Abstract:
A method and system for attaching a canopy to a vehicle, such as an aircraft, is provided. The system includes first and second sections. The first section attaches to the second section with a portion of the canopy being secured between the attached first and second sections. The canopy is molded to conform with the secured first and second sections. In one embodiment, the canopy is molded to include one or more fastener receiving holes with or without bushings. In another embodiment, the first or second sections include one or more channels for receiving an inflatable bladder. The first or second sections are configured to be received by the vehicle.

Description:
RELATED APPLICATIONS 
     This invention relations to copending U.S. patent application Ser. No. 10/366,949, filed Feb. 13, 2003, U.S. patent application Ser. No. 10/367,064, filed Feb. 13, 2003, U.S. patent application Ser. No. 10/367,404, filed Feb. 13, 2003, U.S. patent application Ser. No. 10/367,403, filed Feb. 13, 2003, U.S. patent application Ser. No. 10/367,062, filed Feb. 13, 2003, all of which are hereby incorporated by reference. 
    
    
     GOVERNMENT LICENSE RIGHTS 
     This invention was made with Government support under U.S. Government contract F33615-97-2-3407 awarded by U.S. Air Force. The Government has certain rights in this invention. 
    
    
     FIELD OF THE INVENTION 
     This invention relates generally to canopies and, more specifically, to attachment mechanisms for vehicle canopies. 
     BACKGROUND OF THE INVENTION 
     Modern aircraft canopies contain many parts. A transparent portion of the canopy may be replaced several times during the life of an aircraft due to scratches and general deterioration. Replacement of the transparent portion entails frame disassembly and reassembly. This is time-consuming, labor intensive, and costly. 
     Attempts have been made to produce frameless aircraft canopies in order to simplify replacement of the transparent portion, among other reasons. However, viable frameless canopy system must include a method for latching. As is known, the frame provides structural stiffness and strong, secure, attachment points for hinges and latches. Prior latching methods include a male hook or pin located on the aircraft structure or canopy frame and a female receiver on the canopy frame structure or aircraft structure respectively. Such discrete latching methods produce concentrated loads, which cause bearing stress in the transparency in the region of the latch. 
     Stress causes problems for transparencies. Glassy polymers craze at low stress levels. The effect of crazing on crack growth and localized failure is not well understood. Polymer transparencies yield at low stress levels and creep occurs after a fraction of service life. Cyclic, long-term loading, such as cockpit pressurization, induces creep and/or craze and reduces service life. Elevated temperatures, such as those experienced by high-speed aircraft, further increase the rate of creep and amplify the effect of crazing. 
     Therefore, there exists an unmet need to produce a latching system for an injection-molded canopy which avoids plastic creep and crazing due to concentrated loads yet securely holds the canopy in place. 
     SUMMARY OF THE INVENTION 
     The present invention is an attachment system for an injection-molded canopy. 
     The present invention provides a method and system for attaching a canopy to a vehicle, such as an aircraft. The system includes first and second sections. The first section attaches to the second section with a portion of the canopy being secured between the attached first and second sections. The canopy is molded to conform with the secured first and second sections. 
     In one aspect of the invention, the canopy is molded to include one or more fastener receiving holes with or without bushings. 
     In another aspect of the invention, the canopy is molded to include one or more channels for receiving an inflatable bladder. 
     In still another aspect of the invention, the first or second sections include one or more channels for receiving an inflatable bladder for pressure sealing. 
     In yet another aspect of the invention, at least one of the first or second sections are configured to be received by the vehicle. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The preferred and alternative embodiments of the present invention are described in detail below with reference to the following drawings. 
         FIG. 1  illustrates a perspective view of an aircraft implementing a canopy closure system formed in accordance with the present invention; 
         FIG. 2  illustrates a perspective view of a canopy attachment system formed in accordance with a first embodiment of the present invention; 
         FIG. 3  illustrates a cutaway view of a second embodiment of a canopy attachment system formed in accordance with the present invention; 
         FIG. 4  illustrates a perspective view of a third embodiment of a canopy attachment system formed in accordance with the present invention; and 
         FIGS. 5 and 6  illustrate cutaways views of two alternate embodiments of the canopy system shown in FIG.  4 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention is a method and system for attaching a canopy to a vehicle, such as an aircraft.  FIG. 1  illustrates a perspective view of an aircraft  20  that uses a framed canopy  22 , such as without limitation a polycarbonate or acrylic canopy, that surrounds a cockpit  24  of the aircraft  20 . The canopy  22  is suitably an injected-molded framed canopy that is molded for attaching a frame. The frame connects and disconnects to the aircraft  20  around a rim of the cockpit  24  for normal flight operations and normal ingress and egress by a pilot. 
       FIG. 2  illustrates a perspective view of a canopy frame system  44  having a canopy  40  that is molded to receive a frame system  44 . The canopy  40  is molded to include equally spaced-apart wedges  50  that are thickest at a predefined height above a bottom edge  52  of the canopy  40 . The wedges  50  taper to meet the outer surface of the canopy  40  at a predefined distance from the bottom edge  52 . 
     The bottom edge  52  of the canopy  40  includes one or more slots  60 . The slots  60  are separated by a predefined distance along the bottom edge  52 . The slots  60  extend some predefined distance into the canopy  40 . The distances are determined relative to the frame system  44 . 
