Composite material external auxiliary fuel tank front tip structure of airplane

Abstract

The invention provides an airplane composite material externally-hung auxiliary fuel tank front tip structure which comprises a front section skin, a rear section skin and a rear section skin. The locking nut is arranged in the drainage hole; the plug is connected with the locking nut, and the plug is used for plugging the drainage hole; and the front tip is connected with the front section skin, and the front tip is used for sealing the plug and the locking nut and guaranteeing the pneumatic shape of the auxiliary fuel tank. The front tip of the composite externally-hung auxiliary fuel tank of the airplane is improved in design, an opening with a certain size is reserved in the front tip of the auxiliary fuel tank before cleaning so as to discharge distilled water after cleaning, it is ensured that the pollution degree of the auxiliary fuel tank before leaving a factory meets the requirement, and meanwhile reliable sealing of the auxiliary fuel tank can be achieved after the front tip is installed.

Description

Technical Field

[0001] This application belongs to the field of aircraft fuel system design technology, specifically relating to a front tip structure of an aircraft composite material external auxiliary fuel tank. Background Technology

[0002] Currently, after final assembly, aircraft external fuel tanks require cleaning of the inside with distilled water to remove impurities introduced during production and meet specified contamination levels. Traditionally, metal external fuel tanks have an opening of a certain size at the front tip before cleaning to ensure the smooth drainage of distilled water after cleaning. After cleaning, the metal front tip is welded to the front skin of the fuel tank to achieve a complete seal.

[0003] The composite material external fuel tank skin uses an integrated molding technology, and is in a closed state after final assembly. It does not have a large opening for the distilled water to drain after cleaning, resulting in unsatisfactory cleaning effect. Some impurities remain in the external fuel tank, and the level of contamination does not meet the standards, which in turn increases the risk of contaminating the aircraft's fuel system. Summary of the Invention

[0004] The purpose of this application is to provide a front tip structure for an aircraft composite material external fuel tank, so as to reduce or avoid the aforementioned problems.

[0005] This application provides a front tip structure for an aircraft composite material external fuel tank, comprising: The front skin has drainage holes for draining distilled water after cleaning. A lock nut is provided inside the drain hole; A plug, connected to the locking nut, is used to seal the drain hole; The front tip, together with the front skin, is used to seal the plug and the locking nut, and to ensure the aerodynamic shape of the auxiliary oil tank.

[0006] Preferably, it further includes a sealing ring disposed between the locking nut and the plug.

[0007] Preferably, both the front tip and the front skin are made of carbon fiber composite material.

[0008] Preferably, both the plug and the locking nut are made of alloy structural steel.

[0009] Preferably, the sealing ring is made of fluorosilicone rubber.

[0010] Preferably, the thickness of the connection between the front tip and the front skin section is 2 mm.

[0011] Preferably, the locking nut and the front skin are pre-cured with epoxy resin, the bottom of the plug is provided with a sealing groove, and the plug is fitted with the end face of the locking nut by a sealing ring. The external thread of the plug is connected with the internal thread of the locking nut, so that the plug and the locking nut fit tightly together, thereby forming a reliable seal.

[0012] Preferably, the front tip is used to ensure the aerodynamic shape of the auxiliary fuel tank. It is formed by secondary curing with epoxy resin together with the front skin. After molding, there is no obvious protrusion, thus ensuring the aerodynamic shape of the auxiliary fuel tank.

