Related architecture: Flying wing of a large, twin-fuselage aircraft with a central wing

Abstract

Several patents have been filed proposing a twin-fuselage aircraft. The two parallel fuselages are separated and connected by at least one wing, known as the center wing. Each fuselage has an outer wing, known as the lateral wing. The shape of the center wing(s) described in these patents does not allow for a stable aircraft, primarily in roll but also in pitch. This is because the center wing has a much too high aspect ratio. The present invention describes a twin-fuselage aircraft for transporting passengers or cargo, with a single, very short-span, and very deep center wing, resulting in an aspect ratio of less than 0.25. This design allows for innovations that improve safety, the payload-to-empty-weight ratio, and ease of operation.The invention positions the aircraft in the medium-range, high-capacity market, whereas long-range aircraft offering the same capacity are significantly heavier. Nevertheless, a long-range version is possible by leveraging the fuel capacity of the central wing and the inherent strength it provides to the aircraft. The idea is to draw inspiration from flying wings, such as Airbus's Maveric concept, without the associated structural and balance challenges, or operational drawbacks. If the concept proves aerodynamically sound at high speed and high altitude, it promises gains in OEW per seat, thus reducing fuel consumption, as well as improved landing gear and tail assembly strength, ease of operation, and safety.

Description

Title of the invention: Related architecture Twin-fuselage wide-body aircraft flying wing with central wing INTRODUCTION

[0001] The present invention belongs to the field of transport aircraft.

[0002] The object of the invention is to provide a solution for large and medium-haul aircraft,

[0003] 1- reproducing as closely as possible the formulas and formats of medium-haul aircraft to benefit from production standardization,

[0004] 2- offering a structural design allowing for weight reduction at equivalent strength,

[0005] 3- a rapid cruising speed thanks to the configuration and rigidity of the planes carriers,

[0006] 4- having good aerodynamic efficiency at high altitude, high speed,

[0007] 5- enabling innovations in architecture (engine, landing gear, structural reinforcement, cabin layout, APUs),

[0008] 6- offering an OEW / seat of approximately 200kg where large long- Current couriers have an OEW / seat weight of 370kg.

[0009] 7- enabling an evolution towards a long-range wide-body aircraft equipped of an OEW / seat moderately greater than 200kg by essentially increasing the depth of the central wing and the power of the engine.

[0010] The invention proposes a related architecture: Flying wing of a twin-fuselage aircraft.

[0011] In the text and figures, the invention adopts as its fuselage model that of single-aisle, medium-range aircraft in the Airbus A321, Boeing 737, Cornac C919, or Irkut MC-21 range. In this range, the aircraft are low-wing. For this reason, the aircraft that is the subject of the invention is a low-wing aircraft. This range of aircraft is characterized by an approximately circular fuselage section with a diameter of 4 meters, making it a de facto standard. Although the invention is applicable to all types of fuselage, it appears relevant to us only with this specific choice. As a result of this choice, the dimensions of the frames, stringers, skin, windows, passenger and cargo bay openings, flooring, and cabin, cockpit, and cargo bay equipment are retained.

[0012] In this range, we have preferentially selected for the figures a reference aircraft with a passenger cabin length offering approximately 236 seats (the symbol - means throughout the text: approximately, about) in economy class. This leads us to design an invention proposing a high-capacity aircraft with around 472 seats in economy class. We will see that The invention allows an increase in fuselage length without significant structural modification and therefore an increase in passenger carrying capacity without the major weight gain that affects large capacity aircraft.

[0013] The single-fuselage aircraft from which the invention is conceived is called the reference aircraft.

[0014] The motorization is naturally derived from the motorizations of the reference device.

[0015] The reference aircraft type A321, B737 and C919 used in the figures employ engines from General Electric / Safran, Pratt & Whitney, and Rolls Royce with a unit thrust of ~140kN. We will refer to this engine model as Ml40.

[0016] High-capacity, long-range twin-engine aircraft use engines from General Electric, Pratt & Whitney, and Rolls Royce with a thrust of ~330kN. We will refer to this engine model as the M330.

[0017] The figures do not conform to the rules of industrial drawing. They are not working drawings. They are a selection of contours conveying information, shown in projection. They serve as a functional explanation and, as such, could be called diagrams. In this respect, the description is more functional than geometric. The figures are generally represented to a scale that corresponds to that of the reference instrument. The dimensions and quantities remain approximate, even though every effort has been made to be plausible.

[0018] The figures are numbered according to the convention required for patent writing. Numbering is abstract. For each figure, we have added a label consisting of a number from 1 to 5, followed by one or more letters. The number 1 indicates a plan view. The number 2 indicates a side view. The number 3 indicates a front view. The number 4 indicates a cabin layout view. The number 5 indicates an axonometric view. The letters specify a different device model. In the description, we refer to the figures with this label.

[0019] The thickened lines indicate reinforcement structures. These may be longerons, but without specifying their thickness or cross-sectional profile; ribs, but without specifying whether they are solid or perforated; reinforced frames; reinforced stringers; or pylons, but without specifying the final design. The number and geometry of these structures are not contractually binding. Furthermore, the ribs of the lateral wings are never drawn. The shape of the canopies, windows, the presence of winglets, the shape of the fuselage nose, and the shape of the engines are intentionally a mix of current solutions so as not to specify a particular reference aircraft.

[0020] It will take 1 year to validate the aerodynamic behavior of the invention both in wind tunnel and in numerical simulation.

[0021] The objective of the invention is to obtain a medium-range aircraft and a long-range aircraft, both large-body aircraft, with an OEW / seat of just over 200kg where it is currently ~370kg for long-range large-body aircraft. ABBREVIATION

[0022] This table gives the meaning of the acronyms used.

