Abstract:
An intake for feeding air to an engine of an aircraft includes an opening for sucking in air, which opening faces in the direction of movement of the aircraft; and an air duct between the opening and the engine, which air duct is curved such that an impact region is arranged in the air duct after the opening in relation to the direction of movement of the aircraft. An object flying into the opening contacts the impact region. The impact region has a penetration region, which is designed to be penetrated by the impinging object.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to an inlet for feeding air to an engine, and an aircraft. 
       BACKGROUND OF THE INVENTION 
       [0002]    In particular during takeoff and landing, and also while flying at low altitude, birds may collide with an aircraft, such as an airplane, and may damage the aircraft 
         [0003]    In the event of such a ‘bird strike’ the engines (such as the fan and/or compressor) may be damaged when the bird or generally other objects contacting the aircraft enter the intake of the engine. This can result in high costs for the repair or the replacement of the engine. 
         [0004]    One approach is to design and to test the engine for a defined bird strike (i.e., an impinging object with maximum weight, maximum density, etc.). This may mean that the engine indeed may be damaged, but in spite of the bird strike does not fail during the flight. The engine can function with reduced output until a safe landing. 
       SUMMARY OF THE INVENTION 
       [0005]    The object of the invention is to make an aircraft safer, wherein only low maintenance costs are incurred. 
         [0006]    This object is achieved in accordance with embodiments of the invention. 
         [0007]    One aspect of the invention relates to an intake for feeding air to an engine of an aircraft. The aircraft may comprise one or more turbines, with which the air from the intake is compressed and ejected again in order to propel the aircraft. 
         [0008]    In accordance with one embodiment of the invention, the intake comprises an opening or an inlet for sucking in air, which points in the direction of movement of the aircraft, and an air duct between the (outer) opening and the engine, i.e. an outlet of the air duct. The air duct is curved in such a way that an impact region in the air duct is arranged after the opening in relation to the direction of movement of the aircraft, such that an object flying into the opening generally hits the impact region. In other words, the air duct of the intake does not run in a straight line to the engine, but can be curved, for example such that there does not have to be a direct line of sight between the opening of the intake and the engine. 
         [0009]    An object flying into the intake along the direction of movement of the aircraft generally contacts an inner wall of the air duct (the impact region). The direction of movement may be a direction of continued movement of the aircraft. The direction of movement may correspond substantially to a longitudinal axis of the aircraft. 
         [0010]    In accordance with one embodiment of the invention, the impact region has a penetration region or a predetermined breaking region or predetermined breaking point, which is designed to be penetrated by the impinging object. By way of example, the penetration region may be destroyed or heavily deformed in the event of contact with the objet flying in. A penetration of the penetration region may signify, here, a plastic deformation of the penetration region. The penetration region may be a component part or an arrangement of component parts in the inner wall of the air duct and/or behind the inner wall, which component part or arrangement of component parts is designed to shatter or to heavily deform in order to absorb at least some of the energy of the impinging object. 
         [0011]    The impinging object can infiltrate the penetration region and/or can break through the penetration region and can be deflected away from the engine. It is thus possible to prevent a bird, for example, from infiltrating the engine, and further subsequent damage can be avoided. Since the remains of the bird or at least a large part of these remains normally do not pass into the engine, the risk of damage to the engine is heavily reduced. 
         [0012]    The penetration region (or the component part or the component parts or materials thereof) can be designed as replacement parts, which can be economically replaced during maintenance following contact with an object. By means of the introduction of a penetration region, a component part that can be easily replaced can be penetrated by a bird, for example, such that said bird does not reach the intake duct. It is thus possible to prevent the bird from damaging the engine, which is generally expensive. The aircraft remains able to continue the flight and to land safely. The comparatively economical replacement part can then be changed. 
         [0013]    It is also possible that the intake intercepts impinging objects with high impact energy. An aircraft can also be protected against heavy birds. Even at high speed, an aircraft can be protected against objects infiltrating the intake. 
         [0014]    In accordance with one embodiment of the invention, at least part of the intake protrudes from the aircraft. By way of example, the region of the intake after the opening may be shaped in a shell-like manner. The penetration region can be arranged in the part of the intake protruding from the aircraft. 
