Engine nacelle structure of unmanned aerial vehicle

Abstract

The utility model relates to an engine nacelle structure of an unmanned aerial vehicle, which belongs to the field of unmanned aerial vehicle body structures and comprises a mounting frame, a nacelle lower component, an upper opening cover, a lip and a fairing. The mounting frame is fixed to one side of the fuselage in the heading direction and used for fixing an engine main mounting connector and mounting a nacelle lower assembly. The nacelle lower assembly wraps the outer diameter wall of the axial lower half portion of the engine, one end of the nacelle lower assembly is fixedly connected with the installation frame, and the other end of the nacelle lower assembly is fixedly connected with the engine auxiliary installation connector and fixedly connected with the upper opening cover in a butt joint mode. The upper opening cover covers the position over the nacelle lower assembly and wraps the outer diameter wall of the axial upper half portion of the engine, one end of the upper opening cover is fixedly connected with the installation frame, and the other end of the upper opening cover is fixedly connected with the nacelle lower assembly. The lip is fixed to the front end of the nacelle lower assembly and the front end of the upper opening cover and used for air diversion. The fairing wraps the mounting frame and is used for guiding air at the mounting frame. The nacelle structure is suitable for small and medium-sized unmanned aerial vehicles, and the double engines are installed on the two sides of the rear fuselage of the unmanned aerial vehicle through the nacelle structure.

Description

Technical Field

[0001] This invention belongs to the field of unmanned aerial vehicle (UAV) airframe structure, specifically relating to an engine nacelle structure for a UAV. Background Technology

[0002] Currently, the engines of small and medium-sized drones are usually installed inside the fuselage. For small twin-engine turbojet hydrogen-powered drones with a takeoff weight of less than one ton, the hydrogen tanks that power the engines and related control equipment are relatively heavy and are located in the front and middle fuselage. Considering the limited internal space of the fuselage, it is not advisable to place the engines inside the fuselage. At the same time, considering the balance of the center of gravity, a pod structure is generally used to place the two engines under the left and right wings. However, this arrangement will affect the lift and drag of the drone.

[0003] Mounting the twin engines on either side of the rear fuselage, this engine nacelle configuration acts like a cantilever beam fixed to both sides of the fuselage. The nacelles not only secure the engines but also reduce aerodynamic drag and protect them from external damage, ensuring normal engine operation. Compared to the conventional configuration where the twin engines are positioned under the left and right wings, this reduces the impact of the engines on lift and drag. However, this configuration is primarily found in large aircraft of 30-40 tons. For large aircraft, the engine nacelle design involves numerous considerations, high design life requirements, complex structural components, and relatively heavy weight, making this configuration unsuitable for small and medium-sized UAVs.

[0004] Therefore, it is necessary to design engine nacelle structures suitable for small and medium-sized UAVs, especially engine nacelle structures suitable for small twin-engine turbojet hydrogen-powered UAVs, with the two engines arranged on both sides of the rear fuselage. Summary of the Invention

[0005] The technical problem to be solved:

[0006] To avoid the shortcomings of the prior art, the present invention provides an engine nacelle structure for a drone, suitable for small and medium-sized drones, which enables the installation of dual engines on both sides of the rear fuselage of the drone.

[0007] The technical solution of this invention is: an engine nacelle structure for an unmanned aerial vehicle (UAV), comprising:

[0008] Mounting brackets are fixedly installed on one side of the fuselage along the flight direction to secure the main mounting joints of the engines and the lower nacelle components; the engines are installed along the flight direction.

[0009] The lower nacelle assembly encloses the axial lower half of the outer diameter wall of the engine. One end of the assembly is fixedly connected to the mounting bracket in a non-detachable manner; the other end is fixedly connected to the auxiliary mounting joint of the engine and is mated and fixedly connected to the upper cover.

[0010] The upper cover fits directly above the lower nacelle assembly, enclosing the upper axial outer diameter wall of the engine. One end is fixedly connected to the mounting bracket, and the other end is fixedly connected to the lower nacelle assembly away from the mounting bracket. The upper cover and the lower nacelle assembly work together to form a cavity that is closed around the perimeter and open at both ends to accommodate the engine. The front opening of the cavity faces the heading.

