Patent Publication Number: US-2022227472-A1

Title: Canopy and door arrangement for a non-pressurized aircraft

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to European patent application No. EP 21400001.0 filed on Jan. 18, 2021, the disclosure of which is incorporated in its entirety by reference herein. 
     TECHNICAL FIELD 
     The present embodiments relate to a non-pressurized aircraft, and, more particularly, to the integration of a hinged door in a non-pressurized aircraft such that the associated hinge is entirely arranged within the outline of the non-pressurized aircraft. 
     BACKGROUND 
     Generally, doors separate environments and provide access to the environments that they separate. When such doors are used in aircrafts, they usually fulfill the following major functions: they close the aircrafts in operation, they contribute to carrying flight loads in corresponding cargo compartments and allow access to these cargo compartments, they allow passengers and crew to enter and exit the aircrafts, and they allow external access to engine compartments. 
     The most commonly used doors are sliding doors or hinged doors. Sliding doors are typically opened and closed in a translational, sliding motion, while hinged doors are opened and closed in a pivotal motion around an axis defined by one or more hinges. 
     A sliding door usually includes one or two rails, generally installed above and below the door leaf (i.e., the moving portion of the door), in which the door leaf slides during an opening and closing movement. 
     For example, document EP 3 326 904 A1 describes a rotary wing aircraft with a fuselage that is equipped with at least one rail, comprising at least one sliding element, in particular a sliding door or a sliding window, that is slidably supported by the at least one rail, wherein the at least one sliding element is at least slidable along the at least one rail by means of an opening sliding movement into an opening movement direction from a fully closed position into a fully opened position, characterized in that a dampening unit is provided that dampens the opening sliding movement of the at least one sliding element upon reaching of the fully opened position. 
     A hinged door usually includes two or more hinges that attach the door leaf to a post (e.g., a post of the helicopter&#39;s canopy). Thus, the door leaf rotates around an axis defined by the two or more hinges during the opening and closing movements of the door leaf. 
     For example, document EP 2 439 135 B1 describes a door assembly, in particular for a helicopter. The door assembly has a post; a door fitted to the post by a first and second hinge arranged on an outer wall of the post, so as to rotate about a hinge axis to open and close a door opening; and an emergency release device having a release handle, and a rod which extends through the post along a release axis substantially perpendicular to the hinge axis, rotates axially, in response to operation of the release handle, from a first to a second angular position to detach the door from the post, and is fixed at one axial end to the first hinge; the release handle being connected to the rod to rotate together with the rod about its release axis. 
     The typical integration of a hinged door on a non-pressurized aircraft, such as a helicopter, is usually driven by contradictory needs that often lead to compromises with regard to the resulting design features. As an example, a pilot needs a wide and unobstructed field of view, which requires small lateral cross-sections for all profiles including the cross-section profiles of the canopy frame and the frame of the door leaf which the hinges attach together. 
     Furthermore, the cabin volume of the non-pressurized aircraft shall be maximized to provide for enough clearance around the pilot&#39;s head to ensure certification with regard to the head travel curve and for the use of night vision goggles. 
     Moreover, the overall volume of the non-pressurized aircraft shall be minimized for low aerodynamic drag, which implies small cross-section profiles and surface area, and low weight. 
     However, huge cross-sections of all profiles may be desirable to assist with seal integration, to fulfil strength and stiffness requirements of primary and secondary structural elements due to flight load cases, ground load cases, dynamic behavior, and bird strike events, to provide for sufficient space for the installation of proper windshields and windows which may be glued and/or screwed, and to provide for sufficient volume to integrate the hinges of the door. 
     Moreover, the resulting design features have to qualify against constantly increasing safety requirements based on the Certification Specifications 29 (CS-29) and the Certification Review Items (CRIB). 
     SUMMARY 
     It is, therefore, an objective to provide a new non-pressurized aircraft with a canopy and door arrangement that overcomes the above drawbacks and leads to optimal design features. In particular, the canopy and door arrangement should be manufacturable, and have a global optimum for weight, cost, and complexity. Furthermore, the non-pressurized aircraft should have a smooth and flush outline for aerodynamic and aesthetic reasons. 
