High fuel efficiency twin fuselage layout passenger aircraft and design method

Abstract

The application provides a high-fuel-efficiency double-fuselage layout passenger plane and a design method, comprising a fuselage, a wing, a tail and a power device; the fuselage comprises a first fuselage and a second fuselage which are symmetrically arranged in parallel; the wing is fixedly arranged above the middle part of the first fuselage and the second fuselage, and the tail is fixedly arranged above the tail part; the power device adopts a wing-hanging double-release layout form and is symmetrically arranged at the leading edge position of the left and right sides of the wing. The application provides a high-fuel-efficiency double-fuselage layout passenger plane and a design method, has the characteristics of energy saving and emission reduction, and provides a corresponding design method and internal layout design method of the double-fuselage layout passenger plane; through minimizing the structure weight of the fuselage and fully utilizing the internal space of the fuselage, energy saving and environmental protection are realized, and the double-fuselage layout passenger plane has the potential to bring more operating profits for airlines.

Description

Technical Field

[0001] The present invention belongs to the technical field of aircraft design, and in particular relates to a high-fuel-efficiency twin-fuselage passenger aircraft and a design method thereof. Background Art

[0002] Next-generation air transport demands increased air traffic volume while improving its environmental friendliness. This requires a step-change improvement in aircraft performance. To this end, the development and technological upgrade of ultra-high aspect ratio wing configurations is a key enabling strategy. However, compared to traditional aircraft, ultra-high aspect ratio wing structures bear higher loads, posing challenges to aircraft layout design and related technologies. Currently, the twin-fuselage concept has emerged as one of the most promising configurations for ultra-high aspect ratio wings. Targeting future high-efficiency aircraft technologies, existing patents such as Chinese invention patent application number 201911322028.6, "A Laminar Flow Technology Demonstration Aircraft," and Chinese invention patent application number 201811256599.X, "A Twin-Fuselage Aircraft," both design twin-fuselage aircraft. However, these inventions are small unmanned aerial vehicles (UAVs) and cannot be applied to passenger aircraft. Summary of the Invention

[0003] In view of the defects of the prior art, the present invention provides a high fuel efficiency twin-fuselage layout passenger aircraft and a design method, which can effectively solve the above problems.

[0004] The technical solution adopted in the present invention is as follows:

[0005] The present invention provides a high fuel efficiency twin-fuselage passenger aircraft, comprising a fuselage (100), wings (200), a tail (300) and a power unit (400);

[0006] The fuselage (100) comprises a first fuselage (101) and a second fuselage (102) which are arranged parallel to each other and symmetrically. The wings (200) are fixedly arranged above the middle parts of the first fuselage (101) and the second fuselage (102). The wings (200) adopt an upper monoplane layout with a symmetrical structure. The middle parts of the first fuselage (101) and the second fuselage (102) are connected as a whole through the wings (200). The tail wing (300) is fixedly arranged above the tail parts of the first fuselage (101) and the second fuselage (102). The tail wing (300) adopts an N-shaped layout with a symmetrical structure. The tail parts of the first fuselage (101) and the second fuselage (102) are connected as a whole through the tail wing (300). The power unit (400) adopts a wing-mounted double-engine layout and is symmetrically arranged at the leading edge positions on the left and right sides of the wings (200).

[0007] Preferably, the first fuselage (101) and the second fuselage (102) have the same shape, and both include a fuselage middle section (A1), a fuselage head section (A2) and a fuselage tail section (A3);

[0008] The middle section (A1) of the fuselage is cylindrical, and the front end of the middle section (A1) gradually shrinks forward along the axial direction of the fuselage to form the conical fuselage head (A2); the lower surface of the tail end of the middle section (A1) gradually shrinks upward along the axial direction of the fuselage to form the flat-shaped fuselage tail (A3) with a horizontal top surface and an inclined and upward-curved bottom surface;

[0009] The axial length of the middle section (A1) of the fuselage is longer than the axial length of the tail section (A3) of the fuselage; and the axial length of the tail section (A3) of the fuselage is longer than the axial length of the head section (A2) of the fuselage.

[0010] Preferably, the wing (200) includes a middle wing (201), a left wing (202) and a right wing (203);

[0011] The left and right sides of the middle wing (201) are fixedly connected to the top center line of the first fuselage (101) and the top center line of the second fuselage (102), respectively;

[0012] The left side of the middle wing (201) extends toward the outside of the first fuselage (101) to form the left wing (202); and the right side of the middle wing (201) extends toward the outside of the second fuselage (102) to form the right wing (203).

[0013] Preferably, the middle wing (201) is in a horizontally arranged rectangular shape;

[0014] The left wing (202) and the right wing (203) are symmetrical with each other, and are arranged to be tilted upward relative to the middle wing (201); the width of the left wing (202) and the right wing (203) gradually decreases from the wing root to the wing tip, forming a trapezoidal wing.

[0015] Preferably, the trailing edge of the left wing (202) is provided with a left flap (2021) and a left aileron (2022); the left aileron (2022) is located outside the left flap (2021);

[0016] The trailing edge of the right wing (203) is provided with a right flap (2031) and a right aileron (2032); the right aileron (2032) is located outside the right flap (2031).

[0017] Preferably, the power plant (400) comprises a first engine nacelle (401), a first engine pylon (402), a second engine nacelle (403) and a second engine pylon (404);

[0018] The first engine nacelle (401) is suspended below the left wing (202) via the first engine pylon (402);

[0019] The second engine nacelle (403) is suspended below the right wing (203) via the second engine pylon (404).