[0011] The lip is a ring-shaped skin structure with a U-shaped cross-section. Its U-shaped opening side is fixedly installed at the front end of the cavity and is used to guide the airflow of the lower nacelle components and the front end of the upper cover.

[0012] The fairing, which wraps around the mounting frame, is fixed at one end to the fuselage skin and at the other end to the outer skin of the lower nacelle assembly and the upper hatch, respectively, and is used to guide airflow at the mounting frame.

[0013] A further technical solution of the present invention is: the mounting frame is a channel beam structure, including a web and a frame plate surrounding the web and perpendicular to the web; one side frame plate of the mounting frame is an inner edge strip, which is fixedly connected to the fuselage; the side frame plate opposite to the inner edge strip is an outer edge strip, which is fixedly connected to the two main mounting joints of the engine; the inner edge strip and the outer edge strip are arranged parallel to each other along the flight direction.

[0014] A further technical solution of the present invention is: a plurality of reinforcing ribs are evenly distributed in the frame plate of the mounting bracket, and the reinforcing ribs are perpendicular to the inner edge strip, the outer edge strip and the web plate; a plurality of weight-reducing holes are evenly distributed on the web plate for weight reduction, and the weight-reducing holes are set away from the reinforcing ribs.

[0015] A further technical solution of the present invention is: the lower nacelle assembly includes a lower outer skin, a lower inner skin, and a lower support frame. The lower support frame is an overall variable cross-section semi-cylindrical frame structure. The lower outer skin covers the outer diameter of the lower support frame and is fixedly connected to it. The lower inner skin covers the inner diameter of the lower support frame and is fixedly connected to it.

[0016] A further technical solution of the present invention is as follows: the lower support frame includes a lower first partition, a lower second partition, a lower third partition, and a lower side beam; the three lower partitions are all semi-circular frame structures and are arranged in parallel along the axis of the lower support frame; one end of each of the three lower partitions is non-detachably fixedly connected to the web of the mounting frame, and the end of each of the three lower partitions away from the mounting frame is fixedly connected to the lower side beam; the lower side beam is a frame beam structure with four lugs on it, in pairs, for docking and fixing with the upper cover; the auxiliary mounting interface of the engine is simultaneously fixedly connected to the lower inner skin and the inner edge strip of the lower side beam at the corresponding positions.

[0017] A further technical solution of the present invention is: the lower first partition frame is located at the foremost end of the lower support frame along the flight direction, and the lower first partition frame is provided with an inner edge strip along the inner diameter and an outer edge strip along the outer diameter for connection with the lip.

[0018] A further technical solution of the present invention is: the upper cover includes an outer cover skin, an inner cover skin, and a cover frame; the cover frame is an integral variable cross-section semi-cylindrical frame structure, the outer cover skin wraps around the outer diameter of the cover frame and is fixedly connected to it; the inner cover skin wraps around the inner diameter of the cover frame and is fixedly connected to it.

[0019] A further technical solution of the present invention is as follows: the cover frame includes a first cover partition, a second cover partition, a third cover partition, an inner cover beam, and an outer cover beam. The three cover partitions are all semi-annular frame structures and are arranged in parallel along the axis of the cover frame. The inner cover beam and the outer cover beam are parallel and are fixed to both ends of the three cover partitions respectively. Two joints are installed at the lower end of the inner cover beam for fixed connection with the reinforcing ribs of the mounting frame. The outer cover beam is provided with two sets of lugs corresponding to the lower side beam for docking and fixing with the two sets of lugs of the lower side beam.

[0020] A further technical solution of the present invention is: the first partition frame of the cover is located at the foremost end of the cover frame along the flight direction, and the first partition frame of the cover is provided with two sets of lugs facing the flight direction. The two lugs in each set are located at the same radial position on the inner diameter and outer diameter of the first partition frame of the cover, respectively, for connecting with the lip.

[0021] A further technical solution of the present invention is: the inner and outer skins at the upper end of the U-shaped opening of the lip are fixedly connected to the two sets of lugs of the first partition frame of the cover by a support plate nut and bolt assembly; the inner and outer skins at the lower end of the U-shaped opening of the lip are fixedly connected to the inner and outer edge strips of the lower first partition frame by a support plate nut and bolt assembly.

