Cargo barrier net for an aircraft

[0001] The invention relates to a cargo securing net in an aircraft.

[0002] There are many types of safety netting and they can be used in many types of applications. Safety nets are commonly used in the aerospace industry, for example as main deck safety nets in an aircraft fuselage. It is very well known to use nets as security devices to control the load in aircraft to hold the load, which otherwise during acceleration and deceleration of the aircraft, during takeoff and landing, and also during extreme slowing down of an aircraft during an emergency landing, could move and invade an area occupied by aircraft personnel, relevant equipment and systems and / or access doors or emergency access routes.

[0003] Traditionally, such security nets include a network of band members arranged vertically and horizontally and stitched together in a rectangular grid pattern. Alternative configurations of the main deck security netting are the "spider web" type in which the band members are arranged radially and circumferentially around the central torus and are stitched together, and rhombic meshes such as those disclosed in EP 1470044 B. Such nets are usually equipped with fastening means, e.g. hooks, clamps, quick connectors, latches, single and double floor connectors, for connecting the net to the aircraft structure, e.g. attachment points around the aircraft fuselage and floor.

[0004] The success of the net acting as a safeguard against the moving load is based on a net forming a profile that, when loaded, does not reach the areas to be protected and at the same time safely distributes the resulting load to the aircraft structure. Currently available networks have many disadvantages, especially when it comes to their ability to provide a mesh that transmits almost equal load to all attachment points. This can lead to excessively high loads on certain attachment points and the need for local strengthening of the aircraft structure. Alternatively, this leads to a complex and expensive grid. For example, with conventional rectangular mesh, most of the load is directed horizontally and vertically, and only a relatively small portion of the load is directed in diagonal directions. This causes an excessive load on some attachment points.

[0005] The object of the present invention is to overcome some of the problems of the prior art or at least to offer an alternative to the security nets of the prior art.

[0006] According to the present invention there is provided a cargo securing net for an aircraft, containing: mesh defined by multiple grid bands; many fastening agents, attached to at least some of the mesh strands, for attaching a safety net in the interior of the aircraft; and at least one tear tape placed between the securing means and the mesh band, cha3 characterized by that the tear tape contains two layers of tape connected to each other by a binding matrix, wherein said two layers of tape are oriented in parallel and superimposed, wherein the binding warp is woven into the fabric of the tape layers, towards the warp, to connect the layers of tape together, which binding matrix is ​​adapted to progressive disruption, when a load is applied to the tear tape, thereby increasing the effective length of the mesh band, with which the tear tape is connected and distributing the load to other strands in the load securing net.

[0007] A device showing the pre-characterized features of claim 1 is known from US 6435786 B1, which document is considered to be the closest in the prior art, and in DE 2913050 A1.

[0008] Tape tapes are well known for other applications, for example as safety harnesses for working at height, equipment for catapulted seats, or weapon unloading systems. The tear tape is generally used to absorb energy, for example, to act as a shock absorber when a user wearing a safety harness falls from a height. The tear tape usually consists of two layers of tape, joined together at defined intervals by a binding matrix, i.e. a material that is connected only with threads of the tape thread. When a force is exerted between two layers of tape, it causes the binding warp to tear and the two layers of tape begin to diverge gradually, thereby helping cushion the momentum. This is useful in a safety harness because it helps to break the fall in a much milder way.

[0009] The tear tape function in the present invention differs slightly from that present in most other applications. By incorporating at least one tear tape in the safety net, it is possible to provide a net that is able to dynamically adapt to providing a more even distribution of the applied load between the net attachment points, e.g. at the attachment points in the fuselage and floor of the aircraft. As mentioned above, when a load is applied to the safety net, this usually results in an excessively high load acting on certain attachment points, while other attachment points remain relatively unloaded. By incorporating tear tapes into the safety net, between the net strands and the fastening means, it is possible to evenly distribute the load between multiple fastening points.

