A flying v 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, an upper surface and a lower surface, and an outer wing section (30) for extending the wingspan, in which each outer wing section has a thickness less than a thickness of the corresponding inner wing section; a central region (12) 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; one or more rear spars (34), in which the rear spar is disposed close to a trailing edge (22) of each wing to carry loads along each wing; a semi-buried engine (16)disposed at the trailing edge of the inner wing section of each wing; an encasement fairing comprising an upper surface and a lower surface; wherein the upper surface of the encasement fairing is disposed in front of the engine and forms a continuous surface with the upper surface of the wing to guide air flow into the engine; wherein the lower surface of the encasement fairing joins with the lower surface of the wing to form a cavity, and the lower surface of the encasement fairing extends below at least a portion of the lower surface of the wing; landing gear (40) movable between a retracted position and a deployed position, the landing gear comprising a strut (44) attached to a bogie (42), the strut pivotably attached to the aircraft, close to the rear spar of the aircraft at one end, and attached to the bogie at the opposite end, the landing gear disposed behind the rear spar; and in which the cavity is formed underneath the upper surface (48A) of the encasement fairing, in front of the engine, in which the cavity is for the storage of equipment, fuel or cargo.

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 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.

[0005] Aircraft require engines to provide propulsion. They also require landing gear to support the aircraft during, for example, taxiing, take-off and landing. In conventional aircraft, the engines are generally located on the wings, and the landing gear is located under the body and under the wings of the aircraft. “Buried” engines, integrated into the wings, are known. See for example the arrangement on the de Havilland Comet, the first commercial jetliner. However, as engines for commercial aircraft have become larger over time, the “buried engine” configuration has fallen out of favour due to a difficult integration into the overall layout of aircraft. In modern jetliners the engines are almost invariably disposed in pods hanging from pylons underneath the wings or mounted at the rear of the fuselage

[0006] V-shaped aircraft are flying wings which provide certain design flexibility for the integration of buried or semi-buried engines. Advantages of such engine integrations techniques are low outer surface area which minimizes drag and the possibility of boundary layer ingestion which increases aircraft performance.

[0007] For V-shaped aircraft in particular, the engine and main landing gear are often located in close proximity due to considerations for weight and balance of the aircraft, considerations for a one-engine-out case, and the landing gear track width of the aircraft to comply with airport constraints. The similar positions of the engines and the main landing gear on V-shaped aircraft are a challenge for integration.

[0008] The integration of both engines and landing gear into the aircraft must be optimised in terms of aerodynamics and weight. The aerodynamic profile of the aircraft must be as streamlined as possible despite the presence of these bulky structural elements. Additionally, the exposed outer surface must be minimised as much as possible. Meanwhile the weight must be optimised, and there is a need to minimise the number and size of reinforced supporting elements to hold the engine and landing gear in place.

[0009] V-shaped aircraft require particularly long landing gear. This is because high angles of attack are required to achieve the necessary lift during take-off and landing. Long landing gear are required to ensure the wing tips or rear of the aircraft are clear of the runway at these high angles of attack. Current V-shaped aircraft concepts stow the large landing gear in the wings which uses up significant cabin space, or in heavy, drag-inducing extensions that are specifically built to house the landing gear. There is therefore a need for a coherent solution to the placement of the landing gear.

[0010] Previously, various design iterations have been performed on V-shaped aircraft with regards to engine and landing gear integration, which are described along with their shortcomings below.

[0011] In a first proposed concept, engines are disposed on each wing, above the wing, supported by pylons (Figure 8). This concept has undesirable weight and drag associated with the pylon attachment, and the reinforcement required to support the engine load and accommodate the compression of structural supporting elements. The landing gear is housed in an inner wing of the V-shaped aircraft when retracted. This reduces the available volume in the inner wing that can be used for storage or cabin space and can also lead to extra outer surface being required which has an associated aerodynamic penalty (if an extension is added underneath the wing to accommodate the landing gear). The landing gear is stored vertically, and the wheels are aligned with the direction of flight. Additionally, aerodynamic interference is caused by the proximity of an upper wing surface, engine pylon and engine nacelle.

[0012] Figure 9 shows the preferred location of the engines along the length of the wing.

[0013] In a second proposed concept, an additional extension or fairing is disposed at a rear of the inner wing (Figure 10). The additional fairing houses the landing gear when retracted. However, the additional fairing adds a significant amount of external surface area and hence aerodynamic drag. The engines are placed on pylons above the additional fairing. This requires additional reinforcement and components to transfer the loads from the weight of the engine to the load-bearing structural beams which adds considerably to the overall weight of the aircraft. Mounting the engines on pylons can also hinder maintenance and replacement of the engines, as they are harder to access from below the aircraft, and they cannot be easily lowered. A top view of a related concept is shown in Figure 11 . In this concept the landing gear is housed in the inner wing, and the engine is mounted on top of the fairing on a pylon.

