CN1906084A - Aircraft fuselage - Google Patents

Abstract

The fuselage is conceived in such a way as to prevent the spread of flames produced by a source of fire and acting on the fuselage from outside the aircraft environment. The fuselage concept takes into account materials or material combinations that will scarcely allow protection of the cabin area of an aircraft (upon emergency landing) to be violated by flames spreading from outside the aircraft environment, which may facilitate an evacuation of passengers from the aircraft. An aircraft fuselage, whose fuselage structure , in addition to other structural elements that are components of the mechanic al strength bracing of the fuselage and help absorb its forces, encompasses an exterior skin (2) consisting of various respective materials, which are designed to be resistant to shear, and incorporated as a bearing element int o the mechanical strength bracing (6,7,8) to absorb and transfer the forces an d torques acting thereupon. The exterior skin (2) is fabricated from a burn- through resistant semi-finished material consisting of a non-metallic materi al or a fireproof metallic material, wherein the semi-finished material can be molded through further processing. Also, the exterior skin may be realized b y a semi-finished material combining a non-metallic material and a metallic material, wherein the produced exterior skin product is a hybrid material th at can be molded and joined through further processing.

Description

body

Cross References to Related Applications

This application claims priority from DE 10 2004 001 078, filed 5 January 2004, and US 60/600,105, filed 9 August 2004, both of which are hereby incorporated by reference.

technical field

The present invention relates to fuselages, in particular fuselages of commercial aircraft.

Background technique

Aluminum structures have been used very successfully in aircraft construction in the past. Without looking further into this fact, any expert and probably even a layman interested in aircraft construction knows that the conventional structural design of an airframe includes an outer fuselage skin made solely of aluminum or an aluminum alloy. The prior art provides relevant examples.

Some accidents, the causes of which, unfortunately, have been found to be caused by kerosene leaks from aircraft performing emergency landings. Accordingly, there may be a need to improve the fire performance of aircraft.

When a fire occurs during an emergency landing on the belly of an aircraft, burning kerosene leaking (ignited) from the aircraft may burn through or burn through the aluminum fuselage and internal insulation of the aircraft structure.

Document "WO 00/75012 A1" discloses a solution which prevents the outbreak of fires in emergency situations as described above. The proposal involves fuselage insulation structures for aircraft fuselages, known as "refractories". This document discloses an insulation package which is laid as the main insulation in the area between the inner fuselage cladding and the outer fuselage skin. Here, the region of the insulation enclosure is protected by means of a film made of refractory material (“flame retardant material”), wherein the region of the refractory film faces directly towards the outer skin of the aircraft fuselage (similar to a fire shield). This proposal, in addition to only providing insufficient fire protection for the isolated enclosure and the interior areas of the fuselage, due to the fact that in the event of a fire the flames of the fire pass right from the outside of the aircraft through the damaged outer skin and reach them a short time later Internal partitions, i.e. (only) fire-resistant and not fire-resistant membranes that also pass through prolonged exposure to fire, the original piece-by-piece arrangement of only fire-resistant membranes will not ensure adequate protection against the interior areas of the fuselage Fire protection class. This document also proposes corresponding connectors for fastening the fuselage insulation, which are generally made of plastic, such as polyamide.

This document makes no mention of other measures of preventive fire protection, which adapt the technical design of the aircraft fuselage to fire safety and, moreover, focus on the outer skin of the fuselage.

Contents of the invention

According to an exemplary embodiment of the present invention, there is provided an aircraft fuselage including an outer skin product. The outer skin product is made of semi-finished material. The semi-finished material is a combination of non-metallic and metallic materials. The outer skin product is a composite material which is moldable and joinable by further processing.

According to another exemplary embodiment of the present invention, an aircraft fuselage is provided, comprising an outer skin made of a burn-through-resistant semi-finished material, the semi-finished material made of non-metallic materials and metallic materials into, wherein the semi-finished material can be molded by a further process.