         [0015]    In accordance with one embodiment of the invention, the part of the intake protruding from the aircraft is separated at least partially from the aircraft upon impact of the object. In this way, the output of the engine indeed may be reduced, but on the other hand the aircraft can still land safely without difficulty, and a repair of the aircraft is possible by simple installation of an economical replacement part. 
         [0016]    In accordance with one embodiment of the invention the penetration region extends from an inner wall of the air duct to an outer wall of the intake, such that an object contacting the penetration region breaks through the penetration region (with sufficiently high impact energy) and leaves the aircraft. The impinging object can be deflected away from the engine, for example by breaking through a part protruding from the aircraft (in a straight line). In this case as well the output of the engine indeed may be reduced. However, the aircraft can land without difficulty and can be repaired economically. 
         [0017]    In accordance with one embodiment of the invention, the penetration region comprises a cavity or a hollow space, in which the object contacting the penetration region is stopped. By way of example a cavity may be arranged behind an inner wall, which is designed to break upon impact of an object, the impinging object being received in said cavity. 
         [0018]    In accordance with one embodiment of the invention, the penetration region comprises a material that at least partially absorbs an impact energy of the impinging object. This material may be, for example, an inner wall of the air duct, which is designed to break upon impact of the object. By way of example, the material may be a plastic and/or a lightweight structure, whereas other parts of the inner wall consist of metal. It is also possible that the material can absorb the entire movement energy of the impinging object by way of plastic deformation, this material being a foam, for example. 
         [0019]    In accordance with one embodiment of the invention, the penetration region comprises a first material, which is designed to absorb a first part of an impact energy of the impinging object, and a second material, which is arranged after the first material in relation to the direction of movement of the aircraft and which is designed to absorb a remaining part of the impact energy. By way of example, the first material may be an easily destroyable part of the inner wall of the air duct, and the second material may be a foam. 
         [0020]    In accordance with one embodiment of the invention, a material for absorbing an impact energy is arranged in a cavity that serves to stop the impinging object. By way of example, the cavity can be lined with this material, for example foam. 
         [0021]    In accordance with one embodiment of the invention, the penetration region comprises a flap, which in a closed position provides part of an inner wall of the air duct. The flap can be held in an open position by means of material arranged in the penetration region. 
         [0022]    In accordance with one embodiment of the invention, the flap is preloaded by way of a spring mechanism, such that the flap, after infiltration of the impinging object into the penetration region, closes the inner wall of the air duct. By way of example, the impinging object may clear away a material in the penetration region that holds the flap in the open position, and may thus release the flap. Even after the contact of the object, the air duct can thus continue to perform its function without great limitation. The air flowing through the opening of the intake can be conveyed further on to the engine. 
         [0023]    In accordance with one embodiment of the invention, a surface of the penetration region in the air duct is provided with a radar-absorbing material. The surface, for example the surface of the flap or the surface of a material of the inner wall of the penetration region, for example may comprise such a material or may be coated therewith. In particular, a replacement part of the penetration region can be produced or disguised with radar-absorbing material. 
         [0024]    In accordance with one embodiment of the invention, the air duct in a surrounding environment of the penetration region has a curvature through at least 90° (for example up to 180°). The air duct may comprise an intake manifold, in which the penetration region is arranged. Predetermined breaking points can be installed in this intake manifold and also in the (outer) covering. A defined region at the intake manifold can thus be designed such that a bird, for example, breaks through the inner wall and no longer infiltrates the region in front of the engine. 
         [0025]    A further aspect of the invention relates to an aircraft, for example a manned or unmanned aircraft or a drone. The aircraft may be a disguised aircraft, which has a low radar signature, a low infrared signature and/or low acoustic signature. The aircraft may be a flying wing. 
         [0026]    In accordance with one embodiment of the invention, the aircraft comprises at least one intake, as has been described above and as will be described below, and an engine, which is arranged offset in relation to the opening of the intake. Here, an object flying into the intake contacts the penetration region, is generally deflected from the air duct of the intake, and cannot infiltrate the engine. 
