Abstract:
A method for refueling and reloading an unmanned aircraft for continuous flight is disclosed herein wherein the unmanned aircraft is maintained and supported by a support aircraft. Both aircraft maintain cargo bays and in-flight operable doors located on the underside of each aircraft for the purposes of docking and exchanging goods. Preferably the goods comprise loadable cartridges and may contain such items as weapons, cargo, or fuel for example. In one embodiment, when both aircraft are in a docked configuration for exchange of goods during flight, the in-flight operable doors open and the support aircraft is capable of loading such cartridges aboard the unmanned aircraft. When necessary the support aircraft may load gear for the purposes of landing the unmanned aircraft. Alternate methods of reloading an unmanned aircraft for continuous flight is disclosed wherein the unmanned aircraft does not have cargo bay doors and the aircraft is supported by a support aircraft.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field of the Invention 
     The present invention relates generally to the equipping and docking of aircraft, and, more particularly to the reloading and refueling of continuous flight unmanned aircraft systems. 
     2. Description of Related Art 
     The cargo transportation industry is crucial to the day-to-day functionality of our society as a whole. In order for goods to get from the manufacturer to the final point of destination, cargo must be shipped and transported via land, sea, or air. Every method has an associated means for transportation of such goods and an expense associated with such transportation means. One such means is air cargo transport. Various weapons are delivered on targets in time of war by manned aircraft or by unmanned guided weapons of various types. Development effort is currently being expended by the U.S. military toward development of unmanned combat aircraft that take off from airfields, deliver weapons on targets, and return to airfields for refueling and reloading of weapons. The unmanned combat aircraft require use of airfields and ground based support personnel. 
     Air cargo transport is currently facilitated by manned aircraft that land and take off from conventional airports. A significant element in operational cost of manned air cargo transport concerns the flight deck crew required for operation of the cargo aircraft and on-board provisions to support the flight crew. During long flights, expensive flight deck crews are often paid to spend many hours merely riding along with the aircraft flying with automatic controls. Eliminating the need for flight crews will decrease the overall operational expenditure and the cost of air cargo shipment. Although an unmanned cargo plane would seem to be an obvious solution, problems arise with considering unmanned aircraft. Landing and take-off of an unmanned aircraft presents problems in providing necessary communication links between ground controllers and the unmanned aircraft. Operation of unmanned aircraft from typical airports presents a potential safety problem to other aircraft and populated areas, thereby making conventional unmanned aircraft approaches for cargo shipment unattractive. Operation of unmanned aircraft from an airport or airbase also requires ground based personnel with special training in take-off, landing and ground support of unmanned aircraft. 
     Every time an unmanned aircraft needs to be recharged with supplies or fuel, there is an expense associated with the manpower necessary to assist and land such an aircraft. The same scenario holds true for take off of such an aircraft. Fuel utilization on take off and landing of a vehicle is inefficient in comparison with the utilization of fuel during flight. Landing of an unmanned aircraft presents additional problems in providing necessary communication links between ground controllers and the unmanned aircraft, particularly in combat situations or when the communication must cross enemy lines. Communications relay aircraft or satellites used for other communications must typically be utilized. 
     Communications relays and antennas typically must be located on towers or in orbiting satellites. Towers provide limited coverage because the curvature of the Earth limits lines of sight. Consequently large numbers of such towers are necessary to provide the desired coverage. The large number of towers presents an exploded operational expense. Orbiting satellites overcome the Earth&#39;s curvature problems, however, they present problems of limited capacity per satellite and high expense for building and placing the satellite in orbit. If a satellite system fails, the time and expense involved in replacing a failed satellite can be exorbitant. 
     Previous attempts to use unmanned aircraft for air cargo or weapons transport have involved a need to periodically land the unmanned aircraft for fuel. Conventional in-flight refueling approaches present difficult problems for unmanned aircraft and increased danger to manned refueling aircraft. Maintaining the necessary relative locations for the tankers and unmanned aircraft for the duration of the fueling operations is difficult. Therefore the unmanned aircraft must land for refueling. In order for such an aircraft to land at a base, such a base must be equipped for ground handling, take-off and landing of unmanned aircraft. Such provisions must be available at any location in which unmanned aircraft are used. Unless ground controllers remain at the home base for unmanned combat aircraft, such controllers and their equipment must be deployed to forward locations to support aircraft operations. Such deployments present logistical problems in addition to problems of locating ground facilities for such deployments. 
