Abstract:
A towed vehicle deployment and retrieval system for attachment to an aircraft. The system includes a pylon support that is designed to mount to an aircraft and project outward therefrom. A stores pylon is mounted to the pylon support. The stores pylon has at least one swaybrace reciprocally attached to it for removably engaging with a towed vehicle. The system also includes a winch that is configured for mounting within the aircraft. The winch controls the feeding and retrieval of a winch cable that is attached to the towed vehicle. A tow cable is removably attached to the aircraft and is engaged with the winch cable using a tow pole such that the tow cable fully supports the towed vehicle when the towed vehicle is in the towing position. A method is also disclosed for attaching a winch cable and towed vehicle to a tow cable.

Description:
FIELD OF THE INVENTION 
     The present invention relates to airborne towed vehicles and, more particularly, to a helicopter mounted system for the deployment and retrieval of airborne towed vehicles. 
     BACKGROUND OF THE INVENTION 
     Mines and similar water submersed explosive devices can cause significant damage to naval vessels, not to mention harm and/or death to personnel on such vessels. One of the methods currently employed to detect and destroy submersed mines is by dragging a towed vehicle over the area of concern. The towed vehicle is submersed behind an aircraft and includes electrical circuitry for detecting and destroying submersed mines. Raytheon Corporation makes an AQ-S20 towed vehicle which is submersible and controlled via fiber optics embedded into a tow cable. Typically, the towed vehicle is hauled behind a helicopter during an Airborne Mine Countermeasures (AMCM) mission. The importance of the AMCM mission was highlighted during the Persian Gulf War when three US Navy warships struck World War I era mines, causing significant damage to the ships and nearly sinking one. 
     Currently, the AMCM towing mission is performed using a Sikorsky Aircraft Corporation S-65 series aircraft, particularly, the US Navy MH-53E and the Japan Naval Defense Force S-80M. These aircraft are very large and include an interior cabin with a retractable ramp. An airborne towed vehicle is retained within the cabin until deployment. The towed vehicle is stored in a cradle which can be moved fore and aft in the cabin. When it is desired to deploy the towed vehicle, the cradle is moved to the rear ramp. An A-frame assembly mounted to the aircraft above the ramp is used to lift the towed vehicle from the cradle. The cradle is then moved away and the ramp is lowered to a vertical position, clearing the area beneath the suspended towed vehicle. The towed vehicle is then lowered into the water using a cabin mounted winch. The cable that supports the towed vehicle includes a tow ball which is designed to engage with a hook formed on a tow boom mounted to the helicopter. This allows the tow boom and helicopter to support the towing loads and unload the winch. The operation is reversed to recover and stow the vehicle. 
     Due to the large size of the S-65 aircraft used in the AMCM mission, these aircraft are only compatible with large naval vessels, such as helicopter/aircraft carriers. To meet the diverse needs of the Navy, the United States military currently maintains forces that are dedicated to performing the AMCM mission. These forces are deployed to areas of concern on an as-needed basis. Accordingly. deployed naval forces must wait until the AMCM forces to arrive, detect and clear the area of mines. 
     A need therefore exists for a more versatile airborne towed vehicle deployment and retrieval system that can be used with smaller aircraft which are more readily available to the naval forces. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a towed vehicle deployment and retrieval system for attachment to an aircraft. The system includes a pylon support that is designed to mount to an aircraft and project outward therefrom. A stores pylon is mounted to the pylon support. The stores pylon has at least one swaybrace reciprocally attached to it for removably engaging with a towed vehicle. 
     The system also includes a winch that is configured for mounting within the aircraft. The winch controls the feeding and retrieval of a winch cable that is attached to the towed vehicle. 
     A tow cable is removably attached to the aircraft and is engaged with the winch cable using a tow pole such that the tow cable fully supports the towed vehicle when the towed vehicle is in the towing position. 
     The foregoing and other features and advantages of the present invention will become more apparent in light of the following detailed description of the preferred embodiments thereof as illustrated in the accompanying figures. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For the purpose of illustrating the invention, the drawings show a form of the invention which is presently preferred. However, it should be understood that this invention is not limited to the precise arrangements and instrumentalities shown in the drawings. 
