Abstract:
A mobile platform personnel berth unit and a method for creating the mobile platform personnel berth unit are provided. A male mandrel is created defining an inner mold line surface of the berth unit. The male mandrel is overlayed with one or more layers of filament strips. The filament layers are thermally cured to create an integrated structural member. The male mandrel is then removed from the structural member. The structural member is profile shaped to create a semi-finished berth unit having a top, a bottom and a pair of integral side panels. Additional entrance and back panels as well as access panels and connecting hardware are then added to complete the berth unit.

Description:
FIELD OF THE INVENTION 
   The present invention relates in general to mobile platform crew rest berth units and more specifically to an aircraft crew rest enclosure structure and method of manufacture. 
   BACKGROUND OF THE INVENTION 
   Mobile platforms including aircraft, trains, ships, etc. often provide rest areas for crew or passengers when the vehicle is intended for operation over lengthy time periods. For simplicity, applications for aircraft crew rest berths are generally described herein. Crew rest berths are enclosures generally provided for an individual to rest or sleep in private, often having curtains or doors, electrical supply outlets, entertainment outlets, etc. Commercial aircraft in particular are required to provide crew rest spaces for aircraft which operate over extended periods of time. Common crew rest areas include bunks or berths, seats, and lavatories for crew use. Aircraft crew rests are often separately provided for flight crew members and for flight attendants. 
   The berth units are frequently built up using fiberglass/honeycomb panels that are joined to form a module. Separate top, bottom and side walls are prefabricated. The walls are connected using multiple brackets, fasteners and fittings. An upper and/or lower support plate is commonly used to support one or more berths to structure of the mobile platform. This construction/installation technique is labor intensive and produces berth units having multiple joints and undesirably high weight. In addition, sub-assembly of the units to the support plate(s) normally must take place on-site on the aircraft during construction, which provides additional delay in construction. 
   It is often a complex process to install crew rest berths on mobile platforms such as aircraft due to the size and weight of the berths, which can be about 300 pounds. This weight necessitates use of on-site special lifting/handling equipment. The structure to support a berth of this weight must also be reinforced or require multiple attachment points to carry not just the dead weight of the berth and support plates, but also the dynamic load of the berth due to berth/platform motion and aircraft motion. Access for installation of crew rest berths is also limited by items such as piping, structure, environmental control system ducting, flight control cabling, fire detection systems, stow-bin support structure and center stow-bins, and electrical cabling positioned adjacent to or passing through the crew rest areas. Installation of all these items needs to be coordinated during construction of the aircraft. 
   Crew rest berths have been positioned in the overhead volume (above the main cabin ceiling) of aircraft, which offers the potential for increased passenger or cargo capacity to the airline operator. Overhead positioned rest units do not displace main deck seats or cargo container volume in the lower lobe, and so increase the volume within the fuselage that is available for revenue service. Existing overhead positioned rest units, however, are excessively heavy as noted above and therefore reduce the payload potential of the aircraft. 
   A further disadvantage of existing crew rest berths is that assembly sequencing of these items is predetermined and therefore installation of crew rest berthing affects the overall construction schedule of the platform or aircraft. The additional structure and special equipment required to construct and install existing berths adds weight, complexity, and cost and therefore increases installation time, negatively affecting the construction schedule. Access space for the installing mechanics and any special equipment is also required. A crew rest berth design providing lower weight as well as faster and simpler installation is therefore desirable. 
   SUMMARY OF THE INVENTION 
   According to a preferred embodiment of the present invention, a method for creating a filament wound crew rest enclosure structure includes selecting a male mandrel defining an inner mold line surface of the berth unit. The male mandrel is overlayed with a plurality of adjoining filament strips. The filament strips in one or more layers are autoclave cured to create an integrated structural member. The male mandrel is then removed from the structural member. The structural member is profile shaped to permit installation of additional front and back panels as well as access panels and connecting hardware which complete the berth unit. 
   According to another preferred embodiment of the present invention, a mobile platform personnel berth unit includes a body having integrally joined perimeter walls defining a substantially hollow interior space. A wall thickness is formed from a plurality of wound filaments. In one preferred embodiment, a material of the body is a graphite composite. According to yet another preferred embodiment of the present invention, a core ply is inserted between layers of the filament strips to stiffen the wall and provide attachment points for additional equipment/fasteners. 