[0020] Preferably, the tail wing (300) includes a first vertical tail wing (301), a second vertical tail wing (302), a first horizontal tail wing (303) and a second horizontal tail wing (304);

[0021] The first vertical tail wing (301) is fixedly mounted above the tail centerline of the first fuselage (101); the second vertical tail wing (302) is fixedly mounted above the tail centerline of the second fuselage (102); the second vertical tail wing (302) and the first vertical tail wing (301) are bilaterally symmetrical;

[0022] The first horizontal tail (303) and the second horizontal tail (304) are symmetrical and arranged in sequence along the direction from the first vertical tail (301) to the second vertical tail (302); one side of the first horizontal tail (303) is fixed to the inner side of the top of the first vertical tail (301); the other side of the first horizontal tail (303) is fixed to one side of the second horizontal tail (304); and the other side of the second horizontal tail (304) is fixed to the inner side of the top of the second vertical tail (302).

[0023] Preferably, a first rudder (305) is provided at the trailing edge of the first vertical tail (301); and a second rudder (306) is provided at the trailing edge of the second vertical tail (302).

[0024] A first elevator (307) is provided at the trailing edge of the first horizontal tail (303); and a second elevator (308) is provided at the trailing edge of the second horizontal tail (304).

[0025] Preferably, inside the first fuselage (101), a cockpit (1011), a first first-class cabin (1012) and a first economy cabin (1013) are arranged in sequence from front to back;

[0026] Inside the second fuselage (102), a super first-class cabin (1021), a second first-class cabin (1022) and a second economy cabin (1023) are arranged in sequence from front to back.

[0027] The application also provides a design method of the high-fuel-efficiency double-fuselage layout passenger aircraft, comprising the following steps:

[0028] Step S1, according to the design requirements, determining a set of aircraft design parameters, and determining the design space of each design parameter in the set of design parameters; determining the target value m of the maximum take-off weight of the aircraft in advance To_target ;

[0029] Step S2, sampling in the design space of each design parameter to obtain initial sampling values of all design parameters;

[0030] Step S3, using formula (1) to estimate the fuselage weight m f of the fuselage (100):

[0031] m f =1.35·(L f ·D f ) 1.28 ·(1+0.05·N e )·(1+0.38·F c )·N f (1)

[0032] Wherein:

[0033] L f is the length of the fuselage (100), specifically the sum of the fuselage lengths of the first fuselage (101) and the second fuselage (102); D f is the average diameter of the fuselage (100); N e is the number of engines installed on the fuselage (100); F c is the aircraft floor coefficient; N f is 2, representing two fuselages;

[0034] Step S4, using formula (2) to estimate the wing weight m wingbox of the wing (200):

[0035]

[0036] Wherein: C is a constant; W / S is the wing load; AR is the aspect ratio; Lambda is the back-sweep angle of the wing quarter-chord line; t / c is the relative thickness of the average wing airfoil; V m is the maximum operating speed; Lambda is the taper ratio of the wing; n z is the maximum positive load coefficient; Z f is the relative position of the fuselage relative to the wingspan; Z e is the relative position of the engine relative to the wingspan; E m , E ws、E AR 、E Λ 、E t 、E V 、E λ 、E nz 、E zf and E ze , are the exponential terms of the corresponding terms respectively;

[0037] Step S5: Use formula (3) to estimate the horizontal tail weight m ht , specifically the sum of the weights of the first horizontal tail (303) and the second horizontal tail (304):

[0038] m ht =0.53·A ht ·DG 0.2 ·(λ ht +0.5) (3)

[0039] Where: S ht is the area of ​​a single horizontal tail; DG is the total design weight of the entire aircraft; λ ht is the aspect ratio of the horizontal tail;

[0040] Step S6: Use formula (4) to estimate the vertical tail weight m vt , specifically the sum of the weights of the second vertical tail (302) and the first vertical tail (301):

[0041]

[0042] Where: S vt is the area of ​​a single vertical tail; λ vt is the aspect ratio of the vertical tail; N vt is the number of vertical tail fins;

[0043] Step S7: Use formula (5) to estimate the weight m of the landing gear. LG :

[0044] m LG =N MLG ×0.0117×W LDG 0.95 ×X MLG 0.43 +N NLG ×0.048×W LDG 0.6 7×X NLG 0.43 (5)

[0045] Where: N MLG The number of main landing gears; W LDG Design landing weight for the aircraft; XMLG The length of the main landing gear strut; N NLG is the number of front landing gear; X NLG is the length of the front landing gear strut;

[0046] Step S8: Use formula (6) to estimate the weight of the propulsion system mps I :

[0047]

[0048] Where: N ENG is the number of engines; W ENGB is the reference engine weight; TR UST is the rated thrust of the engine; T RSO is the rated thrust of the reference engine; E EXP is the engine weight scaling parameter; the benchmark engine is the engine selected as the reference standard among various engines;

[0049] Step S9: Use formula (7) to estimate the empty mass m e :

[0050] m e =m f +m wingbox +m ht +m vt +m LG +m pSI (7)

[0051] Step S10: Use formula (8) to estimate the maximum take-off weight of the aircraft m TO :

[0052] m TO =m crew +m pay +m fuel +m e (8)

[0053] Where: m crew is the crew mass; m pay为 Payload mass; m fuel is the fuel quality;

[0054] Step S11, the maximum take-off weight of the aircraft estimated in step S10 (mm) TO and the aircraft's maximum takeoff weight target value (mm) TO_target The deviation of the sampling direction is determined, and the sampling direction is determined, thereby returning to step S2, re-sampling in the design space of each design parameter, obtaining the sampling values ​​of all design parameters, and then repeating steps S3 to S11; if the iterative cycle is continuously performed until the maximum take-off weight m of the aircraft estimated in step S10 isTO and the aircraft's maximum takeoff weight target value m TO_target If the deviation meets the design accuracy requirement, step S12 is executed;

[0055] Step S12: Output the sampled values ​​of all design parameters and the maximum take-off weight of the aircraft m TO ; Based on the sampling values ​​of all design parameters, a high fuel efficiency twin-fuselage layout passenger aircraft was designed.