[0014] In a third proposed concept (Figure 12), a large dedicated structure extends in front of the engine to a rear spar of the inner wing, to attach the engine to the wing and to house a folding landing gear when retracted. In this concept, the engine is lowered relative to the wing, to be ‘semi-buried’, and it is not mounted on top of the wing. The main attachment of the engine to the wing is located in front of the engine in this concept. This leads to long load paths between the engine and the wing, which causes a high weight of the dedicated structure in front of the engine. The folding mechanism of the landing gear and its location in front of the engine adds complexity to the design and further increases the size and weight of the large, dedicated structure in front of the engine. The volume to integrate main elements such as the structure to carry the engine and the main landing gear with a folding mechanism in the region in front of the engine is limited, leading to more required outer volume which increase overall outer surface area of the aircraft in this region and less flexibility to shape an optimal engine intake.

[0015] The landing gear of an aircraft may also be known as the undercarriage.

[0016] An advantage of attaching the engines using pylons or external structures is that the engine does not reduce the available internal space inside the aircraft. However, using pylons and external structures comes with a weight and aerodynamic penalty. Therefore, there is a need for effective engine integration without significantly reducing the available space inside the aircraft for storage.

[0017] It is an object of the present invention to reduce or substantially obviate the aforementioned problems.

[0018] STATEMENT OF INVENTION

[0019] 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, an upper surface and a lower surface; 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; 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; one or more rear spars, in which each rear spar is disposed on or close to a trailing edge of each wing to carry loads along each wing; a semi-buried engine disposed at the trailing edge of the inner wing section of each wing; a encasement fairing comprising an upper surface and a lower surface; wherein the upper surface of the encasement fairing is disposed in front of the engine and forms a continuous surface with the upper surface of the wing to guide airflow into the engine; wherein the lower surface of the encasement fairing joins with the lower surface of the wing to form a cavity and the lower surface of the encasement fairing extends below at least a portion of the lower surface of the wing; landing gear movable between a retracted position and a deployed position, the landing gear comprising a strut attached to a bogie, the strut pivotably attached to the aircraft, the strut being close to the rear spar of the aircraft at one end, and attached to the bogie at the opposite end, the landing gear disposed behind the rear spar; and in which the cavity is formed underneath the upper surface of the encasement fairing, in front of the engine, in which the cavity is suitable for the storage of equipment, fuel or cargo.

[0020] There are a number of advantages to the claimed integration of the landing gear and engine.

[0021] The semi-buried engine advantageously ingests a portion of the boundary layer which can lead to overall efficiency gains and reduce the amount of skin friction drag. Additionally, by ‘burying’ the engine, the surface area can be minimised due to the potential dual function of some of the surface area, correspondingly leading to less drag. In particular, the footprint of the lower surface of the engine fairing is to some extent shared with the footprint of the inner wing surface and also with the encasement fairing. In this design, a single surface can partly fulfil a number of the above functions.

[0022] The shared footprint of the lower surface of the engine fairing and the lower surface of the inner wing section leads to aerodynamic advantages as two independent surfaces are replaced by one smooth surface that fulfils both functions.

[0023] An upper surface of the encasement fairing advantageously enables the engine to be buried with minimum loss to the inflow. The air can therefore flow smoothly over the wing and into the engine.

[0024] The engine may be disposed close to the landing gear to enable integration of the associated fairings. The landing gear may be disposed between the rear spar and the trailing edge in what can otherwise be an underutilised volume.

[0025] The strut may be pivotably attached to the rear spar to minimise load paths and therefore reduce reinforcement and associated weight. It may pivot downwards when required and be stored within the aircraft in flight to minimise drag.

[0026] The bogie may be disposed in front of the engine in the cavity within the encasement fairing. This allows storage of this large component. Additionally, the bogie may be in front of the engine rather than below the engine, as was the case in a number of previous designs which means it is easier to access the engine from below for maintenance or detachment.

[0027] The encasement fairing has a lower surface that joins with the lower surface of the wing to form the cavity. The lower surface of the encasement fairing extends below at least a portion of the lower surface of the wing of the encasement fairing to form a cavity of sufficient size for the bogie of the landing gear, or for other storage. A door or cover may be provided which opens to allow the landing gear to move to a deployed position.

[0028] The encasement fairing may be a landing gear encasement fairing.

[0029] The semi-buried engine may be attached to the rear spar. This advantageously shortens load paths between the engine and the load-bearing elements of the aircraft. This minimises the weight associated with reinforcement or additional load-bearing parts required if the engine is far from the rear spar. In particular, the engine may be laterally attached to the rear spar, rather than attached in front of the engine, to shorten the load paths, and create a vacant space in front of the engine that can be used for storage. For example, the space may be used to store the landing gear bogie.

[0030] The semi-buried engine may be disposed substantially behind an upper surface of the inner wing (or inner wing section, or wing). The semi-buried engine may be disposed substantially above an upper surface of the inner wing (or inner wing section, or wing). This advantageously provides partial shielding from the ground which leads to low noise, and shorter vertical load paths to the rear spar.

