An aircraft

Abstract

An aircraft (10) comprising: a starboard swept wing (14A) and a port swept wing (14B), each swept wing having an inner wing section (32) comprising an integrated payload fuselage and an outer wing section (34) for extending the wingspan, in which each outer wing section (34) has a thickness less than a thickness of the corresponding inner wing section (32); a central region (12) where the starboard swept wing meets the port swept wing; a starboard transition region where the starboard inner wing section (32A) meets the starboard outer wing section (34A); a port transition region where the port inner wing section (32B) meets the port outer wing (34B) section; in which at least one high-lift device is disposed on or at a trailing edge of the inner wing section of each swept wing.

Description

[0001] AN AIRCRAFT

[0002] The present invention relates to an aircraft.

[0003] BACKGROUND TO THE INVENTION

[0004] A V-shaped aircraft has been previously devised by the inventor, which has been disclosed in his patent applications (including DE102014201040A1 , N2034242 and GB2319730.4) and in a number of published papers on the concept. Proof-of concept prototypes have been made. V-shaped aircraft can have fuselage sections integrated into the wings. The layout of V-shaped aircraft enables lift to be generated across the whole aircraft. This is unlike in conventional aircraft, where the wings and fuselage are distinct, and lift is generated by the wings whilst minimal lift is generated by the fuselage.

[0005] Aircraft need lift to counteract their weight to become and remain airborne. This is usually achieved by designing the wing shape and controlling the wing angle with respect to the inflow such that an upwards lift force is generated due to the pressure difference above and below the wings. Lift is proportional to the square of the velocity of the aircraft. Therefore, achieving sufficient lift can be a challenge at low speeds, for example during take-off and landing.

[0006] V-shaped aircraft can have roughly double the wing area of conventional aircraft. Therefore, much of the necessary lift at take-off and landing can be generated by means of angle of attack changes only. To maximise the lift, high angles of attack are required.

[0007] Yet, using high angles of attack at take-off and landing means that a long landing gear is required to ensure the wing tips or rear of the aircraft are clear of the runway.

[0008] However, a long landing gear has several disadvantages. A long landing gear increases the weight of the aircraft, leading to higher fuel consumption and reduced payload capacity. It can also be challenging to integrate a long landing gear into the aircraft, leading to potential construction challenges and structural compromises.

[0009] Furthermore, relying only on the clean wing shape of V-shaped aircraft to generate lift limits possibilities for fine tuning of the lift distribution and trimming in order to minimize drag. Ways of increasing lift and decreasing the angle of attack at lower speeds have been studied in the past by installing split flaps in regions on the lower belly of a V-shaped aircraft. However, drag increases through the use of belly flaps only. The drag may be considerable, and the amount of additional lift is limited.

[0010] It is an object of the present invention to reduce or substantially obviate the aforementioned problems.

[0011] STATEMENT OF INVENTION

[0012] According to the present invention there is provided an aircraft comprising: a starboard swept wing and a port 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 the inner wing section is greater than the sweep angle of the outer wing section; a central region where the starboard swept wing meets the port swept wing; a starboard transition region where the starboard inner wing section meets the starboard outer wing section; a port transition region where the port inner wing section meets the port outer wing section, in which at least one high-lift device is disposed on or at a trailing edge of the inner wing section of each swept wing.

[0013] The high-lift devices enable the aircraft to take-off and land with a decreased angle of attack as compared to the prior art. In turn, this means shorter landing gear can be used.

[0014] High-lift devices may be disposed on an upper surface of the aircraft. The high-lift devices may extend in use. The high-lift device may be secured to an inner wing section.

[0015] The high-lift device may be pivotable about an axis proximal and parallel to a trailing edge of the inner portion of the wing. The high-lift device may alternatively be extendable from a trailing edge of the inner wing section. The high-lift device, for example a flap, may be movable from a neutral position to one or more deployed positions.

[0016] ‘Thickness’ as used herein refers to an absolute thickness rather than a thickness to chord ratio.

[0017] The at least one high-lift device may be disposed in front of (i.e. forwards of) a centre of gravity of the aircraft. A deployed high-lift device can add additional camber to the wings, which produces a nose-down pitching moment. By disposing the one or more high-lift devices in front of the centre of gravity, the upwards lift generated creates an upwards pitching moment to counteract the nose-down pitching moment. Therefore, the one or more high-lift devices can be deployed without significantly influencing the overall pitching moment. This is advantageous as conventional trimming to counteract a pitching moment is more limited on Flying V designs than on conventional aircraft. The present invention differs from past blended wing body (BWB) designs, which can only have belly flaps on the lower surface of the wing as an option for a pitch-neutral flap. The present invention advantageously allows for placement of pitch-neutral flaps at the trailing edge of the aircraft.

