Abstract:
A method and apparatus for transferring fuel onto or off of an aircraft. A refueling transfer duct is deployed from an aft station of the aircraft being serviced while the aircraft is flying, wherein the transfer apparatus comprises a hose with a controllable drogue attached to its free end. The refueling duct is positioned through control signals sent by a tanker aircraft to the controllable drogue to form a favorably positioned refueling duct capable of a finite final docking maneuver. The positioned refueling duct is connected to the tanker aircraft positioned behind the aircraft to form a connection. The fuel is transferred through the connection to a fuel tank or fuel storage system located within the aircraft.

Description:
BACKGROUND INFORMATION 
     1. Field 
     The present disclosure relates generally to aircraft and in particular to refueling aircraft. Still more particularly, the present disclosure relates to a method and apparatus for moving fuel between two aircraft during flight. 
     2. Background 
     Air refueling is a process of transferring fuel from one aircraft to another aircraft during flight. A tanker aircraft is the aircraft that typically provides fuel to another aircraft. The aircraft receiving fuel is referred to as a refueling aircraft. This process allows the aircraft receiving fuel to remain in flight for longer periods of time. As a result, an aircraft may extend its range through this type of process. A series of air refuelings may provide a range that is limited only by crew fatigue and maintenance factors, such as engine oil consumption. 
     Further, when an aircraft can receive extra fuel in the air, the aircraft can takeoff with a greater payload, such as weapons, cargo, or personnel. In this manner, the maximum takeoff weight may be maintained by balancing the larger payload with less fuel. 
     A tanker aircraft is especially designed for transferring fuel to an aircraft during flight. Various mechanisms may be used to provide the refueling. These mechanisms include, for example, a boom and receptacle system, and a probe and drogue system. With a boom and probe system, a long rigid hollow shaft may be attached to the rear of the tanker aircraft. This attachment is flexible allowing the boom to move with respect to the tanker aircraft. At the end of this tube is a nozzle attached on the flexible ball joint. The nozzle mates to a receptacle that is mounted on the aircraft that is to receive the fuel. 
     The refueling aircraft flies in formation directly below and behind the boom. When cleared, the aircraft moves forward into a contact position. This positioning may be aided either with voice commands or visual commands from a crew member operating the boom. Once the aircraft receiving the fuel reaches the contact position, the pilot attempts to hold the refueling aircraft in place with little relative motion with respect to the tanker aircraft. When refueling is complete, the pilot of the refueling aircraft may then disengage the receptacle from the boom. 
     Another system used in refueling is a probe and drogue system. This type of system involves the use of a drogue attached to a flexible hose that extends from the tanker aircraft or boom attached to the tanker aircraft. A drogue is a funnel shaped or cone shaped refueling duct that is towed behind an aircraft. The drogue may function as a target for the probe to create a connection between the tanker aircraft and the aircraft receiving fuel. Further, the drogue itself may include a connector to facilitate the connection between the tanker aircraft and the refueling aircraft. 
     With a probe and drogue system, the tanker aircraft flies at a straight and level route. The drogue attached to the hose trails behind and below the tanker aircraft. The pilot of the refueling aircraft has a probe attached to the refueling aircraft and flies the aircraft to place the probe directly into the drogue. 
     This type of system typically requires a closure rate of at least two knots to provide a soft contact to lock valves in the probe and drogue together for refueling. If the speed is too high, damage may occur to the probe or drogue. 
     If an approach by a pilot of a receiving aircraft to the drogue of a tanker aircraft does not occur at a desired angle and speed, damage to one or more components, such as a probe or valves in the drogue, may occur. Further, if the valves are not properly locked in the drogue and the probe, fuel may spill out. 
     These types of refueling processes are commonly used for refueling military aircraft. No such fueling has been performed on any regular basis for commercial aircraft. This type of refueling requires training of the pilots flying the aircraft to receive the fuel. As can be seen, from these two currently used systems, pilots flying aircraft receiving the fuel perform a number of different steps for the refueling process, are skilled in flying the aircraft in a manner to engage the drogue or boom, and to maintain a tightly controlled position during the refueling process. 
     SUMMARY 
     The advantageous embodiments provide a method and apparatus for refueling an aircraft. In one advantageous embodiment, a refueling duct is deployed from an aft position of the aircraft while the aircraft is flying, wherein the refueling duct comprises a hose and a controllable drogue. The refueling duct is positioned through control signals sent by a tanker aircraft to the controllable drogue to form a positioned refueling duct. The positioned refueling duct is connected to the tanker aircraft positioned behind and above the aircraft to form a connection. The fuel is transferred through the connection to a fuel storage system located within the aircraft. 