[0022] Beneficial effects

[0023] The beneficial effects of this invention are as follows: This invention provides an engine nacelle structure for unmanned aerial vehicles (UAVs), suitable for small and medium-sized UAVs, particularly small twin-engine turbojet hydrogen-powered UAVs. This engine nacelle structure allows for the installation of twin engines on both sides of the rear fuselage. As a cantilever structure, the engine nacelle structure possesses sufficient rigidity. It is a semi-monocoque structure composed of inner and outer skins and a frame, which not only secures the engine but also adjusts airflow between the engine and the fuselage, reducing aerodynamic drag and protecting the engine from external damage, ensuring normal engine operation. The structural design comprehensively considers the requirements for engine installation, disassembly and maintenance, and aerodynamic rectification, providing a configuration for installing twin engines on the left and right sides of the rear fuselage for small and medium-sized UAVs. This solves the problem of occupying valuable fuselage space when the engine is installed inside the fuselage. Furthermore, compared to using a podded nacelle structure installed under the left and right wings, it reduces the engine's impact on lift and drag.

[0024] In this invention, the main mounting joint of the engine is fixedly connected to the mounting bracket. Since the engine is a cantilever structure mounted on both sides of the fuselage, the lower structural component is designed as a cantilever beam structure mounted on the mounting bracket. It has good rigidity and can provide a secondary mounting interface for the secondary mounting joint of the engine, thereby enhancing the support rigidity of the side of the engine away from the fuselage. The upper cover is designed as a load-bearing cover with good rigidity to ensure the overall rigidity of the nacelle.

[0025] The disassembly and assembly sequence of this invention is reasonable and convenient, meeting the disassembly and maintenance needs of engines. In the design, material selection, thickness design, and weight-reduction hole design fully consider weight reduction requirements while meeting the product's strength and rigidity requirements, thus satisfying lightweighting standards. Attached Figure Description

[0026] Figure 1 This is a schematic diagram showing the installation positions of the engine nacelle structure of the present invention on both sides of the rear fuselage;

[0027] Figure 2 This is a schematic diagram of the engine nacelle structure of the present invention;

[0028] Figure 3 A schematic diagram showing the connection between the main and auxiliary mounting joints of the engine and the engine nacelle structure of this invention (viewed from rear to front along the flight path);

[0029] Figure 4 This is a cross-sectional view of the internal installation of the engine nacelle structure of the present invention (viewed from rear to front along the flight direction);

[0030] Figure 5 This is a schematic diagram of the mounting bracket in this invention;

[0031] Figure 6 This is a schematic diagram of the structure of the lower nacelle component in this invention;

[0032] Figure 7 This is a schematic diagram of the upper cover structure in this invention;

[0033] Figure 8 This is a schematic diagram of the connection structure between the outer side beam and the lower side beam of the cover in this invention;

[0034] Figure 9 This is a schematic diagram of the connector structure in this invention;

[0035] Figure 10 This is a schematic diagram of the lip structure in this invention.

[0036] Explanation of reference numerals in the attached drawings: 1. Mounting frame; 11. Web plate; 12. Inner edge strip; 13. Outer edge strip; 14. Reinforcing rib; 2. Lower nacelle assembly; 21. Lower outer skin; 22. Lower inner skin; 23. Lower first bulkhead; 231. Inner edge strip of the lower first bulkhead; 232. Outer edge strip of the lower first bulkhead; 24. Lower second bulkhead; 25. Lower third bulkhead; 26. Lower side beam; 261. Lug of the lower side beam; 3. Top cover opening; 31 31. Outer skin of the hatch; 32. Inner skin of the hatch; 33. First bulkhead of the hatch; 331. Lug of the first bulkhead of the hatch; 34. Second bulkhead of the hatch; 35. Third bulkhead of the hatch; 36. Inner side beam of the hatch; 37. Outer side beam of the hatch; 371. Lug of the outer side beam of the hatch; 38. Connector; 4. Lip; 41. Inner skin of the lip; 42. Outer skin of the lip; 5. Fly cowl; 6. Fuselage; 7. Engine; 71. Main mounting connector; 72. Secondary mounting connector. Detailed Implementation

[0037] The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the invention, and should not be construed as limiting the invention.