[0023] APU Auxiliary Power Unit

[0024] ILS Instrument Landing System

[0025] OEW Operational Empty Weight / Operational Empty Weight. Patents examined and available at espacenet.com

[0026] EP2769910 Twin-fuselage gyroplane 2014 / 02 / 11. It's more like a helicopter.

[0027] EP3098162 Body-body aircraft 2015 / 05 / 26. Center wing extension far beyond the limit of 0.25 that we set for ourselves.

[0028] FR2180076 1973 / 11 / 23. Several central wings with an aspect ratio far exceeding the We set a limit of 0.25. It is the fuselages that must withstand the aerodynamic forces exerted on the central wings, contrary to the invention.

[0029] FR2623468 Multi-fuselage aircraft and seaplanes with three lifting surfaces 1987 / 11 / 24. Several central wings with aspect ratios far exceeding the 0.25 limit we set for ourselves. It is the fuselages that must withstand the aerodynamic stresses experienced by the central wings, contrary to the invention.

[0030] FR2922192 Twin-fuselage aircraft 2009 / 12 / 18. Multiple center wings The aspect ratio far exceeds the 0.25 limit we have set. It is the fuselages that must withstand the aerodynamic stresses experienced by the central wings, contrary to the invention.

[0031] FR2935351 Aircraft with fuselage suspended under the wing 2010 / 03 / 05.

[0032] FR3079209 Wide-body aircraft with non-planar variable-geometry wings 2019 / 09 / 27.

[0033] GB1044922 Flying device with double fuselage arrangement 1966 / 10 / 05. THE The fuselages are not parallel.

[0034] USD106275S Design for an airplane or the like 1937 / 10 / 05

[0035] US20020003190 Blended wing and multiple-body airplane configuration 2003 / 12 / 23. Concerns 747 fuselages. Central wing includes a 3rd fuselage.

[0036] US20060016931 High-lift, low-drag dual fuselage aircraft (no side wing) 2006 / 01 / 26. 2 central wings with aspect ratios far exceeding the 0.25 limit we set for ourselves.

[0037] US20100044521 Twin-fuselage aircraft (unrealistic engine position for the engines) 2012 / 04 / 17. 2 central wings with aspect ratios far exceeding the limit of 0.25 is the value we are setting for ourselves. It is the fuselages that must withstand the aerodynamic forces exerted on the central wings, contrary to the invention.

[0038] US20140263831 Cross-wing Twin-Fuselage Aircraft 2014 / 09 / 18. The proposal However, the closer approach involves a central wing aspect ratio well beyond our upper limit of 0.25, which precludes the innovations of our proposal. The rearward engine placement necessitates strengthening the fuselages, thus increasing their weight. It also requires moving the wings aft to ensure proper center of gravity, an option that complicates achieving rigidity.

[0039] US1294412A Twin-fuselage construction 1919 / 02 / 18. Very extended center wing. beyond the limit of 0.25 that we set for ourselves.

[0040] US4165058 Tandem wing airplane 1979 / 08 / 21. 2 central wings with a very high aspect ratio beyond the 0.25 limit we have set for ourselves. It is the fuselages that must withstand the aerodynamic forces experienced by the central wings, contrary to the invention.

[0041] US8702031B2 VTOL twin fuselage amphibious aircraft with tilt-center wing, engine and rotor 2014 / 04 / 22. The central wing aspect ratio is well beyond the 0.25 limit we set for ourselves. The fuselages are supposed to withstand the aerodynamic stresses experienced by the central wings, whereas the opposite is true in this invention.

[0042] US4165058A Tandem wing airplane 1979 / 08 / 21. Multiple center wings The aspect ratio far exceeds the 0.25 limit we have set. It is the fuselages that must withstand the aerodynamic stresses experienced by the central wings, contrary to the invention. Central wing innovations

[0043] The central wing is the keystone of the invention. Other innovations stem from this innovation.

[0044] The central wing considered in the invention is a wing with a very small wingspan and a large depth. Consequently, its aspect ratio is very low and less than 0.25.

[0045] The central wing is intended to have a chord of significant length in order to obtain a sufficient wing area.

[0046] These chord dimensions will allow it to benefit from a significant thickness while maintaining a low relative thickness (thickness / chord). The central wing, supported by multiple spars and ribs made of materials such as high-strength aluminum or carbon fiber, will naturally offer a very strong and rigid structure for a particularly modest weight. This is why ribs are shown in the figures, even though this is not the case for the lateral wings.

[0047] It is equipped with primary and secondary longitudinal members.

[0048] The primary longerons extend into the central fuselage box, which are attached to the spars of the lateral wings.

[0049] The secondary spars are located forward and aft of the primary spars. They are integral with the ribs of the central wing. This is what gives this structure exceptional rigidity. Consequently, the secondary spars will naturally extend to the fuselage floor and be attached to reinforced frames (Item 34) designed to support the fuselages. Thus, the central wing acts as a supporting gantry and exoskeleton for the two fuselages. This innovation will strengthen the fuselages in their resistance to the formidable bending moments that occur during hard landings or in turbulence. In the same vein, the lateral ribs of the central wing, adjacent to a fuselage, can be made integral with the latter, in order to further strengthen the fuselages against bending. It is no longer necessary to have a heavy fuselage, because it is resized and stiffened, like that of long-haul aircraft.It is foreseeable that the fuselage can be further lengthened compared to the reference medium-haul aircraft without having to change the caliber of the frames and stringers.

[0050] The rigidity of this structure will allow the grafting of powerful high-lift flaps, air brakes and oversized flaperons.

[0051] The design of a hypercritical airfoil will be facilitated because its rigidity will help control the buffeting effect, which is its weakness. This will be conducive to achieving a high cruising speed. A supercritical airfoil offers the advantage of a wing with a greater thickness than a conventional airfoil. This will increase the fuel capacity in the central wing. This central location of a significant mass is beneficial to the maneuverability of the aircraft, which is the subject of the invention.