     FIG. 1 is an isometric view of a portion of a Sikorsky Aircraft Corporation H-60 series helicopter with a pylon mounted towed vehicle. 
     FIGS. 2A and 2B are isometric views of a mechanism for engaging a towed vehicle to a stores pylon showing the mechanism with the towed vehicle engaged and disengaged. 
     FIG. 3 is a partial isometric view of the helicopter with the towed vehicle lowered on a winch cable and a tow pole attached to the winch cable. 
     FIG. 4 is an enlarged isometric view of the attachment of the tow pole to the winch cable. 
     FIG. 5 is an enlarged isometric view of the attachment of a tow cable to the aircraft. 
     FIGS. 6A through 6H illustrate the operation of the deployment and retrieval system according to the present invention. 
     FIG. 7 is an isometric view of a Sikorsky Aircraft Corporation H-60 series helicopter illustrating the tow cable in its towing position. 
     FIG. 8 is an isometric view of an alternate skid-mounted embodiment of the deployment and retrieval system according to the present invention. 
     FIG. 9 is an isometric embodiment of an Sikorsky Aircraft Corporation H-60 series helicopter with the skid-mounted embodiment of the invention in FIG.  8 . 
     FIG. 10 is an enlarged isometric view of an alternate embodiment of the cup on the tow pole. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following discussion includes a description of the invention as it is intended in connection with one or more preferred embodiments. It should be understood that the following description is not intended to limit the invention to those embodiments. On the contrary, it is intended that the invention cover all alternatives, modifications and equivalents as may be included within its spirit and scope as defined by the appended claims. 
     Certain terminology is used herein for convenience only and is not to be taken as a limitation on the invention. Particularly, words such as “upper,” “lower,” “left,” “right,” “horizontal,” “vertical,” “upward,” and “downward” merely describe the configuration shown in the figures. Indeed, the components may be oriented in any direction and the terminology, therefore, should be understood as encompassing such variations unless specified otherwise. 
     Referring now to the drawings, wherein like reference numerals illustrate corresponding or similar elements throughout the several views, the present invention is illustrated in a helicopter mounted embodiment as it is currently contemplated. FIG. 1 is an isometric view of a portion of a Sikorsky Aircraft Corporation H-60 helicopter aircraft  10 . In this embodiment, the helicopter  10  includes a pylon support  12  that is mounted to the aircraft through a fitting  14  and support struts  15 . The fitting and support struts are similar to those used to attach the External Stores Support System (ESSS) that is currently used on the H-60 series helicopters. A stores pylon  16  is attached to the pylon  12 . preferably at its distal end. The stores pylon  16  includes a pylon stowage system  18  on the bottom of the stores pylon  16 . 
     Referring now to FIGS. 2A and 2B, the salient features of the pylon stowage system  18  are shown in more detail. The stowage system  18  includes one or more swaybraces  20 . In the illustrated embodiment, there is a forward swaybrace and an aft swaybrace. The swaybraces  20  are shaped to conform to a portion of a stowed item, e.g., a towed vehicle  22 . In the illustrated embodiment, the swaybraces  20  include an arcuate surface that is configured to contact the towed vehicle  22 . The arcuate surface preferably includes a store rest pad  24  that is made from a resilient material, such as urethane. Each swaybrace  20  has at least one, and more preferably two, guide shafts  26  extending upward from the swaybrace  20  and which slide within fittings  28  on the stores pylon  16 . A compression spring  30  is located between the fitting  28  and a collar  32  on each shaft  26 . The compression springs  30  apply a downward preload on the stowed item when attached to the stores pylon  16 . 
     A proximity or limit switch  34  is mounted to the stores pylon  16  and is engaged when the stowed item  22  is winched into its completely stowed position (FIG.  2 B). When engaged, the proximity switch sends a signal to turn the winch off, preventing further upward retraction of the stowed item  22 . If the system includes a proximity switch on each swaybrace, then the winch is turned off only when both proximity switches are activated. 
     Referring back to FIG. 1, a roller bumper  36  is attached to the forward portion of the stores pylon  16  and includes one or more mounting brackets  38  that are attached to the stores pylon  16 . A roller  40  is rotatably supported by the brackets  38 . The roller  40  is preferably made from a soft resilient material, such as urethane. The roller  40  is designed to assist in guiding and positioning the stowed item during deployment and retrieval. 