   A filament wound crew rest enclosure structure of the present invention provides several advantages. By integrally forming the walls, top and bottom surfaces of a crew rest enclosure, the number of connecting fittings is reduced. By using one or more filament wound layers of a graphite or graphite/polymeric material composite, a weight of the crew rest enclosure can be reduced to about 75 pounds or less, which permits two mechanics to install the crew rest enclosure by hand without the need for special handling equipment. By using an automated computer controlled tape laying machine, construction complexity is reduced compared to the known process of forming individual panels and joining the panels using a plurality of connectors and fasteners. 
   The features, functions, and advantages can be achieved independently in various embodiments of the present invention or may be combined in yet other embodiments. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
       FIG. 1  is a perspective view of a filament wound crew rest enclosure structure according to a preferred embodiment of the present invention; 
       FIG. 2  is a perspective view similar to  FIG. 1  further showing a male mandrel supporting an integrated structure for the crew rest berth of one preferred embodiment of the present invention; 
       FIG. 3  is a perspective view of a filament application device used to wind individual filaments of material about the male mandrel of the present invention; 
       FIG. 4  is a perspective view of an exemplary male mandrel of the present invention having a partially completed plurality of filament strips wrapped thereon; 
       FIG. 5  is a partial cross-sectional view taken at Section  5 - 5  of  FIG. 4 ; 
       FIG. 6  is a partial cross-sectional view similar to  FIG. 5  showing another preferred embodiment of the present invention; 
       FIG. 7  is a partial cross-sectional view similar to  FIG. 5  showing yet another preferred embodiment of the present invention; 
       FIG. 8  is a partial cross-sectional view similar to  FIG. 5  showing yet still another preferred embodiment of the present invention; 
       FIG. 9  is a perspective view of a berth assembly of the present invention having a pair of joined berths supported from structure of a mobile platform; 
       FIG. 10  is a perspective view generally showing a underside view looking forward of a single crew rest berth of the present invention; 
       FIG. 11  is a cross sectional view taken at section  11 - 11  of  FIG. 10 ; 
       FIG. 12  is a flow diagram of exemplary operations for creating a mobile platform personnel berth of one embodiment of the present invention; and 
       FIG. 13  is a flow diagram of exemplary operations for creating a mobile platform personnel berth of another embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
   Referring generally to  FIG. 1  and according to a preferred embodiment of the present invention a crew rest berth  10  includes an upper first wall  12 , a lower second wall  14 , a first side wall  16  and a second side wall  18 . First and second side walls  16 ,  18  generally oppose each other and are shown in  FIG. 1  configured in parallel to each other. The invention is not limited to the specific geometry shown in  FIG. 1 . A crew rest berth  10  of the present invention can be formed in any geometric shape suitable for application of the filament strips of the present invention. An end connection  22  is machined into or provided on at least one end of crew rest berth  10 . End connections  22  are adapted to support end panels not shown in this view for clarity. A cavity  20  is formed substantially throughout crew rest berth  10  bounded by each of first and second walls  12 ,  14  and first and second side walls  16 ,  18  and the end panel(s). 
   Crew rest berth  10  includes a berth length “A”, a major height “B” and a minor height “C”. Dimensions “A”, “B” and “C” are predetermined based on the geometry of the mobile platform in which crew rest berths  10  are installed. In a preferred embodiment of the present invention, berth length “A” is approximately 2.44 meters (8 feet). This length provides ample space for a person occupying crew rest berth  10  with additional room for necessary personal items. 
   Referring now to  FIG. 2 , an integrated structure  23  formed about an exemplary male mandrel  24  is shown. Integrated structure  23  is formed in one of a plurality of construction stages during creation of crew rest berth  10 . Male mandrel  24  is constructed of a material structurally sufficient to retain the desired shape of crew rest berth  10  during this construction stage. For example, male mandrel  24  can be made from a metal material such as aluminum or a polymeric material. An inner mold line surface  26  of crew rest berth  10  is defined by a perimeter shape of male mandrel  24 . Inner mold line surface  26  therefore defines a subsequent inner boundary of crew rest berth  10 . Male mandrel  24  can extend beyond the ends of crew rest berth  10  as shown or can be sized to substantially equal the berth length “A” of crew rest berth  10 . A plurality of filament windings  28  are wound about male mandrel  24  to form the wall thickness and the general shape of crew rest berth  10  in a process further detailed as follows. 