[0031] Each semi-buried engine may be disposed substantially halfway between the central region and the corresponding transition region. This results in a low yawing and rolling moment in case of an engine failure.

[0032] The strut of the landing gear may be pivotably attached to the bogie. This allows for rotation of the bogie, for example to ensure it is substantially level with the ground when deployed and / or stored.

[0033] The bogie may include at least two wheels. The bogie may include at least four wheels. This facilitates landing on conventional runways. In alternative embodiments, the bogie may support a single wheel. Alternative landing gear such as skis or floats may also be used. In these embodiments, the cavity holds the alternative bulk of the landing gear.

[0034] The bogie may be disposed in front of the strut, relative to the direction of travel, when the landing gear is retracted. This facilitates forward retraction of the landing gear.

[0035] The aircraft may comprise door(s) or openable cover(s) for the bogie on the underside of the inner wing.

[0036] The landing gear may be oriented to ensure that when it is deployed, the wheels are oriented in a forward-facing direction, relative to the direction of flight.

[0037] The strut of the landing gear may be able to rotate about a longitudinal axis of the strut, to ensure that when the landing gear is deployed, the wheels are oriented in a forwardfacing direction, relative to the direction of travel of the aircraft.

[0038] Two or more landing gear may be provided. Each wing may have landing gear. Each inner wing section may have landing gear. Three or more landing gear may be provided. A landing gear may be provided near the central region of the aircraft. A landing gear may be provided on each wing. A landing gear may be provided on each inner wing section.

[0039] The height of the rear spar may be lowered in front of the engine as compared to the height of the rear spar further along the wing in either direction in front or behind the engine, to allow air to flow substantially unimpeded into the engines. This modification of the rear spar enables the engine to be lowered further, which can further shield the engine behind the wing and reduce the aerodynamic penalty associated with the surface of the engines.

[0040] The lower surface of each wing may be shaped to accommodate part of the cavity. In other words, part of the encasement fairing may extend below the level of the lower surface of much of the inner wing. That is to say, there may be a “bulge” in the lower surface of the wing, immediately in front of the engine, to accommodate the cavity. However, the surface is preferably smooth and continuous. In an embodiment, the cavity holds the bogie of the landing gear.

[0041] The lower surface of the inner wing may form a continuous surface with the lower surface of the encasement fairing.

[0042] An upper surface of the encasement fairing may be discontinuous with a rear portion of the upper surface of the inner wing. This allows separate optimisation of the engine encasement fairing and the inner wing fairing.

[0043] Discontinuous in this context may mean that there is a gap between the surfaces, or may mean that the upper surface of the encasement fairing diverges from the upper surface of the encasement fairing.

[0044] The upper surface of the inner wing and the upper surface of the encasement fairing may be connected by an intermediate surface. The change of angle between the two upper surfaces and the intermediate surface may be abrupt (instead of gradual) where each surface meets the next.

[0045] A structural spar may be disposed between the engine and the rear spar. The structural spar may provide an attachment point for one or more flaps. The structural spar may provide an attachment point for one or more landing gear doors for the bogie. Each landing gear door may have a rotation axis substantially parallel to the direction of flight, i.e. in a streamwise direction to minimise any negative effect on the aerodynamics when the doors open.

[0046] The engines may be lowerable for maintenance.

[0047] The sweep angle of each inner wing section may be greater than 60° to minimise drag.

[0048] According to a second aspect of 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, an upper surface and a lower surface; 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; 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; a rear spar disposed on the trailing edge side of each wing to carry loads along each wing; a semi-buried engine disposed at the trailing edge of the inner wing section of each wing; a landing gear encasement fairing comprising an upper surface and a lower surface; wherein the upper surface of the landing gear encasement fairing is disposed in front of the engine and forms a continuous surface with the upper surface of the wing to guide airflow into the engine; wherein the lower surface of the landing gear encasement fairing joins with the lower surface of the wing to form the landing gear cavity and the lower surface of the landing gear encasement fairing extends below at least a portion of the lower surface of the wing; and landing gear movable between a retracted position and a deployed position, the landing gear comprising a strut attached to a bogie, the strut pivotably attached to the aircraft, close to the rear spar of the aircraft at one end, and attached to a bogie the opposite end, the landing gear disposed behind the rear spar and the bogie being held in a landing gear cavity formed underneath the upper surface of the landing gear encasement fairing, in front of the engine, when the landing gear is in the retracted position.

[0049] Any feature or independently selected combination of features presented with respect to the first aspect of the invention may be provided in the second aspect of the invention.

[0050] Where there is reference to the encasement fairing in the first aspect, this should be read as the landing gear encasement fairing for this second aspect.

[0051] Where there is reference to the cavity in the first aspect, this should be read as the landing gear cavity for this second aspect.