     These objectives are solved by a non-pressurized aircraft comprising the features of claim  1 . 
     More specifically, a non-pressurized aircraft with an outline, comprises a door leaf, a canopy frame, and a hinge. The canopy frame has a canopy frame cross-section profile that comprises first and second canopy frame faces that are arranged at a predetermined angle relative to each other, and a third canopy frame face that is arranged between the first and second canopy frame faces. The hinge is entirely arranged within the outline of the non-pressurized aircraft and pivotally mounts the door leaf to the third canopy frame face. 
     The described embodiment has a specific arrangement of the three main functional canopy frame faces on the canopy frame cross-section profile. The functional canopy frame faces are dedicated to windshield installation, hinge integration, and seal integration. The orientation of each of the three canopy frame faces is optimized to provide the desired function and to limit the impact on field of view of the aircraft operator at the same time. The resulting cross-section profile sizes of the canopy frame and a door frame are the estimated minimum cross sections which fulfill static needs in an economical way. 
     The canopy frame face dedicated to windshield attachment is oriented parallel to the outline of the non-pressurized aircraft. The canopy frame face related to seals integration is advantageously oriented approximately in the direction of view of the aircraft operator (i.e., the pilot and/or co-pilot) in nominal position. The canopy frame face dedicated to hinge integration is allocated on an inclined canopy frame face between the canopy frame face dedicated to windshield attachment and the canopy frame face dedicated to seals integration. 
     The hinge line, which is the connection line between the two hinge-lugs that are furthest apart from each other (i.e., the most upper and most lower hinges), is generated by the hinges placed on an inclined canopy frame face of the canopy frame cross-section profile. The hinges are always attached to the inclined canopy frame face positioned inside the outline of the non-pressurized aircraft, whereas the hinge line can be either fully inside or outside the outline or any configuration in between. 
     The outline and the door contour (i.e., the separation line) between the two furthest apart hinge positions (i.e., defined by the upper and lower hinges) is essentially straight or low curved. 
     The cross-section profiles of the canopy frame and the door frame advantageously include a closed profile made from fiber reinforced plastics, metals, or a combination thereof. 
     The cross-section profiles of the canopy frame and the door frame provide sufficient space for the integration of two fully independent seals. 
     The flush outline provides for an aerodynamic and aesthetic improvement over prior art solutions and can be achieved without any negative impact on field of view and/or overall volume of the canopy area. 
     The canopy and door arrangement provides the option to easily integrate fail-safe functionality on the hinges by adding further hinges. Compared to a typical fail-safe device such as an anti-burst pin, the benefit of the above-described canopy and door arrangement is to have full hinge functionality even after failure of one attachment point. 
     Canopy frame and door frame cross-section profiles are optimized together and have a maximum field-of-view masking angle of approximately 18°. 
     The above-described canopy and door arrangement enables the integration of any, currently known emergency exit concept including a jettisonable door, a jettisonable window, or a jettisonable window frame without any negative impact on the field-of-view masking angle. 
     The canopy frame and door frame cross-section profiles are kept simple without any excessive geometrical shape adaption all along the canopy frame and door frame. Thus, manufacturing is eased and typical critical areas in a composite layup are removed. Furthermore, the clean and smooth shape of the affected canopy and door frames is free of stress concentrations and therefore beneficial for direct and optimized load transfer. 
     The hinge elements are arranged in a way that a lip seal fulfilling the rain gutter function can be installed on the canopy without any interference or interaction with another part. 
     According to one aspect, the first, second, and third canopy frame faces are separated by smooth curved transition zones. 
     According to one aspect, the non-pressurized aircraft further comprises a windshield that is attached to the first canopy frame face of the canopy frame cross-section profile. 
     According to one aspect, at least one of an adhesive, a plurality of rivets, or a plurality of bolts attaches the windshield at the first canopy frame face. 
     According to one aspect, the non-pressurized aircraft further comprises an additional hinge that pivotally mounts the door leaf to the canopy frame. 
     According to one aspect, the hinge and the additional hinge define a hinge line, wherein the non-pressurized aircraft further comprises a fail-safe hinge that is installed on the hinge line and pivotally mounts the door leaf to the canopy frame. 