A fuselage according to an exemplary embodiment of the present invention may be conceived in such a way that it prevents the spread of flames from an ignition source and prevents burning onto the fuselage from outside the aircraft environment. Fuselage considerations for materials or combinations of materials which will allow (in the event of an emergency landing) protection of the cabin area of the aircraft with little intrusion from fire spreading outside the environment of the aircraft and which is believed to reliably facilitate the evacuation of passengers from the aircraft . Furthermore, it is believed that the fire safety of the outer fuselage skin of an aircraft fuselage can thereby be improved to obtain higher burn-through characteristics of the outer skin.

Description of drawings

The invention is described in more detail with reference to exemplary embodiments and with reference to the accompanying drawings.

Figure 1 shows the aircraft fuselage of a passenger aircraft, depicting elements of the fuselage structure and internal equipment according to an exemplary embodiment of the present invention;

Figure 2 shows selected areas of the outer skin and other structural elements of a fuselage structure according to an exemplary embodiment of the invention.

Detailed ways

FIG. 1 schematically shows a section of a passenger aircraft fuselage, limited to the section area of an aircraft cabin 1 . This structure will likely be familiar to experts in aircraft construction, and shows the relationship that the observer would know from this figure: the flammable inner cladding 3 is placed very close to the outer skin 2 (of the fuselage) when compared to When assembled, the outer skins 33 enclose a space 19 in which a fuselage partition (not shown in FIG. 1 ) is installed. If the outer skin 2 , conventionally realized in aluminum material or aluminum alloy, is installed in this configuration, the observer will be aware of the extent of the type of fire described at the outset. Additional components and elements shown in FIG. 1 and integrated into the interior equipment and fuselage structure of the aircraft cabin 21 (based on the example herein) will not be described as they are considered irrelevant to the present invention.

FIG. 2 shows a skin field section of the outer skin 2 secured to the stringers 8 . This outer skin area is limited to an area within two ribs 6 and 7 fastened to the stringers, the ribs 6 and 7 being perpendicular to the longitudinal axis of the fuselage. For the sake of completeness, the mentioned outer skin 2, stringers 8 and ribs 6, 7 are elements of the mechanical strength bracing of the fuselage and participate in the absorption of forces, wherein the outer skin 2 includes different materials, generally somewhat Reference is made to the material "aluminum or aluminum alloy", which is designed to resist shearing. The outer skin 2 acts as a bearing incorporated into mechanical strength supports to absorb and transmit the forces and torques exerted thereon.

It is believed that the proposed solution follows the preventive concept of aircraft fire protection, so that the resulting high burnthrough characteristics of the outer skin 2 can increase the technical fire safety of passenger aircraft or military aircraft, first of all passenger aircraft, and thus believe that the fire situation described at the beginning is not could develop into a catastrophe, for example after an aircraft has made a successful emergency landing.

The proposed solution is based on A) the material used for the outer skin 2, which is provided with a fire-resistant (plate-shaped) semi-finished material comprising non-metallic material or fire-resistant metallic material, wherein this semi-finished material can be molded by further processing to form the outer fuselage Skin 2 Curved profile inwards.

On the other hand, B) proposes that the outer skin 2 is realized by combining semi-finished materials including non-metallic materials and metallic materials. The outer skin product manufactured from the material composition is a hybrid material which can be molded and joined by further processing. This material composition is achieved by means of non-metallic and metallic materials containing carbon and glass fibers (mixed fiber architecture) or only carbon and glass fibers and/or ceramic fibers, wherein the metallic material comprises aluminum or titanium or an aluminum-titanium alloy.

The desired structure is covered by the resin layer or embedded in the resin. The outer skin product obtained from this material composition has a sandwich design. This sandwich design consists of composite materials and the metal materials mentioned are adhesively bonded in layers (films), which impart burn-through resistance to the outer skin exposed to fire flames for a long time. In addition, the sandwich design is implemented using glare material, which has high burn-through characteristics.

Going back to steps A) and B), we extend the scope by making the outer skin 2 [or processing semi-finished materials] using non-metallic materials containing carbon fiber materials or glass fiber materials or ceramic fiber materials or silicate fiber materials. It may be recalled that when manufacturing the outer skin 2 according to B), a material composition comprising a plurality of non-metallic materials is taken into account. In this case, the non-metallic material is realized as plastic with glass or plastic fibers (GFK and/or CFK materials). The material composition mentioned here can be realized as GFK or CFK material and aluminum or titanium or alloys thereof.