[0010] When the load acts on the safety net of the present invention, it will be transferred through the net strands in the usual way. Initially, certain attachment points will experience greater load due to the mesh geometry as well as the size and shape of the load acting on it. However, when a sufficiently large load acts on the attachment point, the tear tape, which is provided between the attachment means and the mesh strands, begins to tear. As the layers of tear tapes tear progressively, they effectively increase the length of the mesh strands. As the length of the mesh band increases, it will change the mesh profile and cause the load to be shared between some other attachment points. The dynamic adaptation of the mesh lasts until the load is more evenly distributed between the mesh attachment points and the load exerted on any of the attachment points does not exceed a certain maximum value, which corresponds to the tensile strength of the tear tape. The load at which the tear tape begins to tear, i.e. its breaking strength, can be adapted to the particular mesh application. When the load exerts an effect on the mesh and the tear tape (s) have been broken, it will be necessary to return the mesh for repair.

[0011] In an embodiment of the invention, each of the securing means is separated from the corresponding mesh web by a tear tape. It is possible to provide tear tapes between only selected web bands and attachment means, but a more flexible solution is offered if a tear tape is provided between each of the attachment means and the corresponding mesh bands, as this allows the network to handle a wider range of potential scenarios.

[0012] In an embodiment of the invention, the tear tape is single-layer. In an embodiment of the invention, the tear tape is multilayer. As will be described below with reference to the drawings, a multi-layer tear tape is a structure formed of many single-layer tear tapes. The choice of single-layer tear tapes or multi-layer tear tapes will depend on many factors, including cost, weight, strength and intended use of the safety net. To function effectively, the tear tape should tear in a controlled and predictable manner. If the tear tape tears too fast, it won't do its job effectively because there won't be enough time for the load to be evenly distributed. The object of the invention is to provide a tear tape that tears in a controlled and progressive manner and provides sufficient time to divide the load between the additional attachment points.

[0013] The load at which the single layer tear tape begins to tear, i.e. its tear strength, can vary to some extent by changing the binding matrix between the layers of the tape. This can be achieved by changing the amount of overlap between the two layers of tape and varying the bond strength. The tear strength of a single-layer tear tape is usually in the range of 3 - 8 kN. It is well known how strength and tear tear characteristics can be controlled. However, in some applications, e.g. in the case of aircraft retaining nets, it may be that the tensile strength of the single-layer tear tape is insufficient to control the loads to which the net will be subjected. Main deck safety nets must normally withstand the force exerted by the maximum load capacity of an aircraft under 9 g of accelerated motion. In such circumstances, it is envisaged that multi-layer tear tapes may be required to deal effectively with emerging forces. Multilayer tear tape is a tape that contains many individual elements of a multilayer tear tape, combined into one structure. The tear strength of a multilayer tear tape depends on the number and strength of the individual tear tape components used. A multi-layer tear tape can have only two elements of a tear tape. In an embodiment of the invention, in a multilayer tear tape a range of 12-30 individual elements of the tear tape is provided. In an embodiment of the invention, the strength of the multilayer tear tape is from 10 kN or 20 kN, or 40 kN, or 60 kN, or 80 kN, or 100 kN, or 120 kN. It should be understood that the tear strength of a multilayer tear tape can be adjusted by varying the size of the overlap between the two layers of the tape and by changing the bond strength of parts or all of the individual components of the tear tape.

[0014] In an embodiment of the invention, the safety net comprises a plurality of tear tapes and the tear tapes are a combination of single-layer and multi-layer tapes. In addition, the tear strength of each single-layer tear tape and each multi-layer tear tape may be different. The tear strength of each tear tape can be selected to suit the specific application of the safety net and the anticipated forces to which it will be exposed.

[0015] In an embodiment of the invention, the safety net is a safety net for the main deck. As described above, the present invention has many applications and may prove useful in any number of industries. However, due to issues related to the uneven distribution of loads in the main deck protection nets, in particular this application has been identified as one that will bring the most benefit from the present invention.

[0016] In an embodiment of the invention, the attachment means are selected from the group of: clamps, hooks, quick-release couplings, latches, single floor connectors and double floor connectors.

[0017] The invention will now be described, by way of example only, with references to the accompanying drawings, in which:

Fig. 1 is a view of the main deck protection net in an aircraft fuselage according to the present invention;

Fig. 2 is a close-up view of the single-layer tear tape of the present invention; and

Fig. 3 is a schematic view of a multilayer tear tape according to the present invention.

