Abstract:
An aerial refueling system for refueling a receiver aircraft in flight comprises a hose reel assembly mounted onto a fuel supply aircraft&#39;s fuselage. The hose reel assembly has a rotatable drum defined by an outside diameter. A hose is wound around the drum and has an outlet end with a drogue affixed thereto. A telescoping stowage tube stores the outlet end of the hose and the drogue when the system is not in use and guides the outlet end and the drogue toward the receiver aircraft when the system is in use. The telescoping stowage tube has a forward end configured to be mounted on the hose reel assembly to receive the hose from the drum and an aft end adapted to be mounted to the door. As a result, the telescoping stowage tube may be extendable between a retracted stowed position and an extended position for refueling.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a fuselage mounted aerial refueling system; and more particularly to a fuselage mounted aerial refueling system wherein the hose reel is secured to the fuselage while a stowage tube is secured to a movable door or ramp; and even more particularly to a fuselage mounted aerial refueling system wherein the hose reel is secured to the fuselage while a stowage tube is secured to a movable door or ramp, the stowage tube being configured to telescope between extended and retracted positions depending upon whether the movable door or ramp is in an open or closed orientation. 
       BACKGROUND OF THE INVENTION 
       [0002]    Fuselage mounted refueling systems contain several common components regardless of the particular installation, including: a hose reel assembly to store and dispense a refueling hose, a stowage tube or other piece of equipment which holds the hose-end components when the system is not in use and guide the hose between the hose reel drum and the exit point through the aircraft skin or outer mold line (OML). Also included is a tunnel or other fixed location exit point where the hose passes through the OML and into the airstream. 
         [0003]    Currently deployed systems generally fall into one of two categories depending on whether the equipment is mounted in the fuselage or on a movable door or ramp. In the former instance, existing systems include a hose reel assembly in a fixed orientation and location inside the fuselage and a single fixed exit point is provided through the aircraft OML. In the latter arrangement, the hose reel and other components are mounted on a cargo door or ramp, moving together from the stowed position with the door or ramp closed into the refueling position when the door or ramp is lowered (opened). 
         [0004]    The ramp/door arrangement is peculiar to roll-on/roll-off type systems which are temporarily installed in multi-role aircraft. On any system incorporating a hose and some sort of drum to wind it on and off, performance and reliability require that the hose remain tangential to the drum outside diameter during winding on/off. On the ramp type systems described above, the hose drum equipment and the stowage tube/hose exit components are all mounted to the ramp to maintain the tangency described regardless of the ramp position or movement. 
         [0005]    A serious limitation inherent in such systems to date, however, is the capacity of the ramp to support the size and weight of the entire refueling system in flight and in use. Further performance limitations result from the lack of structural rigidity inherent in a moving door or ramp, such as increased vibration and high loads created by hose tension being applied to the ramp or door rather than solid aircraft structure like the cargo bay floor. 
       SUMMARY OF THE INVENTION 
       [0006]    In one aspect of the present invention, a removable refueling system may be installed and anchored securely to the non-moving aircraft structure (fuselage) while having the exit point through the aircraft OML move up and down with door/ramp movement, all the while maintaining the tangency of the hose guide/stowage tube to the drum. The ability to mount the hose reel assembly and associated equipment to the floor or other fixed structure increases the allowable system weight, minimizes the effect and interaction of other equipment such as the ramp, and enhances system performance by minimizing vibration and other detrimental effects. To that end, a telescoping mechanism has been added to the stowage tube to address the issues resulting from the OML exit point moving as the door/ramp moves and the distance between the OML and the drum changes. 
         [0007]    In a further aspect of the present invention, a refueling system may allow the hose drum unit to rotate about the drum&#39;s central axis to thereby maintain tangency between the stowage tube and the drum O.D. during winding on/off of the hose. Several means could be employed to provide and control such rotation, such as but not limited to “slaving” the reel mounting hardware to the ramp door via a linkage to thereby insure that the drum will always be oriented for optimum performance as the door opens and closes. 