[0056] The high fuel efficiency twin-fuselage passenger aircraft and design method provided by the present invention have the following advantages:

[0057] The present invention proposes a highly fuel-efficient twin-fuselage passenger aircraft and a design method that has the characteristics of energy conservation and emission reduction. It also proposes a corresponding design method and internal layout design method for the twin-fuselage passenger aircraft. By minimizing the fuselage structure weight and making full use of the fuselage's internal space, energy conservation and environmental protection are achieved, and it has the potential to bring more operating profits to airlines. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 A perspective view of a fuel-efficient twin-fuselage passenger aircraft provided by the present invention;

[0059] Figure 2 A schematic diagram of the interior cabin of a high-fuel-efficiency twin-fuselage passenger aircraft provided by the present invention.

[0060] in:

[0061] 100 - fuselage; 101 - first fuselage; 102 - second fuselage; A1 - middle fuselage section; A2 - head fuselage; A3 - tail fuselage; 1011 - cockpit; 1012 - first class cabin; 1013 - first economy cabin; 1021 - super first class cabin; 1022 - second first class cabin; 1023 - second economy cabin;

[0062] 200-wing; 201-middle wing; 202-left wing; 2021-left flap; 2022-left aileron; 203-right wing; 2031-right flap; 2032-right aileron;

[0063] 300-tail; 301-first vertical tail; 302-second vertical tail; 303-first horizontal tail; 304-second horizontal tail; 305-first rudder; 306-second rudder; 307-first elevator; 308-second elevator;

[0064] 400-power unit; 401-first engine nacelle; 402-first engine pylon; 403-second engine nacelle; 404-second engine pylon. DETAILED DESCRIPTION

[0065] In order to make the technical problems, technical solutions and beneficial effects solved by the present application more clearly understood, the present application will be further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0066] The present application provides a high fuel efficiency double fuselage layout passenger aircraft and a design method. The double fuselage layout passenger aircraft has significant advantages in energy efficiency compared to traditional passenger aircraft. The double fuselage layout can reduce the shear force of the wing structure and the wing root bending moment, allowing further increase in the wing aspect ratio, improving the aerodynamic efficiency and fuel efficiency of the aircraft, and reducing emissions. The use of high horizontal tail layout can increase the control arm of the tail, thereby reducing the required tail area and reducing the structural weight of the horizontal tail. At the same time, it can also effectively reduce the adverse effects of wing downwash on the horizontal tail. In addition, due to the end plate effect of the high horizontal tail, the aerodynamic efficiency of the vertical tail is increased, and the vertical tail area of this layout can also be reduced. The most distinctive feature of the double fuselage concept is the unique fuselage layout. Currently, there is no published fuselage design method for double fuselage aircraft. The present application fills this gap. One nose of one fuselage is designed as a cockpit, and the nose of the other fuselage is arranged with two super first class seats to provide the best view. This layout can make full use of the fuselage space and bring more operating profits to airlines.

[0067] Referring to Figure 1 The present application provides a high fuel efficiency double fuselage layout passenger aircraft, which comprises a fuselage 100, a wing 200, a tail 300 and a power device 400.

[0068] The fuselage 100 comprises a first fuselage 101 and a second fuselage 102 arranged in parallel and symmetrically. The wing 200 is fixedly arranged above the middle part of the first fuselage 101 and the second fuselage 102, and the wing 200 adopts an upper single wing layout form in a symmetrical structure. The wing 200 connects the middle part of the first fuselage 101 and the second fuselage 102 as a whole. The tail 300 is fixedly arranged above the tail part of the first fuselage 101 and the second fuselage 102, and the tail 300 adopts an n-shaped layout form in a symmetrical structure. The tail 300 connects the tail part of the first fuselage 101 and the second fuselage 102 as a whole. The power device 400 adopts a wing-mounted double release layout form and is symmetrically arranged at the leading edge position on the left and right sides of the wing 200.

[0069] The fuselage 100, the wing 200, the tail 300 and the power device 400 will be described in detail as follows:

[0070] (I) Fuselage 100

[0071] In the present invention, the first fuselage 101 and the second fuselage 102 have the same shape. The first fuselage 101 is the left fuselage, and the second fuselage 102 is the right fuselage. Both fuselage sections include a fuselage middle section A1, a fuselage head section A2, and a fuselage tail section A3.

[0072] The middle section A1 is cylindrical in shape. The front end of the middle section A1 gradually contracts forward along the fuselage axis to form a tapered nose A2. The lower surface of the tail end of the middle section A1 gradually contracts upward along the fuselage axis to form a flat, duckbill-shaped tail section A3 with a horizontal top surface and an inclined, upward-curved bottom surface.

