A floating characteristic test model based on an equivalent cavity

Abstract

This invention belongs to the technical field of waterborne emergency landing tests for aircraft, and proposes a floating characteristic test model based on an equivalent cavity. The test model features a separated structural design based on the interface between adjacent sections. The internal structure of the model mainly comprises two parts: a high-strength waterproof frame and a stringer structure. The equivalent volume of the cavity structure and the approximate simulation scheme of leakage sources are based on the actual aircraft cavity structure and leakage source distribution sections. The model surface skin material adopts a vacuum-sealed composite material layup structure to achieve structural volume control. The frame, stringer structure, and cavity structure volume equivalent simulation structure are fixed and bonded through pre-reserved contact slots. This invention provides a new approach to the structural design of waterborne emergency landing floating characteristic test models, and can better meet the requirements of fuselage structural strength and equivalent cavity design for test missions, laying the foundation for waterborne emergency landing floating characteristic model tests.

Description

Technical Field

[0001] This invention belongs to the field of aircraft water landing test technology, specifically relating to a floating characteristic test model based on an equivalent cavity. Background Technology

[0002] The water landing and floating characteristic test model needs to undergo two stages during the test: high-speed deployment and floating on the water surface. To ensure that the model does not suffer damage due to insufficient structural strength or poor watertightness during these stages, each component of the model must be comprehensively designed based on overall strength and test design requirements. Among them, the fuselage, as the structure that generates the strongest impact on the water surface and has the most internal water ingress, not only needs to have high overall structural strength, but also its internal cavity volume and leakage conditions, as well as the watertightness and leakage conditions at typical wing locations, should be as similar as possible to the actual aircraft. Otherwise, the test results cannot truly represent the water surface floating characteristics of the actual aircraft.

[0003] Chinese Civil Aviation Regulations Part 25, "Airworthiness Standards for Transport Category Aircraft," sets forth specific requirements for the water buoyancy of fixed-wing aircraft: "It must be demonstrated that, under reasonably possible water conditions, the aircraft's buoyancy time and trim allow all occupants to disembark and board the required lifeboats." Model testing, as one of the recommended methods for airworthiness compliance verification, is widely used in current civil aircraft development due to its advantages of being intuitive, efficient, and accurate. To ensure the smooth conduct of buoyancy characteristic model tests, the design and fabrication of the test models are particularly important. In particular, the equivalent simulation of the internal cavity volume and seepage characteristics of the actual aircraft remains a major challenge in the model fabrication process.

[0004] In the traditional design and fabrication of floating characteristic models, the fuselage fairing typically employs a one-piece design and a "skin + honeycomb + bulkhead" structure. While the one-piece design ensures the integrity of the internal bulkhead, there is usually a significant abrupt change in curvature at the junction of the fuselage and landing gear fairing. This one-piece design inevitably leads to weak bonding between the skin and the honeycomb at this point, affecting structural strength. Secondly, the traditional honeycomb structure, skin, and bulkhead are usually three completely different materials, and the thickness of the honeycomb structure and skin often differs by as much as five times. In addition, the honeycomb structure has high rigidity, and the skin has a certain curvature, making it impossible to achieve a seamless bonding between the honeycomb and the skin during installation.

[0005] Secondly, adopting a honeycomb-like partial block form not only reduces the overall structural strength of the "skin + honeycomb" structure to some extent, but also adds structural weight due to the bonding of the honeycomb blocks, making it more difficult to control the empty weight of the model.

[0006] Finally, due to the complexity of the actual aircraft structure, traditional structural designs often overlook the differences between the model's internal structural volume, and the water absorption and storage characteristics of the honeycomb and frame materials and the actual aircraft. This makes it difficult for the test model to maintain consistency with the actual aircraft's internal volume, empty weight after a single test, center of gravity position, and water filtration characteristics of the aircraft's internal structure. This affects the accurate feedback of the floating characteristic model test on the actual aircraft's floating motion attitude and floating time.