     In another advantageous embodiment, a method is provided for refueling an aircraft. A tanker aircraft is positioned behind the aircraft while the aircraft is in flight, wherein the aircraft has a refueling duct deployed from an aft position. The refueling duct is connected to the tanker aircraft positioned behind the aircraft to form a connection and fuel is transferred through the connection. 
     In yet another advantageous embodiment, an apparatus comprises an aircraft and refueling duct located at an aft position of the aircraft and capable of being deployed behind the aircraft and capable of receiving fuel while the aircraft is in flight. 
     The features, functions, and advantages can be achieved independently in various embodiments of the present disclosure or may be combined in yet other embodiments in which further details can be seen with reference to the following description and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The novel features believed characteristic of the advantageous embodiments are set forth in the appended claims. The advantageous embodiments, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an advantageous embodiment of the present disclosure when read in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is a diagram illustrating two aircraft used in a refueling process in accordance with an advantageous embodiment; 
         FIG. 2  is a top view of an aircraft and a tanker aircraft in accordance with an advantageous embodiment; 
         FIG. 3  is a diagram illustrating a side view of an aircraft and a tanker aircraft in accordance with an advantageous embodiment; 
         FIG. 4  is a block diagram illustrating components used for refueling an aircraft in accordance with an advantageous embodiment; 
         FIG. 5  is a block diagram of a controllable drogue in accordance with an advantageous embodiment; 
         FIG. 6  is a diagram of a controllable drogue in accordance with an advantageous embodiment; 
         FIG. 7  is a flowchart of a process for refueling an aircraft in accordance with an advantageous embodiment; and 
         FIG. 8  is a flowchart of a process for refueling operations in accordance with an advantageous embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     With reference now to the figures and in particular with reference to  FIG. 1 , a diagram illustrating two aircraft used in a refueling process is depicted in accordance with an advantageous embodiment. In this example, aircraft  100  is a refueling aircraft that is to receive fuel. Tanker aircraft  102  is a source of fuel for aircraft  100 . 
     In this example, aircraft  100  has refueling duct  104 , which trails from aft position  106  of aircraft  100 . Refueling duct  104  takes the form of hose  108  and drogue  110 . Tanker aircraft  102  includes probe  112 . This probe also may be referred to as a stinger and is capable of coupling with drogue  110 . In this example, tanker aircraft  102  is located behind aircraft  100  for the refueling process. Tanker aircraft  102  is located above aircraft  100  as well as being behind aircraft  100 . By being located above aircraft  100 , pumping or transferring fuel from tanker aircraft  102  to aircraft  100  is achieved using less horsepower in the pumping equipment due to utilizing gravity assistance in the transfer of fuel with this type of positioning. 
     The different advantageous embodiments recognize that extensive training and practice is needed to successfully perform refueling of aircraft during flight. In particular, the different advantageous embodiments recognize that the pilot of the aircraft engaging refueling duct  104  requires more training and skill than the pilot of the aircraft from which refueling duct  104  is located. Currently used refueling configurations require the pilot of the aircraft receiving fuel to position the aircraft and engage refueling duct  104 . 
     Further, the different advantageous embodiments recognize that although it would be advantageous to refuel commercial aircraft during flight, the training and process is also made more difficult because commercial aircraft are harder to maneuver than many military aircraft. In this manner, commercial aircraft may have increased ranges without requiring landing and taking off. By avoiding additional landing and takeoffs of an aircraft, fuel usage also may be conserved. 
     Thus, the different advantageous embodiments position tanker aircraft  102  with respect to aircraft  100 , rather than using the common practice of having the refueling aircraft position itself with a tanker aircraft. In this manner, the number of pilots that need to be trained to perform aerial refueling is reduced. 
     With the different advantageous embodiments, only pilots of tanker aircraft  102  need to have the skills and training to perform aerial refueling. The more numerous numbers of pilots for aircraft  100  do not require any extensive training. Instead, the pilots and/or crew of aircraft  100  may only need to deploy and retrieve refueling duct  104 . In some cases and in consideration of various design configurations, the deployment and retrieval of refueling duct  104  may be initiated by tanker aircraft  102 . 
     With reference next to  FIG. 2 , a top view of an aircraft and a tanker aircraft is depicted in accordance with an advantageous embodiment. In this example, a top view of aircraft  100  and tanker aircraft  102  from  FIG. 1  is depicted. As can be seen, tanker aircraft  102  is directly behind aircraft  100 . 