     The canopy frame system  44  includes a first section  66  and a second section  68 . The first section  66  includes wedge-shaped cavities  70  that are shaped to receive the wedges  50  of the canopy  40 . The second section  68  includes an interior section  74  and an exterior section  76  that form a canopy receiving channel  80 . Perpendicular to a longitudinal axis of the channel  80  are one or more securing walls  82  spaced apart to be received by the slots  60 . 
     The canopy frame system  44  is formed by inserting the canopy  40  into the second section  68 . The channel  80  receives a portion of the canopy  40  below the wedges  50 . The receiving slots  60  receive corresponding securing walls  82 , thereby avoiding motion of the second section  68  relative to the canopy  40 . The first section  66  is then slid into position over the wedges  50  of the canopy  40 , thereby coming in contact with the second section  68 . The second section  68  is then fastened to the first section  66  using fasteners (not shown) installed through channel  80  into solid material in first section  66  between the wedge-shaped cavities  70 . The canopy  40 , the first section  66 , and the second section  68  are shaped such that when the first section  66  is properly mated and fastened to the second section  68  with the canopy  40  inserted therebetween, a smooth outer surface is present between the outer surfaces of the canopy  40 , the first section  66 , and the second section  68 . 
     The exterior section  76  includes a channel  88  that is open at a base edge  90  of the second section  68 . The opening of the channel  88  is 180° opposite the opening of the channel  80 . The channel  88  and the base edge  90  of the second section  68  are configured to be received by canopy securing mechanisms (not shown) that are included around an edge of an aircraft cockpit. Examples of canopy securing mechanisms are those used in conventional military aircraft, such as the F-16 and F/A-18. It can be appreciated that the canopy can be molded with other shapes that are secured within frame components. 
       FIG. 3  illustrates another embodiment of a framed canopy  100  attached to a canopy frame structure  102 . The frame structure  102  includes a first securing arm  110  and a second securing arm  108 . The first securing arm  110  has a closed angle L-shaped cross-section and includes a row of floating plate nuts  140  mounted to an upper surface of the arm  110 . The second securing arm  108  includes a squared, U-shaped cross-section with end walls  116  and  118 . The second securing arm  108  is attached to securing arm  110  with a row of bolts  145  that pass through an opening in both arms  108  and  110  and are received by the nuts  140 . 
     The canopy  100  includes a thickened base  120  around the periphery of the canopy  100 . The thickened base  120  includes a step  115  along the inboard surface for receiving a part of the second securing arm  108 . The outboard shape of the canopy  100  provides a locking surface  125  that receives the first securing arm  110 . A groove  130  along the bottom surface of the base of the canopy  100  provides clearance for plate nuts  140  and bolts  145  that attach the second locking arm  108  to the first locking arm  110 . A form-in-place seal (not shown) is used on the surfaces of the base  120  that bear-up with the second locking arm  108  to the first locking arm  110 . 
     The canopy frame structure  102  is secured to aircraft structure by a canopy locking mechanism (not shown). The canopy securing mechanism suitably includes multiple latches around the edge of the aircraft cockpit. 
       FIG. 4  illustrates a perspective view of a canopy frame system  198  formed in accordance with an alternate embodiment of the present invention. The canopy frame system  198  includes a canopy  200  that is injection molded to include fastener holes  202  at a predefined height above a base edge of the canopy  200 . The system  198  also includes a canopy frame section  208 , a head plate  210 , and a plurality of fasteners  212 . The fasteners  212  mount through the head plate  210  and the fastener holes  202  and are received by the frame section  208 . The canopy frame section  208  includes components for attaching the canopy frame section  208  in a conventional manner to a cockpit rail or sill. 
       FIG. 5  illustrates a cross-sectional view of an embodiment of the system  198  shown in FIG.  4 . The frame section  208  includes a slanted seat  218  that receives the base edge and a portion of an inside edge of the canopy  200 . The frame section  208  includes threaded receiving holes  220  within a vertical portion of the slanted seat  218 . The head plate  210  includes holes for receiving the fasteners  212 , such that heads of the fasteners  212  become flush with an outer surface of the head plate  210 . The fasteners  212  pass through the head plate  210 , the fastener holes  202 , and into respective threaded receiving holes  220 . The fasteners  212  securely mate the head plate  210  and frame section  208  to the canopy  200 . 
       FIG. 6  illustrates a cross-sectional view of another embodiment of the system  198  shown in FIG.  4 . As shown in  FIG. 6 , the injected molded holes  202  include bushings  230  that protect the canopy  200  from the fasteners  212 . The bushings  230  are made of a material, such as a polymer or a metallic, for protecting the canopy  200  from the fasteners  212 . The bushings  230  are either included in the injection mold that forms the canopy  200  or the bushings  230  are inserted into the holes  202  after the canopy  200  has completed the molding process. Soft polymer bushings can aid in compensating for differentials in thermal expansion in the dissimilar-material assembly. 
     While the preferred embodiment of the invention has been illustrated and described, as noted above, many changes can be made without departing from the spirit and scope of the invention. Accordingly, the scope of the invention is not limited by the disclosure of the preferred embodiment. Instead, the invention should be determined entirely by reference to the claims that follow.