[0018] The at least one high-lift device may be a flap. The at least one high-lift device may be any of a plain flap, split flap, single slotted flap, multi slotted flap, fowler flap, or any combination of such. Flaps may be of various sizes depending on aircraft size and type I intended purpose. The at least one high-lift device could alternatively be any of a, slot, boundary layer control, blown flap, or co-flow jet, or any similar high-lift device. Any combination of any high-lift device disclosed, or suitable high-lift device may be used. High-lift devices generate lift, for example by increasing the camber of the wing and the wing area.

[0019] The inner wing may comprise a rear spar. The rear spar may run along a length of each wing, closer to a trailing edge of each wing. An inner wing fairing may be provided at a trailing edge of the rear spar. The one or more high-lift devices may be disposed on or integral to the inner wing fairing. Storage volumes may be provided in the inner wing fairing, for example for fuel. The rear spar provides a sound structural base from which to attach the high-lift devices and / or the inner wing fairing.

[0020] One extension having an internal volume may be provided at a trailing edge of the central region. At least one extension having an internal volume may be provided at a trailing edge of at least one of the starboard and port transition regions. This increases the storage capacity of the aircraft without having an unduly negative effect on aerodynamics. For example, the extension may be used for fuel. It may be used for cargo or passengers. It also further necessitates the use of high-lift devices due to the increased weight of the aircraft.

[0021] One or more engines may be provided at or extending from a trailing edge of each of the inner wings. The one or more engines may be provided substantially halfway along each inner wing. The high lift device may be disposed otherwise than in front of the engines. I.e. the high lift device may be laterally spaced from the engine. This allows for substantially undisturbed inflow to the engine, and efficient integration of the high- lift devices with the engines. For example, the high-lift device may have a lateral edge parallel to a streamwise direction.

[0022] Each of the high-lift devices may be attached and guided by one or more corresponding attachment means. The attachment means may be provided parallel and proximal to the lateral edge of the high-lift devices. The attachment means may be provided on or integral to the central extension. The one or more attachment means for attaching and guiding the high-lift devices may be a flap track fairing.

[0023] One high-lift device may be provided on each inner wing section. Alternatively, multiple high-lift devices may be provided on each inner wing section.

[0024] Two or more high-lift devices may be provided on each wing, wherein the two or more high-lift devices may have minimal gaps at each join for minimising any negative effect on the aerodynamics of the aircraft. The high-lift devices could have a join part way along a trailing edge of each wing.

[0025] The starboard and port high-lift devices may join together in a central region if no central extension is provided.

[0026] Where two high-lift devices meet each other, there may be minimal gaps between the high-lift devices to minimise any negative effect on the aerodynamics of the aircraft.

[0027] Additionally, fairings may also be designed to mitigate gaps for airflow between high- lift devices, for example flaps, during their deployment.

[0028] T railing edge flaps may be superior to belly flaps (i.e. flaps provided on a lower surface of the wings) for a number of reasons. Belly flaps used in isolation without additional flaps may increase drag. Furthermore, belly flaps may be limited to less efficient types of flaps, such as split flaps, rather than more efficient types of flaps such as slotted flaps or fowler flaps.

[0029] The sweep angle of inner wing sections may be greater than 50°, preferably greater than 55° or even more preferably greater than 60°. The sweep angle of the inner wing section is greater than the sweep angle of the outer wing section. The higher sweep angle of the inner wing section allows the inner wing section to be relatively thick while minimising transonic drag.

[0030] BRIEF DESCRIPTION OF THE DRAWINGS

[0031] 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:

[0032] Figure 1 shows a perspective view of the aircraft in a first embodiment;

[0033] Figure 2 shows a side view of an alternative embodiment; and

[0034] Figure 3 shows an alternative embodiment of the aircraft, from above.

[0035] DESCRIPTION OF PREFERRED EMBODIMENTS

[0036] 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. Each wing 14 extends laterally from the central region 12. Each wing 14 encloses an integrated payload fuselage indicated at 20. Each wing 14 further comprises leading edges 18A, 18B and trailing edges 22A, 22B. The leading edges 18A, 18B and the trailing edges 22A, 22B are substantially parallel to each other. Engines 16A, 16B are disposed at the trailing edges 22A, 22B of each wing 14A, 14B. Flaps 26A, 26B, described further below, are disposed on or at a trailing edge of each wing.

[0037] For brevity, the starboard wing 14A and not the port wing 14B is described fully throughout the description. The port wing is symmetrical to the starboard wing and will comprise identical features. Symmetrical I identical features labelled on the starboard wing as xA will be labelled on the port 10 wing as xB. 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.

