal volume behind the trailing edge of the wings, the at least one extension being disposed in at least one of the first and second transition region.

17. An aircraft as claimed in any previous claim, in which the aircraft comprises at least one extension having an internal volume behind the trailing edge of the wings, the at least one extension being disposed in the central region.

18. An aircraft comprising: a port swept wing and a starboard swept wing, each swept wing having an inner wing section comprising an integrated payload fuselage and an outer wing section for extending the wingspan, in which each outer wing section has a thickness less than a thickness of the corresponding inner wing section, and in which the sweep angle of each outer wing section is lower than the sweep angle of the corresponding inner wing section ; a central region where the port swept wing meets the starboard swept wing; a port transition region where the port inner wing section meets the port outer wing section; a starboard transition region where the starboard inner wing section meets the starboard outer wing section; at least one rear spar on each wing, in which the rear spar is disposed close to a trailing edge of the wing to carry loads along the respective wing; and a deployable fin disposed in each transition region.

19. An aircraft as claimed in claim 18, in which each fin is deployable from a flat position, in which the fin forms a substantially continuous surface with the surface to which it is attached, to a deployed position.

20. An aircraft as claimed in claim 18 or claim 19, in which the deployable fin is oriented streamwise in the deployed position.21 . An aircraft as claimed in any previous claim, in which the deployable fin is substantially vertical when in the deployed position.

22. An aircraft as claimed in any previous claim, in which each deployable fin is attached to an upper and / or lower surface of the wing.

23. An aircraft as claimed in any previous claim, in which an extension mechanism associated with the fins is preloaded.

24. An aircraft as claimed in any previous claim, in which the fins are disposed on a lower surface of the wing and deploy downwards.

25. An aircraft as claimed in claim 24, in which the fins are equipped with outrigger gear.

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