   As best seen in  FIG. 3 , a filament application device  30  is provided to show one example of equipment that can be used to automatically install filament windings  28 . In this example, filament application device  30  includes a mandrel support section  32  and a filament application section  34 . Mandrel support section  32  further includes a head stock  36  and a tail stock  38  both supported by stock support legs  40 . A mandrel longitudinal axis  42  is formed through male mandrel  24  when male mandrel  24  is rotatably supported between head stock  36  and tail stock  38 . Male mandrel  24  can be rotated by head stock  36  in either of the directions of mandrel arc of rotation “D”. Rotational torque for driving male mandrel  24  via head stock  36  is provided by, for example, an electric motor (not shown). 
   Filament application section  34  further includes an application head  44  which directs placement of the plurality of filament windings  28  about male mandrel  24 . Application head  44  can travel in either of the directions of mandrel displacement arrows “E”. As will be evident to a skilled practitioner, application head  44  is also displaceable either toward or away from male mandrel  24  and in either an upward or downward direction as viewed in  FIG. 3 . 
   Filament windings  28  are fed to application head  44  via a head driver  46  which also functions to displace application head  44  as required. Both application head  44  and head driver  46  are movably supported on a head support frame  48  which in turn is supported for motion in the direction of mandrel displacement arrows “E” by a pair of support legs  50 . 
   A computer  52  which can be either locally or remotely positioned relative to application head  44  and head driver  46  is provided to permit preprogrammed operational movement of application head  44 . One or more computer programs can be programmed into computer  52  for one or a plurality of geometries of male mandrel  24 , varying thicknesses or widths of filament windings  28 , varying quantities of layers of filament windings  28  and various patterns for applying filament windings  28 . Computer  52  provides for automated assembly of crew rest berths  10  thus reducing manpower required for construction of crew rest berths  10 . Individual filament windings  28  can also be applied manually to male mandrel  24  if the geometry of male mandrel  24  does not permit automatic application via application head  44 . 
   Referring generally to  FIG. 4 , male mandrel  24  is shown having a portion of a first layer  53  of filament windings  28  applied thereon. A filament portion  54  supplied by application head  44  of filament application device  30  is applied to male mandrel  24  as male mandrel  24  rotates about mandrel longitudinal axis  42  in a first one of the arcs of rotation “D”. It is desirable to install filament windings  28  as a continuous filament member for each wall thickness layer to reduce a total number of filament joints. Application head  44  is translated in the general direction of arrow “F” which is timed with the rotation speed of male mandrel  24  to apply one or more individual layers of abutting or overlapping filament windings  28 . A release agent  55  can be applied to male mandrel  24  prior to or during application of filament windings  28  to subsequently aid in releasing integrated structure  23  from male mandrel  24 . 
   Referring generally to  FIGS. 5 through 8 , a plurality of individual layers and layering techniques are shown for installation of filament windings  28 . In one embodiment shown in  FIG. 5 , a single layer of overlapping filament windings  28  is provided by overlapping successive filament windings  28  using a plurality of overlapped portions  56 . This embodiment provides for bonding between adjoining ones of the filament windings  28 . In the embodiment shown in  FIG. 6 , filament windings  28  generally abut with each other, providing a plurality of abutting joints  58 . This embodiment is particularly suited for applications having multiple layers of filament windings  28 . 
   As best seen in  FIG. 7 , a multiple layer embodiment of filament windings  28  is shown. A first layer or ply  60  is applied to male mandrel  24  as shown. A second ply  62  and a third ply  64  are then successively applied over first ply  60 . In this embodiment, filament windings  28  are applied having a plurality of the abutting joints  58 . Filament windings  28  of each ply can be aligned over successive plies, crossed, for example in a herring-bone arrangement, or perpendicularly arranged. Filament winding joints between layers of filament windings can be aligned or preferably staggered. Additional plies (not shown) can also be provided to achieve a desired stiffness or strength.  FIG. 7  also shows an exemplary berth unit support fitting  65  which can be at least partially overlapped during the filament application process such that support fitting  65  is structurally connected to at least one of first, second and/or third plies  60 ,  62  and  64  with or without the use of additional fasteners (not shown). 