[0073] Among them: the axial length of the middle section A1 of the fuselage is longer than the axial length of the tail section A3 of the fuselage; the axial length of the tail section A3 of the fuselage is longer than the axial length of the head section A2 of the fuselage.

[0074] The distance between the first fuselage 101 and the second fuselage 102 can be designed according to the requirements of the International Civil Aviation Organization (ICAO). For example, ICAO Code C airports require that the wheelbase of the aircraft's main landing gear does not exceed 9 meters. In the present invention, a main landing gear is installed directly below each fuselage. Therefore, the wheelbase constraint of the main landing gear is equal to the distance constraint between the two fuselages of a twin-fuselage aircraft, that is, the distance between the two fuselages does not exceed 9 meters.

[0075] Furthermore, the interior of the first fuselage 101 is arranged from front to back in sequence with a cockpit 1011, a first-class cabin 1012 and a first economy cabin 1013; the interior of the second fuselage 102 is arranged from front to back in sequence with a super first-class cabin 1021, a second first-class cabin 1022 and a second economy cabin 1023.

[0076] Therefore, a twin-fuselage aircraft adopts a dual-cabin interior layout: the nose of the left fuselage is designed as the cockpit 1011, while the nose of the other fuselage is arranged with two Super First Class seats 1021. This provides the best view and fully utilizes the fuselage space. This design provides more options for passengers and generates higher operating profits for airlines.

[0077] Furthermore, for the twin-fuselage passenger aircraft provided by the present invention, the fuselage geometry design method for twin-fuselage passenger aircraft is adopted. In order to ensure the same passenger capacity as the single-fuselage passenger aircraft used as a reference, it is necessary to ensure that the total floor area in the cabin is the same. When designing the twin-fuselage passenger aircraft of the present invention, the fuselage cabin length l and the fuselage cabin equivalent diameter d of each fuselage are both the same as those of the single-fuselage passenger aircraft. This ensures that the total floor area remains l*d, while ensuring that the total external surface area of ​​the twin-fuselage aircraft is the same as that of the single-fuselage aircraft, meeting the passenger luggage carrying space and weight requirements of passenger aircraft design standards and requirements.

[0078] (2) Wing 200

[0079] In the present invention, the wing 200 adopts a symmetrical upper wing layout, and the wing 200 includes a middle wing 201, a left wing 202, and a right wing 203; the left and right sides of the middle wing 201 are fixedly connected to the top centerline of the first fuselage 101 and the top centerline of the second fuselage 102 respectively; the left side of the middle wing 201 extends outward from the first fuselage 101 to form the left wing 202; the right side of the middle wing 201 extends outward from the second fuselage 102 to form the right wing 203.

[0080] The middle wing 201 is a horizontally arranged rectangular shape; the left wing 202 and the right wing 203 are symmetrical, and the left wing 202 and the right wing 203 are arranged to be tilted upward relative to the middle wing 201; the width of the left wing 202 and the right wing 203 gradually decreases from the wing root to the wing tip, forming a trapezoidal wing.

[0081] Furthermore, the trailing edge of the left wing 202 is provided with a left flap 2021 and a left aileron 2022; the left aileron 2022 is located outside the left flap 2021; the trailing edge of the right wing 203 is provided with a right flap 2031 and a right aileron 2032; the right aileron 2032 is located outside the right flap 2031.

[0082] (3) Tail 300

[0083] In the present invention, the tail 300 is arranged above the rear of the twin fuselages, and includes twin vertical tails and a high-mounted forward-swept horizontal tail. The high-mounted forward-swept horizontal tail is embedded between the twin vertical tails. The combined front view of the tail 300 presents an N shape.

[0084] Specifically, the tail 300 includes a first vertical tail 301, a second vertical tail 302, a first horizontal tail 303 and a second horizontal tail 304;

[0085] A first vertical tail 301 is fixedly mounted above the tail centerline of the first fuselage 101; a second vertical tail 302 is fixedly mounted above the tail centerline of the second fuselage 102; the second vertical tail 302 is symmetrical to the first vertical tail 301;

[0086] The first horizontal tail 303 and the second horizontal tail 304 are symmetrical and are arranged in sequence from the first vertical tail 301 to the second vertical tail 302; one side of the first horizontal tail 303 is fixed to the top inner side of the first vertical tail 301; the other side of the first horizontal tail 303 is fixed to one side of the second horizontal tail 304; and the other side of the second horizontal tail 304 is fixed to the top inner side of the second vertical tail 302.

[0087] Furthermore, a first rudder 305 is provided at the trailing edge of the first vertical tail 301 ; a second rudder 306 is provided at the trailing edge of the second vertical tail 302 ; a first elevator 307 is provided at the trailing edge of the first horizontal tail 303 ; and a second elevator 308 is provided at the trailing edge of the second horizontal tail 304 .

[0088] (4) Power unit 400

[0089] In the present invention, the power unit 400 is a wing-mounted twin-engine type, including a first engine nacelle 401, a first engine pylon 402, a second engine nacelle 403 and a second engine pylon 404; the first engine nacelle 401 is suspended below the left wing 202 through the first engine pylon 402; the second engine nacelle 403 is suspended below the right wing 203 through the second engine pylon 404.

[0090] The present invention proposes a high fuel efficiency twin-fuselage passenger aircraft having the following features:

[0091] (1) Compared with conventional passenger aircraft, the wing 200 of the present invention significantly increases the aspect ratio, effectively reduces induced drag, and can improve the aerodynamic efficiency and fuel efficiency of the passenger aircraft, reduce emissions, and increase the revenue of the airline.