[0007] Currently, there is no buoyancy model that comprehensively considers the structural strength, cavity volume, seepage characteristics, and water filtration characteristics of an aircraft. Summary of the Invention

[0008] The purpose of this invention is to design a floating characteristic test model based on an equivalent cavity in order to overcome the shortcomings of the prior art.

[0009] To solve this technical problem, the technical solution of the present invention is as follows:

[0010] A floating characteristic test model based on an equivalent cavity is provided. The floating characteristic test model adopts a segmented structure, which discretizes the aircraft into a fuselage 1 with fairing, a wing 2, a tail 3, and an engine 4.

[0011] The fuselage 1 with fairing is divided into two parts by the junction of the fuselage and the fairing. After the division, the fuselage 1 with fairing is separated into two parts: a separate fuselage 5 and a separate fuselage fairing 6. The two parts are separated by the fuselage skin.

[0012] The shapes of the individual fuselage 5, wings 2, tail 3, individual fuselage fairing 6, and engine 4 are all simulated using a vacuum-sealed high-strength thin-walled skin structure 7. The quality of the skin after vacuuming is determined by the material thickness and surface density.

[0013] The internal structure of the separate fuselage 5 includes a high-strength bulkhead structure 8 with drainage holes, a stringer structure 9, a fully enclosed bulkhead 10, a cargo hold floor 11, and a load-bearing beam structure 12. The high-strength bulkhead structure 8 and the stringer structure 9 are fixed and bonded through pre-reserved contact slots and are glued to the vacuum-sealed high-strength thin-walled skin structure 7. The load-bearing beam structure 12 passes through and is fixed to the high-strength bulkhead structure 8 and the fully enclosed bulkhead 10. In addition, the separate fuselage 5 also has a center of gravity plate device 13 for lifting and adjusting the state of the model test, a watertight instrument box 14 for installing and waterproofing the test instruments, and a cavity volume equivalent module 15.

[0014] The internal structure of the separate fuselage fairing 6 is respectively arranged with a high-strength partition frame structure 8 with water flow holes, a stringer structure 9 and a cavity volume equivalent module 15. The connection method between the high-strength partition frame structure 8, the stringer structure 9 and the skin is the same as above.

[0015] The internal structure of the wing 2 is respectively arranged with a high-strength bulkhead structure 8 with water flow holes, a stringer structure 9, a fully enclosed bulkhead 10, a load-bearing beam structure 12, and a cavity volume equivalent module 15; wherein, the connection method of each component is the same as that of the internal structure of the individual fuselage 5.

[0016] The internal structure of the tail fin 3 has a common aviation-grade plate frame structure 16 and stringer structure 9; the two are fixed and bonded together by pre-reserved slots and glued to the skin structure 7.

[0017] The engine 4 includes a vacuum-evacuated high-strength thin-walled skin 7 and a structural volume equivalent module 15.

[0018] Within the fully enclosed bulkhead 10 of the individual fuselage 5, wing 2, and individual fuselage fairing 6, and the enclosed section formed by the cargo hold floor 11 and skin structure 7, each section is in an independent state. Fluid entering the model can only flow freely within the enclosed section through the water flow holes below the high-strength bulkhead structure 8.

[0019] Within the enclosed section formed by the fully enclosed partition 10 and the vacuum-evacuated high-strength thin-walled skin structure 7, each section is in an independent state. Fluid entering the model can only flow freely within the enclosed section through the water flow holes below the high-strength partition structure 8.

[0020] The engine 4 is a flow structure with openings at both ends. Its internal structural volume and centroid are similar to those of the actual engine by adding a cavity volume equivalent module 15 inside the high-strength thin-walled skin structure 7 of the engine 4 under vacuum.

[0021] The separate fuselage 5 and separate fuselage fairing 6 are located below the cargo hold floor 11 in a vacuum-sealed high-strength thin-walled skin structure 7, and have leakage source simulation holes 17 of a certain size. The leakage source simulation holes 17 are calculated one by one according to the location, size, and shape of leakage sources in the closed section of the actual aircraft and determined by equivalent leakage flow simulation tests.