[0052] BRIEF DESCRIPTION OF THE DRAWINGS

[0053] 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:

[0054] Figure 1 shows a perspective view of an aircraft;

[0055] Figure 2 shows a close up of the aircraft shown in Figure 1 ;

[0056] Figure 3a is a perspective view of an embodiment of the aircraft, showing the position of the engine and landing gear, when the landing gear is in the deployed position;

[0057] Figure 3b is a perspective view of the embodiment shown in Figure 3a, showing the landing gear in the stowed position;

[0058] Figure 4a is a partial perspective view of the embodiment shown in Figure 3a, as viewed from behind and along the starboard inner wing section of the aircraft, in which the landing gear is in the deployed position;

[0059] Figure 4b is a partial perspective view of the embodiment shown in Figure 3b, in which the landing gear is in the stowed position; Figure 5 is a top perspective view of the embodiment shown in Figures 3 and 4, in which the fairings are shown in full;

[0060] Figure 6 is a bottom perspective view of the embodiment shown in Figure 5;

[0061] Figure 7 is an enlarged partial perspective view of the embodiment shown in Figures 5 and 6, showing the fairings around the engine in more detail;

[0062] Figure 8 shows a perspective view of the engines and landing gear in one embodiment of a previous aircraft concept;

[0063] Figure 9 is a schematic showing the possible positions of the engines in an alternative embodiment of a previous aircraft concept;

[0064] Figure 10 shows a perspective view of the engines and landing gear in an alternative embodiment of a previous aircraft concept;

[0065] Figure 11 shows a plan view of engines and landing gear in an alternative embodiment of a previous aircraft concept; and

[0066] Figure 12 shows a perspective view of engines and landing gear in an alternative embodiment of a previous aircraft concept.

[0067] DESCRIPTION OF PREFERRED EMBODIMENTS

[0068] 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. 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. The aircraft has landing gear 40A, 40B. Landing gear 40A, 40B are shown in a retracted position.

[0069] 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 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.

[0070] 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 50 degrees. In an embodiment, 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.

[0071] The inner wing section 32A comprises the payload fuselage. In an embodiment, the payload fuselage is disposed substantially within the inner wing section 32A.

[0072] Each wing comprises a rear spar 34A. The rear spar 34A is disposed close to the trailing edge 22A of the wing 14A, for carrying loads along the wing.

[0073] The rear spar 34A is also substantially parallel to the trailing edge 22A of the wing 14A. A rear of the payload fuselage is substantially parallel to the trailing edge 22A of the wing 14A.

[0074] A winglet 35A is provided on the outer wing portion 30A at an outer end of the wing. The winglet 35A is substantially perpendicular to the outer portion of the wings 30A for reducing drag. The winglet 35A is oriented substantially vertically.

[0075] Referring to Figure 2, a close up of the aircraft of Figure 1 showing the engine and landing gear can be seen.

[0076] The engine 16A is disposed substantially halfway along the inner wing section 32A. The engine 16A has an engine fairing 36A that substantially surrounds the sides of the engine. The engine fairing 36A forms an engine nacelle. The front and back of the engine are open and not enclosed by the engine fairing 36A. The engine has an upper fairing and lower fairing. There is an engine inlet at the front of the engine, relative to the direction of travel. The engine inlet is substantially circular.

[0077] The engine 16A is ‘semi-buried’. It is disposed at a similar height to the wings and not entirely above or below them. More specifically, the engine 16A is disposed partially above the wing 14A whilst still overlapping with the wing 14A. Seen from a front view, a portion of the engine 16A overlaps with the inner wing section 32A. Seen from a top view, a portion of the engine 16A overlaps with the inner wing section 32A. A part of the boundary layer on the upper wing surface is ingested by the engines which may lead to overall efficiency gains. A number of adaptations have been made to the upper surface of the wing to enable the engine 16A to be semi-buried, which are discussed in more detail below.

[0078] Advantageously, a footprint of the engine nacelle and inner wing surface overlap such that one surface can function as both the nacelle and the inner wing surface. This synergy advantageously leads to reduced weight. The dual functionality leads to reduced surface area of the aircraft, and hence reduced aerodynamic drag.

[0079] The engine 16A is laterally attached to the rear spar 34A. The lateral attachment can be seen most clearly on the port wing at region 60B. Laterally, in this instance, means in a direction substantially perpendicular to the streamwise direction. Laterally is also intended to mean spaced apart from the middle of the aircraft in a horizontal direction. In this way, the load paths between the rear spar and engine are minimised, which reduces the reinforcement required for the load-bearing elements and hence the weight of the aircraft. Additionally, lateral engine attachment avoids the need for a space in front of the engine to be used for engine attachment and can therefore be used to store a portion of the landing gear 40A.

[0080] The landing gear 40A, described in more detail further below, is movable between a retracted and deployed position. The landing gear 40A comprises a strut 44A and a bogie 42A. In this embodiment, the bogie 42A comprises four wheels.

[0081] In this embodiment, there is a landing gear encasement fairing. It will be appreciated that in other embodiments, the landing gear encasement fairing may be a more general encasement fairing, and may form a space in which fuel, cargo and / or other aircraft components can be stored.