     For military combat aircraft, personnel and equipment must be deployed to war theater airbases to support unmanned combat aircraft. Support personnel must be deployed to bases used by unmanned aircraft to refuel the aircraft and to reload or change weapons carried by the aircraft. The requirement to return to base between missions for refueling and reloading of weapons reduces the number of missions executable within a given time by each unmanned combat aircraft. Airbase use by unmanned aircraft presents problems similar to those found at conventional airports. Shared use of bases between manned and unmanned aircraft presents base capacity, safety and air traffic control problems. 
     Manpower and facility provisions necessary in both the civilian and military arenas provide an excessive expense to the operation of unmanned aircraft. Landings necessary to the utilization of unmanned aircraft are further complicated in the military arena where airbase traffic can become very heavy during time of war and where ground support personnel must be deployed. Therefore maintaining the aircraft in a situation of continuous flight addresses not only facility and personnel provisions but the issues of flight safety for manned aircraft operated from forward military airbases during time of war and combat availability of the manned aircraft for combat missions. There is, therefore, a need for an unmanned aircraft capable of operation over a long period of time without the need to land for the purposes of refueling and reloading of payloads. 
     SUMMARY OF THE INVENTION 
     The present invention achieves technological advances as an unmanned aircraft capable of continuous flight such that the problems of landing facilities and personnel are addressed and solved. Concern with untimely disclosure of information to an enemy is obviated by creating an aircraft capable of continuous flight. 
     A system consisting of an in-flight reloadable and in-flight refuelable continuously flying unmanned aircraft and a companion support aircraft enables the continuously flying unmanned aircraft to operate on a continuous basis without landing for either a series of military or commercial missions. The support aircraft is typically a much larger aircraft such as a wide body transport and may be either manned or unmanned. The support aircraft ferries and loads fuel, cargo, or weapons to the continuously flying unmanned aircraft. Both aircraft are specially configured to dock with each other during flight. In-flight refueling provisions are further included in both the continuously flying unmanned aircraft and the support aircraft to enable the support aircraft to refuel the continuously flying unmanned aircraft while it is docked with the support aircraft. 
     The present invention provides an unmanned aircraft able to operate over long periods of time and over a multiplicity of missions without need to land for the purposes of refueling or reloading of payloads. The unmanned aircraft is able to carry a multiplicity of different payloads within standard payload bay cartridges and such may be loaded and unloaded from a support aircraft during flight while the unmanned aircraft and the support ships are docked. 
     The present invention further provides a practical means for unmanned aircraft to dock and launch from support aircraft during flight. 
     The present invention also provides a means to transfer fuel from a support aircraft to unmanned aircraft while docked together during flight. 
     The present invention also provides a means to transfer fuel from the support aircraft to the unmanned aircraft while the unmanned aircraft is attached to extendable attachment devices of the support aircraft with these devices in the extended position. 
     The present invention also provides a means to remove the landing gear from the unmanned aircraft after takeoff, thus allowing the weight and space to be available for payloads. 
     The present invention also provides a means to extend and retract the landing gear of the unmanned aircraft while the unmanned aircraft is attached to extendable attachment devices of the support aircraft with these devices in the extended position. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a more complete understanding of the present invention, reference is made to the following detailed description taken in conjunction with the accompanying drawings, wherein like numerals refer to like elements, wherein: 
     FIG. 1 is a side view of a preferred embodiment of two docked aircraft for the exchange of goods. 
     FIG. 2 is an exploded view of an embodiment of two docking aircraft. 
     FIGS. 3 a-d  are examples of cartridges loadable by the support aircraft of a preferred embodiment. 
     FIGS. 4 a-d  are examples of cartridges loadable by the support aircraft of an alternative embodiment. 
     FIG. 5 is a flow diagram of the refueling method. 
     FIG. 6 is a flow diagram of the reloading method. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention provides a preferred embodiment of a method for exchanging goods between a support aircraft and an unmanned aircraft capable of continuous flight. FIG. 1 is a side view of a preferred embodiment of two docked aircraft for the exchange of goods. In the preferred embodiment, the process of docking a continuously flying unmanned aircraft  10  with a support aircraft  30  is accomplished while flying the continuously flying unmanned  10  aircraft in an inverted position as shown so that the payload cartridge bay  12  of the continuously flying unmanned aircraft  10  faces the payload cartridge loading and unloading bay  32  of the support aircraft  30 . Orientation of the payload cartridge bay  12  of the continuously flying unmanned aircraft  10  toward the bay  32  of the support aircraft  30  enables cartridges to be loaded and unloaded through the same set of bay doors used for dropping weapons or other payloads. Thus a need for separate payload loading or unloading doors and separate landing gear doors on the continuously flying unmanned aircraft  10  is obviated. 