     According to one aspect, the canopy frame further comprises a fourth canopy frame face that is arranged opposite the second canopy frame face on the canopy frame cross-section profile, wherein the door leaf comprises a door frame with a door frame cross-section profile that comprises a rear door frame face, and wherein a first virtual extension of the fourth canopy frame face and a second virtual extension of the rear door frame face intersect essentially in at least one intersection point. 
     According to one aspect, a point of the at least one intersection point coincides with a nominal eye reference point of an aircraft operator. 
     According to one aspect, an additional predetermined angle at the nominal eye reference point between the first and second virtual extensions is smaller than 19 degrees. 
     According to one aspect, the door frame cross-section profile comprises a front door frame face that is arranged opposite the rear door frame face on the door frame cross section profile, wherein the non-pressurized aircraft further comprises at least one seal that is arranged between the front door frame face and the second canopy frame face when the door leaf is in a closed position. 
     According to one aspect, the at least one seal further comprises first and second seals that are independent of each other. 
     According to one aspect, at least one of the canopy frame or the door frame is a closed profile. 
     According to one aspect, at least one of the canopy frame or the door frame comprises a composite material. 
     According to one aspect, the composite material comprises fiber reinforced plastics. 
     According to one aspect, the door leaf further comprises a jettisonable window that is adapted to be jettisoned in case of an emergency. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments are outlined by way of example in the following description with reference to the attached drawings. In these attached drawings, identical or identically functioning components and elements are labeled with identical reference numbers and characters and are, consequently, only described once in the following description. 
         FIG. 1  is a diagram of an illustrative non-pressurized aircraft with a canopy and door arrangement in accordance with some embodiments, 
         FIG. 2  is a three-dimensional diagram of an illustrative outline of a non-pressurized aircraft with an illustrative canopy and door arrangement in accordance with some embodiments, 
         FIG. 3  is a diagram of illustrative canopy frame and door frame cross-section profiles with a hinge that is entirely arranged within the outline of a non-pressurized aircraft in accordance with some embodiments, and 
         FIG. 4  is a diagram of the illustrative canopy frame cross-section profile of  FIG. 3  with hinge, windshield, and seal integration in accordance with some embodiments. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a diagram of an illustrative non-pressurized aircraft  100 . Non-pressurized aircraft  100  may be a rotary-wing aircraft  100 , which is sometimes also referred to as rotorcraft  100 . The rotary-wing aircraft  100  is exemplarily illustrated as a helicopter. Thus, for purposes of simplicity and clarity, the non-pressurized aircraft  100  is hereinafter referred to as the “helicopter”  100 . 
     Illustratively, helicopter  100  may have a fuselage  120  that forms an airframe of the helicopter  100 . The airframe may define an outline of the helicopter  100 . 
     By way of example, the fuselage  120  is connected to a suitable landing gear and exemplarily forms a cabin  123  and a rear fuselage  127 . The rear fuselage  127  is connected to a tail boom  130 . 
     Illustratively, helicopter  100  may have at least one rotor  110 , which is illustratively provided as a multi-blade rotor  110 , for providing lift and forward or backward thrust during operation. The at least one multi-blade rotor  110  comprises a plurality of rotor blades  112  that are mounted at an associated rotor head  114  to a rotor shaft  115 , which rotates in operation of the helicopter  100  around an associated rotor axis  117  in a rotor plane  119 . 
     By way of example, helicopter  100  may include at least one counter-torque device  140  configured to provide counter-torque during operation, i.e., to counter the torque created by rotation of the at least one rotor  110  for purposes of balancing the helicopter  100  in terms of yaw. 
     If desired, counter-torque device  140  may be shrouded. The at least one counter-torque device  140  is illustratively provided at an aft section of the tail boom  130  and may have a tail rotor  145 . The aft section of the tail boom  130  may include a fin  150 . Illustratively, the tail boom  130  may be provided with a suitable horizontal stabilizer  135 . 
     Illustratively, a canopy  170  may form the front portion of the cabin  123 . If desired, the canopy  170  may have a frame or be frameless. As shown in  FIG. 1 , canopy  170  includes the radome, a windshield  180 , frames, and smaller windows to improve the visibility of the aircraft operator. 