[0052] The choice of a supercritical profile also offers the advantage of having a center of pressure moved towards the rear compared to a conventional profile, which is favorable to its positioning (the positioning of the central wing on the figures is to be specified by calculation and tests).

[0053] The lift of the central wing will benefit from the presence of the 2 fuselages on its sides which will oppose the wingtip vortices.

[0054] It is desirable that the surface quality of the central wing be exceptionally well finished.

[0055] In the figures, the few fuselage windows facing the central wing that are not obscured by the latter have been retained. They could all be removed if the risks of claustrophobia proved illusory.

[0056] The central wing may be offered in a standard version and an extended version. In the latter case, it is the depth that will be increased. Consequently, the thickness will undergo a corresponding increase. In the diagrams illustrating the invention, with an A321 or a B737 as the reference aircraft, the depth increases from ~24m to ~32m. This This operation is designed to increase the kerosene carrying capacity and the lift generated by the increased weight resulting from this increased capacity. With a wing approximately 24m deep and 4m wide, the central wing's fuel capacity can be estimated at over 80m³. With a wing approximately 32m deep and 4m wide, the central wing's fuel capacity can be estimated at over 140m³.

[0057] The standard center wing corresponds to medium-haul requirements, while the extended center wing corresponds to long-haul requirements. The wingspan of the center wing has been fixed at 4 m in almost all diagrams except for a few where it has been increased to 6 m. In the first case, this gives an aspect ratio of 0.17 and 0.125 (respectively a wing area of ​​96 m² and 128 m²) depending on the depth, and in the second case, it gives an aspect ratio of 0.25 and 0.19 (respectively a wing area of ​​144 m² and 192 m²). These dimensions are approximate and will need to be determined by calculation and testing.

[0058] This central wing design gives the aircraft an appearance that is close to that of the flying wing, whose aerodynamic efficiency is recognized, but without the structural complexity, nor the technical and operational organizational difficulties.

[0059] If the leading edge of the central wing, drawn straight perpendicular to the forward movement of the aircraft, i.e. without a sweep, creates an excessive transonic shock, it will be necessary to work on the profile of the leading edge and on appendages such as canard wings to solve the problem.

[0060] Figures 5a, 5b, 5c, 5d, 5e show the external appearance of the central wing.

[0061] If the thickness of the central wing hinders the installation of a safety door on the fuselage, a reduced emergency exit accessible by a retractable staircase (Item 54) will have to be chosen. Side wing innovations

[0062] It is not possible to maintain the dimensions of the wings of the conventional aircraft from which the invention is derived.

[0063] The wing can be lightened by removing the main landing gear attachment system and the accompanying reinforcement elements if the formula chosen for the main landing gear (and which we prefer) is to be fixed to the central boxes.

[0064] It will need to be reinforced to take into account the increased thrust and weight of the engine.

[0065] If there were no central wing, the lateral wing area would naturally be approximately twice that of the reference aircraft. The presence of the central wing implies a relative reduction in the area and wingspan of the lateral wings compared to those of the wings of a conventional wide-body aircraft.

[0066] Initially, we believe that there will be at most 2 sizing classes, one for medium-haul and one for long-haul.

[0067] In the medium-haul version, equipped with a standard central wing and engines with an overall thrust of -560 kN, the aircraft, the subject of the invention, will be fitted with standard side wings.

[0068] In the long-haul version, equipped with an enlarged central wing, with engines of an overall thrust of ~660kN, the aircraft, the subject of the invention, will be equipped with slightly enlarged lateral wings.

[0069] It is not assumed that the incidence of the central wing is exactly the same as that of the lateral wings.

[0070] It may be necessary to choose angles of incidence such that the angles of incidence of maximum fineness coincide on the respective polars (at cruising speed). Box girder innovations

[0071] The wing of an aircraft is subjected to the most intense stresses to which the aircraft can be exposed:

[0072] Hard landings and turbulence result in formidable upward and downward bending moments. In flight, wing drag and engine thrust produce forward and backward bending moments.

[0073] The weight of the engines and tanks gives rise to downward bending moments.

[0074] It is the longitudinal frame-box assembly that ensures resistance to these stresses. It is on this assembly that the engines and the main landing gear are fixed.

[0075] The longeron-box assembly is responsible for providing the necessary strength without compromising the aerodynamic performance of the aircraft through an overly imposing geometry.

[0076] The solution we propose, which is the subject of the invention, facilitates achieving this result. Compared to a conventional wing, the invention uses two box sections instead of one. The presence of two box sections plays the same role as the piers of a bridge and allows the lateral wings to be lighter compared to a conventional wide-body solution, which has the structure of a bridge with a single pier. Tail innovations

[0077] The conventional cruciform tail assembly of aircraft suffers from a weakness: limited resistance to the rudder pedals acting on the rudder. The moment exerted at the base of the rudder is very significant. The invention proposes a horizontal plane mounted on top of two fins, one on each fuselage. The invention considerably improves the rudders' resistance to bending because it acts as a bracing system for them.

[0078] The strength of the tail assembly allows for greater deflection of the two rudders and an increase in their surface area. This enables good crosswind correction. This design reduces the height of the fin and its induced drag. The bending moments of each fin at the base of the fuselage will be significantly reduced and replaced by shear forces that are much easier to control. Reinforcement of the frames and stringers at the base of each fin should suffice. There is no longer a need for the fin spar and horizontal stabilizer spar to pass through the fuselage by means of a tail box. The elimination of the tail box will be used to lengthen the pressurized cabin and provide valuable additional volume for long-haul flights (Item 43).