[0022] The skin structure 7, high-strength partition structure 8, stringer structure 9, fully enclosed partition 10, watertight instrument box 14, and cavity volume equivalent module 15 are all made of carbon fiber cloth and T080 glass fiber cloth composite, and are strengthened and reduced in thickness by vacuum technology.

[0023] The airtightness characteristics of the individual fuselage 5, wing 2, and individual fuselage fairing 6 are determined based on the airtightness requirements of the actual aircraft and are geometrically similar to them. The separation surface between the individual fuselage 5 and the individual fuselage fairing 6 is their interface, and the separation is achieved by treating the individual fuselage 5 as a single unit.

[0024] The fully enclosed bulkhead 10 and cargo hold floor 11 in the separate fuselage 5 are geometrically similar to the cabin bulkhead and cargo hold floor of the actual aircraft, respectively.

[0025] The fully enclosed bulkhead 10 in the wing 2 maintains a similar geometric position to the fuel tank wall of the actual aircraft.

[0026] The fully enclosed bulkhead 10 in the separate fuselage 5, wing 2, and separate fuselage fairing 6, and the structural volume and centroid of the enclosed section formed by the vacuum-evacuated high-strength thin-walled skin structure 7, need to be measured separately during the model structure design. By adding a cavity volume equivalent module 15, the similarity relationship with the volume and centroid of the actual aircraft section can be achieved.

[0027] The specific installation locations of the cavity volume equivalent module 15 within the engine 4, the separate fuselage 5, and the separate fuselage fairing 6 are as follows:

[0028] The cavity volume equivalent module 15 inside the separate fuselage 5 is installed above the floor at the front of the fuselage; the cavity volume equivalent module 15 inside the separate fuselage fairing 6 is installed on the lower surface of the middle part of the skin of the component; the cavity volume equivalent module 15 inside the engine 4 is installed in the center of the engine, and the cavity volume equivalent module 15 is bonded to the inner wall of the engine 4 through an plexiglass plate to achieve the cavity volume equivalent module 15 being suspended.

[0029] The internal airtightness characteristics, structural volume, and leakage source distribution of components such as the separate fuselage 5, wing 2, engine 4, and separate fuselage fairing 6 are similar to the parameters of the actual aircraft.

[0030] The adjacent components of the separate fuselage 5, wing 2, tail 3, engine 4, and separate fuselage fairing 6 are fixed to the vacuum-sealed high-strength thin-walled skin structure 7 by adhesive bonding.

[0031] The floating characteristic test model utilizes a vacuum-sealed high-strength thin-walled skin structure 7, a high-strength partition frame structure 8, and a stringer structure 9 with internal overlap, replacing the traditional "skin + honeycomb + partition frame" structural form. This increases the structural strength and water filtration capacity of the individual structure to a certain extent, and ensures the equivalent simulation of the internal cavity volume and seepage characteristics of the individual structure.

[0032] Similarity refers to satisfying the Froude number similarity criterion and the Reynolds number similarity criterion for aerodynamic forces. Here, similarity means that the scale of the actual machine and the model satisfies the Froude number similarity criterion.

[0033] The beneficial effects of this invention are:

[0034] This invention proposes a floating characteristic test model based on an equivalent cavity. It includes a segmented design scheme for the model, equivalent simulation of the cavity structure volume, and approximate simulation of leakage sources. Specifically, the test model is designed with a segmented structure based on the interface between adjacent segments; the internal structure of the model mainly consists of a high-strength waterproof frame and a stringer structure; the equivalent simulation of the cavity structure volume and approximate simulation of leakage sources are based on the actual machine's cavity structure and leakage source distribution sections. The model's surface skin material adopts a vacuum-sealed composite material layup structure to achieve structural volume control.

[0035] The fuselage structure proposed in this invention can effectively reduce the thickness of the skin material and improve the seepage and filtration characteristics of the internal structure while ensuring the overall structural strength of the fuselage and landing gear fairing. By comprehensively considering the structural characteristics of the internal cavities of the model during the design process, a realistic simulation of the floating motion characteristics of the actual aircraft can be achieved.