[0018] Referring to Fig. 1, a main deck securing net 2 according to the present invention is shown. The safety net 2 is generally of a traditional construction and comprises a plurality of horizontal band members 4 and a plurality of vertical band members 6 stitched together at intersection points 8. The band members 4, 6 may be strips of polyester tape, but the present invention can be used for safety nets made of any material. The safety net 2, like this one, is considered to be a rectangular mesh because the horizontal and vertical band members 4, 6 define the rectangular layout, but it will be clear that the present invention can be applied to the safety mesh 2 with a different layout. The main deck securing net 2 is arranged in the space defined by the fuselage 10 and the aircraft floor 12. Fastening means in the form of staples 14 are provided at each end of most horizontal band members 4 and at each end of portions of vertical band members 6. Buckles 14 are attached to attachment points 16 provided in fuselage 10 and aircraft floor 12.

[0019] As discussed above, it has been found that such mesh geometry does not distribute the load particularly efficiently, therefore excessive loads tend to affect some of the attachment points 16. In particular, when the load acts on the center of the safety net 2, the members belt 4, 6 tend to transfer the load horizontally and vertically, meanwhile a proportionally smaller load acts in an oblique direction.

[0020] As can be seen in more detail with reference to Figs. 2 and 3, tear tapes 18, 30 are provided at each end of the tape member 4.6, between the tape members 4.6 and the fastening clamp 14. The tear tapes 18.30 can single-layer (as shown in Figure 2) or multi-layer (as shown in Figure 3). The choice of single-layer 18 or multi-layer 30 will depend on the loads to which mesh 2 is designed to support.

[0021] Turning to Fig. 2, there is shown a close-up of the web 6 of the safety net 2 with a single-layer tear tape 18 sandwiched between the web 6 of the net and the clamp 14.

[0022] As can be seen in fig. 1, the attachment clamp 14 engages with the attachment point 16 on the fuselage 10 and the aircraft floor 12 during the use of the net 2. The single-layer tear tape 18 comprises two layers of tape 18a and 18b, connected to each other by a binding matrix 20. The two layers of tape 18a, 18b are oriented in parallel and are superimposed, and the bonding matrix 20 connects the tape layers 18a and 18b together. The bond warp 20 is woven into the fabric of the tape layers 18a and 18b only in the warp direction. When sufficient force is applied to the web strand 6, the bonding matrix 20 begins to tear and the two layers of tape 18a, 18b begin to separate in a controlled and progressive manner. The force required to separate the layers of tape 18a, 18b can be adjusted by changing the extent of engagement between the bonding matrix 20 and the tape layers 18a, 18b with respect to the extent of overlap and bond strength. The band members 4.6 are polyester tapes, and the bonding warp 20 is also made of polyester. It will be apparent to those skilled in the art that other materials may also be used to form the safety net 2 of the present invention. These include, but are not limited to, nylon, polyethylene, very high molecular weight polyethylene and aramid bands.

[0023] The web strip 6 overlaps part of one of the tape layers 18b and these two elements are fastened together by sewing 22, which is well known in the prior art. The second band layer 18a overlaps another section of band material 26 and these two elements are attached to each other by a suitable stitch 24. Further band material 26 passes through the hole in the buckle 14 and is looped and sewn to attach the buckle 14.

[0024] Fig. 3 is a schematic view of the mesh band 6 with a multi-layer tear tape 30 sandwiched between the mesh band 6 and the fastening clamp 14. As can be seen in Fig. 1, when the net 2 is used, the fastening clamp 14 engages with the fastening point 16 in the fuselage 10 and aircraft floor 12. The multi-layer tear tape 30 is made of a plurality of individual pieces 32 of the tear tape (indicated by the shaded area). Each of the individual elements 32 of the tear tape 32, forming the multi-layer tear tape 30, is shaped in the same way as the single-layer tear tape 18 of Fig. 2. The multilayer tear tape 30 comprises 14 individual elements 32 of the tear tape, but the total number of individual elements 32 of the tear tape can be selected to suit the desired properties of the mesh 2. Usually, it will be between 12 and 30 individual pieces 32 of the tear tape in the multi-layer tear tape 30. As before, each individual tear tape element 32 includes two layers of tape 34a, 34b connected to each other by a binding matrix (not shown). The two layers of tape 34a, 34b are oriented in parallel and are superimposed, and the binding matrix connects the tape layers 34a, 34b together. The binding warp is woven into the fabric of the tape layers 34a, 34b only in the warp direction.

