Abstract:
The invention relates to a section of fuselage for an aircraft, including frames and bays for receiving cabin windows. According the the disclosed embodiments, at least some of the frames include at least one frame segment that surrounds at least one bay, the frame segment having two branches that are disposed to the side of the bay. The ends of the branches are attached to each of the ends of the frame segment such as to form a Y.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to International Application PCT/FR2008/050006 filed 3 Jan. 2008, which claims priority to French Application No. 07 52537 filed on 5 Jan. 2007, the disclosure of which are incorporated by reference herein their entireties. 
     
    
     BACKGROUND 
       [0002]    1. Field 
         [0003]    The disclosed embodiments relate to a section of a fuselage for an aircraft and an aircraft including such a section. 
         [0004]    2. Brief Description of the Related Developments 
         [0005]    It is known that commercial planes include a typically pseudo-cylindrical fuselage reinforced by stiffening elements such as stringers and frames so as to resist the mechanical constraints which are exerted in flight for example. 
         [0006]    In commercial aircrafts for example, openings are provided in the side walls of the fuselage to receive windows and makes it possible for the passengers to directly see the environment outside the fuselage. 
         [0007]    However, these windows generate many drawbacks. First, a window on an airplane must provide a heat and sound insulation of the internal space of the fuselage from the outside in order to provide some comfort to the passengers. It must also be air and water tight. 
         [0008]    The frame of the window which is typically riveted to the skin of the fuselage must also resist the mechanical constraints such as the loads resulting from the flexion of the fuselage and the pressurization which is applied to the window. 
         [0009]    The window must then have the aero-dynamical profile of the aircraft. 
         [0010]    All these constraints led the manufacturers to a specific stiffening of the window area. 
         [0011]      FIG. 1  is a partial view of a section of the fuselage of an aircraft of the prior art. This section includes windows  1  which are regularly spaced while being aligned along a longitudinal axis  2  of the fuselage section. It also includes frames  3 , also called torques, which make it possible to mechanically reinforce the section of the fuselage and to give the side the shape thereof. The frame pitch which means the distance separating two successive pitches  3  is greater than the width of the windows  1 . 
         [0012]      FIG. 2  schematically shows the mechanical constraints which these windows  1  can be submitted to. 
         [0013]    The mechanical constraints are of two types. These are generally shearing forces  4  connected to the flexion of the fuselage and pressurization forces  5  which transversally act and longitudinally act with respect to the fuselage section. 
         [0014]    All these constraints led the manufacturers to a specific stiffening of the window area  1  with over-thicknesses of the fuselage wall at the opening of the window  1  and a frame to guarantee the mechanical resistance of the window. 
         [0015]    The assembling of the windows  1  in the openings of the side walls of the fuselage section is carried out using mechanical fasteners. 
         [0016]    However, this assembling means a task which is difficult to the operators and time consuming. This assembling is thus expensive as regards the detention of the plane in case of maintenance. 
         [0017]    In addition, these specific reinforcements of the fuselage wall also mean an additional weight which has a negative effect on the plane consumption of kerosene. 
         [0018]    Thus, there exists a need for reducing the specific mass of the aircraft fuselage while providing the mechanical behavior of the wall of the fuselage at the level of the aircraft, in the vicinity of windows. 
       SUMMARY 
       [0019]    The aim of the disclosed embodiments are thus to provide a simple fuselage section for an aircraft, which has a simple design and operation, having a very high mechanical resistance for legal section of an airplane while enabling to reduce the mass of the fuselage structure of this aircraft. 
         [0020]    This reduction in the mass of the fuselage structure is all the more important since the pattern of the window mesh is repeated many times on the latter. 
         [0021]    Another aim of the disclosed embodiments ares a fuselage section including sections having greater dimensions than those met in the state of the art. 
         [0022]    For this purpose, the disclosed embodiments relate to a fuselage section for an aircraft including frames and openings for receiving windows. 
         [0023]    According to the disclosed embodiments, at least some of these frames include at least one frame sector surrounding at least one opening, with this frame sector including two branches positioned laterally with respect to the opening, with the ends of said branches being coupled so as to form a Y at each end of this frame sector. 