     In order for the two aircraft to dock properly, a sensor system may be carried aboard the support aircraft  30  to precisely measure the relative location of the continuously flying unmanned aircraft  10  during approaches to and departures from the docked configuration in a preferred embodiment. A master guidance control system aboard the support aircraft  30  provides the necessary commands to the control system of the continuously flying unmanned aircraft  10  to fly the aircraft into the desired docking position, (i.e., attitude and velocity before, during, and after docking). Special control surfaces may be utilized on the continuously flying unmanned aircraft  10  to allow fine shifting of aircraft position for docking without need to change any aircraft attitude from the desired attitude for docking. 
     FIG. 2 is an exploded view of the two aircraft as they are docking. A continuously flying unmanned aircraft  10  is equipped with a specially designed payload cartridge bay  12  with in-flight operable doors. The payload cartridge bay  12  is equipped with provisions to allow a loading or unloading mechanism in the support aircraft  30  to both detach and remove payload cartridges between the bays  12 ,  32  and insert into and attach payload cartridges between the bays  12 ,  32  while the two aircraft are docked during flight. In a preferred configuration, a payload cartridge bays  12 ,  32  are located on the bottoms of aircraft  10 ,  30  fuselage and at the aircraft center of mass. The payload cartridge bay  12  is located on the bottom side of the continuously flying unmanned aircraft  10  so that a single bay may be used for dropping of weapons and for the aircraft landing gear. This bottom location also aids in placing the door away from aircraft aerodynamic control surfaces. Subsequently, in the preferred embodiment the payload bay  32  of the support aircraft  30  is located on the bottom of the support aircraft fuselage and as far as practical from aircraft engines and aerodynamic control surfaces. The support aircraft  30  is equipped with a payload cartridge load and unload bay  32  with doors that are operable both on the ground and in-flight. 
     The continuously flying unmanned-aircraft is equipped with capture and attachment provisions  34  to enable a properly equipped support aircraft  30  to attach to a continuously flying unmanned aircraft  10  while the continuously flying unmanned aircraft  10  is flying proximate near the support aircraft  30 . The capture and attachment devices  34  of the support aircraft  30  are preferably extendable and are designed to pull the attached continuously flying unmanned aircraft  10  into position and hold the aircraft  10  in solid contact with appropriately designed support surfaces on the surface of the support aircraft  30  so that the two aircraft are flying as a single unitary aircraft. These attachment devices  34  are further capable of pushing away the continuously flying unmanned aircraft  10  from the support ship  30  and then releasing it for independent flying. 
     The forward extendable capture and attachment devices  34  of the support aircraft  30  may be extended alone for initial capture of the unmanned aircraft  10  for secure connection at the forward capture sockets  14 . The aft extendable capture and attachment device  34  may then be extended to capture the unmanned aircraft  10  at the corresponding aft attachment point  14  while the unmanned aircraft  10  is being restrained by the forward capture and attachment device  34 . Furthermore the docking means, made up of capture sockets  14  and attachment and capture devices  34 , maybe utilized as a refueling means if both sockets  14  and devices  34  are maintained in fluid communication with both a fuel storage and a fuel supply respectively. This capability enables the use of smaller and less complex support aircraft  30  as tankers for the support of unmanned aircraft  10  on long missions. 
     FIGS. 3 a-d  and FIGS. 4 a-d  are examples of cartridges loadable by the support aircraft. A wide range of payload cartridges may be used. Such payload cartridge types include weapons, cargo, fuel, or landing gear, for example. FIGS. 3 a-d  are examples of internally mounted type payload cartridges. Each cartridge  40 ,  50 ,  60 , and  70  includes a mounting pallet  44 ,  54 ,  64 , and  74 , a cartridge enclosure  47 ,  57 ,  67 , and  77 , and the specific payload. Referring to FIG. 3 a  there is illustrated a weapon cartridge  40  in accordance with an aspect of the present invention, in which a weapon  42  is releasably mounted by a mounting device  46  to an inside surface of the mounting pallet  44  within the cartridge enclosure  47 . The outside surface of the mounting pallet  44  is configured to be releasably mounted to an internal surface of a support aircraft in a bay area. The outside surface of the mounting pallets  54 ,  64 , and  74  of each cartridge illustrated in FIGS. 3 b-d  are also configured to be releasably mounted to an internal surface of a support aircraft in a bay area. 