[0082] The inner wing 32A comprises a landing gear encasement fairing. The landing gear encasement fairing is a structure disposed in front of the engine that is a continuation of the engine fairing and connects the engine smoothly to the inner wing. The landing gear encasement fairing has an upper surface 48A in front of the engine 16A, close to the base of the inlet. The upper surface 48A is continuous and smooth with the upper surface of the inner wing 32A. The landing gear encasement fairing also has a lower surface 38A below the engine 16A. The upper surface 48A of the landing gear encasement fairing forms a continuous surface with the upper surface of the inner wing 32A to guide airflow into the engine 16A. A landing gear cavity is formed underneath the upper surface 48A of the landing gear encasement fairing. The landing gear cavity is partly enclosed by the landing gear encasement fairing. The landing gear cavity can also be said to be formed by the lower surface 38A of the landing gear encasement fairing. The lower surface 38A of the landing gear encasement fairing is a substantially smooth continuation of the engine fairing 36A.

[0083] The landing gear cavity holds at least a portion of the landing gear. In particular, the bogie 42A is held in the landing gear cavity. The lower surface 38A of the engine fairing may bulge slightly in this region in order to accommodate the bogie 42A.

[0084] The engine 16A has a longitudinal axis. The longitudinal axis of the engine 16A is aligned with the direction of flight to align with the airflow. In contrast, the inner wing 32A has a large sweep angle. The relative angle of these two components means that there is a space created in front of the engine 16A when the outer portion of the engine 16A is connected to the rear spar 34A.

[0085] The landing gear 44A is disposed between the rear spar 34A and the trailing edge 22A in the retracted position. When stowed, the landing gear 40A is stored such that its length lies substantially horizontal in the inner wing section 32A. When stowed, the bogie 42A lies such that the four wheels are stored in a substantially horizontal plane. Finally, the landing gear 40A is disposed in front of the engine 16A. When stowed the landing gear 40A is not directly below the engine 16A.

[0086] The strut 44A is pivotably attached at attachment point 46A to the rear spar 34A of the aircraft 10 at one end. The strut 44A is pivotably attached to a bogie 42A at the opposite end. The bogie 42A can therefore rotate such that the four wheels are substantially horizontal when deployed and hence each wheel can contact the ground.

[0087] The bogie 42A of the landing gear 40A has a set of four wheels. The axis of rotation of the strut 44A is set at an acute angle to the rear spar 34A. The angle is such that when rotatably deployed, the wheels of the bogie 42A are oriented forwards, i.e. in the direction of flight to enable, for example, taxiing. When deployed, the strut 44A of the landing gear 40A is substantially vertical. To deploy the landing gear40A, it is pivoted downwards about the rotatable connection 46A. To retract the landing gear 40A, the landing gear pivots upwards about the rotatable connection 46A. The landing gear 40A is said to be forward retracting because the rotatable connection is closer to the back of the aircraft 10, whilst the bogie 42A is closer to the front of the aircraft 10. Therefore, the bogie 42A pivots forwards and upwards to retract.

[0088] The lower surface of the inner wing section 32A has doors (not shown) that open to allow the rotational deployment of the bogie 42A. The doors are specifically for the bogie 42A. The axis of rotation of the doors is advantageously oriented substantially streamwise, i.e. substantially parallel to the direction of flight. This is described in more detail below.

[0089] The profile of the inner wing section 32A, and in particular the shape of the upper surface 48A of the landing gear encasement fairing, is designed to ensure that the airflow to the engine is optimised to accommodate the fact that it is semi-buried. Put differently, the adapted profile of the inner wing allows a low engine inlet.

[0090] In previous V-shaped aircraft concepts, the profile of the inner wing section is substantially unchanged along the wing. However, in this concept, there is a modified upper surface 48A of the landing gear encasement fairing in front of the engine to accommodate the airflow. The upper surface 48A of the landing gear encasement fairing has increasing curvature with decreasing distance to the engine 16A. Close to the engine 16A, the upper surface 48A of the landing gear encasement fairing reaches a close-to semicircular edge directly at an inlet of the engine 16A. Alternatively, this may not form a be a semi-circle but a smaller arc of a circle. The upper surface of the inner wing 32A is substantially concave across the majority of the wing, apart from a region in front of the engine (the upper surface 48A of the landing gear encasement fairing) where it transitions to a convex shape to match the circular profile of the engine inlet. The upper surface of the inner wing 32A is substantially convex, as viewed along an axis along the inner wing. At the upper surface 48A of the landing gear encasement fairing, the surface is locally concave, as viewed along a longitudinal axis of the engine 16A.

[0091] The rear spar 34A has an upper edge 50A. A portion of the upper edge 50A of the rear spar 34A in the region in front of the engine is curved in front of the engine 16A. To accommodate this lowered upper surface of the inner wing section 32A, the height of the rear spar 34A is decreased, relative to the rest of the rear spar 34A, in the region in front of the engine 16A.