     An articulated overhead pulley  42  is rotatably mounted to the stores pylon  16  and/or the pylon support  12 . The pulley  42  directs a winch cable  44  which is attached to the towed vehicle  22  in a conventional manner. The winch cable  44  is engaged with a conventional winch  46  (shown in FIG. 3) that is located within the helicopter cabin. The winch  46  is controlled to feed and retract the winch cable  44  causing the towed vehicle to be raised and lowered. It should be readily apparent that the winch  46  and the winch cable  44  must be capable of lifting the stowed item  22 . For example, a towed vehicle hanging from the aircraft can weigh upwards of 1500 pounds. Those skilled in the art would readily be capable of selecting the appropriate winch and cable for use in the present invention. One type of winch cable currently used for towing items includes fiber optic lines and electrical conductors for providing electrical and optical communication between the towed item and the aircraft. 
     As discussed above, during operation, the towed vehicle  22  is submersed within the water. This results in significantly higher loads being imposed on the winch cable  44 . If the winch  46  were to accommodate these high loads, it would have to be significantly larger and heavier. To minimize the size of the winch, the present invention transfers the towing loads from the winch to the aircraft. In order to do so, the winch cable  44  is attached to a tow cable  48  mounted on the aircraft. FIGS. 3 and 4 illustrate the engagement of the winch cable  44  with the tow cable  48 . A tow ball  50  is attached to the winch cable  44  in a conventional manner, e.g., by clamping onto the cable. Tow balls on winch cables are conventional in the art and are currently used in the winching assemblies on the H-65 series helicopters. The tow ball  50  has a curved or semi-hemispherical lower surface that is designed to seat within a capture receptacle or cup  52  mounted on a tow pole  54 . More particularly, the cup  52  is pivotally attached to two arms  55  of a yoke  56  formed on one end of the pole  54 . The cup  52  has a slotted opening  53  which allows the winch cable  44  to pass through the cup  52  until the tow ball  50  seats within the cup  52 . The tow pole  54  is of sufficient length to be held by a crewmember until the tow ball  50  seats in the cup  52 . 
     A tow ball retainer lock pin  58  is mounted to the cup  52  and is connected to a control cable  60  that extends along the pole  54 . The control cable  60  is attached to a return spring-loaded collar at the crewman&#39;s handle end (not shown) which allows the crewmember to lock and unlock the tow ball  50  within the cup  52 . 
     A cable cutter  62  is mounted to the cup  52  adjacent to the winch cable  44 . The cable cutter  62  is conventional in the art and is designed, upon actuation, to sever the winch cable  44 . A control wire  64  connects the cable cutter  62  to a control source, such as in the cockpit, so as to permit the pilot the capability of jettisoning the towed article in case of emergency. 
     An alternate embodiment of the cup  52  and yoke  56  is shown in FIG.  10 . In this embodiment, there are two cable cutters  62  to provide redundancy in the system in case of emergency. 
     The tow cable  48  is attached to the tow pole  54 . As such, when the tow ball  50  is seated and locked within the cap  52 , the winch cable  44  and towed vehicle  22  are attached to the tow cable  48  through the tow pole  54 . As will become more apparent below, the attachment of the tow cable  48  to the winch cable  44  is designed to allow the tow cable  48 , when taut, to carry most, if not all, of the towing loads, thus essentially unloading the winch  46 . 
     FIG. 5 shows the attachment of the tow cable  48  to the aircraft. The end of the tow cable  48  includes a cable tension in-line load cell  66  which is designed to sense tension loads on the tow cable  48 . A lug  68  is formed on the load cell  66  and is pivotally attached to a universal joint roller bearing swivel  70  that is mounted on a mounting frame  72 . The mounting frame  72  is removably attached to the aircraft in a suitable location, such as on the helicopter tailcone. 
     In order to control the cable cutter  62  and provide data from the towed vehicle (such as tow cable tension and tow line angle), an electrical interface  74  may be incorporated into the aircraft adjacent to the mounting frame. The control wire  64  for the cable cutter  62  and a control wire  67  from the load cell  66  attach to the electrical interface  74 . The electrical interface  74  is connected to suitable electronics in the aircraft interior. Although not shown, a sensor can be incorporated in a conventional manner to monitor the skew angle of the tow cable  48 . 