[0038] 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 32A that attaches to the central region 12. Engine 16A is disposed on the inner wing section 32A. The wing 14A comprises an outer wing section 30A which extends from the inner wing section 32A. The inner wing section 32A has a positive sweep angle. Preferably, the inner wing section 32A has a sweep angle of over 60 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 32A.

[0039] Each wing section 32A, 30A has a leading edge 18A. In this embodiment, the leading edge 18A extends along the inner wing section 32A and the outer wing section 30A. The leading edge 18A runs in a straight line along a front of the inner wing section 32A. There is then a vertex in the transition region where the leading edge 18A transitions to a significantly smaller sweep angle in the outer wing section 30A. The trailing edge 22A runs in a straight line along a rear of the inner wing section 32A. There is then a vertex in the transition region where the trailing edge 22A 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 32A which integrates the payload fuselage. The outer wing section 30A is much thinner, more akin to the wing of a conventional aircraft.

[0040] In this embodiment, a central flap and an outer flap 26A are provided on starboard wing 14A. The flaps 26A are disposed at the trailing edge 22A of the inner wing section 32A. In this embodiment, there are therefore four flaps on the aircraft, two on each inner wing 32A. The flaps 26A form a continuation of an upper surface of the aircraft. The interface of the central and outer flaps 26A is minimal to ensure the airflow is not disrupted by the break.

[0041] The central flap 26A of the starboard wing 14A meets a corresponding central flap 26B of the port wing 14B in the central region 12 of the aircraft 10. The interface of central flaps 26A and 26B has minimal gaps between the central flaps 26 in the central region 12 to minimise formation of disturbed airflow in flight. That is to say, the surfaces of flaps 26A are substantially continuous to provide a continuous surface for air to flow over. In this embodiment, the wing 14A has a rear spar. The rear spar 28A is disposed at the rear of the wing 14A, near the trailing edge 22A. The wing 14A has a rear wing fairing 24A. A rear wing fairing 24A is disposed from the rear spar 28A. The rear wing fairing 24A is disposed in a streamwise direction. The rear wing fairing 24A is disposed in a backwards direction, relative to the direction of travel. In this embodiment, two flaps 26A are disposed on a trailing edge of the rear wing fairing 24A. One central flap is provided, proximate to the central region 12 of the aircraft 10, and one outer flap is provided. Central and outer flaps are defined along an axis parallel to the trailing edge of the inner wing. Each flap 26A can extend the rear wing fairing 24A. That is to say, two flaps, a central flap and an outer flap are provided on each wing.

[0042] Outer edges of each flap 26A may have a lateral edge parallel to a streamwise direction, one of which is indicated at 9A. The outer flap 26A has a lateral edge parallel to the streamwise direction to enable undisturbed air flow in front of the engine 16A. A structural element is present at or near this lateral edge 9A. The structural element further comprises means to attach and guide the deployment and retraction of flaps 26, for example flap track fairings. The surfaces of flaps 26A, 26B are substantially continuous to provide a continuous surface for air to flow over.

[0043] A winglet 34A is provided on the outer wing portion 30A at an outer end of the wing 14A. The winglet 34A is substantially perpendicular to the outer portion 30A of the wing for reducing drag. The winglet 34A is oriented substantially vertically.

[0044] Figure 2 shows a side view of an alternative embodiment of the aircraft 10, shown from the port side. The approximate centre of gravity is indicated by dot 40.

[0045] A cross section through the centre of the aircraft 10 is shown in dashed lines. The cross section is through a substantially central, vertical and streamwise cross section through the central region 12 of the aircraft 10. The rear wing fairing 24 is shown at a trailing edge of the central region. Flap 26 is disposed at the trailing edge of the rear wing fairing 24. In this figure, the flap is shown in the extended position, for instance in a position suitable for take-off. The flap 26 would retract towards the rear wing fairing 24 in the retracted position.

[0046] The flap 26 is disposed in front of the centre of gravity. Disposing the one or more high- lift devices in front of the centre of gravity enables substantially pitch neutral deployment. Figure 3 shows an alternative embodiment of the aircraft 110. As in previous embodiments, the aircraft 110 comprises a central region 112, a starboard wing 114A and a port wing 114B. The wings 114 extend laterally from the central region 112. The wings 114 enclose an integrated payload fuselage 120. Each wing 114 comprises leading edges 118A, 118B and trailing edges 122A, 122B. Winglets 134 are provided, as in previous embodiments.

[0047] In this embodiment, a central storage tank 152 is disposed at a trailing edge of a central region 112 of the aircraft.

[0048] An outer tank 150A is disposed at a trailing edge of a transition region between inner wing 132A and outer wing 130A.