[0079] In order to prevent the structure from folding, the horizontal stabilizer-plane connection will be reinforced, if necessary faired, as priority is given to the removal of the tail box (FigLabel 3a, 3b, 3c).

[0080] The horizontal plane is no longer affected by the disturbed flow around the fuselage.

[0081] The horizontal plane is located further from the jet blast than in the apparatus of reference.

[0082] It does not obstruct the passage of cargo shipments.

[0083] In the figures, the horizontal plane is rather oversized.

[0084] The horizontal plane can be fitted with a compartment to house a high-speed satellite antenna. This location has the advantage of being free of any skyward-facing surface that could reflect unwanted echoes. This location, away from the air-conditioned areas, will benefit from the low flight temperatures, which are conducive to reducing the receiver's noise temperature, thus improving communication quality. Main landing gear innovations

[0085] The main landing gear is responsible for making initial contact with the runway. The aircraft, weighing tens of tons, can exert significant stress on this component, especially if the landing is rough due to pilot incompetence or in crosswind or gusty conditions. The main landing gear is constructed of highly resistant materials and attached to highly resistant structural elements.

[0086] In the configuration of the reference aircraft, the main landing gear consists of 2 landing gears, each comprising 1 axle with 2 wheels.

[0087] In the aircraft, which is the subject of the invention, the main landing gear is obviously reinforced. It consists of 2 landing gears, each comprising 2 axles with 2 wheels in the range of those of wide-body aircraft such as the A330, the A350 or the B787 Dreamliner.

[0088] In the configuration of the reference aircraft from which the invention is based, the main landing gear is attached to the wing spars. This solution, referenced as STP1, is applicable to the invention.

[0089] The invention provides an alternative solution, referenced as STP2, which offers valuable advantages. The invention proposes attaching the main landers to the central modules.

[0090] The use of the STP1 solution in a four-engine version of type M140 under the lateral wings leads to a length of the main landing gear legs relaxed, without load, of ~3.2m and a track width of ~15m.

[0091] The use of the STP1 solution in a twin-engine version of type M330 under the side wings leads to a length of the main landing gear legs relaxed, without load, of ~4m and a track width of ~15m.

[0092] The use of the STP2 solution in a four-engine version of type M140 under the lateral wings leads to a length of the main landing gear legs relaxed, without load, of ~2.2m and a track width of ~10 to 12m (FigLabel la, 2a, 3a, 3c).

[0093] The use of the STP2 solution in a twin-engine version of type M330 under the lateral wings leads to a length of the main landing gear legs relaxed, without load, of ~3m and an overall track of ~ 10 to 12m (FigLabel 1b, 2b, 3b).

[0094] The STP1 solution leads to a clearance of ~15m which is rather excessive.

[0095] The STP2 solution leads to a track width of ~10 to 12m, which is quite sufficient for stability and security.

[0096] Since the STP2 solution is more compact than the STP1 solution, weight will be saved for equivalent rigidity.

[0097] We prefer the STP2 solution. It is the one shown in all the figures.

[0098] In a configuration with an enlarged center wing, we recommend attaching the main landing gear closer to the plane of symmetry of the fuselage so as to maintain a track width of ~ 10 to 12m (FigLabel le, 3c, 5c_St, 5d_St).

[0099] The prominent landing gear bays on the fuselage will be faired in a spindle shape. The overall profile of the landing gear bays will be less prominent than that of the reference aircraft and will therefore improve the aircraft's aerodynamic qualities.

[0100] This very robust configuration of the main landing gear, model STP2, should allow a proportionally increased maximum landing mass.

[0101] On the reference aircraft, the main landing gear is fixed to the wing spar. In the event of a very hard landing, if the spar is deformed, repairs will be costly.

[0102] On the apparatus, the subject of the invention, according to solution STP2, the main landing gear is fixed to the central box girders. If there is any deformation, it will be more localized and repairs will be simpler and less expensive.

[0103] Figures schematically show the main landing gear attachment pylon (Item 47) on the box girder. They show that by attaching the main landing gear at the most At the bottom of the fuselage, the length of the main landing gear leg is reduced. The pylon material will preferably have extensive plastic properties to withstand a very hard landing without damaging the wing box. Innovations in the front landing gear

[0104] The design of the nose landing gear located under the nose of the fuselage is abandoned. It is replaced by a nose landing gear attached to a secondary spar of the central wing. Because the central wing has significantly greater strength than a fuselage, this innovation improves the safety of the system. Its position reduces the risk of the landing gear being thrown towards the engines located under the wings during taxiing.

[0105] The front of the 2 fuselages is lightened and relieved of stresses.

[0106] It reduces the turning radius. A U-turn on the track is possible in the in most circumstances.

[0107] The support triangle remains favorable to equilibrium on the ground.

[0108] The wheel can be deployed backwards in a conventional scheme or forwards for more advanced positioning and more spacious housing.

[0109] 1. Rearward deployment. This is the traditional method. The aerodynamic effect It supports the descent mechanism and secures the operation. The support triangle is slightly reduced. Housing the landing gear in the central wing may require a fairing.

[0110] 2. Forward deployment. The aerodynamic effect resists the mechanism The descent requires increased power from the mechanism. The lifting triangle is slightly enlarged. Housing the landing gear in the central wing is facilitated. As this is the solution we prefer, it is the one shown in the figures (FigLabel 2a, 2b). Engine

[0111] We have described a wide-body aircraft derived from a medium-range aircraft and which, in its initial design, is itself a medium-range aircraft. However, we have determined that it can be easily converted into a wide-body long-range aircraft by essentially increasing the size of the central wing to accommodate additional fuel tanks. This long-range conversion results in a significantly increased takeoff weight and therefore requires significantly increased engine power.

[0112] We offer the following engine options depending on the needs identified.