[0092] (2) Increasing the aspect ratio of the wing increases the bending moment and shear force of the wing structure, which increases the design requirements for the wing structure's strength and stiffness. The present invention adopts a twin-fuselage layout. By replacing the traditional large central fuselage with two fuselages, a first fuselage 101 and a second fuselage 102, located on the outer sides of the wings, the maximum bending moment of the wing is reduced, making the wing structure lighter.

[0093] (3) At the same time, the present invention adopts a fuselage geometry design method for twin-fuselage passenger aircraft. In order to ensure the same passenger capacity as the single-fuselage passenger aircraft used as a reference, it is necessary to ensure that the total floor area in the cabin is the same. The present invention designs a twin-fuselage passenger aircraft, and the fuselage cabin length l and the fuselage cabin equivalent diameter d of each fuselage are both the same as those of the single-fuselage passenger aircraft. This ensures that the total floor area remains l*d, while ensuring that the total external surface area of ​​the twin-fuselage aircraft is the same as that of the single-fuselage aircraft, meeting the passenger luggage carrying space and weight requirements of passenger aircraft design standards and requirements.

[0094] (4) The thickness of an aircraft fuselage structure is related to its diameter. The design of the present invention reduces the diameter of both fuselages in a twin-fuselage layout compared to conventional layouts, resulting in a reduction in the thickness of each fuselage structure. This invention ensures that the total external surface area of ​​a twin-fuselage aircraft is the same as that of a single-fuselage aircraft, thereby reducing the aircraft's gross weight and increasing its payload capacity.

[0095] (5) The twin-fuselage layout means that the main landing gear does not require an external fairing, and the length and structure of the main landing gear struts can be shortened and simplified, which helps to reduce the weight of the landing gear and its fairing and reduce resistance.

[0096] (6) The distance between the two fuselages of the present invention is designed according to the requirements of the International Civil Aviation Organization (ICAO). For example, ICAO Code C airports require that the wheelbase of the aircraft's main landing gear does not exceed 9 meters. The present invention installs a main landing gear directly under each fuselage, so the wheelbase constraint of the main landing gear is equal to the distance constraint between the two fuselages of a twin-fuselage aircraft, that is, the distance between the two fuselages does not exceed 9 meters, which meets the design standards for passenger aircraft.

[0097] (7) The landing gear design of a twin-fuselage aircraft differs from conventional configurations. A twin-fuselage aircraft has a nose landing gear and a main landing gear located at the centerline of each fuselage. However, even with the addition of a nose landing gear, the twin-fuselage design is simpler and lighter than that of conventional aircraft. For very large cargo aircraft, this weight reduction can reach up to 30%.

[0098] (8) The present invention adopts a high-mounted forward-swept horizontal tail, thereby reducing the area and structural weight of the horizontal tail by increasing the tail lever arm, and preventing the stability and control effect of the horizontal tail from being affected by the wing downwash. The horizontal tail of the present invention is embedded between the two vertical tails, and uses the end plate effect to reduce induced drag, thereby reducing the tail area and reducing the weight of the aircraft. The horizontal tail has a higher aspect ratio and a higher lift coefficient, thereby reducing the volume ratio of the aircraft's horizontal tail, making the horizontal tail lighter.

[0099] (9) The present invention adopts a double-cabin interior layout for a twin-fuselage aircraft, where the nose of one fuselage is designed as a cockpit, while the nose of the other fuselage is arranged with two super first-class seats to provide the best view and make full use of the fuselage space, thereby bringing more profits to the airline company.

[0100] The present invention also provides a design method for a high fuel efficiency twin-fuselage passenger aircraft, comprising the following steps:

[0101] Step S1: Determine the aircraft design parameter set according to the design requirements, and determine the design space of each design parameter in the design parameter set; predetermine the aircraft maximum take-off weight target value m TO_target ;

[0102] Step S2, sampling in the design space of each design parameter to obtain initial sampling values ​​of all design parameters;

[0103] Step S3: Use formula (1) to estimate the weight m of the fuselage 100. f :

[0104] m f = 1.35 · (L f · D f ) 1.28 · (1 + 0.05 · N e ) · (1 + 0.38 · F c ) · N f (1)

[0105] wherein:

[0106] L f is the length of the fuselage 100, specifically the sum of the fuselage lengths of the first fuselage 101 and the second fuselage 102; D f is the average diameter of the fuselage 100; N e is the number of engines installed on the fuselage 100;

[0107] F c is the airplane floor coefficient; N f is 2, representing having two fuselages;

[0108] Step S4, the wing weight m wingbox of the wing 200 is estimated by using formula (2):

[0109]

[0110] wherein: C is a constant; W / S is the wing load; AR is the aspect ratio; A is the back-sweep angle of the wing quarter-chord line; t / c is the relative thickness of the average wing airfoil; V m is the maximum operating speed; l is the taper ratio of the wing; n z is the maximum positive load coefficient; Z f is the relative position of the fuselage relative to the wingspan; Z e is the relative position of the engine relative to the wingspan; E m , E ws , E AR , E Λ , E t , E V , E λ , E nz , E zf and Ez e are the exponential terms of the corresponding items;

[0111] Specifically, the empty weight m eThe most significant difference in the calculations is in the wing weight estimation, which is caused by the different load distribution on the wing. This means that the wing mass estimation method for traditional aircraft cannot be directly applied to twin-fuselage aircraft. Therefore, it is necessary to estimate the structural mass of the wing by combining the wing's spanwise mass distribution (including the wing structural mass, fuel mass, and concentrated masses (such as engines)) with the aerodynamic loads. However, the linear approximation method for the lift distribution in the wing structure is not accurate enough for the physics-based wing mass estimation method. In addition, because this traditional method was published decades ago, it is not applicable to advanced composite structures.