The composites mentioned include heat-resistant composites, which are also characterized by resistance to high temperatures and high tensile strength. It is proposed that the heat protection material be realized as carbon fibers coated with a material of a nitride or carbide composition, such as corundum, silicon nitride or boron nitride, and a metallic or ceramic material into which the coated carbon fibers are embedded middle.

Furthermore, the fire-resistant metal material mentioned in A) is realized as titanium or aluminum alloy.

In order to complete the preventive aircraft fire protection concept (mentioned here), C) additionally propose (burn through) the outer surface of the outer skin 2 - ie the outer skin exposed to the atmosphere outside the aircraft environment Area—A plate-like panel 5 is attached based on the example of FIG. 2 . This panel 5 is also realized as a burn-through-resistant semi-finished product using non-metallic or fire-resistant metallic materials. On the other hand, the panel 5 can be realized according to B) from a semi-finished product of the mentioned material composition using non-metallic and metallic materials, the outer skin product of which is a hybrid material, wherein the panel can also be molded by further processing and connect. The panels 5 will have fire safety properties and can also be molded to form the outer contour of the outer skin 2 . Can be achieved by GLARE material. In addition, preventive fire safety may already be achieved by joining the panels 5 with their outer contours cut to the outer skin 2 , the entire outer surface of the outer skin 2 being of course covered. It is thus assumed that the outer skin 2 is even realized from a material comprising aluminum or an aluminum alloy and is precisely connected to a burnthrough-resistant plate-like sheet.

Burnthrough resistant aircraft fuselages are believed to be used to achieve a higher level of safety for passenger aircraft exposed to external fire. A burnthrough-resistant aircraft fuselage provides optimal protection against fire entering the cabin as it is furthest from the passenger seats installed in the fuselage and prevents the flame from penetrating at its source. If the aircraft fuselage is now made of burnthrough-resistant materials—such as using carbon fiber structures as much as possible—there may be no need to fit burnthrough-resistant connectors to install additional "fire barriers" (not discussed in detail here), which is caused by the space 4. The fuselage spacer encased inside is encapsulated and fully encapsulated by a burn-through resistant film made of fire-resistant film material. So-called fire barriers will function limited to the minimum requirements of the fuselage structure, since this requires no weight gain and additional components to ensure burn-through protection, although the latter will not be able to have the same high rating as the introduced aircraft fuselage grade.

An advanced really reliable burnthrough resistant aircraft can be achieved by replacing the outer skin 2 which usually consists of aluminum sheets about 1.5-3mm thick by a burnthrough resistant sheet of the kind presented.

Burnthrough resistant outer skin sheets are realized using materials such as:

a) Carbon fiber material (CFK) containing aromatic polyamide (aramide),

b) glass fiber material (GFK),

c) fire-resistant metals similar to titanium,

d) ceramic fiber materials, and

e) Silicate fiber material.

The advantage of these materials is that they have a significantly higher melting point than aluminium.

Thus, these materials are significantly more resistant to fire in the event of a fire.

Different materials can be combined with each other to achieve optimum properties in terms of processing, strength, weight and burn-through characteristics. Reference is then made to so-called "composites" or "sandwich structures". In this case, the dissimilar materials are bonded or glued together. The behavior in fire can be further optimized or improved here by especially using high-temperature-resistant adhesives.

The burnthrough-resistant sheet constructed in this way can then be riveted together with the ribs 6 , 7 and stringers 8 in the same way as conventional aircraft aluminum outer skin sheets.

Reinforcements called stringers 8 and ribs 6, 7 are responsible for the particular structural integrity of the aircraft fuselage, which can still be made of conventional material (aluminum), since they are already located on the inside with respect to the outer skin 2 of the aircraft and are made of The anti-burn-through sheet 5 protects against so-called "post-impact fire" flames. Nevertheless, all other parts such as stringers 8, ribs 6, 7 and clips etc. can be manufactured from the same burnthrough resistant material.