[0092] The upper surface 48A of the landing gear encasement fairing is discontinuous (see 56A) with a rear portion of the upper surface of the inner wing 32A. This allows separate optimisation of the landing gear encasement fairing and the inner wing fairing. However, the landing gear encasement fairing still forms a continuous surface with the upper surface of a middle or front portion of the inner wing 32A. The discontinuity between the landing gear encasement fairing and inner wing 32A is specifically in an area behind the rear spar 34A. This enables separate optimisation of the engine inlet, and the inner wing fairing. It also enables possible integration of flaps into the inner wing fairing.

[0093] A structural element in the region of 52A extends from the rear spar 34A. The structural element may also be used to attach flaps (not shown) in an inner region of the inner wing 32A. In this embodiment, the structural element 52A can optionally attach one or more landing gear doors for the bogie 42A. Each landing gear door has an axis of rotation. The rotation axis of each landing gear door may be disposed in a substantially streamwise direction, to minimise drag when the doors are open. Each landing gear door opens downwards. Having one structural element that can hold the landing gear door and also attach flaps will minimise the number of required parts and hence weight of the aircraft.

[0094] Figures 3 and 4 show a second embodiment of the aircraft 110 and illustrate the relative position of the engine 116 and the landing gear 140, when the landing gear is in the stowed position and when the landing gear is in the deployed position. Reference numbers correspond to those used for the first embodiment. This embodiment is substantially identical to the previous embodiment, though the relative dimensions may be slightly altered. Additionally, in this embodiment, the landing gear 140 is attached to the rest of the aircraft 110 near to the rear spar 134, rather than being attached to the rear spar.

[0095] Note that some features are omitted from Figures 3-4 for clarity. For example, the structure of the fairing around the engine is not shown, and nor is the structure behind the rear spar, or the wingtips. This is so that the position of the landing gear and engine can be seen clearly. As in previous embodiments, the landing gear 140 comprises a strut 144 and a bogie 142. The bogie 142 comprises wheels in this embodiment. The strut 144 is pivotably attached to the aircraft 110 as in previous embodiments. Additionally, the bogie 142 is pivotably attached to the strut 144. For simplicity, only the strut 144 and bogie 142 of the landing gear but it is envisioned that the landing gear 140 would comprise all necessary or standard components, such as reinforcing struts or attachment means for attachment to the rest of the aircraft 110.

[0096] Figure 3a shows the landing gear 140 in the deployed position, i.e. ready for landing or for take-off. The landing gear 140 is positioned in front of the engine 116, relative to a streamwise direction. The landing gear is behind the rear spar 134, relative to a streamwise direction. In this orientation, the strut 144 is substantially vertical.

[0097] The wheels of the bogie 142 are substantially aligned with the streamwise orientation when in the deployed position.

[0098] Figure 3b shows the landing gear 140 in the stowed position. The landing gear is stowed behind the rear spar 134, relative to a streamwise direction. The bogie 142 of the landing gear is in front of the engine 116 when stored.

[0099] When stowed, in this embodiment the strut of the landing hear is substantially parallel to the rear spar 134A. Likewise, the axis of rotation of the wheels on the bogie is substantially perpendicular to the rear spar 134A. In this embodiment, the bogie is substantially level to the ground when stored, i.e. the wheels are all substantially in a horizontal plane. However, it will be appreciated that, in other embodiments, the orientation of the bogie may be otherwise, for example it may be stored vertically. In this embodiment, when stowed, the strut is substantially parallel to the rear spar 134A.

[0100] Figures 4a and 4b show the embodiment shown in Figures 3a and 3b, but from behind the aircraft, and in particular as viewed along the inner wing section 132A of the starboard wing 114A.

[0101] These figures show the semi-buried nature of the engine 116A. A part of the engine 116A overlaps with the wing 114A, when viewed from behind the aircraft 110. The rest of the engine 116A is above the wing 114A.

[0102] These figures also show the landing gear in the deployed position (Figure 4a) and in the stowed position (Figure 4b). Figures 5 to 7 show an embodiment of the invention, and in particular show the shape of the fairings of the aircraft 210.

[0103] As in previous embodiments the aircraft 210 has an engine 216A. The engine 216A has a fairing 236A that substantially surrounds the sides of the engine 216A. The engine fairing 236A forms an engine nacelle. The engine 216A is semi-buried, in a similar manner to that described previously.

[0104] The inner wing section 232A comprises an encasement fairing, indicated generally at 262A. The encasement fairing 262A is disposed in front of the engine 216A. The encasement fairing 262A is a continuation of the engine fairing 236A.

[0105] As in previous embodiments, the encasement fairing 262A comprises an upper surface 248A and a lower surface 238A.

[0106] As in previous embodiments, a cavity is formed within the encasement fairing 262A.

