Abstract:
The invention provides a cargo hook apparatus for securing cargo external to an aircraft for transportation, the apparatus comprising, pendent sling means, an attachment for securing the pendent sling means to the aircraft, and a cargo hook assembly, where the cargo hook assembly comprises a high-strength, lightweight alloy, and where the cargo hook assembly weighs less than about 55 pounds.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention relates to the field of systems for securing and transporting cargo external to an aircraft. 
         [0003]    2. Description of Related Art 
         [0004]    The cargo-carrying capability of aircraft is limited to cargo having overall external dimensions that are compatible with the dimensions of the aircraft cargo door(s), i.e., that can be loaded through the cargo door(s). Pragmatically, therefore, oversized cargo (external dimensions greater than the cargo door dimensions) or cargo having unusual external dimensions/configurations cannot be transported internally within the aircraft. 
         [0005]    Various aerial transport systems are known that utilize an external securement system for transportation of larger loads. Helicopters, in particular, are often adapted for use in the transportation of large or bulky goods externally to the craft, such as timber, vehicles, and particularly large cargo containers. Typical underslung load hooks are capable of carrying external loads of at least 10,000 pounds. 
         [0006]    One system for securing loads involves an underslung hook assembly, with a hook rigged to a pendent line, which is in turn attached to the aircraft external surface. U.S. Pat. No. 4,441,750, teaches a cargo sling system for suspension from an aircraft. The system includes a remotely actuable hook assembly and a guide that includes ring-like retainers through which sling lines pass after passage about the load. 
         [0007]    U.S. Pat. No. 6,167,928, discloses a method of logging a tree utilizing a logging tool with a body having a connection for a lifting device using a hook. A guide extends vertically downwards away from the body when the tool is connected only to the lifting device. There is a hook on the body to one side of the guide for engaging an object. When the hook engages an object and the body is lifted by the lifting device, the body rotates and the guide rotates about the hinge so that the guide continues to extend vertically. 
         [0008]    For safety concerns, the systems are typically provided with a system for releasing the load under controlled circumstances. U.S. Pat. No. 5,850,991, teaches a mechanical emergency dual-release mechanism for an external cargo hook system of an aircraft, where the hook assembly is operative to jettison an externally-attached cargo. The cabin pulley assembly is functionally interconnected to the cargo hook assembly and operative in response to a mechanical stimulus generated by means of the cockpit pulley assembly or the cabin pulley assembly to activate the cargo hook assembly to jettison the externally-attached cargo. 
         [0009]    These and other related hook assemblies typically include a release that is actuable from the aircraft, which can be electric, manual, or both. An external cargo hook system allows oversized cargo or cargo having unusual external dimensions/configurations to be readily transported by the aircraft. While an external cargo hook system does enhance the versatility of the aircraft, it also poses some considerations that impact the overall design of the aircraft. 
         [0010]    One disadvantage of the systems is that the components add both weight and drag to the aircraft. Drag is a particular problem for aircrafts that are capable of high speed flight, and the problem is magnified where the aircraft pendent guide lines and hooks are attached. Externally-attached cargo is typically suspended some distance below the aircraft such that the aircraft and its externally-attached cargo in effect define a pendent, or pendulum system, with the aircraft acting as the fixed support for the pendent. The weight and bulk of this system can reduce the speed and or add enough to the weight of the aircraft to decrease fuel efficiency. 
         [0011]    The added weight is particularly problematic for aircraft systems that are only occasionally employed in the transport of cargo, yet are required to carry a cargo assembly at all times. In this situation, the assembly can add considerable weight, even when stowed on board the aircraft, and decrease the fuel efficiency of the aircraft in normal operation. 
         [0012]    None of the prior approaches have been able to provide and external cargo system that addresses the requirements of aircraft systems that are capable both of flight at high speeds and still be rigged for carrying external loads. 
       SUMMARY OF THE INVENTION 
       [0013]    This invention provides a cargo hook apparatus for securing cargo external to an aircraft for transportation, the apparatus comprising, pendent sling means, an attachment for securing the pendent sling means to the aircraft, and a cargo hook assembly, where the cargo hook assembly comprises a high-strength, lightweight alloy, and where the cargo hook assembly weighs less than about 55 pounds. 