[0113] Formula C4xM140: Standard center wing, medium-haul use. 2 M140 engines under each lateral wing (FigLabel la, 2a, 3a, 3c, 5a, 5c).

[0114] Formula C2xM330: Increased center wing depth, increased side wings, long-range use. 1 M330 engine under each side wing (FigLabel 1b, le, 2b, 3b, 5b, 5d).

[0115] In the figures, the position of the engines is approximate. The raised position of the horizontal plane of the tail assembly should allow the fuselage to be brought closer to the engine mounting points.

[0116] The option of fully rear-mounted engines, which is the one chosen in Airbus's Maveric project, was considered but does not appear to us to be relevant. It requires significantly stiffening the rear of the fuselages, thus increasing their weight, and reconsidering the wing position to guarantee the center of gravity, which is far from straightforward.

[0117] Nevertheless, the idea of ​​adding an additional engine at the rear to the C4xM140 configuration, while certainly contrary to the current trend favoring twin-engine configurations, and transforming the medium-range version into a long-range version, is not far-fetched. An additional M140 engine is mounted at the rear, between the two fuselages, to create the C5xM140 configuration. It is possible that this five-engine configuration could allow for an extension of the engines' potential beyond that of the twin-engine version. The rear fuselage sections will need to be reinforced with internal ribs (item 33), and mounting spars for the additional engine (item 55) will need to be installed. To obtain the long-range version, the standard center wing must be replaced with the extended center wing. This necessitates lengthening the fuselages behind the center wing box to accommodate the additional engine.To restore balance and center of gravity, the fuselages forward of the central wing box are significantly lengthened. This increases the fuselage length by approximately 5 meters (Fig. Label Id, 5e). Passenger capacity thus increases by 7 rows in economy class, for a total of 84 seats. The combined thrust of the five engines, 700 kN, appears well-suited to this version of a high-capacity, long-range aircraft. It is noteworthy that the trailing edge of the central wing is located within the intake area of ​​the additional engine. It is hoped that this arrangement has a positive effect on the aerodynamics of the central wing. However, it likely prevents full deflection of the central wing flaps when the additional engine is barely powered. This design would naturally be necessary for a manufacturer that does not have the M330 engine available.

[0118] The evolution of engines in terms of power and specific consumption will only facilitate the choice of engine and increase the range of the aircraft, which is the subject of the invention.

[0119]

[0120] Cockpit innovations

[0121] It can be imagined that the device equips 2 cockpits, each occupied by a pilot with a control distribution and switching device.

[0122] The solution, which equips only a single cockpit for the two pilots in the same format as the cockpit of the single-fuselage aircraft from which the invention is based, is simpler and sufficient. It will be necessary to add the controls for the central wing control surfaces as well as the operating controls for the additional passenger cockpit. The fuselage occupied by the flight crew is designated the master fuselage, and the other the slave fuselage. In the figures, we have chosen the port fuselage as the master fuselage. Observation cameras should be placed on the slave fuselage to reflect the pilots' blind spot onto their instrument panel, which is essential during taxiing. This solution frees up commercial space in the slave fuselage.

[0123] The slave cockpit fuselage can advantageously accommodate a second weather radar and an ILS electrically connected to the master cockpit as redundancy. The crew will need to familiarize themselves with parallax relative to the runway centerline.

[0124] The abandonment of the integrated nose landing gear under the nose of the fuselage of the reference aircraft frees up space to install a rest compartment for 2 pilots useful in the case of a double crew on long-haul flights (FigLabel 4a).

[0125] Since the liberty was taken to remove part of the flooring above the rest compartment to increase the ceiling height and consequently the comfort of the occupants, the cabinets and equipment located in this area will have to be suspended from the ceiling. The same space is freed up in the slave fuselage for commercial use. It can serve as a secure compartment for the escorted transport of diplomatic or confidential documents. This compartment is illustrated in the figures by item 35. Passenger cabin innovations

[0126] Compared to a cabin with 8 or 10 seats per row, which is observed in conventional high-capacity aircraft, the 6-seat-per-row format implies a reduction in overcrowding and a decrease in ambient noise.

[0127] Independent and simultaneous access to the two cabins ensures rapid loading and unloading / evacuation of the aircraft of the invention. Most airports allow the positioning of two jetways without modifications to their facilities (Fig. 1a).

[0128] This provides economies of scale in manufacturing and operational gains in operation.

[0129] Removing the tail box allows the pressurized cabin (Item 43) to be extended. This volume allows for the installation of additional logistics equipment for long-haul flights.

[0130] It is recommended that the portholes on the central wing side not be obscured by the latter be kept in order to prevent a feeling of claustrophobia.

[0131] The architecture of large, single-fuselage aircraft, by increasing the diameter and length of the fuselage, necessitates significant stiffening of the latter, leading to an increase in fuselage weight both in absolute terms and relative to the weight per seat, which is a drawback. Conversely, the aircraft that is the subject of this invention does not suffer from this disadvantage. On the contrary, stiffening the fuselages by means of the secondary spars of the central wing will allow them to be lengthened without increasing the diameter of their components, frames, and stringers.

[0132] With a low engine configuration, 4 Ml40 engines, small fuel capacity center wing, a medium-haul economy class operation offering -470 seats is conceivable.

[0133] With a powerful engine, 2 M330 engines, large fuel capacity center wing, a long-haul economy class operation offering -450 seats is conceivable.

[0134] The slave fuselage is suitable for the installation of a business class section at its front. It has toilets at the front of the fuselage.

[0135] The slave fuselage is suitable for the installation of a VIP compartment at its front. It has private restrooms and private access from the tarmac (FigLabel 4b). APU Innovations

[0136] Every conventional aircraft has an APU. It is possible to keep an APU in the tail of each fuselage in the format of the single-fuselage aircraft from which the invention is based. A provision is made for partially diverting the power produced to the fuselage in the event of an APU failure. This redundancy increases safety compared to conventional aircraft. Electrical connections can advantageously be made through the empennage or the center wing.