         [0024]    Advantageously, the disclosed embodiments can be applied to any type of known aircraft fuselage. Purely as an illustration, the side wall of a fuselage section for a double deck aircraft includes for each deck a row of openings intended to received windows and frames. At least some of the frames include, each, two frame sectors, i.e. a frame sector per window and per deck. 
         [0025]    The fuselage section of the disclosed embodiments are particularly adapted to the fuselage of an aircraft wherein the width of the windows is substantially as big as or even greater than the distance separating two successive frames of the fuselage. 
         [0026]    In addition, a frame sector may surround a window whether in one piece or several parts. In this later case, these parts are then spaced by one or several cross members. As an illustration, a cross member may divide a field of view into two openings having a triangular, semi-circular or any other shape. 
         [0027]    In various particular embodiments of this fuselage section, each having its particular advantages and liable to many possible technical combinations: 
         [0028]    the branches of the frame sector form a recess for receiving means for fixing a window onto said opening. 
         [0029]    These means for fixing a window preferably include a fastening clip and members for making this clip integral with the frame of the window. These integration members include for example studs, screws and bolts. 
         [0030]    the frame sector including a window fixed to said opening by means for fixing a window include a fastening clip, at least the part of the perimeter of this fastening clip has a shape cooperating with the branches of the frame sector for the uptake of efforts. 
         [0031]    The fastening clip which is to be mounted on the frame of the window has thus preferably the shape of the side perimeter of which may match the internal periphery of each branch of this frame sector so as to uptake the opening efforts and the deviations thereof. 
         [0032]    said frame including at least two frame portions, with this fuselage section including members for fixing this frame sector on the frame portions, 
         [0033]    this fastening members including splice-plates, 
         [0034]    the frame sector is made in one piece and of composite material, 
         [0035]    Advantageously, these frame sectors are made of composite material meeting the mechanical resistance and resistance to corrosion criteria related to the applications in the field of aeronautics. 
         [0036]    For example, it is made of a composite material based on carbon fibers and resin manufactured using an injection or stamping method. 
         [0037]    Two successive frame supports in the longitudinal direction of the fuselage section are connected together through a stabilizing plate. 
         [0038]    This stabilizing plate makes it possible to advantageously define a recess between two frame sectors liable to receive one or several extended element(s) such as cables or air conditioning ducts. 
         [0039]    Such fuselage section includes a stringer positioned between the opening and at least one end of the frame sector. 
         [0040]    Finally, the disclosed embodiments relate to an aircraft having a fuselage, the side walls of which are provided with windows. 
         [0041]    According to the disclosed embodiments, the fuselage includes at least one fuselage section such as previously described. 
         [0042]    Advantageously, the transversal dimension of the windows of said aircraft is greater than or equal to the distance separating two successive frames of the fuselage. 
         [0043]    The disclosed embodiments will be described in greater detail and referring to the appended drawings, wherein: 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0044]      FIG. 1  schematically shows the partial view of a fuselage section of the prior art aircraft; 
           [0045]      FIG. 2  is a schematic representation of the mechanical constraints which can be exerted inside the windows of the fuselage section of  FIG. 1 ; 
           [0046]      FIG. 3  is a perspective view of the fuselage section for an aircraft according to a particular embodiment of the disclosed embodiments; 
           [0047]      FIG. 4  is a schematic representation of the mechanical constraints which can be exerted on the windows of the fuselage section of  FIG. 3 ; 
           [0048]      FIG. 5  schematically shows the fuselage section of  FIG. 3  as a front view; 
           [0049]      FIG. 6  is a sectional view along axis A-A of the fuselage section of  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION 
       [0050]      FIG. 3  shows a fuselage section for an aircraft according to a particular embodiment of the disclosed embodiments. The fuselage section can be one composite fuselage section. As an illustration, the fuselage section can be carbon fiber-based. 
         [0051]    The fuselage section includes frames  10  and windows  11  mounted on openings. These windows  11  are aligned and regularly spaced along the longitudinal axis  12  of the fuselage section. 