[0107] The upper surface 248A of the encasement fairing 262A is disposed in front of engine 216A. The upper surface 248A is disposed in front of a base of the engine air inlet. The upper surface 248A is continuous with at least part of an upper surface of the inner wing section 232A, e.g. continuous with a portion of the upper surface of the inner wing section 232A that lies directly in front of the engine 216A relative to the direction of travel and the upper surface 248A of the encasement fairing.

[0108] The upper surface 248A of the encasement fairing 262A is lowered in front of the engine, relative to the rest of the upper surface of the wing, so that air is guided smoothly into the inlet of the engine 216A. In front of the engine 216A, the upper surface 248A of the encasement fairing 262A substantially matches the curvature of the engine 216A and / or the engine fairing 236A.

[0109] The upper surface 248A of the encasement fairing is discontinuous (see the region at 256A) with a rear portion of the upper surface of the inner wing 232A.

[0110] Put another way, a curvature or surface contour of the upper surface of the inner wing 232A is interrupted where it meets the engine fairing 236A. A curvature or surface contour of the upper surface 248A of the encasement fairing is interrupted where it meets the engine fairing 236A. The curvature or surface contour of the upper surface of the inner wing 232A is interrupted in front of (relative to the direction of travel), and to one side of the engine 216A.

[0111] The ‘interruption’ or ‘discontinuity’ or ‘discontinuous’ nature of the relevant parts may correspond to an abrupt change of surface contour or angle or to an edge being formed between the respective surfaces where they meet. In some embodiments, the respective surfaces may transition gradually into each other.

[0112] The discontinuity is on the side of the encasement fairing 262A furthest from a tip of the wing. In particular, the upper surface 248A of the landing gear encasement 262A curves upwards to meet the semi-circular profile of the lower half of the engine, relative to the upper surface of the inner wing 132A. This is described in more detail below.

[0113] The engine 216A is substantially cylindrical. Therefore, the engine fairing 236A curves around and substantially matches the shape of the engine. The engine fairing 236A joins to the rest of the aircraft surface at the front of the engine. The engine fairing 236A joins to the rest of the aircraft surface at starboard side of the engine. Therefore, the engine fairing 236A meets the top surface of the wing at an angle, such as an acute angle. This is shown clearly on the port wing 214B at 266B.

[0114] Figure 6 shows the lower surface 238A of the encasement fairing 262A. The lower surface 238A of the encasement fairing 262A is disposed below the engine 216A. The lower surface 238A of the encasement fairing joins with a lower surface of the inner wing. The lower surface 238A of the encasement fairing does not join smoothly with the lower surface of the inner wing 232A. The lower surface 238A bulges outward relative to the lower surface of the inner wing 232A. This bulge provides additional space inside the cavity for storage. The bulge of the lower surface 238A of the encasement fairing thins towards the front of the aircraft to minimise any aerodynamic penalties associated with the bulge. Additionally, the bulge is disposed towards a rear of the aircraft, to minimise its aerodynamic impact.

[0115] Figure 7 shows the fairings around the engine from above. The engine fairing 236 has a front edge 264. The front edge 264 is substantially circular and surrounds the engine 216. Air flows inside the front edge 264 of the engine fairing 236 into the engine 216.

[0116] An upper edge 256A is formed by discontinuity on the side of the engine 216A closer to the centre of the aircraft. In this figure, it can be seen how the front edge 264 of the engine fairing 236A is substantially circular around the engine, and then smoothly joins with the upper edge 256A closer to the central region of the aircraft.

[0117] In terms of the surfaces in this region in front of the engine 216A, the upper surface 248A of the encasement fairing 262A directs air into the engine. The upper surface of the inner wing 232A is discontinuous from the upper surface 248A of the encasement fairing in this region. The two surfaces are connected by a part of the engine fairing, providing an upper edge 256A and a lower edge 257A. The upper edge 256A also helps to guide air from above the wing surface into the engine 216A.

[0118] In other words, the front edge 264A and the upper edge 256A form a part of a spiral or part-spiral edge as they curve forwards towards the front of the aircraft 210.

[0119] The front edge 264A of the engine fairing 236A and the upper edge 256A formed by the discontinuity are asymmetrical. For example, they are asymmetric when viewed along a plane longitudinally bisecting the engine, i.e. in plan view.

[0120] The structure below the engine is not shown in detail in Figure 7 but can be seen in Figure 6. The engine fairing continues below the wing and smoothly joins with the lower surface 238A of the encasement fairing 262A. The encasement fairing 262A bulges or protrudes below the lower surface of the inner wing 232A. The encasement fairing 262A is substantially oriented in a streamwise direction to minimise the aerodynamic impact. Likewise, the encasement fairing 262A tapers towards the front of the wing to further reduce any significant negative aerodynamic impact.

[0121] Any feature or independently selected combination of features presented with respect to a given embodiment may be provided in another of the embodiments.