[0036] It has the following advantages:

[0037] 1. The fuselage and landing gear fairings are designed separately, separating the fuselage and landing gear fairings into two independent structures. This not only retains the advantages of the single fuselage's arc-shaped overall structure and enhances its structural strength, but also creates conditions for repairing individual components in case of accidental damage to the fuselage and landing gear fairings during later testing, thus reducing the difficulty and time of model repair to a certain extent.

[0038] 2. Compared to traditional structural forms, the skin thickness of this invention can be controlled within 1 / 3 of the traditional "skin + honeycomb" thickness. Since the skin is the main contributor to the internal structural volume of the fuselage, reducing the skin thickness can significantly reduce the internal structural volume of the fuselage, thus ensuring the similarity of the internal cavity volume between the model and the actual aircraft.

[0039] 3. Based on the airtightness characteristics, structural volume ratio, and leakage source parameters of the actual aircraft compartment, research on test model design technology that considers the model water inflow, fluid seepage characteristics, and fluid distribution in the compartment is carried out during the test model design stage. The possible test interference situations that may occur during the test are handled at the beginning of the design and the impact is minimized, effectively ensuring the reliability of the test.

[0040] 4. The high-strength thin-walled skin layup material, high-strength waterproof frame structure and stringer structure proposed in this invention have the same structural properties. During the laying process, especially in the case of vacuum-sealed high-strength thin-walled skin, it can be laid in one step as a whole. Compared with the traditional "skin + honeycomb" form, it can effectively avoid the problems of reduced overall strength caused by bonding segmented honeycomb to the skin and increased structural weight caused by bonding segmented honeycomb, thus creating favorable conditions for subsequent model weight control and balancing.

[0041] 5. The high-strength waterproof bulkhead structure and stringer structure combination proposed in this invention divides the fuselage and landing gear fairings along the length and width directions respectively. By bonding and fixing the bulkhead, stringers and skin together, the overall strength of individual structural components is effectively improved. In model design, the thickness of the skin can also be appropriately reduced by taking advantage of this structural feature to reduce the volume of the internal structure.

[0042] 6. The high-strength thin-walled skin layer material, high-strength waterproof frame structure, and stringer structure proposed in this invention are all smooth, water-resistant, high-strength, thin-walled materials. During testing, there will be no changes in model weight or center of gravity, or difficulties in filtration and drying due to water absorption or storage in the structure. After a single test, the test personnel can quickly filter out the water inside the fuselage to conduct subsequent tests. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the vacuum-sealed skin layer structure of the present invention;

[0044] Figure 2 This is a schematic diagram of the floating characteristic test model of the present invention;

[0045] Figure 3 This is a schematic diagram of the fuselage and landing gear fairing separation design of the present invention;

[0046] Figure 4 This is a schematic diagram of the connection between the high-strength waterproof partition frame structure and the stringer structure of the present invention;

[0047] Figure 5 This is a schematic diagram of the equivalent module of the engine's internal cavity volume. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] The following detailed explanation of the floating characteristic test model based on an equivalent cavity of the present invention, with reference to the accompanying drawings, is provided in detail.

[0050] Figure 2This is a schematic diagram of the floating characteristic test model of the present invention, mainly comprising a fuselage 1 with fairing, wings 2, tail 3, engine 4, separate fuselage 5, separate fuselage fairing 6, high-strength thin-walled skin structure 7, high-strength bulkhead structure 8, stringer structure 9, fully enclosed bulkhead 10, cargo hold floor 11, load-bearing beam structure 12, center of gravity plate device 13, watertight instrument box 14, cavity volume equivalent module 15, and aviation shelf bulkhead structure 16, etc. The fuselage optimization design proposed in this invention is as follows: The model adopts a separate design method for the fuselage and landing gear fairing, adjusting the traditional integrated fuselage and fairing design structure to a separate fuselage 5 and separate fairing 6 structure with the joint surface of the two as the separation surface. The separate fuselage 5 is equipped with 4 fully enclosed bulkheads and 15 high-strength bulkhead structures 8 with water flow holes. The fully enclosed bulkheads 10 divide the separate fuselage 5 into 5 small spatial areas. The individual fuselage fairing 6 is a closed, integral structure, inside which is installed a high-strength partition frame structure 8 with water flow holes. The water flow holes on the high-strength partition frame structure 8 are semi-circular holes with a diameter of 7mm, mainly used to allow water to flow freely within the enclosed area.