[0038] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0039] See Figure 1 Using a right-handed coordinate system, with the reverse heading as the positive X-axis and the Z-axis pointing vertically upwards, this embodiment provides an engine nacelle structure for a UAV, suitable for small to medium-sized twin-engine UAVs. This invention allows for the symmetrical mounting of two engines on both sides of the UAV fuselage, providing a configuration where the engines are mounted on the rear sides of the fuselage for small to medium-sized twin-engine UAVs. Compared to configurations where the engines are mounted inside the fuselage, this saves internal space and facilitates engine inspection and maintenance. Compared to pod-type nacelles where the engines are mounted under the wings, it also reduces the impact of the engines on lift and drag. The overall structure, while ensuring support rigidity and strength, is lightweight and easy to assemble and disassemble, reducing the UAV's weight and facilitating engine disassembly and maintenance.

[0040] See Figure 2The engine nacelle structure of the UAV in this embodiment includes a mounting bracket 1, a lower nacelle assembly 2, an upper cover 3, a lip 4, and a fairing 5. The engine 7 is installed inside it via a main mounting joint 71 near the inner side of the fuselage 6 and an outer auxiliary mounting joint 72.

[0041] Referring to 2 and 3, mounting bracket 1 is the main mounting bracket for the engine, which is fixedly installed on one side of the fuselage 6 along the flight direction, serving as a cantilever structure to connect the fuselage 6 and the engine 7; at the same time, mounting bracket 1 is also used to fix and install the lower nacelle component 2.

[0042] For details, please refer to the following: Figure 5 Mounting bracket 1 is a channel beam structure with an overall rectangular frame, machined from thick aluminum alloy plates. Mounting bracket 1 includes a web plate 11 and edge frame plates surrounding and perpendicular to the web plate 11. One side frame plate along the length of mounting bracket 1 is an inner edge strip 12, which is connected and fixed to the skin and internal structural frame of the fuselage 6 via a bracket nut and bolt assembly. The other side frame plate, parallel and opposite to the inner edge strip 12, is an outer edge strip 13, which is connected to the two main mounting joints 71 of the engine 7 via a bracket nut and bolt assembly. The engine 7 has two annular sleeves on its outer diameter. The main mounting joint 71 and auxiliary mounting joint 72 are located at the maximum outer diameter on both horizontal sides of the engine 7. The engine 7 is mounted along its flight direction, with the main mounting joint 71 located inside the engine 7, closer to the fuselage 6, and the auxiliary mounting joint 72 located outside the engine 7.

[0043] To ensure support strength, two reinforcing ribs 14 are evenly distributed inside the edge frame plate of the mounting bracket 1. The reinforcing ribs 14 are perpendicular to the inner edge strip 12, the outer edge strip 13 and the web plate 11. In order to achieve the weight reduction effect, three weight reduction holes are provided on the web plate 11, avoiding the two reinforcing ribs 14. The weight reduction holes are round holes, and the perimeter of the holes is reinforced with bosses to avoid stress concentration.

[0044] See Figure 2-4 and Figure 6 The lower nacelle component 2 is a cantilever structure installed on the mounting bracket 1. It gaps around the axial lower half outer diameter wall of the engine 7. One end is fixedly connected to the mounting bracket 1 in a non-detachable manner. The other end provides an auxiliary mounting interface for the engine 7 to increase the support rigidity of the engine structure. This end is fixedly connected to the auxiliary mounting joint 72 of the engine 7 and is connected to the upper cover opening 3.