[0122] The present invention does not interfere with possibilities for a family concept. The region in front of the engines which may have dedicated geometries to allow optimal inflow conditions may be a part of a component which exists for all family versions of the V-shaped aircraft. Both the sideways engine attachment to the rear spar (for example at 34A), and the landing gear attachment to the rear spar may be designed to connect to dedicated family modules or to a single module present for all family versions. 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, an upper surface and a lower surface, 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; 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; one or more rear spars, in which the rear spar is disposed close to a trailing edge of each wing to carry loads along each wing; a semi-buried engine disposed at the trailing edge of the inner wing section of each wing; an encasement fairing comprising an upper surface and a lower surface; wherein the upper surface of the encasement fairing is disposed in front of the engine and forms a continuous surface with the upper surface of the wing to guide air flow into the engine; wherein the lower surface of the encasement fairing joins with the lower surface of the wing to form a cavity, and the lower surface of the encasement fairing extends below at least a portion of the lower surface of the wing; landing gear movable between a retracted position and a deployed position, the landing gear comprising a strut attached to a bogie, the strut pivotably attached to the aircraft, close to the rear spar of the aircraft at one end, and attached to the bogie at the opposite end, the landing gear disposed behind the rear spar; andin which the cavity is formed underneath the upper surface of the encasement fairing, in front of the engine, in which the cavity is for the storage of equipment, fuel or cargo.

2. An aircraft as claimed in claim 1 , in which the encasement fairing is a landing gear encasement fairing, the cavity is a landing gear cavity, and the bogie of the landing gear is held in the landing gear cavity when the landing gear is in the retracted position.

3. An aircraft as claimed in claim 1 or claim 2, in which each semi-buried engine is laterally attached to a corresponding rear spar.

4. An aircraft as claimed in any preceding claim, in which each semi-buried engine is disposed substantially behind an upper surface of the inner wing.

5. An aircraft as claimed in any preceding claim, in which each semi-buried engine is disposed substantially halfway between the central region and the corresponding transition region.

6. An aircraft as claimed in any preceding claim, in which the strut of the landing gear is pivotably attached to the bogie.

7. An aircraft as claimed in any preceding claim, in which the bogie includes at least two wheels.

8. An aircraft as claimed in any preceding claim, in which the bogie is disposed in front of the strut, relative to the direction of travel, when the landing gear is retracted.

9. An aircraft as claimed in any preceding claim, further comprising one or more doors for the bogie on the underside of the inner wing.

10. An aircraft as claimed in any preceding claim, in which the landing gear is oriented to ensure that when it is deployed, the wheels are oriented in a forward-facing direction, relative to the direction of travel of the aircraft.11 . An aircraft as claimed in any preceding claim, in which the strut of the landing gear is able to rotate about a longitudinal axis of the strut, to ensure that when the landing gear is deployed, the wheels are oriented in a forward-facing direction, relative to the direction of travel of the aircraft.

12. An aircraft as claimed in any preceding claim, in which the height of the rear spar is lowered in front of the engine as compared to the height of the rear spar further along the wing in either direction in front or behind the engine, to allow air to flow substantially unimpeded into the engines.

13. An aircraft as claimed in any preceding claim, in which the lower surface of each wing is shaped to accommodate part of the landing gear or the cavity.

14. An aircraft as claimed in any preceding claim, in which the upper surface of the encasement fairing is discontinuous with a rear portion of the upper surface of the inner wing.

15. An aircraft as claimed in any preceding claim, further comprising a structural spar between the engine and the rear spar.

16. An aircraft as claimed in claim 15, in which the structural spar provides an attachment point for one or more flaps.

17. An aircraft as claimed in claim 15 or 16, when dependent on claim 9, in which the structural spar provides an attachment point for the one or more doors for the bogie.

18. An aircraft as claimed in claim 17, in which each door has a rotation axis substantially parallel to the direction of flight.

19. An aircraft as claimed in any preceding claim, in which the engines are lowerable for maintenance.

20. An aircraft as claimed in any preceding claim, in which the sweep angle of each inner wing section is greater than 60°.21 . 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, an upper surface and a lower surface, 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; 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; one or more rear spars, in which the rear spar is disposed close to a trailing edge of each wing to carry loads along each wing; a semi-buried engine disposed at the trailing edge of the inner wing section of each wing; a landing gear encasement fairing comprising an upper surface and a lower surface; wherein the upper surface of the landing gear encasement fairing is disposed in front of the engine and forms a continuous surface with the upper surface of the wing to guide air flow into the engine; wherein the lower surface of the landing gear encasement fairing joins with the lower surface of the wing to form the landing gear cavity, and the lower surface of the landing gear encasement fairing extends below at least a portion of the lower surface of the wing; and landing gear movable between a retracted position and a deployed position, the landing gear comprising a strut attached to a bogie, the strut pivotably attached to the aircraft, close to the rear spar of the aircraft at one end, and attached to the bogie at the opposite end, the landing gear disposed behind the rear spar, and the bogie being held in a landing gear cavity formed underneath the upper surface of the landing gear encasement fairing, in front of the engine, when the landing gear is in the retracted position.

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