     Helicopter  100  may have one or more doors that provide access to the cabin  123 . The doors may be hinged doors or sliding doors. As shown in  FIG. 1 , helicopter  100  has at least two doors with respective door leaves  160 . 
     Each one of the two door leaves  160  is shown with a door frame and a window. If desired, the window and/or the door leaf  160  may be jettisonable. For example, the window may be a jettisonable window that is adapted to be jettisoned in case of an emergency. 
     Illustratively, the front door of the two doors may be a hinged door. Thus, one or more hinges may pivotally mount the door leaf  160  to one of the canopy frames. If desired, at least one of the one or more hinges may be entirely arranged within the outline of the helicopter  100 . 
       FIG. 2  is a three-dimensional diagram of an illustrative isometric view of a portion of a non-pressurized aircraft  100  with a fuselage  120  that includes an illustrative canopy  170  and a portside door arrangement in accordance with some embodiments. The fuselage  120  with the canopy  170  and the portside doors  210 ,  215  may define an outline of the non-pressurized aircraft  100 . 
     Illustratively, the canopy  170  may include a radome, a windshield  180 , and frames, which are sometimes also referred to as canopy frames. The windshield  180  and the radome may be attached to the canopy frames. 
     The portside doors  210 ,  215  may include a cockpit door  210  and a cabin door  215 . Illustratively, cockpit door  210  is a hinged door with a door leaf  160 . 
     By way of example, a hinge  220  may pivotally mount the door leaf  160  to canopy frame  370 . The hinge  220  may be entirely arranged within the outline of the non-pressurized aircraft  100 . As shown in  FIG. 2 , an additional hinge  225  may pivotally mount the door leaf  160  to the canopy frame. The additional hinge  225  may be entirely arranged within the outline of the non-pressurized aircraft  100 . 
     The hinge  220  and the additional hinge  225  may define a hinge line  227 . The hinge line  227  may lie entirely inside the outline, entirely outside the outline, or partially inside and partially outside the outline of the non-pressurized aircraft  100 . 
     As an example, the hinge line  227  may be inside the outline of the non-pressurized aircraft  100 , and all hinges  220 ,  225  may be hidden hinges that are invisible from the outside of the non-pressurized aircraft  100  when the door leaf  160  is in a closed position. As another example, the hinge line  227  may be outside the outline of the non-pressurized aircraft  100  to provide for an increased door opening angle for operational use. 
     Illustratively, a fail-safe hinge  229  may be installed on the hinge line  227  and pivotally mount the door leaf  160  to the canopy frame  370 . If desired, several fail-safe hinges  229  may be installed on the hinge line  227  and pivotally mount the door leaf  160  to the canopy frame  370 . Fail-safe hinges  229  may ensure full functionality of the cockpit door  210  in case of a failure of one or both hinges  220 ,  225 . 
     By way of example, the door leaf  160  may be equipped with a window  264 . Window  264  may be a fixed, non-jettisonable window  264 . 
     If desired, window  264  may be a jettisonable window  264  that is adapted to be jettisoned in case of an emergency. Thus, in an emergency, an aircraft operator (e.g., a pilot or co-pilot) may leave the non-pressurized aircraft through the jettisoned window opening after having jettisoned the window  264 . 
     The jettisonable window  264  may include at least the windowpane. Preferably, the jettisonable window  264  includes the window frame and the windowpane to provide for a wider emergency exit. 
     Illustratively, the door leaf  160  may be jettisonable. For example, the hinges  220 ,  225  that pivotally mount the door leaf  160  to the canopy frame  370  may enable the jettisoning of the door leaf  160 . 
     Consider the scenario in which hinges  220 ,  225  include first and second hinge elements and hinge pins that pivotally connect the first and second hinge elements. Consider further that the first hinge element is attached to the canopy frame  370  and the second hinge element to the door leaf  160 . In this scenario, the door leaf  160  may be jettisoned by removal of the hinge pins. If desired, the door leaf  160  may be jettisoned by jettisoning of the first hinge elements from the canopy frame  370 . 