[0051] Figure 3 This is a schematic diagram of a separate fuselage and landing gear fairing design. Figure 3 The high-strength bulkhead structure 8 inside the separate fairing 6 has the same longitudinal X-axis coordinate as the high-strength bulkhead structure 8 inside the separate fuselage 5, so as to enhance the lateral structural strength of the fuselage; the cargo hold floor 11 is positioned and installed and fixed through the rectangular holes reserved on the high-strength bulkhead structure 8; the lower abdomen of the high-strength thin-walled skin structure 7 is provided with a damage simulation hole 17.

[0052] The skin of various components such as the fuselage, wings, tail, and engines uses a vacuum-sealed high-strength thin-walled skin layup material 7. A schematic diagram of the structure of the high-strength thin-walled skin layup material 7 is shown below. Figure 1 As shown, the high-strength thin-walled skin layup material 7 consists of 6 layers. In conventional experiments, its thickness is 5 mm. After vacuuming with a suction tube, the thickness is 1.6 mm, only 1 / 3 of the conventional thickness, and the areal density increases by approximately 0.3 kg / m³. 2 The specific operation is as follows: First, according to the preset skin properties, bond the carbon fiber cloth and the composite fiber cloth. Then, use a vacuum tube to slide on the surface of the bonded layers to push / expel the air between the two layers of cloth and make the layup denser. After the operation, the skin thickness is effectively reduced while its strength is significantly increased.

[0053] The fuselage 5, the individual fairing 6, and the wing 2 are each equipped with a high-strength waterproof bulkhead structure 8, a stringer structure 9, and a fully enclosed bulkhead 10, all featuring drainage holes. The high-strength waterproof bulkhead structure 8, the stringer structure 9, and the fully enclosed bulkhead 10 are fixed and bonded together via pre-reserved contact slots and glued to the skin 7. A connection diagram is shown below. Figure 4 As shown.

[0054] The drainage holes are located at the bottom of the bulkhead, primarily for the free flow of water inside the fuselage. To simulate external water inflow, the surface of the vacuum-sealed, thin-walled skin structure 7 of the separate fuselage 5 and separate fuselage fairing 6, located below the cargo hold floor 11, is provided with leakage source simulation holes 17 with a diameter of 5mm-20mm. Figure 3 As shown. Among them, the leakage source simulation hole 17 is calculated one by one according to the location, size, shape and other characteristics of the leakage source in the actual closed section of the aircraft, and determined by equivalent simulation test of leakage flow. For example, the inner diameter of the hole in fuselage sealing area 1 is 5mm, the inner diameter of the hole in fuselage sealing area 2 is 10mm, the inner diameter of the hole in fuselage sealing area 3 is 18mm, the inner diameter of the hole in fuselage sealing area 4 is 16mm, the inner diameter of the hole in fuselage sealing area 5 is 14mm, and the diameter of the hole on the lower surface of the skin of the double-sided single fuselage fairing 6 is 20mm.

[0055] Engine 4, separate fuselage 5, separate fuselage fairing 6, and other components are equipped with cavity volume equivalent modules 15. Specifically, the cavity volume equivalent module 15 within the separate fuselage 5 is mounted above the floor at the front of the fuselage, as shown in the image. Figure 1 The volume equivalent module 15 of the cavity within the individual fuselage fairing 6 is installed on the lower surface of the middle part of the skin of this component; the volume equivalent module 15 of the cavity within the engine 4 is installed in the center of the engine, and the volume equivalent module 15 of the cavity is bonded to the inner wall of the engine 4 through an plexiglass plate to achieve the suspension of the volume equivalent module 15 of the cavity, as shown in the schematic diagram. Figure 5 As shown.