     Tanker aircraft  102  is substantially along axis  200 . Axis  200  is substantially central with respect to aircraft  100 , in this example. Of course, in other advantageous embodiments, tanker aircraft  102  may be located off axis  200  or even substantially off axis  200  from aircraft  100 . This type of positioning may occur through moving or positioning drogue  110  off axis  200 . Of course, in other advantageous embodiments, refueling duct  104  may be located in another position. For example, refueling duct  104  may be located on aft side  202  of wing  204  of aircraft  100 . 
     Turning now to  FIG. 3 , a diagram illustrating a side view of an aircraft and a tanker aircraft is depicted in accordance with an advantageous embodiment. In this example, tanker aircraft  102  is located below aircraft  100 . This type of positioning may be used for a reverse transfer of fuel from aircraft  100  to tanker aircraft  102 . 
     This type of reverse transfer of fuel may be performed if aircraft  100  has too much fuel, resulting in having more weight than desired. Typically, aircraft  100  would dump or release the extra fuel. By returning the extra fuel to tanker aircraft  102 , the cost of fuel lost from dumping fuel is avoided. Additionally, environmental issues are avoided by use of this recovery method. Of course, refueling of aircraft  100  also may be performed from this positioning or from that of positioning on aft side  202 , depending on the type of fuel transfer system present in tanker aircraft  102  and aircraft  100 . 
     Turning now to  FIG. 4 , a block diagram illustrating components used for refueling an aircraft is depicted in accordance with an advantageous embodiment. In this example, aircraft  400  is an example of aircraft  100  in  FIG. 1 . Aircraft  400  includes fuel storage system  402 , hose drum unit  404 , and refueling duct  406 . 
     Fuel storage system  402  contains a set of compartments that may be used to hold fuel  424  used by aircraft  400 . A fuel storage system is any apparatus that may be used to store or hold fuel. Fuel storage system  402  may be, for example, one or more fuel tanks having a set of compartments and/or cavities or voids within aircraft  400  designed to receive and hold fuel. In these examples, fuel storage system  402  may be filled during flight through the use of refueling duct  406 . 
     In these examples, refueling duct  406  is comprised of hose  408  and controllable drogue  410 . In other embodiments, refueling duct  406  may take other forms. For example, refueling duct  406  may be a boom that is controllable or non-controllable by aircraft  400 . In other advantageous embodiments, refueling duct  406  may comprise a boom with controllable drogue  410  being attached to one end of the boom. Further, in other advantageous embodiments, controllable drogue  410  may be a non-controllable drogue. 
     Hose drum unit  404  is a unit that may deploy and retrieve refueling duct  406 . Further, hose drum unit  404  also may provide a storage compartment for refueling duct  406 . Hose drum unit  404  may deploy hose  408  with controllable drogue  410  for refueling. Refueling duct  406  may be deployed in aft location with respect to aircraft  400 . This aft location may, for example, be at the tail of aircraft  400 , or at the trailing edge of a wing, such as wing  204  in  FIG. 2 , of aircraft  400 . After refueling has completed, hose drum unit  404  may then reel in hose  408  and controllable drogue  410  after the refueling process has completed. 
     Controllable drogue  410  may reduce the challenges associated with refueling aircraft during flight. Controllable drogue  410  is capable of being controlled to change its position with respect to aircraft  400 . The change of the position of controllable drogue  410  may be effected by changing surfaces on controllable drogue  410 . The change in the surface may change the aerodynamics of controllable drogue  410 , resulting in a change of position of controllable drogue  410  with respect to aircraft  400 . Controllable drogue  410  may be implemented using any known controllable drogue systems. 
     Tanker aircraft  412  is an example of tanker aircraft  102  in  FIG. 1 . In this example, tanker aircraft  412  includes storage system tank  414 , probe  416 , control unit  418 , and transceiver  420 . Control unit  418  may be operated by an operator in tanker aircraft  412  to control controllable drogue  410 . 
     The signals for controlling controllable drogue  410  may be transmitted to controllable drogue  410  through transceiver  420 . Further, transceiver  420  also may receive signals from controllable drogue  410  that verify the execution of commands or verify other parameters, such as whether a connection has been made between probe  416  and controllable drogue  410 . 
     Further, control unit  418  also may be employed to maneuver probe  416  to further facilitate a connection to probe  416  and controllable drogue  410 . 