[0112] Therefore, the present invention employs the Vortex Lattice Method (VLM) tool (AVL) to estimate the spanwise aerodynamic load distribution based on input wing geometry parameters. By integrating the spanwise aerodynamic load distribution along the wing span, the reduced shear force due to the aerodynamic load can be obtained. Subsequently, the reduced bending moment is obtained by integrating the distribution along the wing span. Furthermore, considering that composite materials will become the primary material for next-generation aircraft, the wing mass estimation method is further improved, using a cutoff strain method to determine the dimensions of the composite wing structure during the preliminary design phase.

[0113] The performance of the aircraft with preliminary size design was analyzed and evaluated, and the proposed wing mass estimation method was used. After iterative calculation until convergence, the weight decomposition and mission segmentation were obtained. On this basis, the present invention innovatively proposed a semi-empirical formula of formula (2): a medium-range (MR) aircraft made of metal materials, a long-range (LR) aircraft made of metal materials, a medium-range (MR) aircraft made of composite materials, and a long-range (LR) aircraft made of composite materials. For each configuration, typical design parameters were selected, and an experimental design (DoE) was performed using the improved physics-based wing mass estimation method. Finally, the estimated wing mass results were used in a multivariate linear regression to obtain the semi-empirical formula of formula (2).

[0114] In formula (2), as a preferred method, constants C and E m 、E ws 、E AR 、E Λ 、E t 、E V 、E λ 、E nz 、E zf and E ze The values ​​of are as follows:

[0115]

[0116] Among them: AL refers to aluminum alloy material, CFRP refers to composite material, MR refers to medium range, and LR refers to long range.

[0117] This paper proposes a wing mass estimation method specifically for advanced twin-fuselage aircraft. It improves upon the semi-analytical wing mass estimation method for twin-fuselage configurations, including improving the accuracy of aerodynamic analysis and extending its application to advanced composite structures. Because the semi-analytical method requires a large number of input parameters that are difficult to obtain during the preliminary sizing phase, a design of experiment (DoE) and regression approach were employed to develop semi-empirical wing mass estimation methods for twin-fuselage configurations under different mission and material conditions. Ultimately, the developed semi-empirical mass estimation method was integrated into the conceptual design and analysis of twin-fuselage aircraft, performing preliminary design and sizing for a medium-range twin-fuselage (MRTF) and a long-range twin-fuselage (LRTF) aircraft. Case studies demonstrate that the developed initial weight estimation method for twin-fuselage aircraft can efficiently analyze the weight distribution of twin-fuselage aircraft within the provided twin-fuselage aircraft sizing and analysis framework.

[0118] Step S5: Use formula (3) to estimate the horizontal tail weight m ht , specifically the sum of the weights of the first horizontal tail 303 and the second horizontal tail 304:

[0119] m ht =0.53·S ht ·DG 0.2 ·(λ ht +0.5) (3)

[0120] Where: S ht is the area of ​​a single horizontal tail; DG is the total design weight of the entire aircraft; λ ht is the aspect ratio of the horizontal tail;

[0121] Step S6: Use formula (4) to estimate the vertical tail weight m vt , specifically the sum of the weights of the second vertical tail 302 and the first vertical tail 301:

[0122]

[0123] Where: S vt is the area of ​​a single vertical tail; λ vt is the aspect ratio of the vertical tail; N vt is the number of vertical tail fins;

[0124] Step S7: Use formula (5) to estimate the weight m of the landing gear. LG :

[0125] m LG =N MLG ×0.0117×W LDG 0.95 ×XMLG 0.43 +N NLG x 0.048 x W LDG 0.67 x X NLG 0.43 (5)

[0126] wherein: N MLG is the number of main landing gears; W LDG is the design landing weight of the aircraft; X MLG is the length of the main landing gear strut; N NLG is the number of front landing gears; X NLG is the length of the front landing gear strut;

[0127] Step S8, the weight of the propulsion system m PSI is estimated using equation (6):

[0128]

[0129] wherein: N ENG is the number of engines; W ENGB is the reference engine weight; TR UST is the rated thrust of the engine; T RSo is the rated thrust of the reference engine; E EXP is the engine weight scaling parameter; the reference engine is the engine selected as the reference standard among the various engines;

[0130] Step S9, the empty mass m e is estimated using equation (7):

[0131] m e = m f + m wingbox + m ht + m vt + m LG + m PSI (7)

[0132] Step S10, the maximum takeoff weight m TO is estimated using equation (8):

[0133] m TO = m crew+ m pay + m fuel + m e (8)

[0134] wherein: m crew is the crew mass; m pay is the payload mass; m fuel is the fuel mass;

[0135] Step S11, the maximum take-off weight of the aircraft estimated in step S10 (mm) TO and the aircraft's maximum takeoff weight target value m TO_target The deviation of the sampling direction is determined, and the sampling direction is determined, thereby returning to step S2, re-sampling in the design space of each design parameter, obtaining the sampling values ​​of all design parameters, and then repeating steps S3 to S11; if the iterative cycle is continuously performed until the maximum take-off weight m of the aircraft estimated in step S10 is TO and the aircraft's maximum takeoff weight target value m TO_target If the deviation meets the design accuracy requirement, step S12 is executed;

[0136] Step S12: Output the sampled values ​​of all design parameters and the maximum take-off weight of the aircraft m TO ; Based on the sampling values ​​of all design parameters, a high fuel efficiency twin-fuselage layout passenger aircraft was designed.