       FIG. 3  is a diagram of illustrative canopy frame  370  and door frame  360  of door leaf  160  cross-section profiles  375 ,  365  at section A-A of  FIG. 2  with a hinge  220  that is placed at the position of section A-A and entirely arranged within the outline  310  of a non-pressurized aircraft (e.g., non-pressurized aircraft  100  of  FIG. 1  or  FIG. 2 ). 
       FIG. 4  is a more detailed diagram of the illustrative canopy frame cross-section profile  375  of  FIG. 3  with hinge  310 , windshield  180 , and seal  380  integration in accordance with some embodiments. The cross-section profiles  375 ,  365  of canopy frame  370  and door frame  360  of  FIG. 3  are shown in a closed door position. 
     Illustratively, at least one of the canopy frame  370  or the door frame  360  is a closed profile. If desired, at least one of the canopy frame  370  or the door frame  360  may include a composite material. By way of example, the composite material may include fiber reinforced plastics. 
     If desired, at least one of the canopy frame  370  or the door frame  360  may include a metallic material. For example, the door frame  360  and/or the canopy frame  370  may include steel or aluminum. By way of example, the metallic material may include additive layer manufacturing. 
     Illustratively, the canopy frame cross-section profile  375  includes first and second canopy frame faces  371 ,  372  that are arranged at a predetermined angle  397  relative to each other, and a third canopy frame face  373  that is arranged between the first and second canopy frame faces  371 ,  372 . If desired, the first, second, and third canopy frame faces  371 ,  372 ,  373  are separated by smooth curved transition zones  376 . 
     Illustratively, the first canopy frame face  371  may be an offset to the outline  310  of the non-pressurized aircraft. By way of example, windshield  180  may be attached to the first canopy frame face  371  of the canopy frame cross-section profile  375 . 
     As an example, at least one of an adhesive, a plurality of rivets, or a plurality of bolts may attach the windshield  180  at the first canopy frame face  371 . If desired, any combination of an adhesive, a plurality of rivets, or a plurality of bolts may attach the windshield  180  at the first canopy frame face  371 . 
     As shown in  FIGS. 3 and 4 , hinge  220  is entirely arranged within the outline  310  of the non-pressurized aircraft and pivotally mounts the door leaf  160  to the third canopy frame face  373 . For example, a first hinge element  221  may be attached to the third canopy frame face  373  of canopy frame  370  and a second hinge element  222  to the door frame  360 . A hinge pin or bolt  224  may connect the first and second hinge elements  221 ,  222 , if desired. 
     The installation of the first hinge element  221  may be exclusively on the surface of the third canopy frame face  373 . If desired, and as shown in  FIGS. 3 and 4 , the first hinge element  221  may interfere with the canopy frame  370  up to the inboard surface. 
     Illustratively, the canopy frame  370  may include a fourth canopy frame face  374 . The fourth canopy frame face  374  may be arranged opposite the second canopy frame face  372  on the canopy frame cross-section profile  375 . 
     By way of example, the door frame  360  may include a rear door frame face  362  on the door frame cross-section profile  365 . A first virtual extension  378  of the fourth canopy frame face  374  and a second virtual extension  368  of the rear door frame face  362  may intersect essentially in at least one intersection point  390 . 
     Illustratively, a point of the at least one intersection point  390  may coincide with a nominal eye reference point  390  of an aircraft operator (e.g., a pilot or co-pilot). The nominal eye reference point  390  together with the first and second virtual extensions  378 ,  368  may define a masking angle  395 , which is sometimes also referred to as a blind angle  395 , that impairs the aircraft operator&#39;s field of view. 
     Illustratively, masking angle  395  at the nominal eye reference point  390  between the first and second virtual extensions  378 ,  368  may be selected to be as small as possible. Preferably, masking angle  395  is smaller than 19 degrees. 
     By way of example, the fourth canopy frame face  374  may be in an alignment with the first virtual extension  378  between the nominal eye reference point  390  and intersecting point  377 . In other words, the fourth canopy frame face  374  forms a vanishing line from the nominal eye reference point  390  and does not protrude from the first virtual extension  378 . 