[0013] The advantages of this application are: The front tip structure can reserve a channel for the discharge of distilled water for cleaning, ensuring that the contamination level of the auxiliary oil tank meets the requirements when it leaves the factory. At the same time, the front tip can achieve reliable sealing of the auxiliary oil tank after installation. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the front tip structure of the composite material external fuel tank of the aircraft in this application; Among them: 1-front tip, 2-plug, 3-locking nut, 4-sealing ring, 5-front skin. Detailed Implementation To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0015] The features and illustrative embodiments of various aspects of this application will now be described in detail. Numerous specific details are set forth in the following detailed description to provide a comprehensive understanding of this application. However, it will be apparent to those skilled in the art that this application can be implemented without some of these specific details. The description of the embodiments below is merely intended to provide a better understanding of this application by illustrating examples. This application is by no means limited to any specific setups and methods set forth below, but covers any improvements, substitutions, and modifications to the structures, methods, and devices without departing from the spirit of this application. Well-known structures and techniques are not shown in the accompanying drawings and the following description to avoid unnecessarily obscuring this application.

[0016] In the description of this application, it should be noted that the directions or positional relationships indicated by terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing this application and simplifying the description, and should not be construed as limiting this application. In addition, the use of ordinal numbers (e.g., "first and second," etc.) is for distinguishing objects and is not limited to this order, and should not be construed as indicating or implying relative importance.

[0017] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly, encompassing both direct connection and indirect connection via an intermediate medium. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0018] It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other, and the various embodiments can be referenced and cited in turn. The present application will now be described in detail with reference to the accompanying drawings and embodiments.

[0019] This application will now be described in further detail; see [link to relevant documentation]. Figure 1 This application provides a front tip structure for an aircraft composite material external fuel tank, comprising: a front skin section having a drain hole for draining distilled water after cleaning; a locking nut disposed within the drain hole; a plug connected to the locking nut for sealing the drain hole; and a front tip connected to the front skin section for sealing the plug and the locking nut, and ensuring the aerodynamic shape of the external fuel tank.

[0020] This application improves the design of the front tip of an aircraft composite material external fuel tank. Before cleaning, an opening of a certain size is left at the front tip of the fuel tank to drain the distilled water after cleaning, ensuring that the contamination level of the fuel tank meets the requirements before leaving the factory. At the same time, after the front tip is installed, the fuel tank can be reliably sealed.

[0021] This application provides a front tip structure for an aircraft composite material external fuel tank, including a front tip 1, a plug 2, a locking nut 3, a sealing ring 4, and a front skin 5.

[0022] The locking nut 3 is 45mm long and has external threads M120×3 and internal threads M56×2. It is pre-cured with epoxy resin to the front skin 5. The external threads of the locking nut 3 can increase the contact area with the front skin 5 and enhance the connection strength between the two.

[0023] The bottom surface of the plug 2 is provided with a sealing groove. The sealing ring 4 is placed in the sealing groove. The external thread size of the plug 2 is M56×2. It is tightened with the internal thread of the locking nut 3, so that the sealing ring 4 is compressed. At this time, the sealing ring 4 and the outer surface of the locking nut 3 form a reliable seal.

[0024] The front skin 5 has a 2mm step that fits into the front tip 1. The two are formed by secondary curing with epoxy resin. After molding, the outer contours of the front tip 1 and the front skin 6 are smoothly transitioned without obvious protrusions, ensuring the aerodynamic shape of the auxiliary fuel tank.

[0025] This application proposes a front tip structure for an aircraft composite material external fuel tank. The structure includes a front tip 1, a plug 2, a locking nut 3, a sealing ring 4, and a front skin section 5. The locking nut 3 and the front skin section 5 are pre-cured with epoxy resin. The plug 2 has a sealing groove at its bottom and is fitted to the end face of the locking nut 3 via the sealing ring 4. The external thread of the plug 4 connects to the internal thread of the locking nut 3, thereby ensuring a tight fit between the plug 4 and the locking nut 3 and forming a reliable seal. The front tip 1 is used to ensure the aerodynamic shape of the external fuel tank. It is formed by secondary curing with epoxy resin, resulting in no obvious protrusions after molding, thus ensuring the aerodynamic shape of the external fuel tank.

[0026] Furthermore, the front tip 1 and the front skin 5 are made of carbon fiber composite material.