[0137] The requirements for auxiliary electrical and mechanical power are increasing rapidly. It will be possible to install 2 or 4 APUs in the central wing (Item 37) near the central boxes (FigLabel la, 1b, le).

[0138] We can reasonably expect 600kW of electrical power from it.

[0139] They will be expected to provide pneumatic power for starting the engines, as well as for pressurizing and air-conditioning the cabins. They will offer the necessary power to restart the engines both on the ground and at altitude. This redundancy makes it possible to consider using commercially available turbocharged diesel engines with electric preheating, which are much more fuel-efficient and much less expensive than turbines.

[0140] This will simplify the propulsion engines on which these functionalities are grafted.

[0141] They will provide electricity for navigation equipment, control surface motors, landing gear and braking motors, de-icing, fuel pumps, cabin pressurization, cabin air conditioning, hospitality, passenger multimedia.

[0142]

[0143] Centering, stability, maneuverability, performance

[0144] Centering is the relative position of the aircraft's center of gravity with respect to its center of aerodynamic thrust.

[0145] The center of gravity must be slightly ahead of the center of thrust. Deviating from this relative position leads to piloting difficulties, even to a total loss of control.

[0146] The center of gravity is calculated for each flight. In a conventional aircraft, the center of gravity must be monitored primarily in the longitudinal direction. In the proposed invention, it must also be monitored in the transverse direction. The load on the two fuselages must be equally distributed between them. For each fuselage, the load will continue to be distributed equally along its length, as is already done for a conventional aircraft.

[0147] The increased spacing between the port and starboard engines compared to a conventional aircraft may make control difficult in the event of an engine failure. This is one reason why a small wingspan central wing is necessary.

[0148] The central wing span choices we have proposed coupled with increased 'power' of the tail fins lead us to believe that the situation will be controllable.

[0149] The strength of the tail assembly of the invention is considerably greater than that of the tail assembly of the conventional aircraft used as a reference. The size of the elevator should facilitate the maintenance of pitch stability. This increased strength should allow for vigorous rudder inputs that are not possible on a conventional aircraft due to the fragility of the rudder.

[0150] On-board measuring devices such as strain gauges send the load distribution to the dashboard when the device, the subject of the invention, is on the ground.

[0151] Depending on the shape of the wing, its dihedral angle, we will gain or lose on roll stability.

[0152] A large portion of the fuel will be stored in the center wing. This is an advantage that this significant weight be at the center of the device.

[0153] The center of pressure of the central wing is likely to shift significantly between the low-speed and high-speed configurations. The nose-up moment of the engines changes considerably between the climb and cruise phases. Fuel displacement will be necessary to balance the aircraft. The large horizontal extension of the central wing facilitates this operation.

[0154] It is not necessary for the lateral wings and the central wing to be set at the same angle of attack. Preferably, angles of attack that make the maximum fineness positions on the polars (evaluated at high speed, high altitude) of the respective wings.

[0155] The cabin configuration means that passengers on the wingside will experience significant vertical movement for moderate roll movements, leading to unpleasant sensations for passengers who are not used to flying. They would be advised to sit on the center wingside. Crosswind landing

[0156] Crosswind landing is a delicate piloting operation where the aircraft can be endangered and which often results in a go-around.

[0157] The aircraft approaches with a drift angle, and the pilot must, just before touchdown, realign the aircraft with the runway centerline. This is called decrabling. This operation must be performed at the precise moment to prevent the crosswind from pushing the aircraft off the runway before touchdown. The resulting effect is to raise the upwind wing and lower the leeward wing, with the risk of a touchdown. The maximum cross-section facing the crosswind is smaller than for a conventional aircraft of the same capacity. For this reason, the invention will likely facilitate this maneuver. Weight and dimensions

[0158] The dimensions are shown in the plan, frontal, and profile views. They do not constitute a manufacturing specification. Calculations of the center of pressure, center of gravity, landing gear positions, and the dimensions and positions of the wings and tail assembly remain to be performed. The purpose of this calculation is to demonstrate that the invention is derived from an A321 or B737 type aircraft.

[0159] The invention, based on the coupling of two fuselages, should lead to weight savings compared to a conventional aircraft of the same capacity and range. This is achieved by:

[0160] On the main wing, because the stiffening is easier to achieve thanks to the 2 boxes.

[0161] On the main landing gear, which is more compact and easier to install on the central boxes than on the wing spars as in the classic solution.

[0162] On the front landing gear reduced to a single unit installed on the front part of the central wing.

[0163] On the tail assembly, the portal design of which is easier to stiffen.

[0164] On fuselages much easier to stiffen than the long and bulky fuselage of conventional wide-body aircraft.

[0165] With a standard center wing and 4xM140 engines, the aircraft, the subject of the invention, should have an OEW of approximately twice that of the aircraft of reference. This gives -97 tonnes for a carrying capacity of -472 passengers in an eco medium-haul version.

[0166] Current wide-body aircraft such as the A350 have an OEW of 142 tonnes for a much lower passenger capacity of -370 passengers. The target OEW per passenger should be around 200 kg or little more, whereas it is around 370 kg for current wide-body long-haul aircraft.

[0167] The 42-tonne difference between the OEW of the medium-range model of the invention and that of a wide-body long-range aircraft such as the Airbus A350 allows us to confidently envision a long-range development. This is based on the choice of a center wing with increased depth, thus providing a large fuel capacity, combined with the choice of an engine configuration consisting of 2xM330s.

[0168] The cabin crew rest area will have to be taken from the passenger cabin. This only very slightly reduces passenger capacity. The technical crew rest area will have been located in the nose of the fuselage.