     Similarly, the rear door frame face  362  may be in an alignment with the second virtual extension  368  between the nominal eye reference point  390  and intersecting point  367 . In other words, the rear door frame face  362  forms a vanishing line from the nominal eye reference point  390  and does not protrude from the second virtual extension  368 . 
     By way of example, the door leaf  160  may be equipped with a window  264 . Window  264  may be a fixed, non-jettisonable window  264 . 
     If desired, window  264  may be a jettisonable window  264  that is adapted to be jettisoned in case of an emergency. Thus, in an emergency, an aircraft operator (e.g., a pilot or co-pilot) may jettison the window  264  and leave the non-pressurized aircraft through the jettisoned window opening. 
     The jettisonable window  264  may include at least the windowpane. Preferably, the jettisonable window  264  includes window frame  267  and windowpane to provide for a wider emergency exit. 
     As shown in  FIG. 3 , the window frame  267  may be attached to the door frame  360 . Illustratively, the jettisonable window  264  may form a unit together with the windowpane and seal  384 . If desired, the entire unit may be jettisoned in case of an emergency. 
     Preferably, the door frame cross-section profile  365  includes a front door frame face  361  that is arranged opposite the rear door frame face  362  on the door frame cross section profile  365 . 
     For tightness and acoustic reasons, at least one seal  380  may be arranged between the front door frame face  361  and the second canopy frame face  372  when the door leaf  160  is in a closed position. Thereby, the at least one seal  380  may close at least a portion of the gap between the front door frame face  361  and the second canopy frame face  372 . 
     Illustratively, the at least one seal  380  may include first and second seals  381 ,  382  that are independent of each other. As an example, first and second seals  381 ,  382  may be mounted to the front door frame face  361 . As another example, first and second seals  381 ,  382  may be mounted to the second canopy frame face  372 . As yet another example, one of the first and second seals  381 ,  382  may be mounted to the front door frame face  361 , while the other one of the first and second seals  381 ,  382  is mounted to the second canopy frame face  372 . If desired, a first portion of at least one of the first and second seals  381 ,  382  may be mounted to the front door frame face  361 , while a second portion of the at least one of the first and second seals  381 ,  382  is mounted to the second canopy frame face  372 . 
     It should be noted that modifications to the above described embodiments are within the common knowledge of the person skilled in the art and, thus, also considered as being part of the present disclosure. 
     For example, as shown in  FIGS. 3 and 4 , hinge  220  is shown with first and second hinge elements  221 ,  222  and a hinge pin or bolt  224  that connects the first and second hinge elements  221 ,  222 . However, hinge pin  224  may be integrated into one of the first and second hinge elements  221 ,  222  instead of being a separate part, if desired. 
     Furthermore, the window  264  is shown to be attached to window frame  267  in  FIGS. 3 and 4 . However, the window  264  may not have a separate window frame  267 . Instead, the windowpane of window  264  may be attached directly to door frame  360 , if desired. 
     REFERENCE LIST 
     
         
           100  aircraft 
           110  multi-blade rotor 
           112  rotor blade 
           114  rotor head 
           115  rotor shaft 
           117  rotor axis 
           119  rotor plane 
           120  fuselage 
           123  cabin 
           127  rear fuselage 
           130  tail boom 
           135  horizontal stabilizer 
           140  counter-torque device 
           145  tail rotor 
           150  fin 
           160  door leaf 
           170  canopy 
           180  windshield 
           210  cockpit door 
           215  cabin door 
           220  hinge 
           221  first hinge element 
           222  second hinge element 
           224  bolt 
           225  hinge 
           227  hinge line 
           229  fail-safe hinge 
           264  window 
           267  window frame 
           310  outline 
           360  door frame 
           361  front door frame face 
           362  rear door frame face 
           365  door frame cross-section profile 
           367  intersecting point 
           368  rear view line, virtual extension 
           370  canopy frame 
           371  first canopy frame face 
           372  second canopy frame face 
           373  third canopy frame face 
           374  fourth canopy frame face 
           375  canopy frame cross-section profile 
           376  smooth curved transition zone 
           377  intersecting point 
           378  front view line, virtual extension 
           380  seal 
           381  first seal 
           382  second seal 
           384  seal 
           390  intersection point, nominal eye reference point 
           395 ,  397  angle