     With aircraft  400  and tanker aircraft  412 , refueling may occur with tanker aircraft  412  located behind aircraft  400 . In these examples, tanker aircraft  412  may have various positions with respect to aircraft  400 . For example, tanker aircraft  412  may be behind and above aircraft  400 . In other examples, tanker aircraft  412  may be below and behind aircraft  400 . In yet other examples, tanker aircraft  412  may be behind and positioned substantially off an axis of aircraft  400 . In other words, tanker aircraft  412  may be located to the left or right of an axis extending through aircraft  400 . 
     In these examples, control unit  418  also may initiate the deployment of refueling duct  406  from aircraft  400 . With this type of embodiment, no need is present for the pilot of aircraft  400  to position or fly aircraft  400  to connect probe  416  with refueling duct  406 . In these examples, a probe may be any structure attached to tanker aircraft  412  that is capable of making a connection to refueling duct  406  in a manner that allows for the transfer of fuel. Instead, the pilot of tanker aircraft  412  flies tanker aircraft  412  in a manner to position tanker aircraft  412  for refueling. In these advantageous embodiments, refueling occurs by transferring fuel  422  from fuel storage system  414  through probe  416  and refueling duct  406  into fuel storage system  402 . 
     Of course, in some advantageous embodiments, a reverse transfer may occur where fuel  424  is transferred from fuel storage system  402  to fuel storage system  414  through refueling duct  406  and probe  416 . This type of reverse transfer may occur if aircraft  400  has too much fuel within fuel storage system  402 . 
     The different components illustrated within aircraft  400  and tanker aircraft  412  are described with respect to particular features that may be found in some or all of the different advantageous embodiments. The illustrations of these particular components, however, are not meant to limit the manner in which aircraft  400  and tanker aircraft  412  may be designed or implemented. Other additional components are present that are not shown. 
     Only components relating to one or more advantageous embodiments are shown for purposes of illustrating features that may be found in these advantageous embodiments. For example, the components connecting refueling duct  406  to fuel storage system  402  are not shown. These components may include, for example, hoses, pipes, pumps, valves, line replaceable units, and other components that are employed in transferring fuel from refueling duct  406  to fuel storage system  402 . 
     Turning now to  FIG. 5 , a block diagram of a controllable drogue is depicted in accordance with an advantageous embodiment. In this example, controllable drogue  500  is a more detailed example of controllable drogue  410  in  FIG. 4 . Controllable drogue  500  includes coupling unit  502 , aerodynamic surfaces  504 , actuators  506 , controller  508 , receiver  510 , and transmitter  512 . 
     In these examples, coupling unit  502  attaches controllable drogue  500  to a hose, such as hose  408  in  FIG. 4 . Further, coupling unit  502  also is capable of providing a connection to a probe, such as probe  416  in  FIG. 4 . In this depicted example, coupling unit  502  includes valve  514 , which may used to control the flow of fuel to and from the aircraft. 
     Aerodynamic surfaces  504  are a set of aerodynamic surfaces. In these examples, the use of the term a set refers to one or more items. A set of aerodynamic surfaces is one of more aerodynamic surfaces. In these examples, aerodynamic surfaces  504  are moveable aerodynamic surfaces that may be moved to change the aerodynamics of controllable drogue  500 . These surfaces may include, for example, without limitation, wings, flaps, ailerons, movable fins, conic shapes, and/or other suitable surfaces. 
     The movement of aerodynamic surfaces  504  may cause controllable drogue  500  to change its position with respect to the aircraft from which controllable drogue  500  is deployed. Actuators  506  may be used to control the movement and/or position of aerodynamic surfaces  504 . Actuators  506  are controlled by controller  508  in these examples. 
     Controller  508  may take various forms. For example, controller  508  may be a computer, an application specific integrated circuit, a program of logic array, or some other suitable device. Controller  508  generates signals in response to control signals received by receiver  510  in these examples. These control signals may be received from an operator of the tanker aircraft to change the position of controllable drogue  500  for establishing a connection to transfer fuel. 
     Further, in some cases, controllable drogue  500  also may include transmitter  512 . Transmitter  512  may be used to send confirmations of commands made to controllable drogue  500  or provide other feedback. For example, transmitter  512  may send information to the tanker aircraft indicating that a correct connection has been made between the boom and coupling unit  502  in controllable drogue  500 . 
     Controllable drogue  500  may be capable of transmitting a homing signal that allows the tanker to automatically guide the controllable drogue to the probe for connection to create a connection with the tanker aircraft to transfer fuel between the tanker aircraft and the aircraft. 