     FIG. 3 b  illustrates a cargo cartridge  50  in which cargo  52  is contained within the cartridge enclosure  57 . Specific examples of types of cargo cartridges include electronic equipment and sensory equipment, for example. Electronic equipment cartridges can have such uses as communication relay aircraft applications. Sensor equipment cartridges can be utilized for mapping or for wartime reconnaissance type missions. 
     FIG. 3 c  illustrates a fuel cartridge  60  in which the cartridge enclosure  67  is configured to preferably store aircraft fuel. Again, the mounting pallet  64  enables the fuel cartridge  60  to be mounted in a bay area of the support aircraft. Fuel cartridges  60  allow for increased ferry ranges for the continuously flying unmanned aircraft  10 . Although the docking means may be further utilized as a refueling means as specified above, in situations where a support ship will not be available for some time it might be necessary to utilize the assistance of fuel cartridges  60 . Such situations might include, but are not limited to, situations of national security of situations wherein the additional cost of a support aircraft is not within the budget of the implied mission, for example. The fuel cartridge enclosure  67  is also preferably configured to allow the unmanned aircraft to access the fuel via a receiving unit located within the unmanned aircraft. 
     FIG. 3 d  illustrates a landing gear cartridge  70  in which take-off and landing gear  72  of a continuously flying unmanned aircraft are mounted within the cartridge enclosure  77 . The landing gear  72  is configured to be retractable into and out-of the cartridge enclosure  77 . Item  80  illustrates extended landing gear and item  78  illustrates completely retracted landing gear. This equipment is used during infrequent take-offs and landings and may therefore be removed shortly after take-off by a support aircraft  30  thereby allowing the same cartridge and gear to be utilized by multiple aircraft. A further advantage of this assembly is that the main cargo bay  12  of the unmanned aircraft  10  may be used for both payload cartridges and landing gear. A landing gear cartridge  70  is re-installed by a support aircraft  30  prior to any landings of the continuously flying unmanned aircraft  10 . Absence of the take-off and landing gear  72  in the continuously flying unmanned aircraft  10  enables a smaller, less massive, less complex and less expensive aircraft than would be possible if the gear were carried as a permanent part of the aircraft. 
     Location of the take-off and landing gear in a payload bay in-flight replaceable cartridge (1) reduces the operational mass of the aircraft by eliminating the mass of the landing gear and landing gear doors from the aircraft except during take-offs and landing, 2) eliminates the need for separate takeoff and landing gear doors and door actuating devices, and (3) eliminates the need for internal volume in the aircraft for takeoff and landing gear. Because the takeoff and landing gear are needed only for takeoff and landing, it is not necessary to provide a set of this equipment for each unmanned aircraft. This equipment can be shared by multiple aircraft. 
     In the preferred embodiment, actuating power to extend  80  or retract  78  the landing gear  72  carried in the landing gear cartridges  70  may be provided by a cartridge loading and unloading device of the support aircraft  30  so that the continuously flying unmanned aircraft  10  is passive with regard to the extend and retract operations and is not required to provide any power for these operations. 
     FIGS. 4 a-b  are examples of flush mounted type payload cartridges. Each cartridge includes a mounting pallet  444 ,  454 ,  464 , and  474  which is configured to be flush mounted to an outside surface of a support aircraft. The flush mount is preferably a releasable type mount. FIG. 4 a  illustrates a weapon cartridge  440  in which a weapon  42  is releasably mounted by a mounting device  446  to the mounting pallet  444 . Note that with the flush mount weapon cartridge  440 , the weapon  42  is preferably of a configuration to minimize drag and/or radar cross section. 
     FIG. 4 b  illustrates a cargo cartridge  450  in which cargo  52  is contained within the cartridge enclosure  457 . The cartridge enclosure  457  is releasably mounted by a mounting device  456  to the mounting pallet  454 . The cartridge enclosure  457  is preferably configured to minimize drag and/or radar cross section. The cargo  52  can be of the type described in FIG. 3 b.    
     FIG. 4 c  illustrates a fuel cartridge  460  in which the cartridge enclosure  468  is configured to preferably store aircraft fuel and is further configured to minimize drag and/or radar cross section. The cartridge enclosure  468  is releasably mounted by a mounting device  466  to the mounting pallet  464 . 
     FIG. 4 d  illustrates a landing gear cartridge  470  in which take-off and landing gear  472  of a continuously flying unmanned aircraft are mounted to the mounting pallet  474 . The landing gear  472  is configured to be retractable to multiple positions. Item  480  illustrates the landing gear  472  fully extended to allow maximum clearance and item  478  illustrates a completely retracted landing gear in which the landing gear  472  is positioned closely to the mounting pallet  474 . 