         [0014]    In a preferred embodiment of the apparatus of the invention, the disengage unit can support a load of at least about 22,000 pounds during transportation at aircraft speeds of at least about 100 knots. In a further preferred embodiment of the invention, the disengage unit can support a load of at least about 24,000 pounds. In a still further preferred embodiment of the invention, the disengage unit can support a load of at least about 26,000 pounds. 
         [0015]    In a different preferred embodiment of the invention, the disengage unit of the apparatus can support the load at aircraft speeds of at least about 150 knots. In further such preferred embodiment, the disengage unit can support the load at aircraft speeds of at least about 200 knots. 
         [0016]    In another preferred embodiment of the invention, the disengage unit weighs less than about 50 pounds. In a different aspect of this preferred embodiment, the disengage unit weighs less than about 45 pounds. 
         [0017]    In an additional preferred embodiment of the invention, the alloy is an aluminum alloy. In a still further preferred embodiment of this embodiment, the aluminum alloy is selected from the group of aluminum alloys consisting of as γ-titanium aluminides and aluminum-metal-matrix-composites. In another preferred embodiment, the alloy is high tensile strength steel alloy. In a still other preferred embodiment, the alloy is high tensile strength titanium-based alloy. 
         [0018]    In one aspect of the invention, the aircraft is a helicopter. 
         [0019]    In another aspect of the invention, the aircraft is an airplane. In a preferred such aspect, the airplane is a propeller powered aircraft. In a different preferred aspect, the airplane is a jet powered aircraft. 
         [0020]    These and other features and advantages of this invention are described in, or are apparent from, the following detailed description of various exemplary embodiments of the apparatus and methods according to this invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    A more complete understanding of the present invention and the attendant features and advantages thereof may be had by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein: 
           [0022]      FIG. 1  illustrates an external cargo hook system adapted for use in carrying an external load by an aircraft. 
           [0023]      FIG. 2  is a side plan view of an exemplary embodiment of a cargo hook assembly of an external cargo hook system. 
           [0024]      FIG. 3  is a perspective view of the cargo hook assembly of  FIG. 2 . 
           [0025]      FIG. 4  is a second perspective view of the cargo hook assembly of  FIG. 3 . 
           [0026]      FIG. 5  is a view of the main body of the hook assembly minus the load arm. 
           [0027]      FIG. 6  is a plan view of the first side plate used in production of the main body of the hook assembly. 
           [0028]      FIG. 7  is a front edge view of the first side plate in  FIG. 6 . 
           [0029]      FIG. 8  is a plan view of the central spacer used in production of the main body. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0030]    The products and methods of the present invention provide an external cargo sling assembly for an aircraft that achieves goals of combinations of strength required for commercial and military cargo transport systems, and is also lightweight enough to be used with various aircraft systems, including on high speed aircrafts used for emergency and military applications. 
         [0031]    Referring now to the  FIG. 1 , wherein like reference characters identify corresponding or similar elements throughout the several views,  FIG. 1  exemplarily illustrates an external cargo hook system  100  as integrated in combination with an aircraft, which could be a helicopter,  102 , for carrying a cargo load  104 . The external cargo hook system  100  comprises a swivel attachment  106 , a series of pendent guide lines  108 , and a cargo hook assembly  110 . 
         [0032]    The cargo hook assembly  110  is configured to allow cargo  104  to be attached externally to the aircraft for transport thereof, with release systems to facilitate the immediate jettison of externally-attached cargo  104  in the event of an emergency situation. 
         [0033]    The cargo hook assembly  110  can accommodate cargo  104  having a maximum weight of about 12,500 kilograms (26,000 pounds), and also accommodates a predetermined range of longitudinal and lateral motion of the externally-attached cargo  104  during flight operations. 
         [0034]    In further reference to  FIGS. 2 ,  3  and  4 , the emergency cargo-release subsystem  112  is a manually operated subsystem, e.g., a manually-actuated release, that includes a cockpit actuation mechanism. Various emergency cargo-release systems are known to the art, and are operative to allow the flight crew, i.e., pilot or co-pilot, to manually actuate the cargo hook assembly  110  to immediately disengage the externally-attached cargo  104 , i.e., jettison the externally-attached cargo  104 , in an emergency situation. 
         [0035]    The present invention is described with respect to external cargo hook systems  100  that are designed to allow the cargo hook assembly  110  to be stowed within the aircraft airframe when the external cargo hook system  100  is not being utilized. Stowage of the cargo hook assembly  110  when not in use allows the helicopter  102 , or other aircraft, to be operated with a cleaner aerodynamic profile, i.e., less profile drag, thereby enhancing the operating efficiency of the aircraft  102 , e.g., higher operating flight speeds, lower fuel consumption. 