         [0008]    Accordingly, the present invention is generally directed to an aerial refueling system for refueling a receiver aircraft in flight from a fuel supply aircraft having a door movable between an open orientation and a closed orientation. The system comprises a hose reel assembly mounted onto the fuel supply aircraft&#39;s fuselage with the hose reel assembly having a rotatable drum defined by an outside diameter. A hose is wound around the drum and has an outlet end and a drogue affixed to the outlet end. A telescoping stowage tube may be configured to store the outlet end of the hose and the drogue when the system is not in use and to guide the outlet end and the drogue toward the receiver aircraft when the system is in use. The telescoping stowage tube may have a forward end configured to be mounted on the hose reel assembly to receive the hose from the drum and an aft end adapted to be mounted to the door. As a result, the telescoping stowage tube may be extendable between a retracted stowed position when the door is in the closed orientation and an extended position when the door is in the open orientation. 
         [0009]    Additionally, the telescoping stowage tube may include an outer housing slidably coupled to an inner housing and the hose within the telescoping stowage tube may lie along a plane tangential to the outside diameter of the drum. The hose reel assembly may also include a hose reel frame with the forward end of the telescoping stowage tube secured to the hose reel frame. Thus, the hose reel frame may pivot so as to maintain the tangential plane of the hose within the telescoping stowage tube relative to the outside diameter of the drum as the door moves between the open orientation and the closed orientation. The telescoping stowage tube may further translate along the hose reel frame in a plane parallel to the axis of rotation of the drum as the hose is wound off or wound onto the drum. To that end, the hose reel frame may include a lead screw and a serving gear nut may couple the forward end of the telescoping stowage tube to the lead screw. The serving gear nut may be configured to translate along the lead screw. 
         [0010]    Still further, the aerial refueling system may further include a stowage tube mount fixedly secured to the door at a first end and pivotally secured to the aft end of the telescoping stowage tube at a second end. The stowage tube mount may further include a swivel with the swivel configured to move the aft end of the telescoping stowage tube as the telescoping stowage tube translates along the hose reel frame. The drogue may remain within the telescoping stowage tube until the drum is rotated to unwind the hose whereby the hose further includes a spring configured to bias the drogue out of the aft end of the telescoping stowage tube as the drum is rotated to unwind the hose. 
         [0011]    Additional objects, advantages and novel aspects of the present invention will be set forth in part in the description which follows, and will in part become apparent to those in the practice of the invention, when considered with the attached figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The above-mentioned and other features are advantages of this invention, and the manner of attaining them, will become apparent and be better understood by reference to the following description of the invention in conjunction with the accompanying drawings, wherein: 
           [0013]      FIG. 1  is a partial schematic view of a refueling system in accordance with the present invention showing the refueling system in a stowed configuration; 
           [0014]      FIG. 2  is a partial schematic view of the refueling system shown in  FIG. 1  showing the refueling system in a trailing configuration; 
           [0015]      FIG. 3  is a cross section view of the refueling system shown in  FIG. 2  with the drogue partially ejected from the telescoping stowage tube; and 
           [0016]      FIG. 4  is an expanded partial view of a hose reel assembly using within the refueling system shown in  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    The following describes a specific application of a general aerial refueling system of the present invention on the V- 22  Osprey cargo aircraft (the “V- 22 ”) wherein the refueling system is mounted to the cargo hold and lower cargo bay door, thereby converting the V- 22  to a part-time tanker for refueling other aircraft. While shown and described with reference to the V- 22 , it should be understood by those skilled in the art that the telescoping stowage tube and rotating hose reel assembly of the present invention may be used on other platforms, such as weapon bay doors or other aircraft (commercial or military) having cargo bay doors where the system requires the stowage tube to be fixed to a rotating door and the hose reel assembly to be fixed to a permanent structural member of the aircraft. 