[0027] Furthermore, the plug 2 and the locking nut 3 are made of metal, preferably alloy structural steel.

[0028] Furthermore, the sealing ring 4 is made of rubber, preferably fluorosilicone rubber.

[0029] Furthermore, the thickness of the connection between the front tip 1 and the front skin 5 is 2mm.

[0030] This application provides a front tip structure for an aircraft composite material external auxiliary fuel tank, including a front tip, a plug, a locking nut, a sealing ring, and a front skin. It can provide a channel to ensure that distilled water after cleaning can be discharged smoothly, ensuring that the contamination level of the auxiliary fuel tank meets the requirements of relevant regulations. At the same time, after the front tip is installed, the auxiliary fuel tank can be reliably sealed.

[0031] The advantages of this application are: The front tip structure can reserve a channel for the discharge of distilled water for cleaning, ensuring that the contamination level of the auxiliary oil tank meets the requirements when it leaves the factory. At the same time, the front tip can achieve reliable sealing of the auxiliary oil tank after installation.

[0032] This application relates to a leading tip structure for an aircraft composite material external fuel tank, belonging to the design technology of leading tips for aircraft composite material external fuel tanks. After the aircraft external fuel tank is assembled, the inside of the tank needs to be cleaned with distilled water to remove impurities mixed in during the production process and meet the specified contamination requirements. Because conventional composite material external fuel tanks use a one-piece molding technology, they are in a closed state after assembly, without a large opening for the distilled water to drain smoothly. This results in some impurities remaining inside the fuel tank, failing to meet the contamination standards, and thus increasing the risk of contaminating the aircraft's fuel system.

[0033] This application improves the design of the front tip of an aircraft composite material external fuel tank. Before cleaning, an opening of a certain size is left at the front tip of the fuel tank to drain the distilled water after cleaning, ensuring that the contamination level of the fuel tank meets the requirements before leaving the factory. At the same time, after the front tip is installed, the fuel tank can be reliably sealed.

Claims

1. A forward tip structure for an aircraft composite material external fuel tank, characterized in that, include: The front skin has drainage holes for draining distilled water after cleaning. A lock nut is provided inside the drain hole; A plug, connected to the locking nut, is used to seal the drain hole; The front tip, together with the front skin, is used to close the plug and the locking nut, and to ensure the aerodynamic shape of the auxiliary oil tank.

2. The forward tip structure of the aircraft composite material external auxiliary fuel tank according to claim 1, characterized in that, Also includes: A sealing ring is disposed between the locking nut and the plug.

3. The forward tip structure of the aircraft composite material external auxiliary fuel tank according to claim 1, characterized in that, Both the front tip and the front skin are made of carbon fiber composite material.

4. The forward tip structure of the aircraft composite material external auxiliary fuel tank according to claim 1, characterized in that, Both the plug and the locking nut are made of alloy structural steel.

5. The forward tip structure of the aircraft composite material external auxiliary fuel tank according to claim 2, characterized in that, The sealing ring is made of fluorosilicone rubber.

6. The forward tip structure of the aircraft composite material external auxiliary fuel tank according to claim 1, characterized in that, The thickness of the connection between the front tip and the front skin section is 2mm.

7. The forward tip structure of the aircraft composite material external auxiliary fuel tank according to claim 1, characterized in that, The locking nut and the front skin are pre-cured with epoxy resin. The bottom of the plug is provided with a sealing groove, which fits against the end face of the locking nut through a sealing ring. The external thread of the plug is connected to the internal thread of the locking nut, thereby making the plug and the locking nut fit tightly together to form a reliable seal.

8. The forward tip structure of the aircraft composite material external auxiliary fuel tank according to claim 1, characterized in that, The front tip is used to ensure the aerodynamic shape of the auxiliary fuel tank. It is formed by secondary curing with epoxy resin together with the front skin. After molding, there is no obvious protrusion, which ensures the aerodynamic shape of the auxiliary fuel tank.

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