[0137] The design method of a high fuel efficiency twin-fuselage passenger aircraft provided by the present invention is applicable to the design of medium-range and long-range aircraft. An embodiment is described below:

[0138] The design of a medium- and long-range twin-fuselage transport aircraft was based on the A320 and B777, incorporating several new technical assumptions. These included a 55% laminar flow area for the wings and tail due to the use of hybrid laminar flow control technology, a 20% reduction in structural mass due to the use of advanced composite materials and structures, and a maximum positive load factor of +1.5g due to the application of load mitigation techniques. Because the twin-fuselage configuration significantly reduces bending moments and shear forces in the wing structure, this twin-fuselage aircraft utilizes an ultra-high aspect ratio wing to improve aerodynamic efficiency and reduce fuel consumption. Consequently, a high wing configuration was adopted to meet clearance requirements between the engine and wing tip. A high tail configuration was adopted to account for aeroelastic properties and to avoid downwash from the wing and engine exhaust flows.

[0139] By adopting the method of the present invention, as part of the parameters, the results are as follows:

[0140] When a passenger aircraft is designed as a medium-range aircraft, the maximum take-off weight is 59,000-60,000 kg, the fuel weight is 13,000-14,000 kg, the wing weight is 5,500-6,000 kg, the fuselage weight is 5,000-5,500 kg, the engine weight is 3,500-4,000 kg, and the landing gear weight is 2,000-2,500 kg; when a passenger aircraft is designed as a long-range aircraft, the maximum take-off weight is 242,000-246,000 kg, the fuel weight is 155,000-158,000 kg, the wing weight is 38,000-40,000 kg, the fuselage weight is 20,000-21,000 kg, the engine weight is 16,000-18,000 kg, and the landing gear weight is 5,000-7,000 kg.

[0141] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A design method for a fuel-efficient twin-fuselage passenger aircraft, characterized in that: The high fuel efficiency twin-fuselage layout passenger aircraft comprises a fuselage (100), wings (200), a tail wing (300) and a power unit (400); The fuselage (100) comprises a first fuselage (101) and a second fuselage (102) which are arranged parallel to each other and symmetrically. The wings (200) are fixedly arranged above the middle parts of the first fuselage (101) and the second fuselage (102). The wings (200) adopt an upper monoplane layout with a symmetrical structure. The middle parts of the first fuselage (101) and the second fuselage (102) are connected as a whole through the wings (200). The tail fin (300) is fixedly arranged above the tail parts of the first fuselage (101) and the second fuselage (102). The tail fin (300) adopts an N-shaped layout with a symmetrical structure. The tail parts of the first fuselage (101) and the second fuselage (102) are connected as a whole through the tail fin (300). The power unit (400) adopts a wing-mounted double-engine layout and is symmetrically arranged at the leading edge positions on the left and right sides of the wings (200). The design method comprises the following steps: Step S1: Determine the aircraft design parameter set according to the design requirements, and determine the design space of each design parameter in the design parameter set; predetermine the aircraft maximum take-off weight target value ; Step S2, sampling in the design space of each design parameter to obtain initial sampling values ​​of all design parameters; Step S3, using formula (1), the weight of the fuselage (100) is estimated : （1）， in: is the length of the fuselage (100), specifically the sum of the fuselage lengths of the first fuselage (101) and the second fuselage (102); is the average diameter of the fuselage (100); the number of engines installed for the fuselage (100); is the aircraft floor coefficient; 2, indicating two fuselages; Step S4, using formula (2), the wing weight of the wing (200) is estimated. : （2）， in: is a constant; is the wing loading; is the aspect ratio; is the sweep angle of the wing quarter chord line; is the relative thickness of the average wing airfoil; is the maximum operating speed; is the taper ratio of the wing; is the maximum positive load factor; is the relative position of the fuselage relative to the wingspan; is the relative position of the engine relative to the wingspan; 、 、 、 、 、 、 、 、 and , are the exponential terms of the corresponding terms respectively; Step S5, using formula (3), estimate the horizontal tail weight , specifically the sum of the weights of the first horizontal tail (303) and the second horizontal tail (304): （3）， in: is the area of ​​a single horizontal tail; is the design gross weight of the entire aircraft; is the aspect ratio of the horizontal tail; Step S6, using formula (4), the vertical tail weight is estimated , specifically the sum of the weights of the second vertical tail (302) and the first vertical tail (301): （4）， in: is the area of ​​a single vertical tail; is the aspect ratio of the vertical tail; is the number of vertical tail fins; Step S7: Use formula (5) to estimate the weight of the landing gear. : （5）， in: The number of main landing gear; Design landing weight for the aircraft; The length of the main landing gear struts; is the number of front landing gear; is the length of the front landing gear strut; Step S8: Use formula (6) to estimate the weight of the propulsion system : （6）， in: is the number of engines; is the base engine weight; is the rated thrust of the engine; is the rated thrust of the reference engine; is the engine weight scaling parameter; the benchmark engine is the engine selected as the reference standard among various engines; Step S9: Use formula (7) to estimate the empty mass : = + + + + + （7） Step S10: Use formula (8) to estimate the maximum take-off weight of the aircraft : （8）， in: for crew quality; is the payload mass; is the fuel quality; Step S11, the maximum take-off weight of the aircraft estimated in step S10 and the aircraft's maximum takeoff weight target The deviation of the sampling direction is determined, and the sampling direction is determined, thereby returning to step S2, re-sampling in the design space of each design parameter, obtaining the sampling values ​​of all design parameters, and then repeating steps S3 to S11; if the iterative cycle is continuously performed until the maximum take-off weight of the aircraft estimated in step S10 is and the aircraft's maximum takeoff weight target If the deviation meets the design accuracy requirement, step S12 is executed; Step S12: Output the sampled values ​​of all design parameters and the maximum take-off weight of the aircraft at this time ; Based on the sampling values ​​of all design parameters, a high fuel efficiency twin-fuselage layout passenger aircraft was designed.