[0169] Removing the 2 tail boxes frees up space to accommodate the extra supplies.

[0170] The strength of certain longerons and landing gear will need to be increased.

[0171] Without a doubt, these modifications will remain below the 42-tonne margin. The aircraft, which is the subject of the invention, should achieve an OEW lower than that of the A350, for a much higher passenger carrying capacity. Operational gains and comfort

[0172] Dual access for boarding and disembarking, dual access for logistics, dual access for baggage hold, reduce downtime at stopover.

[0173] Onboard service roaming is reduced compared to that of a conventional wide-body aircraft.

[0174] The architecture of the invention reduces the feeling of close quarters, suffocation and overcrowding that emerges from 2-aisle cabins.

[0175] Access for supplies and toilets is less far away. Redundancy and security

[0176] The architecture according to the invention is advantageously suited to the installation of two weather radars and to the duplication of certain safety-critical radio navigation instruments. It is also advantageously suited to the installation of several APUs, which are essential for safety.

[0177] The aircraft's stocky body and its elevated position on its landing gear reduce the risk of the rear of the fuselage contacting the runway during a takeoff or landing that is too steep.

[0178] This twin-fuselage design should improve the chances of a belly landing or water landing with less risk of snagging a wing or engine. We have not drawn the evacuation slides, but there is no doubt that their installation is possible on both the lateral and center wing sides. FIGURES

[0179] [Fig.1] Label the Structural Plan View, medium-range vocation. Standard narrow central wing. 2 M140 engines under each lateral wing. Short nose landing gear opening forward. 2 short main landing gears fixed to the central box of each fuselage on the outer lateral side.

[0180] [Fig.2] Label 1b Structural plan view, long-range design. Narrow central wing with increased depth. 1 M330 engine under each lateral wing. Semi-long nose landing gear opening forward. 2 semi-long main landing gears fixed to the central box of each fuselage on the outer lateral side.

[0181] [Fig.3] Label the Structural Plan View, long-range vocation. Widened and deepened central wing. 1 M330 engine under each lateral wing. Semi-long nose landing gear opening forward. 2 short main landing gears fixed to the central box section of each fuselage mid-section.

[0182] [Fig.4] Label Id View Structural plan, long-range design. Center wing increased in depth. 2 M140 engines under each lateral wing + 1 M140 engine at the rear between the 2 fuselages. Fuselage increased forward and aft of the wing box. Short nose landing gear opening forward. 2 short main landing gears fixed to the center wing box of each fuselage on the outer lateral side.

[0183] [Fig.5] Label 2a Profile View. Standard narrow center wing. 2 M140 engines under each lateral wing. Short nose landing gear opening forward. 2 short main landing gears fixed to the center box of each fuselage on the outer lateral side.

[0184] [Fig.6] Label 2b Profile View. Narrow central wing with increased depth. 1 M330 engine under each lateral wing. Semi-long nose landing gear opening forward. 2 semi-long main landing gears fixed to the central box of each fuselage on the outer lateral side.

[0185] [Fig.7] Label 3a Front View. Standard narrow center wing. 2 M140 engines under each lateral wing. Short nose landing gear. 2 short main landing gears fixed to the center box of each fuselage on the outer lateral side.

[0186] [Fig.8] Label 3b Frontal View. Narrow central wing increased in depth. One M330 engine under each lateral wing. Semi-long nose landing gear. Two semi-long main landing gears fixed to the central box of each fuselage on the outer lateral side.

[0187] [Fig.9] Label 3c Front View. Standard center wing enlarged. 2 M140 engines below each lateral wing. Short nose landing gear. 2 short main landing gears fixed to the central box of each fuselage mid-section.

[0188] [Fig. 10] Label 4a View Pilot rest compartment. Profile and plan views.

[0189] [Fig. 11] Label 4b View VIP Compartment. Plan and access views.

[0190] [Fig. 12] Label 5a Axonometric perspective view, medium-haul vocation. Wing Standard narrow central section. 2 Ml40 engines under each lateral wing.

[0191] [Fig. 13] Label 5a_St Idem 5a, cutaway view. Short front axle opening towards The front. 2 short main landing gears fixed to the central box of each fuselage on the outer lateral side.

[0192] [Fig. 14] Label 5b Axonometric perspective view, long-haul vocation. Wing Narrow central section increased in depth. 1 M330 engine under each lateral wing.

[0193] [Fig. 15] Label 5b_St Idem 5b, cutaway view. Semi-long front axle opening towards The front. 2 semi-long main landing gears fixed to the central box of each fuselage on the outer lateral side.

[0194] [Fig. 16] Label 5c Axonometric perspective view, medium-haul vocation. Wing Standard enlarged central section. 2 Ml40 engines under each lateral wing.

[0195] [Fig. 17] Label 5c_St Idem 5c, cutaway view. Short front axle opening towards The front. 2 short main landing gears fixed to the central box of each fuselage mid-zone.

[0196] [Fig. 18] Label 5d Axonometric perspective view, long-haul vocation. Wing Central wing widened and increased in depth. 1 M330 engine under each lateral wing.

[0197] [Fig. 19] Label 5d_St Idem 5d, cutaway view. Semi-long front axle opening towards The front. 2 semi-long main landing gears fixed to the central box of each fuselage mid-zone.

[0198] [Fig.20] Label 5e Axonometric perspective view, long-haul vocation. Wing Narrow standard center wing with increased depth. Fuselages enlarged in front and behind the wing box. Two Ml40 engines under each lateral wing. One Ml40 engine at the rear between the two fuselages.