         [0018]    As will be discussed in greater detail below, the telescoping stowage tube is required to safely eject the refueling assembly (i.e., drogue and refueling hose) into the airstream, with the maximum amount of clearance between the refueling assembly and aircraft structure. Because the hose reel assembly is mounted to a permanent structural member (e.g., the fuselage) and the telescoping stowage tube is mounted to the cargo bay door, the stowage tube angle changes as the cargo door opens and closes. This stowage tube angle change requires the stowage tube to extend while the door is down (open) for trail (unwind) and rewind hose reel operations so as to maintain a tangential relationship between the hose within the telescoping stowage tube and the hose reel drum. To that end, the stowage tube angle should match the natural catenary angle of the refueling hose so that all hose tension changes are transferred through the hose reel assembly, such as through the torque arm and boost cylinder of the hose reel assembly. 
         [0019]    In the case of the V- 22 , the aircraft has a safety requirement that both the upper and lower cargo bay doors must be closed if the personnel in the cabin are required to ditch the aircraft (i.e., attempt to perform a controlled landing of the disabled or distressed aircraft). This safety requirement drives an additional mechanism to allow for further telescoping of the stowage tube assembly. That is, when the lower cargo door is in the up (closed) orientation, the aft end of the stowage tube must be forward of the cargo bay door so that the upper cargo bay door can fully close prior to ditching. However, when the lower cargo bay door is in the down (open) orientation, such as in preparation for and during refueling operations, the aft end of the stowage tube must be aft of the lower cargo bay door to ensure no contact is made with the door or other aircraft component during the trailing (unwinding) or the rewinding of the refueling hose. As will be described in more detail below, this actuation may be performed by, and without limitation solely thereto, a linear actuator, springs, cables and/or linkages slaved to the lower cargo bay door. 
         [0020]    Turning now to the figures, and with specific reference to  FIGS. 1-3 , an aerial refueling system in accordance with the present invention is indicated by reference numeral  10 . Aerial refueling system  10  is generally comprised of a hose reel assembly  12  mounted to a structural component of the fuel supply aircraft  13 , such as fuselage  14 . Hose reel assembly  12  includes a rotatable drum  16  defined by an outside diameter  18 . Hose  20  is wound around drum  16  as is known in the art (see also  FIG. 4 ). As can be seen most clearly in  FIG. 3 , aft end  22  of hose  20  is configured to carry a drogue refueling assembly  24  with inflatable drogue  26 . Prior to ejection of drogue refueling assembly  24  during refueling operations or when aerial refueling system  10  is in a stowed condition (such as shown in  FIG. 1 ), a portion of hose  20 , including aft end  22  and drogue refueling assembly  24 , is stored within telescoping stowage tube  28 . Telescoping stowage tube  28  includes a forward end  30  configured to be mounted onto hose reel assembly  12  to receive hose  20  from drum  16  and an aft end  32  adapted to be mounted to a door/ramp of aircraft  13 , such as cargo bay door  34 . To that end, aft end  32  may be pivotally mounted to stowage tube mount  36  at pivot  38 . In this manner, aft end  32  (and thus telescoping stowage tube  28 ) may pivot as cargo bay door  34  reciprocates between the closed orientation ( FIG. 1 ) and the open orientation ( FIGS. 2-3 ). 
         [0021]    In one aspect of the invention, telescoping stowage tube  28  comprises an outer housing  40  slidably coupled to inner housing  42 . In this manner, the length of telescoping stowage tube  28  may change, as will be discussed in greater detail below. It should be noted that, while being shown and described as overlapping concentric housings in sliding arrangement, telescoping stowage tube may be constructed in any suitable form. However, the sliding engagement of outer housing  40  with inner housing  42  is sufficiently rigid to accommodate lateral stresses exerted upon telescoping stowage tube  28  during use. 
         [0022]    When deploying aerial refueling system  10  for inflight refueling operations, cargo bay door  34  moves from the closed orientation ( FIG. 1 ) to an open orientation ( FIGS. 2-3 ). As cargo bay door  34  pivots about hinge  44  (generally in the direction indicated by arrow  46 ), telescoping stowage tube  28  extends generally in the direction indicated by arrow  48  from a retracted stowed position ( FIG. 1 ) to an extended position ( FIGS. 2-3 ) as described above. With telescoping stowage tube  28  in its fully extended position, hose  20  may be unwound from drum  16  to direct refueling assembly  24  and drogue  26  in the trail position (i.e., extending outwardly from fuel supply aircraft  13  so as to safely couple with the receiver aircraft (not shown)) as is known in the art. 