   In a further embodiment shown in  FIG. 8 , a first or base ply  66  of filament windings  28  is applied to male mandrel  24 . At least one core ply  68  is then applied over base ply  66 . In a preferred embodiment of the present invention core ply  68  is a honeycomb layer of material having a plurality of honeycomb-shaped cells  69 . Core ply  68  has a core ply thickness “G” which is built up of multiple layers of cells  69  or formed at least equal to a single layer thickness of filament windings  28 , and preferably greater than a single layer thickness of filament windings  28 . The purpose for core ply  68  is to increase a total ply thickness “H” to stiffen the configuration of crew rest berth  10  and also to at least locally provide additional thickness for further installation of items including fasteners and supported equipment within crew rest berth  10 . It is desirable that core ply  68  be thicker (core ply thickness “G”) than any one filament winding  28  but yield the same or a lower weight in an equivalent width of filament windings  28 . An exemplary material for core ply  68  is NOMEX®, which is available from the DuPont Corporation. At least one overlying ply  70  is then applied over core ply  68 . 
   After the desired number of layers of filament windings  28  and/or core ply  68  are applied to male mandrel  24 , male mandrel  24  is then placed in an autoclave or oven. A temperature within the autoclave is raised to a sufficient temperature to bond and harden each of the layers and filament windings  28  into the general shape of integrated structure  23 . Each filament winding  28  is pre-impregnated with an adhesive material which is heat activated at the elevated temperature within the autoclave to bond into integrated structure  23  (shown in  FIG. 2 ). An exemplary autoclave temperature range is approximately 134-162° C. (300-350° F.) for curing phenolic material or phenolic containing adhesive materials, and length of cure time is variable from one to in excess of 10 hours. As will be obvious to the skilled practitioner, cure temperature and time can vary depending on the number of layers and thickness of filament windings  28 . 
   Male mandrel  24  with cured windings  28  in the form of integrated structure  23  is then removed from the autoclave (not shown) and the male mandrel  24  is then removed from integrated structure  23 . Male mandrel  24  can be removed in a number of ways, including providing male mandrel  24  in a plurality of pieces or segments which can be disassembled for removal from integrated structure  23 . Male mandrel  24  can also be slightly tapered in a longitudinal direction such that the release agent  55  applied between male mandrel  24  and the first layer of filament windings  28  permits male mandrel  24  to be slid out of contact with integrated structure  23 . Further techniques can also include cooling male mandrel  24  to shrink male mandrel  24  away from integrated structure  23  or longitudinally cutting integrated structure  23  to allow removal from male mandrel  24 . Cutting integrated structure  23  to remove it from male mandrel  24  is less desirable because an additional joint results which must then be re-joined for example by adhesive, requiring additional application and cure times with possibly reduced structural integrity. 
   Referring now to  FIG. 9 , a pair of crew rest berths  10  including a first berth  72  and a second berth  74  are shown installed within an aircraft  75  and supported from a plurality of structural support members  76 . In this embodiment, structural support members  76  reflect frames of aircraft  75 . A berth assembly  71  formed by first and second berths  72 ,  74  can be supported by any type of structural support member  76  of aircraft  75 . One of the advantages of the present invention includes that a reduced quantity of connecting fittings  78  can be used to support each crew rest berth  10  of berth assembly  71  to structural support members  76 . Connecting fittings  78  (and similar connectable items) are preferably connected to crew rest berth  10  by overlapping at least a portion of connecting fittings  78  below or between layers of filament windings  28  during application of filament windings  28 . 
   The reduced quantity of connecting fittings  78  is achievable due to the reduced weight of each crew rest berth  10  manufactured by the process described herein. In a preferred embodiment, a weight of each crew rest berth  10  is approximately 75 pounds or less which permits each crew rest berth  10  to be manually lifted into place to form berth assembly  71 . By subsequently interlocking first and second berths  72 ,  74 , berth assembly  71  is completed. 