[0199] [Fig.21] Label 5e_St Same as 5e, cutaway view. Short front axle opening towards The front. 2 short main landing gears fixed to the central box of each fuselage on the outer lateral side. Items in the figures:

[0200] Label

[0201] 1 Side wing

[0202] 2 Central wing

[0203] 3 Tail assembly

[0204] 4 Port fuselage

[0205]

[0206]

[0207]

[0208]

[0209]

[0210]

[0211]

[0212]

[0213]

[0214]

[0215]

[0216]

[0217]

[0218]

[0219]

[0220]

[0221]

[0222]

[0223]

[0224]

[0225]

[0226]

[0227]

[0228]

[0229]

[0230]

[0231]

[0232]

[0233]

[0234]

[0235] 5 Starboard fuselage 6 Port engine 7 Starboard engine 8 Central engine 9 Wheel with landing gear retracted 10 Wheel with landing gear extended 11 Landing gear leg pivot axis 12 Forward spar of the side wing 13 Center spar of lateral wing 14 Rear spar of lateral wing 15 Center wing box 16 Engine pylon attachment 17 Lateral wing airfoil at the wing root on the fuselage 18 Standard center wing airfoil 19 Extended center wing airfoil 20 Horizontal stabilizer of the tail assembly 21 Elevator 22 Rudder 23 Airbrake 24 High-lift slat 25 Aileron 26 Flaperon 27 Boarding bridge 28 Forward cargo bay 29 Rear cargo bay 30 Primary spar of center wing-center wing boxes 31 Secondary spar of center wing 32 Tail assembly spar 33Internal fuselage reinforcement rib for rear engine support 34 Secondary spar center wing-fuselages (spar + reinforcement frames) 35 Port side pilot rest cabin 2 seats / Starboard cargo bay corporate valuables, diplomatic pouch

[0236]

[0237]

[0238]

[0239]

[0240]

[0241] 36 Main landing gear fairing 37 APU 38 Floor 39 Rest cabin access hatch 40 Rest cabin access ladder 41 Rest cabin bench

[0242] 42 Central wing ribs

[0243] 43 Pressurized cabin extension

[0244] 44 Drift spar

[0245] 45 Horizontal plane spar

[0246] 46 Reinforced frame

[0247] 47 Main landing gear mounting pylon

[0248] 48 Main landing gear leg

[0249] 49 Front landing gear leg

[0250] 50 Reinforced smooths

[0251] 51 Satellite dish

[0252] 52 Reinforcement of the horizontal stabilizer-plane connection

[0253] 53 Abandoned

[0254] 54 Secure exterior access with retractable steps

[0255] 55 Rear engine support frame

Claims

Demands

1. The present invention describes an aircraft for the transport of passengers or goods with two parallel fuselages connected by a single central wing, giving it a flying wing appearance. The invention adopts as its fuselage design that of single-aisle, medium-range aircraft in the Airbus A321, Boeing 737, Cornac C919, or Irkut MC-21 families, which have very similar dimensions. This type of aircraft is considered the reference aircraft. The central wing has a short wingspan (between 4 and 6 m in the figures, but to be determined by calculation) and a long wingspan (between 24 m and 32 m in the figures, but to be refined by calculation), certainly giving it an aspect ratio of less than 0.

25. Each fuselage has, on the opposite side of the central wing, a wing, called a lateral wing, with a geometry similar to that of the reference aircraft (increased by 25% in dimension, i.e. -50% in surface area on the figures but to be refined by calculation).

2. According to claim 1, the central wing is provided with primary and secondary spars. The primary spars extend into the central fuselage boxes, which are integral with the spars of the lateral wings. The secondary spars are located forward and aft of the primary spars. They are integral with the ribs of the central wing so as to impart exceptional rigidity to the structure. The secondary spars naturally extend to the fuselage floor and are attached to reinforced frames designed to support the fuselages. Thus, the central wing acts as a supporting gantry and exoskeleton for the two fuselages.

3. According to claim 1, the forward landing gear is removed from both fuselages. It is replaced by a single landing gear located forward and in the middle of the center wing. The space freed up at the front of each fuselage allows for the creation of a compartment. This could be a rest area for the pilots or a cargo bay for valuables.

4. According to claim 1, the two main landing gears are fixed, one under each fuselage, to the central box, such that their overall track is approximately -10 to 12 m. This positioning of the two main landing gears reduces the length of the landing gear leg compared to a landing gear fixed to the wing spars.

5. According to claim 1, the traditional cruciform tail assembly is eliminated from both fuselages. It is replaced by a horizontal stabilizer mounted on top of two fins, one on the tail of each fuselage. The horizontal stabilizer-fin connection is reinforced and, if necessary, faired. The structural rigidity allows the two tail boxes to be eliminated. Reinforcements to the frames and stringers will replace them. The space freed up at the rear of each fuselage allows the pressurized cabin to be extended. This volume can be used for logistics or crew comfort.

6. According to claim 1, the central wing houses two or four additional APUs near the central bays. These APUs can relieve the propulsion engines of functions that consume power and complicate their architecture.

7. According to claim 2, the fuselages, supported by the secondary spars of the central wing, can be lengthened in front and behind their central box by several rows of passengers without having to take over the overall mechanical characteristics of the frames and stringers.

8. According to claim 1, only one cockpit of the two fuselages is operational for piloting. The fuselage equipped with the operational cockpit is designated the master fuselage. The other fuselage is designated the slave fuselage. The non-operational cockpit receives some redundant instruments such as weather radar and ILS connected to the operational cockpit. The instrument panel of the operational cockpit has additional controls for maneuvering the center wing and for performing the functions assigned to it on the slave fuselage.

9. According to claim 1, to meet the power requirements of an aircraft in an increased passenger and fuel capacity version, an auxiliary engine from the M140 range, in addition to the conventional engine fixed to the lateral wings, can be installed at the rear, between the 2 fuselages.

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