[0056] Test results of typical ply test specimens of high-strength thin-walled skin structure 7 and high-strength waterproof structure 8 show that the bending strength of the test specimens is significantly higher than that of other similar ply structures. The specific values ​​of the test results of typical ply test specimens are shown in Table 1 below:

[0057] Table 1

[0058]

[0059] This invention, based on the airtightness characteristics, structural volume ratio, and leakage source parameters of actual aircraft compartments, conducts research on experimental model design technology during the experimental model design stage, considering the model's water inflow, fluid seepage characteristics, and fluid distribution within the compartments. This addresses potential experimental interferences from the outset, minimizing their impact and effectively ensuring experimental reliability. The high-strength thin-walled skin layup material, high-strength waterproof frame structure, and stringer structure proposed in this invention possess identical structural properties. During installation, especially with vacuum-sealed high-strength thin-walled skin, a one-step integral installation can be achieved. Compared to the traditional "skin + honeycomb" approach, this effectively avoids the overall strength reduction and structural weight increase caused by bonding segmented honeycomb sections to the skin, creating favorable conditions for subsequent model weight control and balancing.

[0060] This invention provides a new approach to the structural design of a floating characteristic test model for forced landing on water. This method can better meet the requirements of fuselage structural strength and equivalent cavity design for the test mission, laying the foundation for the floating characteristic test model for forced landing on water.

Claims

1. A floating characteristic test model based on an equivalent cavity, characterized in that: The floating characteristic test model adopts a segmented structure, which discretizes the aircraft into a fuselage (1) with fairing, wings (2), tail (3) and engine (4). The fuselage (1) with fairing is divided into two parts by the junction of the fuselage and the fairing. After the division, the fuselage (1) with fairing is separated into two parts: a separate fuselage (5) and a separate fuselage fairing (6). The two parts are separated by the fuselage skin. The shapes of the individual fuselage (5), wings (2), tail (3), individual fuselage fairing (6), and engine (4) are all simulated using a vacuum-sealed high-strength thin-walled skin structure (7); The internal structure of the separate fuselage (5) is respectively arranged with a high-strength bulkhead structure (8) with water flow holes, a stringer structure (9), a fully enclosed bulkhead (10), a cargo hold floor (11), and a load-bearing beam structure (12); among them, the high-strength bulkhead structure (8) and the stringer structure (9) are fixed and fixed to the vacuum-evacuated high-strength thin-walled skin structure (7); the load-bearing beam structure (12) passes through the high-strength bulkhead structure (8) and the fully enclosed bulkhead (10) and is fixed to them; in addition, the separate fuselage (5) is also equipped with a center of gravity plate device (13) for lifting and adjusting the state of the model test, a watertight instrument box (14) for installing and waterproofing the test instruments, and a cavity volume equivalent module (15). The internal structure of the individual fuselage fairing (6) is respectively arranged with a high-strength partition frame structure (8) with water flow holes, a stringer structure (9) and a cavity volume equivalent module (15); The internal structure of the wing (2) is respectively arranged with a high-strength bulkhead structure (8) with water flow holes, a stringer structure (9), a fully enclosed bulkhead (10), a load-bearing beam structure (12) and a cavity volume equivalent module (15); wherein, the connection method of each component is the same as that of the internal structure of the individual fuselage (5); The internal structure of the tail fin (3) has an aviation-grade laminate frame structure (16) and a stringer structure (9); both are fixed together and fixed to a high-strength thin-walled skin structure (7); The engine (4) includes a vacuum-evacuated high-strength thin-walled skin structure (7) and a cavity volume equivalent module (15). The individual fuselage (5) and the individual fuselage fairing (6) are provided with leakage source simulation holes (17) in the vacuum-sealed high-strength thin-walled skin structure (7) below the cargo hold floor (11).