   Referring specifically to  FIG. 10 , an exemplary arrangement having additional items connectible to first berth  72  is shown. One or more component attachment structures  80  can be applied to any of the non-adjoining walls of berth assembly  71 . Component attachment structures  80  permit the further attachment of items such as system piping, electrical cabling, ventilation ducting, etc., which are supported to one of the berths of berth assembly  71 . Each crew rest berth  10  can also be provided with an access panel  82  which in the embodiment shown is connected to an end wall  84 . As noted above, each of these items are preferably connected to crew rest berth  10  by overlaying at least a portion of the item with filament windings  28  during application of filament windings  28 . 
   Referring generally to  FIG. 11 , an exemplary connection is shown between end wall  84  and each of first and second walls  12 ,  14 . A first connecting joint  86  is created adjacent a distal end  87  of crew rest berth  10 . Similarly, a second connecting joint  88  is created adjacent distal end  87  of crew rest berth  10  of second wall  14 . In one embodiment, each of first and second connecting joints  86 ,  88  are formed by removing a pre-determined amount of total ply thickness “H”. A first connecting end  90  of end wall  84  and a second connecting end  92  of end wall  84  are overlapped with first and second connecting joints  86 ,  88 , respectively. An adhesive  94  is applied at each junction between end wall  84  and the connecting joints of crew rest berth  10 . End wall  84  is connected in a similar manner to each of first and second side walls  16 ,  18  of crew rest berth  10 . These joints are redundant and therefore not shown for simplicity. 
   Connecting joints  86 ,  88  are preferably created using an automated machining process to minimize labor time. Connecting joints  86 ,  88  can also be formed by hand removal of the material. Additional embodiments, not shown, include having first connecting end  90  of end wall  84  and second connecting end  92  of end wall  84  sized to either overlap or slide within unmodified ends of crew rest berth  10  and adhesively sealed. 
   Referring to  FIG. 12 , the operations for creating a mobile platform personnel berth include the operations of: supplying a male mandrel defining an inner mold line surface of a berth unit ( 100 ); applying at least one filament strip to the male mandrel to create at least one filament layer ( 102 ); thermally curing the at least one filament layer to create an integrated structural member ( 104 ); and removing the male mandrel from the structural member ( 106 ). 
   Referring to  FIG. 13 , according to another embodiment of the present invention, the operations for creating a mobile platform personnel berth include the operations of: creating a male mandrel defining an inner mold line surface of a berth unit ( 110 ); applying a first filament ply over the male mandrel ( 112 ); covering the first filament ply with a core ply ( 114 ); overlaying the core ply with at least a second filament layer ( 116 ); curing the filament layers to create an integrated structural member ( 118 ); and removing the male mandrel from the structural member ( 120 ). 
   Material for filament windings  28  is preferably predominantly a graphite (carbon) base material pre-impregnated with an adhesive portion. A phenolic adhesive is used in one preferred embodiment. A source for filament windings  28  in pre-impregnated form is Cytec Engineered Materials, Inc., of Tempe, Ariz. Use of graphite material provides high strength and reduced weight compared to common crew rest berths. At least one and preferably approximately three layers of filament windings  28  are used. Less than three or more than three layers can be used at the designer&#39;s discretion. The invention is not limited to the use of graphite material for filament windings  28  or to the number of filament winding or core ply layers. Other materials such as fiberglass and alternate polymeric materials or composite materials can be used. Phenolic material or phenolic material with one or more additives which meet flammability standards is one preferred material group for the adhesive used to bond the filament strips in applications such as aircraft interiors where flammability requirements are invoked. 
   A filament wound crew rest enclosure structure of the present invention provides several advantages. By integrally joining the walls, top and bottom surfaces of a crew rest enclosure, the number of connecting fittings is reduced. By using one or more filament wound layers of a graphite and/or graphite/polymeric material a weight of the crew rest enclosure can be reduced to about 75 pounds or less, which permits two mechanics to manually install the crew rest enclosure without the need for special handling equipment. By using an automated computer controlled tape laying machine, construction time is reduced compared to the known process of forming individual panels and manually joining the panels using a plurality of connectors and fasteners. 
   While various preferred embodiments have been described, those skilled in the art will recognize modifications or variations which might be made without departing from the inventive concept. The examples illustrate the invention and are not intended to limit it. Therefore, the description and claims should be interpreted liberally with only such limitation as is necessary in view of the pertinent prior art.