[0025] The mesh 6 passes through the center of the tear tape 30 and is attached to the clamp 14. The web strand 6 passes through the hole in the buckle 14 and is folded back and stapled to secure the buckle 14 in place. Bypass 36 is located in band 6, which acts as security for band 6. Bypass 36 is an excess stretch of tape that ensures that the tear tape 30 will first take any load that will be exerted on the web 6. In the event that all individual elements 32 of the tear tape break, the mesh band 6 will then act as back-up protection and take over the load.

[0026] Sections of the spacer tape 38 are provided between the mesh band 6 and the individual elements 32 of the tear tape. The spacer tape 38 is sewn to the web 6 of the net and subsequent sections of the spacer tape 38 by means of seams, as is known in the prior art.

The spacers 38 are cascaded to allow the single tear tape elements 38 to be combined into one structure.

[0027] The advantage of multi-layer tear tapes 30 is that they can generally achieve a much higher maximum tear strength than single-layer tear tapes 18. This is important in applications such as the retaining nets 2 of the main deck, because the nets 2 must be able to withstand the force exerted by the maximum load capacity of the aircraft under forward acceleration (overload) of 9 g. Currently available single-layer tear tapes 18 would not be able to handle such heavy loads and would not tear in a controlled and progressive manner. Ideally, for applications such as safety nets 2 of the main deck, the multi-layer tear tape 30 should begin to tear after being subjected to a load of 60 - 110 kN. However, the multilayer tear tape 30 comprising two tear tape elements 32 may have a tear strength of only 10 kN, and the maximum tear strength of the multilayer tear tape 30 may exceed 110 kN. The multilayer tear tape 30 should then continue to tear in a controlled and progressive manner as the load increases.

[0028] The general operation of the present invention will be described below. The skilled artisan will bear in mind that the operation of the net 2 will be the same, regardless of specific applications and whether the net 2 comprises single-layer tear tapes 18, multi-layer tear tapes 30 or a combination of both. As mentioned above, the choice of single-layer or multi-layer tape is generally dictated by the required strength. It is envisaged that both single-layer and multi-layer tear tapes 18.30 can be used in the same safety net 2 to provide different properties for individual 4.6 mesh bands as required.

[0029] When a force is exerted on the entire area of ​​the safety net 2, it is generally accepted by some of the 4.6 mesh bands, unlike others. This means that the attachment points 16 to which 4.6 grids are attached will experience a greater load than other attachment points 16. However, if the 4.6 band of the network that experiences a greater load contains a tear tape 18.30, then the mesh 2 can function dynamically to change the mesh geometry and distribute the load. When the 4.6 band of the network experiences load, it is transferred to the tear strips 18.30. When the force exceeds a predetermined level (which may be specified by the manufacturer), then the tear tape 18.30 will begin to tear in a controlled and progressive manner. When the tear tape 18.30 tears, it increases the effective 4.6 strand length of the mesh and changes the geometry of mesh 2. When the 4.6 mesh band lengthens, the load is shared with other 4.6 mesh bands, and thus with other attachment points 16 (usually those adjacent to the first 4.6 mesh band). If the load experienced by these 4.6 grid bands and the attachment points 16 is still too high, then their tear tapes 18.30 will begin to tear in a controlled and progressive manner. This process will continue until the load is evenly distributed in such a way that none of the attachment points 16 experiences a higher load than previously determined.

[0030] Multilayer tear tapes 30 operate in the same general manner as individual tear tapes 18. When the load is applied to the 4.6 mesh band, it will be transferred to the multilayer tear tapes 30. The load can either act on all elements 32 of individual tear tapes at the same time, or it will act more on one or more individual elements 32 of tear tapes than on others. If the load exceeds a predetermined value, then the individual elements 32 of the tear tape will begin to tear. Because each individual element 32 breaks, the load will be transferred to the other individual elements 32. The effective length of the mesh band will gradually increase until the load is absorbed by the other 4.6 mesh bands, and the load experienced by the mesh band no longer exceeds the tear strength of the tear tape 30. As mentioned above, the mesh band may be provided with a bypass 36 such that in the case where all individual pieces 32 of the tear tape break, the 4.6 mesh band will take over the load. This provides protection so that the net can function and prevent the intrusion of the load into the protected area.

[0031] The above description is provided by way of example only and it will be understood by those skilled in the art that the present invention can generally be applied to protective nets. The scope of the present invention is limited only by the scope of the claims.

Amsafe Bridport Limited

Proxy:

EP 2 202 149 B1