[0045] Specifically, the lower nacelle assembly 2 includes a lower outer skin 21, a lower inner skin 22, and a lower support frame located between the inner and outer skins, serving as a skeleton for installation and support. For example... Figure 6As shown, the lower support frame is a variable cross-section semi-cylindrical frame structure, including a lower first partition 23, a lower second partition 24, a lower third partition 25, and a lower side beam 26. All three lower partitions are semi-ring-shaped frame structures. The lower first partition 23, lower second partition 24, and lower third partition 25 are arranged coaxially and parallel to each other from front to back along the flight direction. The lower side beam 26 is fixedly connected to the outer ends of the three lower partitions. The three lower partitions have different inner and outer diameters, and these varying inner and outer diameters meet the aerodynamic performance requirements for engine installation and the nacelle structure. The inner ends of the three lower partitions are non-detachably fixed to the web plate 11 of the mounting frame 1 using high-strength bolts and high-strength nuts, ensuring the tightness and reliability of the connection. The outer ends of the three lower partitions are fixedly connected to the lower side beam 26. In this embodiment, the three lower partitions and the lower side beam are all machined frame structures with weight-reducing holes and reinforcing ribs, machined from thick aluminum alloy plates. The lower outer skin 21 wraps around the outer diameter of the lower support frame and is fixedly connected to it in a conformal fit. The lower inner skin 22 wraps around the inner diameter of the lower support frame and is fixedly connected to it in a conformal fit. Both the lower outer skin 21 and the lower inner skin 22 are made of thin aluminum alloy sheet, which is lightweight and has good formability and fit. Figure 3 As shown, the auxiliary mounting joint 72 is fixedly connected to the lower outer skin 21 and the inner edge strip on the inner side of the lower side beam 26 at the corresponding position by means of a plate nut and bolt assembly.

[0046] To achieve the docking and securing of the lower nacelle component 2 and the upper cover 3, such as Figure 6 As shown, the lower side beam 26 has four lugs 261 on its inner and outer edge strips, arranged in pairs, with each pair of lugs located in the same axial position, for docking and fixing with the upper cover 3. To achieve a mating connection with the lip 4, the lower first partition 23 at the foremost end of the lower support frame has an inner edge strip 231 along its inner diameter and an outer edge strip 232 along its outer diameter, for mating and connecting with the lip 4.

[0047] Referring to 2, 4, and 7, the upper cover 3 is fitted over the lower nacelle assembly 2, and the gap covers the upper axial outer diameter wall of the engine 7. One end of the upper cover 3 is fixedly connected to the mounting bracket 1, and the other end is fixedly connected to the end of the lower nacelle assembly 2 away from the mounting bracket 1. The upper cover 3 and the lower nacelle assembly 2 cooperate to form a cavity that is closed around the perimeter and open at both ends to accommodate the engine 7. The front opening of the cavity faces the heading.

[0048] For details, please refer to Figure 7The upper hatch 3 includes an outer hatch skin 31, an inner hatch skin 32, and a hatch frame sandwiched between the inner and outer hatch skins, serving as a mounting and support structure. The hatch frame, acting as the mounting skeleton, is an overall variable cross-section semi-cylindrical frame structure, including a first hatch partition 33, a second hatch partition 34, a third hatch partition 35, an inner hatch side beam 36, and an outer hatch side beam 37. The first hatch partition 33, the second hatch partition 34, and the third hatch partition 35 are all semi-annular frame structures, coaxially arranged and parallel to each other along the flight direction from front to back. The inner hatch side beam 36 and the outer hatch side beam 37 are parallel and fixed to both ends of the three hatch partitions. The inner hatch side beam 36 is located on the inner side of the hatch frame closer to the fuselage 6, and the outer hatch side beam 37 is located on the outer side of the hatch frame farther from the fuselage 6. Two... Figure 9 The connector 38 shown is fixedly connected to the two reinforcing ribs 14 of the mounting bracket 1 through a bracket nut and bolt assembly, with the connector 38 in contact with the reinforcing rib 14. The outer side beam 37 of the hatch has two sets of lugs 371 corresponding to the lower side beam 26, for docking and fixing with the two sets of lugs 261 of the lower side beam 26. The outer skin 31 of the hatch covers the outer diameter of the hatch frame and is fixedly connected to it in a conformal shape; the inner skin 32 of the hatch covers the inner diameter of the hatch frame and is fixedly connected to it in a conformal shape. The three hatch frames have different inner and outer diameters, and the changing inner and outer diameters form a variable-size cross-section to meet the aerodynamic performance requirements of engine installation and use and nacelle structure. In this embodiment, the outer skin 31 and inner skin 32 of the hatch are made of thin aluminum alloy sheet bent from sheet metal. The components of the hatch frame are machined from thick aluminum alloy sheet, and each frame and side beam structure is designed to reduce weight, with weight-reduction holes on its web.

[0049] During the specific installation, such as Figure 8 As shown, a set of lugs on the outer side beam 37 of the hatch is engaged between a set of lugs on the lower side beam 26, and the lugs are fixedly connected by a bracket nut and bolt assembly. The lower outer skin 21 of the lower nacelle assembly 2 extends above the lower side beam 26, forming an external enclosure around the docking point. The inner skin 32 of the upper hatch 3 extends above the outer side beam 37 of the hatch, forming an internal enclosure around the docking point.