     With reference now to  FIG. 6 , a diagram of a controllable drogue is depicted in accordance with an advantageous embodiment. In this example, controllable drogue  600  is an example of controllable drogue  410  in  FIG. 4 . Coupler  602  may provide a connection to a hose, such as hose  408  in  FIG. 4 . Nozzle  604  provides opening  606  to allow the insertion of a probe. In this example, wings  608  and  610  are examples of controllable air surfaces that may be moved to change the position of controllable drogue  600  while in flight. For example, wings  608  and  610  may be rotated along the direction of arrow  612  to generate lift to move controllable drogue  600  upward with respect to an aircraft. Wings  608  and  610  may be moved on the direction of arrow  614  to move controllable drogue  600  in a downward direction to provide for loading from a flight above. Wings  608  and  610  may be moved independently of each other to cause controllable drogue  600  to roll in different directions. 
     Further, the loading of fuel from above may occur with wings  608  and  610  in the current position. Wings  608  and  610  may be controlled using a control unit, such as controller  508  in  FIG. 5 . The movement of wings  608  and  610  may be moved using actuators, such as actuators  506  under the control of a controller. 
     With reference now to  FIG. 7 , a flowchart of a process for refueling an aircraft is depicted in accordance with an advantageous embodiment. The process illustrated in  FIG. 7  may be implemented using an aircraft, such as aircraft  400  in  FIG. 4 . Further, this process also involves a tanker aircraft, such as tanker aircraft  412  in  FIG. 4 . 
     The process begins by deploying a refueling duct, comprising a hose and a controllable drogue, from an aft position of the aircraft while the aircraft is flying (operation  700 ). This deployment may be initiated by operators in the aircraft. In other embodiments, the deployment of the refueling duct may be initiated through signals sent by the operators of the tanker aircraft. Further, in other advantageous embodiments, the refueling duct may take other forms in addition to or instead of a hose on a controllable drogue. For example, the controllable drogue may be mounted on a beam in some embodiments. 
     The refueling duct is positioned through control signals sent by the tanker aircraft to the controllable drogue to form a positioned refueling duct (operation  702 ). In these examples, these control signals are radio frequency signals sent by a transmitter in the tanker aircraft to a receiver in the controllable drogue. The operator of the tanker aircraft may send signals to the controllable drogue to change the position of the controllable drogue with respect to the aircraft. Further, this change in positioning may make it easier for the tanker aircraft to make a connection to the controllable drogue and/or reduce the connection time need for coupling with the drogue. This movement or positioning of the controllable drogue may be at a location around the aircraft that reduces turbulence. This turbulence may be, for example, a trailing vortex, downwash, or up wash caused by the aircraft in the leading position that is to receive the fuel. 
     Thereafter, the positioned refueling duct is connected to the tanker aircraft positioned behind and above the aircraft to form a connection (operation  704 ). In these examples, the connection with the positioned refueling duct is made through a probe mounted on the tanker aircraft. This probe may make a connection with the refueling duct that allows for the transfer of fuel between the tanker aircraft and the aircraft. In this example, the tanker aircraft is positioned behind and above the aircraft. In other illustrative examples, the tanker aircraft may have other positions, such as behind and below the aircraft. 
     Next, the process transfers fuel through the connection to a fuel storage system located within the aircraft (operation  706 ). In other embodiments, fuel may be transferred in the other direction from the fuel storage system in the aircraft back to the tanker aircraft. 
     After the transfer of fuel has completed, the connection between the refueling duct and the tanker aircraft is terminated (operation  708 ). Thereafter, the positioned refueling duct is retrieved (operation  710 ), with the process terminating thereafter. 
     With reference now to  FIG. 8 , a flowchart of a process for refueling operations is depicted in accordance with an advantageous embodiment. The process illustrated in  FIG. 8  is a more detailed description of an air refueling process. This same process may be performed for defueling or moving excess fuel from an aircraft to a tanker aircraft. 
     The process illustrated in  FIG. 8  assumes that a refueling process has been scheduled for the aircraft. This scheduling may include an identification of coordinates as well as a time for the refueling operation. 
     The process begins with the receiving aircraft and the tanker aircraft making radio contact to confirm refueling coordinates (operation  800 ). Thereafter, the process confirms a visual sighting for day or by tanker forward luminary lighting for night time operations (operation  802 ). Once a visual sighting is made in operation  802 , the tanker aircraft crew acknowledges to the receiving aircraft the readiness to encounter the refueling duct (operation  804 ). 