         [0036]    Referring again to  FIGS. 2 ,  3  and  4 , the cargo hook assembly  110  comprises a main body  130  and a disengage unit  132 . The disengage unit  132  comprises a load arm  134 , and a keeper  136 . The disengage unit  132  is operative to facilitate the attachment of cargo  104  in combination with the cargo hook assembly  110  for subsequent transport of such cargo  104 . The keeper  136  mechanically interacts with the load arm  134  to preclude the attached cargo  104  from inadvertently disengaging from the cargo hook assembly  110  during transport of such cargo  104 . 
         [0037]    The disengage unit  132  is connected with the emergency cargo-release subsystem  112 , in an arrangement that controls the status of the keeper  136 ′in combination with the cargo hook assembly  110 . The disengage unit  132  is operative, in response to mechanical actuation (from the primary emergency cargo-release subsystem  112 ) to automatically disengage/jettison cargo  104 . 
         [0038]    The subsystem  112  generally comprises a pulley axle  140  and a cable connector  142 , with a pulley return spring (not shown) operative to return the pulley axle  140  to a releasing position. 
         [0039]    A cockpit control cable will secured through the cable router  144 , and routed to the helicopter  102 , so that the other end thereof terminates in an actuating device or mechanism, e.g., a release handle (not shown), in the cockpit. Manual actuation of the cockpit release handle by the pilot or copilot results in a physical displacement of the cockpit control cable that causes a corresponding rotation of the pulley axle  140 . Upon cessation of the manual actuation force by the pilot/co-pilot, the pulley axle  140  is operative to bias the subsystem back to the neutral position. 
         [0040]    In reference now to  FIG. 5 , and also  FIGS. 2 ,  3  and  4 , it is seen that the main body  130  is assembled from component parts, including first and second side plates  150  and  152 , and a central spacer  160 . 
         [0041]      FIG. 6  shows a plan view of the first side plate  150 . Second side plate  152  is a mirror image of first side plate  150 . Plate  150  includes a top hole  154  for securing to the swivel  106 . A middle hole  156  is fitted to the emergency cargo-release subsystem  112 . Finally, there is a large hole  158  that supports the load arm  134  in attachment to the hook assembly  110 . 
         [0042]      FIG. 7  is a front edge view of the first plate  150 , showing the reduction in weight produced by scaling down the width of material used in the central region, with thicker material applied over the load bearing sections. 
         [0043]      FIG. 8  is a view showing the central spacer  160 , which is affixed between the first and second side plates  150  and  152  in the production of the main body. As seen from the profile in  FIG. 8 , in addition to being produced of a lightweight material, the central spacer  160  utilizes a minimal amount of material. There is sufficient material left to engage the periphery of the side plates  150  and  152 , however, providing reinforcement to the load bearing regions to provide the strength and durability required for the expected loads of the assembly  110 . These regions mainly comprise the swivel assembly attachment at hole  154 , and the location for attachment of the load arm  134  at hole  158 . 
         [0044]    Thus, when the main body  130  is fully assembled, the interior has large regions of open space, reducing both the amount of material and overall weight of the assembly  110 . 
         [0045]    The cargo hook assembly  110  is produced of lightweight materials, particularly as to the hook assembly main body  130 , load arm  134  and keeper  136 . It is now observed that a cargo hook assembly  110  of sufficient strength to support a cargo  104  load of 26,000 pounds and more can be obtained in a hook assembly  110  of as little as 45 pounds total weight, or less. The components materials employed are high strength metal alloys, preferably having a relatively low density. The use of high strength materials such as γ-titanium aluminides as well as aluminum-metal-matrix-composites, and the like, are particularly appropriate materials for this purpose. 7075-T6 aluminum alloy is a preferred material for forming the main body side plates  150  and  152  and central spacer  160 . 
         [0046]    Other high strength aluminum alloys, titanium metal alloys and other metallic and non-metallic high strength materials, including the various reinforced and composite materials known to the art, may also be suitable. 
         [0047]    The result is cargo hook assembly  110  that reduces the weight required to be carried by an aircraft. 
         [0048]    While this invention has been described in conjunction with the specific embodiments outlined above, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, the preferred embodiments of the invention, as set forth above, are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of this invention.