[0050] See Figure 7 In order to achieve the installation of the lip 4, the first partition 33 of the lip frame at the front end of the lip frame is provided with two sets of ear pieces 331 facing the flight direction. The two ear pieces 331 in each set are located at the same radial position on the inner diameter and outer diameter of the first partition 33 of the lip, respectively, for connecting with the lip 4.

[0051] In this embodiment, the front end of the upper cover 3 and the lip 4, the outer side and the lower part of the nacelle 2, and the inner side and the mounting bracket 1 all adopt a quick-release connection form of the plate nut and bolt assembly, which is convenient for disassembly and assembly.

[0052] See Figure 10The lip 4 is a U-shaped, semi-enclosed annular skin structure formed by bending a thin aluminum alloy sheet. It is detachably installed at the front end of the lower nacelle assembly 2 and the upper cover 3, serving as a guide for airflow at the front end of the lower nacelle assembly 2 and the upper cover 3. The U-shaped opening of the lip 4 closes the front end of the lower nacelle assembly 2 and the upper cover 3. The upper inner skin 41 and the upper outer skin 42 at the U-shaped opening are fixed to the two sets of lugs 331 of the first bulkhead 33 of the cover by a bracket nut and bolt assembly. The lower inner skin 41 at the U-shaped opening is connected to the inner edge strip 231 of the lower first bulkhead, and the lower outer skin 42 at the U-shaped opening is connected to the outer edge strip 232 of the lower first bulkhead. The inner and outer skins of the lip 4 and the inner and outer edge strips of the lower first bulkhead 23 are fixedly connected by a bracket nut and bolt assembly.

[0053] See Figure 1 , 2 The fairing 5 is detachable and encloses the mounting frame 1. The fairing 5 is a 1mm thick laminated structure made of carbon fiber fabric, with outward-facing flanges at both ends. One flange is fixed to the skin of the fuselage 6, while the other flange is fixed to the outer skin of the lower nacelle assembly 2 and the upper cover 3. The flanges at both ends of the fairing 5 are connected by a bracket, nut, and bolts for easy assembly and disassembly. The fairing 5 serves to guide airflow at the mounting frame 1.

[0054] When engine 7 needs to be disassembled and repaired, first remove the cowling 5, that is, remove the bolts connecting it to the fuselage skin 6, the outer skin of the lower nacelle assembly 2, and the outer skin of the upper cover 3; remove the upper cover 3, that is, remove the bolts connecting the upper cover 3 to the lip 4 at the front, and the bolts connecting the inner and outer sides of the upper cover 3 to the mounting bracket 1 and the lower nacelle assembly 2; then remove the bolts connecting the inner and outer skins of the lip to the inner and outer edge strips of the lower first bulkhead 23 of the lower nacelle assembly 2. Engine 7 can then be disassembled and repaired. When reinstalling, first reconnect the lip 4 to the lower nacelle assembly 2, then install the upper cover 3, and finally install the cowling 5.

[0055] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. An engine nacelle structure for an unmanned aerial vehicle (UAV), characterized in that, include: Mounting brackets are fixedly installed on one side of the fuselage along the flight direction to secure the main mounting joints of the engines and the lower nacelle components; the engines are installed along the flight direction. The lower nacelle assembly encloses the axial lower half of the outer diameter wall of the engine. One end of the assembly is fixedly connected to the mounting bracket in a non-detachable manner; the other end is fixedly connected to the auxiliary mounting joint of the engine and is mated and fixedly connected to the upper cover. The upper cover fits directly above the lower nacelle assembly, enclosing the upper axial outer diameter wall of the engine. One end is fixedly connected to the mounting bracket, and the other end is fixedly connected to the lower nacelle assembly away from the mounting bracket. The upper cover and the lower nacelle assembly work together to form a cavity that is closed around the perimeter and open at both ends to accommodate the engine. The front opening of the cavity faces the heading. The lip is a U-shaped annular skin structure with its U-shaped opening fixedly installed at the front end of the cavity, used for air diversion of the lower nacelle assembly and the front end of the upper cover; The fairing, which wraps around the mounting frame, is fixed at one end to the fuselage skin and at the other end to the outer skin of the lower nacelle assembly and the upper hatch, respectively, and is used to guide airflow at the mounting frame.