     By utilizing the aforementioned payload cartridges, an increase in use rate is achieved for the support vehicle because it does not waste time in returning to an airfield, landing, and taking off between missions. By greatly reducing the number of aircraft take-offs and landings there is inherently a reduction in airfield capacity requirements. The number of sites equipped to handle take-off, landing and ground handling of unmanned aircraft is reduced. 
     FIG.  5  and FIG. 6 are flow diagrams of the refueling method and the reloading method, respectively. In FIG. 5, the refueling method requires docking  100  a support aircraft and a continuous flying aircraft preferably for the purposes of refueling the continuous flying aircraft. As detailed above, the support aircraft  10  preferably observes an inverted flight pattern when docking with the support aircraft  30 . Once in such a flight pattern, the payload cartridge bay  12  of the continuously flying unmanned aircraft  10  faces the payload cartridge loading and unloading bay  32  of the support aircraft  30 . If fuel cartridges  60  and  460  are utilized in the refueling process  110 , the support aircraft  30  may then load the cartridges and set the cartridges aboard the continuous flight aircraft  10 . If the refueling process  110  consists of refueling the continuous flight aircraft  10  via the docking means  14 ,  34  then the support aircraft  30  will refuel the continuous flight  10  aircraft via such means by way of hoses or connectors, for example. Once refueled, the support aircraft  30  is able to launch  120  the continuous flight aircraft  10  back into flight patterns consistent with the specific mission of the aircraft  10  and the support aircraft  30  may then proceed to another continuous flight aircraft and repeat the process. 
     With regard to FIG. 6, the support aircraft  30  and the continuous flight aircraft  10  undergo steps similar to those of the refueling  110  acts of FIG. 5 wherein the refueling  110  involves cartridges  60  or the like. Both aircraft may be either manned or unmanned, however in a preferred embodiment the support aircraft  30  is manned and the continuous flight aircraft  10  is unmanned. As above, the support aircraft  30  preferably observes an inverted flight pattern while docking  130  with the support aircraft  30 . Once in such a flight pattern, the payload cartridge bay  12  of the continuously flying unmanned aircraft  10  faces the payload cartridge loading and unloading bay  32  of the support aircraft  30 . The two aircraft are then capable of utilizing merely the engine power of the support aircraft  30  as the two aircraft are then capable of unitary flight, “belly-to-belly”. Orientation of the payload cartridge bay  12  of the continuously flying unmanned aircraft  10  toward the bay  32  of the support aircraft  30  thus enables cartridges  40 ,  50 ,  70 ,  440 ,  450  and  470  to be loaded and unloaded during the attachment/detachment process  140  through the same set of bay doors used for dropping of weapons or other payload and avoids a need for separate payload loading or unloading doors and separate landing gear doors on the continuously flying unmanned aircraft  10 . 
     The support aircraft  30  has storage for payload cartridges  40 ,  50 ,  60 ,  70 ,  440 ,  450 ,  460  and  470  has internal machinery for moving the payload cartridges  40 ,  50 ,  60 ,  70 ,  440 ,  450 ,  460  and  470  between storage positions and the cartridge loading and unloading bay  32  of the support aircraft  30 . The support aircraft  30  preferably has a device specially designed to move payload cartridges  40 ,  50 ,  60 ,  70 ,  440 ,  450 ,  460  and  470  into and out of the cartridge bay  12  of the continuously flying unmanned aircraft  10 . Such a device has the capability to both attach the cartridges  40 ,  50 ,  60 ,  70 ,  440 ,  450 ,  460  and  470  to attachment points in the continuously flying unmanned aircraft  10  and to detach the cartridges  40 ,  50 ,  60 ,  70 ,  440 ,  450 ,  460  and  470  from such attachment points to allow removal from the bay  12 . In a preferred embodiment, actuating power for such attach and detach operations  140  is provided by the device of the support aircraft  30  so that the continuously flying unmanned aircraft  10  is passive with regard to the attach and detach operations  140 . 
     Once reloaded the support aircraft  30  is able to launch  150  the continuous flight aircraft  10  back into a flight pattern consistent with the specific mission of the aircraft  10  and the support aircraft  30  may then proceed to another continuous flight aircraft and repeat the process. 
     Although a preferred embodiment of the method and system of the present invention has been illustrated in the accompanied drawings and described in the foregoing detailed description, it is understood that obvious variations, numerous rearrangements, modifications and substitutions can be made without departing from the spirit and the scope of the invention as defined by the appended claims.