         [0023]    With reference to  FIG. 3 , to eject refueling assembly  24  and drogue  26  through telescoping stowage tube  28 , hose  20  may include a spring  50  which is fully compressed in the stowed position to bias refueling assembly  24  and drogue  26  out exit orifice  52  defined by terminus of aft end  32  of telescoping stowage tube  28 . When in the stowed position ( FIG. 1 ), spring bias of spring  50  is maintained due to hose  20  being wound about drum  16 . However, when hose  20  is commanded to the trail position after cargo bay door  34  has been opened and telescoping stowage tube  28  has been extended ( FIGS. 2-3 ), drum  16  will rotate in the trail direction at a fixed speed to eject hose  20  through telescoping stowage tube  28 . The bias stored within spring  50  will operate to push refueling assembly  24  and drogue  26  towards exit orifice  52 . Once refueling assembly  24  reaches the airstream, drogue  26  will inflate and create drag on hose  20  while drogue  26  and hose  20  extend outwardly from fuel supply aircraft  13  toward the full trail position. 
         [0024]    Because hose reel assembly  12  is mounted to fuselage  14  and aft end  32  of telescoping stowage tube  28  is mounted to cargo bay  34 , the stowage tube angle changes as cargo bay door  34  opens and closes (compare angle A in  FIG. 1  with angle A′ in  FIG. 2 ). To accommodate stowage tube angle changes, hose reel assembly  12  may be configured to rotate as cargo bay door  34  pivots about hinge  44  so as to keep the relative angle B between telescoping stowage tube  28  and hose reel assembly  12  substantially the same throughout movement of cargo bay door  34  and hose reel assembly  12 . To that end, hose reel assembly  12  may include a hose reel frame  54  pivotally mounted onto mounting frame  56  of hose reel assembly  12 . Pivoting control of hose reel frame  54  may be slaved to pivoting control of cargo bay door  34  such that angle B is maintained as cargo bay door  34  opens and telescoping stowage tube  28  extends from its retracted stowed position to the extended position as described above. In this manner, hose  20  may remain in a plane P that is tangential to outside diameter  18  of drum  16 . By maintaining hose  20  in a tangential plane relative to outside diameter  18 , hose wear properties may be improved and hose tension changes may be transferred through the structural components of hose reel assembly  12 , such as though torque arm  58  and boost cylinder  60  (see  FIG. 4 ). In one aspect of the present invention, drum  16  of hose reel assembly  12  will rotate around the fuel inlet (not shown) so that hard lines can be used to couple aerial refueling system  10  with a fuel storage tank (not shown) without any fuel leaks. 
         [0025]    With reference to  FIG. 4 , hose reel frame  54  may include a lead screw  62  and serving gear nut  64  whereby forward end  30  of telescoping stowage tube  28  may be mounted to serving gear nut  64 . Serving gear  64  is configured to translate along lead screw  62  as lead screw  62  is rotated. Lead screw  62  may be slaved to drum  16  rotator control such that gear nut  64  and forward end  30  of telescoping stowage tube  28  translate orthogonally to the winding/unwinding hose  20  from drum  16 . Orthogonal translation of telescoping stowage tube  28  permits proper unwinding/rewinding of hose  20  onto drum  16 . To prevent or minimize lateral stresses to telescoping stowage tube  28  during orthogonal translation of forward end  30 , stowage tube mount  36  may include a swivel  66  configured to permit movement of aft end  32  as forward end  30  translates. 
         [0026]    Although the invention has been described with reference to preferred embodiments thereof, it is understood that various modifications may be made thereto without departing from the full spirit and scope of the invention as defined by the claims which follow. While specific reference has been made to rotational movements of device components, it should be understood by those skilled in the art that such rotations may be reversed and that such teachings are within the scope of the present invention.