2. The engine nacelle structure of the UAV according to claim 1, characterized in that, The mounting frame is a channel beam structure, including a web and a frame plate surrounding the web and perpendicular to the web; one side frame plate of the mounting frame is an inner edge strip, which is fixedly connected to the fuselage; the side frame plate opposite to the inner edge strip is an outer edge strip, which is fixedly connected to the two main mounting joints of the engine; the inner edge strip and the outer edge strip are arranged parallel to each other along the flight direction.

3. The engine nacelle structure of the UAV according to claim 2, characterized in that, Multiple reinforcing ribs are evenly distributed inside the frame plate of the mounting bracket, and the reinforcing ribs are perpendicular to the inner edge strip, the outer edge strip, and the web plate; multiple weight-reducing holes are evenly distributed on the web plate for weight reduction, and the weight-reducing holes are set away from the reinforcing ribs.

4. The engine nacelle structure of the UAV according to claim 3, characterized in that, The lower nacelle assembly includes a lower outer skin, a lower inner skin, and a lower support frame. The lower support frame is an overall variable cross-section semi-cylindrical frame structure. The lower outer skin covers the outer diameter of the lower support frame and is fixedly connected to it. The lower inner skin covers the inner diameter of the lower support frame and is fixedly connected to it.

5. The engine nacelle structure of the UAV according to claim 4, characterized in that, The lower support frame includes a lower first partition frame, a lower second partition frame, a lower third partition frame, and a lower side beam; the three lower partition frames are all semi-circular frame structures and are arranged parallel to each other along the axis of the lower support frame; one end of each of the three lower partition frames is non-removably fixed to the web of the mounting frame, and the end of each of the three lower partition frames away from the mounting frame is fixedly connected to the lower side beam; the lower side beam is a frame beam structure with four lugs, two in a group, for docking and fixing with the upper cover; the auxiliary mounting interface of the engine is simultaneously fixedly connected to the lower inner skin and the inner edge strip of the lower side beam at the corresponding position.

6. The engine nacelle structure of the UAV according to claim 5, characterized in that, The lower first partition frame is located at the foremost end of the lower support frame along the flight direction. The lower first partition frame has an inner edge strip along the inner diameter and an outer edge strip along the outer diameter for connection with the lip.

7. The engine nacelle structure of the UAV according to claim 6, characterized in that, The upper cover includes an outer cover skin, an inner cover skin, and a cover frame; the cover frame is an overall variable cross-section semi-cylindrical frame structure, the outer cover skin wraps around the outer diameter of the cover frame and is fixedly connected to it; the inner cover skin wraps around the inner diameter of the cover frame and is fixedly connected to it.

8. The engine nacelle structure of the UAV according to claim 7, characterized in that, The cap frame includes a first cap partition, a second cap partition, a third cap partition, an inner cap side beam, and an outer cap side beam. All three cap partitions are semi-circular frame structures and are arranged parallel to each other along the cap frame axis. The inner and outer cap side beams are parallel and fixed to both ends of the three cap partitions. Two joints are installed at the lower end of the inner cap side beam for fixed connection with the reinforcing ribs of the mounting frame. The outer cap side beam has two sets of lugs corresponding to the lower side beam for mating and fixing with the two sets of lugs on the lower side beam.

9. The engine nacelle structure of the UAV according to claim 8, characterized in that, The first partition frame of the cover is located at the foremost end of the cover frame along the flight direction. The first partition frame of the cover has two sets of lugs facing the flight direction. The two lugs in each set are located at the same radial position on the inner and outer diameters of the first partition frame of the cover, respectively, for connecting with the lip.

10. The engine nacelle structure of the UAV according to claim 9, characterized in that, The upper inner and outer skins of the U-shaped opening of the lip are fixedly connected to the two sets of lugs of the first partition frame of the cover by a support plate nut and bolt assembly; the lower inner and outer skins of the U-shaped opening of the lip are fixedly connected to the inner and outer edge strips of the lower first partition frame by a support plate nut and bolt assembly.

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