     Thereafter, the receiving aircraft deploys the refueling duct (operation  806 ). In other advantageous embodiments, the refueling duct may be deployed based on reading frequency signals sent to the aircraft from the tanker aircraft. The receiving aircraft then activates the refueling duct for remote control (operation  808 ). The receiving aircraft communicates that the refueling duct is ready to receive fuel (operation  810 ). 
     Next, the tanker aircraft crew performs a control check of the drogue (operation  812 ). This operation may include various commands to maneuver the refueling duct into a position for engagement with the tanker aircraft. In these examples, the control check may maneuver the refueling duct upwards. Further, the refueling duct may be moved to the left or right, depending on the particular implementation. 
     The tanker aircraft in the next operation approaches the refueling duct for engagement (operation  814 ). The approach in operation  814  also may include repositioning the refueling duct to facilitate a capture and engagement between the refueling duct for the receiver aircraft and the probe for the tanker aircraft. 
     Thereafter, the tanker aircraft engages the refueling duct (operation  816 ). The engagement in operation  816  may involve contact between the probe and the refueling duct in a manner that causes a seal to occur through which fuel may be transferred between the receiving aircraft and the tanker aircraft. After the refueling duct has been engaged, fuel is transferred from the tanker aircraft to the receiving aircraft (operation  818 ). 
     A progressive read out of fuel moved and approximate time remaining for the refueling is provided (operation  820 ). This information may be provided to both the receiving aircraft and the tanker aircraft. A determination is then made as to whether the transfer of fuel is complete (operation  822 ). If the transfer of fuel is not complete, the process returns to operation  818 . 
     Otherwise, the tanker aircraft disengages the probe from the refueling duct (operation  824 ). After the tanker aircraft has disengaged from the refueling duct, the receiving aircraft retrieves the refueling duct (operation  826 ). The receiving aircraft then may report the flight status (operation  828 ). This status may include an estimated time and any schedule impacts that occurred during the refueling. The receiving aircraft then continues on the scheduled route (operation  830 ), with the process terminating thereafter. 
     Thus, the different advantageous embodiments provide a method and apparatus for re-fueling or de-fueling an aircraft. In one or more of the different advantageous embodiments, a refueling duct is deployed from an aircraft while the aircraft is flying. The refueling duct may include a hose and controllable drogue. The refueling duct is positioned through control signals sent by the tanker aircraft to the controllable drogue to form a position refueling duct. A connection is made to the position refueling duct by the tanker aircraft positioned behind the aircraft. Fuel may then be transferred through the connection to or from a fuel storage system located within the aircraft. 
     The different advantageous embodiments allow operators in the tanker aircraft to have features to control the drogue in the positioning of the refueling duct. This control of the drogue makes it easier for the connection to occur. Further, the positioning of the controllable drogue may be performed to allow the tanker aircraft to make the connection in an area around the aircraft in which the airflow is smoother. Updrafts, downdrafts, and vortexes may be avoided by positioning the controllable drogue. 
     Further, by allowing the tanker aircraft to position itself with respect to the aircraft and to position the controllable drogue, the pilot of the aircraft receiving the fuel does not need to perform any actions to make the connection. As a result, the training and practice needed by pilots to make this connection is avoided for pilots of the aircraft receiving fuel. In this manner, refueling of commercial aircraft may be made more feasible. 
     In this manner, refueling of aircraft is made easier because the training needed to perform a refueling operation is reduced for the aircraft receiving fuel. The crew of the aircraft receiving fuel may only need training to know how to deploy and retrieve a refueling duct. In some cases, this process may be automated and controlled by the tanker aircraft. The crew of the aircraft receiving fuel need only establish a normal steady condition of flight and does not need to have extra ordinary training or skill in engaging a refueling apparatus and holding an appropriate position for a refueling operation. This type of training and experience is found with the crew of the tanker aircraft. With less tanker aircraft than aircraft receiving fuel, the amount of training and experience needed is reduced. In this manner, the fueling operations may be made more common for commercial uses in addition to simplifying current refueling operations. 
     The description of the different advantageous embodiments has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the embodiments in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. Further, different advantageous embodiments may provide different advantages as compared to other advantageous embodiments. The embodiment or embodiments selected are chosen and described in order to best explain the principles of the embodiments, the practical application, and to enable others of ordinary skill in the art to understand the disclosure for various embodiments with various modifications as are suited to the particular use contemplated.