2. The floating characteristic test model based on an equivalent cavity according to claim 1, characterized in that: Within the enclosed section formed by the fully enclosed bulkhead (10) in the individual fuselage (5), wing (2), and individual fuselage fairing (6), and the cargo hold floor (11) and high-strength thin-walled skin structure (7), each section is in an independent state. The fluid entering the model can only flow freely within the enclosed section through the water flow hole below the high-strength bulkhead structure (8).

3. The floating characteristic test model based on an equivalent cavity according to claim 1, characterized in that: Within the enclosed section formed by the fully enclosed partition (10) and the vacuum-evacuated high-strength thin-walled skin structure (7), each section is in an independent state. The fluid entering the model can only flow freely within the enclosed section through the water flow hole below the high-strength partition structure (8).

4. The floating characteristic test model based on an equivalent cavity according to claim 1, characterized in that: The engine (4) is a flow structure with openings at both ends. Its internal structural volume and centroid are similar to those of the actual engine by adding a cavity volume equivalent module (15) inside the high-strength thin-walled skin structure (7) in which the engine (4) is vacuumed.

5. The floating characteristic test model based on an equivalent cavity according to claim 1, characterized in that: The high-strength thin-walled skin structure (7), high-strength partition structure (8), stringer structure (9), fully enclosed partition (10), watertight instrument box (14), and cavity volume equivalent module (15) are all made of carbon fiber cloth and T080 glass fiber cloth composite.

6. The floating characteristic test model based on an equivalent cavity according to claim 1, characterized in that: The airtightness characteristics of the individual fuselage (5), wing (2), and individual fuselage fairing (6) are determined according to the airtightness requirements of the actual aircraft and are geometrically similar to them; wherein, the separation surface of the individual fuselage (5) and the individual fuselage fairing (6) is the interface between the two, and the two are separated by setting the individual fuselage (5) as a whole; The fully enclosed bulkhead (10) and cargo hold floor (11) in the separate fuselage (5) are geometrically similar to the cabin bulkhead and cargo hold floor of the actual aircraft, respectively. The fully enclosed bulkhead (10) in the wing (2) maintains a similar geometric position to the fuel tank wall of the actual aircraft.

7. The floating characteristic test model based on an equivalent cavity according to claim 1, characterized in that: The structural volume and centroid of the fully enclosed bulkhead (10) in the separate fuselage (5), wing (2), and separate fuselage fairing (6) and the closed section enclosed by the vacuum-evacuated high-strength thin-walled skin structure (7) are measured separately during the model structure design. By adding a cavity volume equivalent module (15), the volume and centroid of the section are similar to those of the actual aircraft.

8. The floating characteristic test model based on an equivalent cavity according to claim 1, characterized in that: The specific installation locations of the cavity volume equivalent module (15) set inside the engine (4), the separate fuselage (5), and the separate fuselage fairing (6) are as follows: The cavity volume equivalent module (15) inside the separate fuselage (5) is installed above the floor of the front section of the fuselage; the cavity volume equivalent module (15) inside the separate fuselage fairing (6) is installed on the lower surface of the middle part of the skin of the component; the cavity volume equivalent module (15) inside the engine (4) is installed in the center of the engine, and the cavity volume equivalent module (15) is bonded to the inner wall of the engine (4) through an organic glass plate to achieve the cavity volume equivalent module (15) being suspended.

9. The floating characteristic test model based on an equivalent cavity according to claim 1, characterized in that: The internal airtightness characteristics, structural volume and leakage source distribution of the individual fuselage (5), wing (2), engine (4) and individual fuselage fairing (6) components are similar to the parameters of the actual aircraft.

10. The floating characteristic test model based on an equivalent cavity according to claim 1, characterized in that: The adjacent components of the individual fuselage (5), wing (2), tail (3), engine (4), and individual fuselage fairing (6) are fixed to the vacuum-sealed high-strength thin-walled skin structure (7) by adhesive bonding.

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