[0049] Flaps are disposed at a trailing edge of the inner wing. The flaps are in front of a centre of gravity of the aircraft 110. An inner flap and outer flap 126A are disposed at a trailing edge of a portion of the inner wing section 132A. The inner flap is the flap closer to the centre region 112 of the aircraft. Flaps 126A are disposed between the engine 152 and the central storage tank 152.

[0050] The outer flap has an edge 160A close to the engine 116A. Edge 160A can include structural elements to attach and guide flaps during deployment. Edge 160A is disposed in a substantially streamwise direction to allow unhindered flow of air into the engines. A fairing in front of the engine provides space for structural elements for attachment points or guides for the flaps.

[0051] The inner flap has an edge 162A close to the central storage tank 152. Edge 162A is disposed in a substantially streamwise direction. Structural elements close to this edge 162A serve as attachment points or guides for the flaps. For example, flap-track fairings near edge 162A.

[0052] Structural elements may be, for example, flap track fairings.

[0053] In this embodiment, like in previous embodiments, a rear spar can serve as the attachment point for structural elements used to attach the flaps. In some embodiments, fuel tanks exist in an inner wing rear fairing. The inner wing rear fairing is in front of the flaps, or above the flaps in the case of split flaps.

[0054] In use, the flaps can be deployed during take-off. Deployment could be by pivoting or extending, or both. Extension increases the wing area which increases the lift. Pivoting can correspond to pivoting the trailing edge of the flap, for example in a downwards direction. This increases the effective camber, and therefore also increases the lift. This can therefore be used to advantageously make the angle of attack less steep during take-off and landing.

[0055] Angle of attack is defined as the angle at which the chord of an aircraft's wing meets the relative incoming flow.

[0056] A high-lift device is defined as a component or mechanism on an aircraft's wing that increases the amount of lift produced by the wing.

[0057] The front and rear of the aircraft is defined relative to the direction of flight.

[0058] Inner and outer are defined relative to a lateral plane across the aircraft, for example in a direction parallel to a line drawn between a tip of the port wing to a tip of the starboard wing.

[0059] 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 starboard swept wing and a port 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 the inner wing section is greater than the sweep angle of the outer wing section; a central region where the starboard swept wing meets the port swept wing; a starboard transition region where the starboard inner wing section meets the starboard outer wing section; a port transition region where the port inner wing section meets the port outer wing section, in which at least one high-lift device is disposed on or at a trailing edge of the inner wing section of each swept wing.

2. The aircraft as claimed in claim 1 , in which the at least one high-lift device is disposed in front of a centre of gravity of the aircraft.

3. The aircraft as claimed in any preceding claim, in which the at least one high- lift device may be any one of a plain flap, split flap, single slotted flap, multi slotted flap, fowler flap, or any combination of such.

4. The aircraft as claimed in any preceding claim, in which the aircraft comprises a rear spar which runs along a length of each wing, closer to a trailing edge of each wing.

5. The aircraft as claimed in claim 5, in which an inner wing fairing is provided at a trailing edge of the rear spar.

6. The aircraft as claimed in claim 4 or claim 5, in which the at least one high-lift device is disposed on or integral to the inner wing fairing.

7. The aircraft as claimed in any one of the previous claims, in which storage volumes are provided in the inner wing fairing.

8. The aircraft as claimed in any preceding claim, in which at least one extension having an internal volume is provided at a trailing edge of the central region.

9. The aircraft as claimed in any preceding claim, in which at least one extension having an internal volume may be provided at a trailing edge of at least one of the starboard and port transition regions.

10. The aircraft as claimed in any preceding claim, in which one or more engines are provided at or from a trailing edge of each of the inner wings.

11. The aircraft of claim 10, in which an outer edge of the at least one high-lift device is laterally spaced from the engine for allowing unhindered airflow to the engine.

12. The aircraft as claimed in any preceding claim, in which each of the high-lift devices are attached and guided by one or more corresponding attachment means.

13. The aircraft as claimed in claim 12, when dependent on claim 11 , in which the attachment means are provided parallel and proximal to the lateral edge.

14. The aircraft as claimed in claim 12, when dependent on claim 8 in which the attachment means are provided on or integral to the central extension.

15. The aircraft of any of claims 12 or 14 in which the attachment means for attaching and guiding is a flap track fairing.

16. The aircraft as claimed in any preceding claim, in which two or more high-lift devices are provided on each wing, wherein the two or more high-lift devices have minimal gaps at each join for minimising any negative effect on the aerodynamics of the aircraft.

17. The aircraft as claimed in any of claims 1 to 7, or any of claims 10 to 16 when not dependent on claims 8 or 9, wherein the starboard and port high-lift devices join together in a central region.

18. An aircraft as claimed in any preceding claim, in which the sweep angle of each inner wing section is greater than 50°.

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