The proposed solution achieves the following advantages. The use of burnthrough resistant aircraft fuselages is particularly effective compared to all other devices used in passenger aircraft fire barriers. No additional parts are believed to be required, which is particularly cost-effective and lightweight. In this case, the passengers are protected against the spread of fire into the cabin compared to all other similar solutions. As the actual fuselage structure of the aircraft is protected from burn-through, components traditionally fitted to the aircraft fuselage - such as internal cladding3 and fuselage partitions - are prevented from falling onto passengers, endangering their safety and impeding evacuation .

List of reference signs

1 aircraft cabin

2 outer skin (of aircraft fuselage)

3 Internal cladding

4 space

5 plate

6, 7 ribs

8 stringers

Claims (16)

1. An aircraft fuselage, the fuselage structure comprising, in addition to the mechanical strength supports of the fuselage and other structural elements for absorbing forces, an outer skin (2) comprising different materials designed to resist shear, and as a bearing incorporated into mechanical strength supports to absorb and transmit forces and torques applied thereto, wherein the outer skin (2) is made of burn-through-resistant semi-finished material comprising non- Metallic or fire-resistant metallic materials, wherein the semi-finished material can be molded by further processing. 2. An aircraft fuselage, in addition to the mechanical strength supports of the fuselage and other structural elements for absorbing forces, the fuselage structure also includes an outer skin (2) comprising different materials, which is designed to resist shear, and incorporated as a bearing into a mechanical strength support to absorb and transmit forces and torques applied thereto, wherein the outer skin (2) is realized as a semi-finished material combining non-metallic and metallic materials, and manufactured The resulting outer skin product is a hybrid material product which can be molded and joined by further processing. 3. Aircraft fuselage according to claim 2, wherein said material composition is achieved by means of a combination of a non-metallic material containing carbon and/or glass fibers and/or ceramic fibers and a metallic material, wherein the metallic material comprises Aluminum or titanium or an aluminum-titanium alloy coated with or embedded in a resin layer. 4. Aircraft fuselage as claimed in claims 2 and 3, wherein the outer skin product obtained from the combination of materials has a sandwich design consisting of composite materials and the mentioned metallic materials bonded in layers, It imparts burn-through resistance to outer skins exposed to fire flames for extended periods of time. 5. Aircraft fuselage according to claims 1 and 2, wherein the outer skin (2) is made of non-metallic material containing carbon fiber material or glass fiber material or ceramic fiber material or silicate fiber material. 6. Aircraft fuselage according to claim 5, wherein a material composition comprising a plurality of non-metallic materials is taken into account when manufacturing the outer skin (2). 7. Aircraft fuselage according to claim 1 or 2, wherein the non-metallic material is realized as plastic reinforced with glass or plastic fibres. 8. Aircraft fuselage according to claim 1, wherein said fire resistant metal is realized by titanium or titanium alloy. 9. Aircraft fuselage according to claims 3 and 7, wherein said material composition is realized by GFK or CFK material and aluminum or titanium or an aluminum-titanium alloy. 10. The aircraft fuselage of claim 4, wherein said composite material comprises a thermally resistant composite material also characterized by high temperature resistance and tensile strength. 11. Aircraft fuselage according to claim 10, wherein said heat-resistant material is realized in carbon fibers coated with a nitride or carbide composite material and metal or ceramic material, wherein the coated carbon fibers are embedded in said metal or ceramic materials. 12. Aircraft fuselage according to one of claims 4 and 10, wherein said sandwich design is realized using a dazzling material with high burn-through characteristics. 13. Aircraft fuselage according to claims 1 and 2, wherein the outer surface of the outer skin (2) - ie the area of the outer skin exposed to the atmosphere outside the environment of the aircraft - is joined with plank plates (5), the plate (5) is realized by a semi-finished product that uses non-metallic materials or fire-resistant metal materials, or is realized by a material combination of semi-finished products that use non-metallic materials and metal materials, and the outer skin made of it The product is a mixed material, wherein the panels can also be molded and joined by further processing. 14. Aircraft fuselage according to claim 13, wherein said panels have fire protection properties and are adapted to the outer contour of the outer skin (2). 15. Aircraft fuselage according to claim 14, wherein said panels are realized by glare material. 16. Aircraft fuselage according to any one of claims 13 to 15, wherein said outer skin (2) is realized in a material containing aluminum or an aluminum alloy and is connected to a burn-through resistant plate-like sheet.