2. The design method of a high fuel efficiency twin-fuselage passenger aircraft according to claim 1, characterized in that: The first fuselage (101) and the second fuselage (102) have the same shape, and both comprise a fuselage middle section (A1), a fuselage head section (A2), and a fuselage tail section (A3); The middle section (A1) of the fuselage is cylindrical in shape, and the front end of the middle section (A1) gradually shrinks forward along the axial direction of the fuselage to form the conical fuselage head (A2); the lower surface of the tail end of the middle section (A1) gradually shrinks upward along the axial direction of the fuselage to form the flat duckbill-shaped fuselage tail (A3) with a horizontal top surface and an inclined and upward-curved bottom surface; The axial length of the middle section (A1) of the fuselage is longer than the axial length of the tail section (A3) of the fuselage; and the axial length of the tail section (A3) of the fuselage is longer than the axial length of the head section (A2) of the fuselage.

3. The design method of a high fuel efficiency twin-fuselage passenger aircraft according to claim 1, characterized in that: The wing (200) includes a middle wing (201), a left wing (202) and a right wing (203); The left and right sides of the middle wing (201) are fixedly connected to the top center line of the first fuselage (101) and the top center line of the second fuselage (102), respectively; The left side of the middle wing (201) extends toward the outside of the first fuselage (101) to form the left wing (202); and the right side of the middle wing (201) extends toward the outside of the second fuselage (102) to form the right wing (203).

4. The design method of a high fuel efficiency twin-fuselage passenger aircraft according to claim 3, characterized in that: The middle wing (201) is in a horizontally arranged rectangular shape; The left wing (202) and the right wing (203) are symmetrical with respect to each other, and are arranged to be tilted upward relative to the middle wing (201); the width of the left wing (202) and the right wing (203) gradually decreases from the wing root to the wing tip, forming a trapezoidal wing.

5. The design method of a high fuel efficiency twin-fuselage passenger aircraft according to claim 3, characterized in that: The trailing edge of the left wing (202) is provided with a left flap (2021) and a left aileron (2022); the left aileron (2022) is located outside the left flap (2021); The trailing edge of the right wing (203) is provided with a right flap (2031) and a right aileron (2032); the right aileron (2032) is located outside the right flap (2031).

6. The design method of a high fuel efficiency twin-fuselage passenger aircraft according to claim 3, characterized in that: The power plant (400) comprises a first engine nacelle (401), a first engine pylon (402), a second engine nacelle (403) and a second engine pylon (404); The first engine nacelle (401) is suspended below the left wing (202) via the first engine pylon (402); The second engine nacelle (403) is suspended below the right wing (203) via the second engine pylon (404).

7. The design method of a high fuel efficiency twin-fuselage passenger aircraft according to claim 1, characterized in that: The tail (300) includes a first vertical tail (301), a second vertical tail (302), a first horizontal tail (303) and a second horizontal tail (304); The first vertical tail wing (301) is fixedly mounted above the tail centerline of the first fuselage (101); the second vertical tail wing (302) is fixedly mounted above the tail centerline of the second fuselage (102); the second vertical tail wing (302) and the first vertical tail wing (301) are bilaterally symmetrical; The first horizontal tail (303) and the second horizontal tail (304) are symmetrical and arranged in sequence along the direction from the first vertical tail (301) to the second vertical tail (302); one side of the first horizontal tail (303) is fixed to the inner side of the top of the first vertical tail (301); the other side of the first horizontal tail (303) is fixed to one side of the second horizontal tail (304); and the other side of the second horizontal tail (304) is fixed to the inner side of the top of the second vertical tail (302).

8. The method for designing a fuel-efficient twin-fuselage passenger aircraft according to claim 7, wherein: A first rudder (305) is provided at the trailing edge of the first vertical tail (301); a second rudder (306) is provided at the trailing edge of the second vertical tail (302); A first elevator (307) is provided at the trailing edge of the first horizontal tail (303); and a second elevator (308) is provided at the trailing edge of the second horizontal tail (304).

9. The design method of a high fuel efficiency twin-fuselage passenger aircraft according to claim 1, characterized in that: Inside the first fuselage (101), a cockpit (1011), a first first-class cabin (1012), and a first economy cabin (1013) are arranged in sequence from front to back; Inside the second fuselage (102), a super first-class cabin (1021), a second first-class cabin (1022) and a second economy cabin (1023) are arranged in sequence from front to back.

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