         [0027]    It is possible that the demands on the engine in terms of bird strike are reduced in this way. The weight of the engine can thus be reduced. Whereas conventional engine designs are generally designed for a maximum bird strike (which is derived statistically), it is possible to ensure by way of the predetermined breaking point that even heavy birds do not damage the engine. 
         [0028]    In particular for military aircraft, which generally also operate at low flying altitude, at which most birds are normally found, the problems emanating from a bird strike can be reduced. 
         [0029]    In accordance with one embodiment of the invention, the engine is arranged against the direction of movement of the aircraft. By means of a reverse engine integration, a radar signature of the aircraft can be reduced further than with a conventionally disguised intake. 
         [0030]    Exemplary embodiments of the invention will be described hereinafter in greater detail with reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0031]      FIG. 1  shows a schematic plan view of an aircraft in accordance with one embodiment of the invention. 
           [0032]      FIG. 2  shows a schematic side view of the aircraft from  FIG. 1 . 
           [0033]      FIG. 3  shows a schematic view diagonally from above of the aircraft from  FIG. 1 . 
           [0034]      FIG. 4  shows a schematic view from the front of the aircraft from  FIG. 1 . 
           [0035]      FIG. 5  shows a schematic side view of an aircraft in accordance with one embodiment of the invention. 
           [0036]      FIG. 6  shows a schematic plan view of the aircraft from  FIG. 5 . 
           [0037]      FIG. 7  shows a schematic side view of an aircraft in accordance with one embodiment of the invention. 
           [0038]      FIG. 8  shows a schematic plan view of the aircraft from  FIG. 7 . 
           [0039]      FIG. 9  shows a schematic cross section through an intake in accordance with one embodiment of the invention. 
           [0040]      FIG. 10  shows a schematic cross section through an intake in accordance with one embodiment of the invention. 
           [0041]      FIG. 11  shows a schematic cross section through an intake in accordance with one embodiment of the invention. 
           [0042]      FIG. 12  shows a schematic cross section through an intake from  FIG. 11 , once a flap has been closed. 
           [0043]      FIG. 13  shows a schematic cross section through an intake in accordance with one embodiment of the invention. 
           [0044]      FIG. 14  shows a schematic cross section through an intake from  FIG. 13 , once a flap has been closed. 
       
    
    
       [0045]    In principle, identical or similar parts are provided with like reference signs. 
       DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0046]      FIGS. 1 to 4  show an aircraft  10  in the form of a highly disguised flying wing. 
         [0047]    The aircraft  10  has a substantially kite-like, flat form, in which all engine openings (intake opening  12  and outlet opening  14 ) are arranged on an upper side. 
         [0048]    Two engines  16  are arranged laterally, symmetrically with respect to a center axis of the aircraft  10  and are arranged against the direction of movement  18  of the aircraft  10 . Also symmetrically with respect to the center axis, there is associated with each engine  16  an intake  20 , by which air is fed to the respective engine  16 , and an outlet  22 , via which the air compressed by the engine  16  is rejected rearward (against the direction of movement  18 ). 
         [0049]    Here, the air flows into an intake opening  12 , which points in the direction of movement  18 , and then into an air duct  24 , which leads to the engine  16 . The air duct  24  has a region  26  with a curvature through 180°, which runs from top to bottom (with respect to a normal flying position of the aircraft  10 ). 
         [0050]    After the curved region  26 , the air duct  24  leads into the engine  16 . The outlet  22  has a region  28  with a curvature through 180°, which runs orthogonally to the curvature of the region  26 . After the region  28 , the outlet  22  leads into the outlet opening  14 . 
         [0051]    In  FIGS. 1 and 2 , an object  30  (a bird) is shown, which flies into one of the intakes  20  against the direction of movement  18  of the aircraft  10 . 
         [0052]    The aircraft  10  shown in  FIGS. 1 to 4  has an intake  20  (or two intakes  20 ) with penetration region, as is described in greater detail in the following figures. 