     The operation of the deployment and retrieval system will now be described with reference to FIGS. 6A through 6H. The figures illustrate the various positions of the winch cable  44  and tow cable  48  during operation. FIG. 6A illustrates the towed vehicle  22  lowered a short distance from the stores pylon  16 . At this point, the weight of the towed vehicle is being supported by the winch  46 . When the towed vehicle  22  is in the position shown in FIG. 6B, a crewmember extends the tow pole  54  out of the aircraft and places the cup  52  around the winch cable  44  below the tow ball  50 . As the winch  46  continues to lower the towed vehicle  22 , the tow ball  50  seats within the cup  52 . The locking pin  58  is actuated (either by the crewmember or by an automated mechanism) locking the tow ball  50  within the cup  52 . The crewmember releases the tow pole  54  as the winch continues to stream the winch cable  44  and towed vehicle  22  downward. 
     Since the towed cable  48  has a fixed length, it will become taut when it reaches its full extension as the winch  44  continues to lower the towed vehicle  22 . This is shown in FIG.  6 C. Starting at the point shown in FIG. 6C, the towed cable begins to carry a portion of the towed vehicle load. FIGS. 6E and 6F show the points where the load from the towed vehicle  22  is completely supported by the tow cable  48 . Further streaming of the winch  46  results in the winch cable  44  becoming slack and allowing the tow cable  48  to transition completely aft to its towing position. 
     FIG. 7 is an isometric view of a Sikorsky Aircraft Corporation H-60 series helicopter with the tow cable  48  in its towing position for towing the towed vehicle  22 . 
     Fiber optic and/or electrical cables are incorporated into or attached to the winch cable  44  in a conventional manner for transmitting signals between the towed vehicle  22  and the aircraft. 
     The present invention provides a novel deployment and retrieval system for use in small and medium size aircraft that do not include a ramp and large cabin, such as a Sikorsky Aircraft Corporation H-60 series helicopter. The system can be easily retrofitted onto existing fleet aircraft, thus greatly expanding the number and availability of aircraft capable of performing an AMCM mission. In order to retrofit an aircraft, the mounting plate  72  is simply attached to a suitable support point on the aircraft (i.e., a point capable of accommodating the anticipated tow load of 6000 pounds). The stores pylon  16  and pylon support  12  are attached to the aircraft and the winch  46  and cable  44  are mounted within the cabin. The towed vehicle  22  is then attached to the stores pylon  16  and the aircraft is ready to perform the AMCM mission. 
     An alternate embodiment of the deployment and retrieval system  100  is shown in FIGS. 8 and 9. In this embodiment, the pylon support and stores pylon are replaced with a skid mounted winching assembly  102 . FIG. 8 shows the skid mounted winching assembly  102  with a towed vehicle  22  attached to the pylon stowage system  104  (solid lines) and suspended from the pylon stowage system  104  (phantom lines). FIG. 9 shows the skid mounted winching assembly as it is intended to be mounted in the door of a Sikorsky Aircraft Corporation H-60 series helicopter aircraft. 
     The frame assembly  102  includes a skid  106  which is designed to be strapped to the floor of the aircraft, e.g., attached to tie-down points. A conventional winch  108  is mounted on the skid  106  and includes a winch cable  110 . A pylon frame or support  112  is attached to the skid  106 . A stores pylon  114  is attached to the pylon frame  112 . The pylon stowage system  104  is attached to the stores pylon  114 . The pylon stowage system  104  is the same as described above. A pulley is rotatably mounted to the pylon frame  112  and directs the winch cable  110  from the winch  108  to the towed vehicle  22 . The operation of the deployment and retrieval system in this embodiment of the invention is the same in the previous embodiment. 
     While the present invention has been described as using a manually engaged tow cable  48 , it is also contemplated that the tow cable can be automatically engaged to the tow ball  50  on the winch cable  44 . Those skilled in the art would readily be capable of modifying the mounting arrangement for providing such a mechanism. 
     Although the invention has been described and illustrated with respect to the exemplary embodiments thereof, it should be understood by those skilled in the art that the foregoing and various other changes, omissions and additions may be made therein and thereto without parting from the spirit and scope of the present invention.