         [0052]    Each frame  10  includes two frame portions  13 ,  14  connected together by a frame sector surrounding a window  11 . The frame sector is made integral with these frame portions  13 ,  14  by means of fixing members. The latter includes for example splice-plates which provide the connection of the frame sector to the frame of the upper structure and the lower structure thus giving a certain flexibility to the positioning. 
         [0053]    These splice-plates can be made of metal or of composite materials. As an illustration, they are made of titanium, inconel or aluminum alloy when they are made of metal. But they can alternatively be made of thermoplastic composites. 
         [0054]    The window  11  includes, in a known way, an external transparent element, at least one internal transparent element and a window frame. 
         [0055]    The internal transparent element of this window preferably has an elliptical shape. Advantageously, the dimensions of the internal transparent element of the window are of the order of 520×299 mm thus offering a wider field of view for the passenger than the known windows of the prior art. 
         [0056]    Of course, the window  11  may have any other shape selected in the group including a triangular shape, a circular, or a rectangular or any other shape. 
         [0057]    Each frame sector includes two branches  15 ,  16  which are positioned laterally with respect to the window  11  and the ends of which are coupled so as to form a Y at each of the ends  17 ,  18  of the frame sector. 
         [0058]    The branches  15 ,  16  also have in their central part a dome-shape so that the frame sector has a substantially elliptical shape. 
         [0059]    Each window  11  is substantially centered on the corresponding frame sector thereof, with a space separating the side branches  15 ,  16  from the frame sector of the perimeter of the window  11 . 
         [0060]    The stiffening elements of the fuselage section further include frames  10  and stringers  19 . The fuselage section includes a stringer  19  positioned between the window  11  and each end  17 ,  18  of the frame sector. This stringer  19  is positioned tangentially to the window  11  and makes it possible to provide edges to the upper and lower ends of the opening of the side wall of the fuselage receiving the window  11 . In addition, the stiffening outside the plane of the fuselage section of the disclosed embodiments is thus minimized. 
         [0061]      FIG. 4  schematically shows the result of a simulation of constraints exerted on the fuselage section and more particularly on the windows  11 . 
         [0062]    It should be noted that the frame sectors of the disclosed embodiments advantageously discharge the flow connected to the Y pressurization about the windows. When comparing  FIGS. 2 and 4 , it should be noted that the windows  11  are thus no longer directly submitted to the constraints resulting from the pressurization, contrarily to the state of the art. The passage of the constraints from the lower zone to the upper zone of the fuselage section makes it possible to increase the dimensions of the windows. 
         [0063]    In addition, the frame sectors are directed along the diagonal of the inter-window mesh which makes it possible for the frame sectors to take up the shearing of the window headpiece (in the case of a vertical gust). 
         [0064]    A stabilizing plate  20  is positioned between two successive frame supports in the longitudinal direction  12  of the fuselage section. These plates  20  make it possible to stabilize the frame sectors and to take up the efforts on the opening. 
         [0065]      FIG. 6  shows a partial sectional view along the axis A-A of the fuselage section in  FIG. 5 . The elements bearing the same references as the elements of  FIG. 3  represent the same objects which will not be described again hereinunder. 
         [0066]    The side wall  21  of the fuselage section includes an opening on which a window  11  is mounted. This window  11  includes an external transparent element  22  and at least an internal transparent element (not shown). A flexible joint makes it possible to assemble the external transparent element  22  and the internal transparent element while keeping them separated from one another through an intermediate space. This joint is for example made of elastomer. 
         [0067]    The side wall  21  of the fuselage section has a chamfer  24  along the perimeter of the opening, with this chamfer  24  having a shape which is substantially similar to that of an edge of the external transparent element  22  so as to laterally and longitudinally lock the external transparent element  22  in this opening. The outermost surface of the transparent element  22  has a shape providing an aerodynamic continuity with the side wall of the aircraft fuselage. 
         [0068]    The window  11  is conventionally fixed on the opening using a fastening clip  23  which is mounted on the frame of the window  11  using nuts and studs. 
         [0069]    The cooperation of the stabilizing plates  20  and the fastening clips  23  with the frame sectors makes it possible to stabilize them.