         [0053]      FIGS. 5 and 6  show that the intake  20  may have a shell-shaped part  40 , which protrudes (upwardly) from the aircraft  10 . When the object  30  reaches the intake  20 , it contacts an inner surface of the part  40 , in other words it contacts an impact surface or an impact region  42 , which is arranged after the opening  12 . The impact region  42  lies in the region  26  of the curvature of the air duct  24 . 
         [0054]    In the embodiment of  FIGS. 5 and 6 , the entire part  40  protruding from the aircraft  10  is designed as a penetration region  44 , i.e. it consists for example of a material that breaks upon impact of the object  30  or tears away from the aircraft  10  or intake  20 . The predetermined breaking point may comprise the covering of the intake  20 , which covering protrudes from the aircraft  10 . An object  30  contacting the penetration region  44  breaks through the penetration region  44  and thus does not reach the engine  16 , since it leaves the aircraft  10  again. 
         [0055]    In the embodiment of  FIGS. 7 and 8 , a penetration region  44  is provided in the part  40  protruding from the aircraft  10  and leads into a cavity  46 . The penetration region  44  of  FIGS. 6 and 7  may also comprise a material that breaks or tears away from the aircraft  10  or intake  20  upon impact of the object  30 . An object  30  contacting the predetermined breaking point  44  breaks through the predetermined breaking point  44  and thus does not pass into the engine  16 , since it lands in the cavity  46 . 
         [0056]      FIG. 9  shows a cross section through an intake  20 , in which the penetration region  44  extends from an inner wall  48  to an outer wall  50  of the intake  20  (or of the protruding part  40 ). The penetration region  44  comprises a material  52  (for example a light foam material), which can be penetrated by an object  30 , and which can also absorb some of the movement energy of the object  30 . The material  52  provides part of the inner wall  48  of the air duct  24  in the region of the curvature  26  and is coated with a radar-absorbing material  54 . The material  52  also provides part of the outer wall  50 . 
         [0057]      FIG. 9  also shows a ramp portion  53 , which is arranged in the penetration region  44  and is used to steer an object  30  penetrating or flying through the penetration region  44  in a new direction, which, for example, points away from the direction of movement  18  of the aircraft  10 . In this way the object  30  can be steered away from component parts after the intake  20 . 
         [0058]      FIG. 10  shows a cross section through an intake  20 , in which a penetration region provides part of the inner wall of  48  of the air duct  24  and leads into a cavity  46 . The cavity  46  is designed such that an object  30  flying into the cavity  46  remains in the cavity  46  (and, for example, cannot break through the rear wall thereof). A first material  56  is arranged in the cavity and can be broken through or penetrated by an object  30 , and is used as a first impact absorber, for example can absorb a first part of the movement energy of the object  30 . A second material  58  is arranged after the first material  56  in the cavity  46  and can absorb the remaining movement energy of the object  30 . 
         [0059]      FIGS. 11 and 12  show an intake  20  similar to  FIG. 9 , but equipped with a flap  60 . 
         [0060]    As  FIG. 11  shows, the flap  60  is held in an open position by the material  52 ,  54 . The flap  60  has a spring mechanism  62 , which is preloaded in such a way that the flap  60  closes when an object  30  has broken through and/or has cleared away the material  54 ,  52  (see  FIG. 12 ). As is shown in  FIG. 12 , the flap  60  in the closed position forms part of the inner wall  48  of the air duct  24 . 
         [0061]      FIGS. 13 and 14  show an intake  20  similar to  FIG. 10 , which is equipped with a flap  60  similarly to  FIGS. 11 and 12 .  FIG. 13  shows that the flap is held in the open position by the material  54 ,  56 ,  58 .  FIG. 14  shows the flap  60  in the closed position once the object  30  has cleared away and compacted the material  54 ,  56 ,  58 . 
         [0062]    In addition it is noted that “comprising” does not rule out any other elements or steps, and “a” or “one” does not rule out a plurality. It is also noted that features or steps that have been described with reference to one of the above exemplary embodiments can also be used in combination with other features or steps of other above-described exemplary embodiments. Reference signs in the claims are not to be considered as limiting.