Abstract:
A system for enabling the use of one electrical servicing cable having a 115V/400 Hz AC cablehead, to supply aircrafts having either a three-phase 115V/400 Hz AC electrical power system, or a 270 VDC/28 VDC electrical power system, for aircraft pre-flight and maintenance operations. The system includes a controller for determining and controlling the supply of appropriate power to an aircraft. The system includes an aircraft electrical servicing adapter that facilitates the safe supply of power to a 270 VDC aircraft via the 115V/400 Hz AC cablehead.

Description:
STATEMENT OF GOVERNMENT INTEREST 
   The following description was made in the performance of official duties by employees of the Department of the Navy, and, thus the claimed invention may be manufactured, used, licensed by or for the United States Government for governmental purposes without the payment of any royalties thereon. 

   TECHNICAL FIELD 
   The following description relates generally to an apparatus for enabling the use of one electrical servicing cable for supplying aircrafts having a three-phase 115V/400 Hz AC power system, or aircrafts having a 270 VDC electrical power system, to enable proper pre-flight and maintenance operations. 
   BACKGROUND 
   Aircrafts require pre-flight and maintenance electrical servicing. When an aircraft is parked on the ground or on an aircraft carrier or the like, power is typically supplied via an electrical cable assembly. The cable assembly typically includes a power source attached at one cable end, and the other end is free to be attached to a power receptacle on the body of the aircraft. Different aircrafts employ different types of electrical power systems, and therefore there is a compatibility requirement for the electrical cable assemblies and the aircraft power receptacles. 
   Traditionally, most of the aircrafts deployed on US Navy ships have a 115 VAC/400 Hz AC, electrical power system. In order to perform maintenance and pre-flight operations, aircrafts are outfitted with an external power receptacle, typically a six pole NATO standard per MS90362. The existing Aircraft Electrical Servicing System (AESS) aboard US Navy ships provide electrical power to embarked aircraft by way of a portable servicing cable assembly with a plug that fits the MS90362 receptacle. Next generation aircrafts like the F-35 Joint Strike Fighter (JSF) have a 270 VDC electrical power system and have a 270 VDC external power receptacle. As a result, any ship or airport that will receive the JSF will need to provide 270 VDC electrical power for maintenance and pre-flight operations. 
   The introduction of JSFs in addition to the traditional aircraft will have a significant cost, infrastructure, size and weight impacts to the carrier ships, if a plurality of power systems are to be provided on each carrier ship. Thus, it is desired to provide a single power system that is compatible with both the 115 VAC/400 Hz AC and the 270V DC systems. It is also desired to have a power supply system that is relatively inexpensive and that does not require a significant change in infrastructure. 
   SUMMARY 
   In one aspect, the invention is an aircraft electrical servicing adapter for use with a power supply system and an aircraft. According to the invention, the power supply system includes a controller, a 28 VDC power source, a 270 VDC power source, and a 115V/400 Hz AC power source, a 115V/400 Hz cablehead plug, and a first power recognition circuit segment. The aircraft is equipped to receive power from a 270 VDC power source and a 28 VDC power source, the aircraft having a 270 VDC receptacle. In this aspect, the aircraft electrical servicing adapter comprises an adapter body, a power end attached to the adapter body, an aircraft end attached to the adapter body, and a second power recognition circuit segment having a diode. In this aspect, the second power recognition circuit segment is provided for completing a single power recognition circuit with the first power recognition circuit segment. The aircraft electrical servicing adapter further includes a socket arrangement having six socket openings located in the aircraft end of the adaptor, for receiving 270 VDC receptacle pins of an aircraft. The adapter also has a receptacle arrangement having six pins, the receptacle arrangement located on the power end of the adaptor for mating with the 115V/400 Hz AC cablehead plug of the power supply arrangement. In this aspect, the receptacle arrangement comprises a two part pin having a first contact portion and a second contact portion, with the first and second contact portions forming at least a portion of the first power recognition circuit segment with the diode connected across the contacts. In this aspect, when the receptacle arrangement is inserted into the 115V/400 Hz AC cablehead plug the single power recognition circuit is completed and communicates to the controller that the adapter is attached to the cablehead. This results in the controller supplying power from the 28 VDC power source and the 270 VDC power source to the cablehead. 
   In another aspect, the invention is a system for supplying power to different types of aircraft. In this aspect, the system includes one or more aircrafts. Each of the one or more aircrafts is equipped to receive power from a 115V/400 Hz AC power source, a 270 VDC power source and a 28 VDC power source. In this aspect, the invention includes a power supply system, the power supply system comprising a controller, a 28 VDC power source, a 270 VDC power source, and a 115V/400 Hz AC power source. The power supply system also includes a 115V/400 Hz AC cablehead plug, and a first power recognition circuit segment for forming a single power recognition circuit with either a second power recognition circuit segment or a third power recognition segment. In this aspect, the invention includes an aircraft electrical servicing adapter. The aircraft electrical servicing adapter comprises an adapter body, a power end attached to the adapter body, and an aircraft end attached to the adapter body. The aircraft electrical servicing adapter further includes a second power recognition circuit segment having a diode, and a socket arrangement having six socket openings located in the aircraft end of the adaptor for receiving 270 VDC receptacle pins of an aircraft. Additionally, the adapter further includes a receptacle arrangement having six pins, with the receptacle arrangement located on the power end of the adaptor for mating with the 115V/400 Hz AC cablehead plug of the power supply arrangement. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other features will be apparent from the description, the drawings, and the claims. 
       FIG. 1  is an exemplary illustration of a system for powering a plurality of aircraft types, according to an embodiment of the invention; 
       FIG. 2  is a schematic illustration of a system for powering a plurality of aircraft types, according to an embodiment of the invention; 
       FIG. 3A  is an exemplary illustration of an aircraft electrical servicing adapter, according to an embodiment of the invention; 
       FIG. 3B  is a perspective illustration of a socket arrangement as viewed from arrow A in  FIG. 3A ; 
       FIG. 3C  is a perspective illustration of a receptacle arrangement as viewed from arrow B in  FIG. 3A ; 
       FIG. 3D  is an exemplary illustration of a two-part pin according to an embodiment of the invention; and 
       FIG. 3E  is an exemplary illustration of an aircraft electrical servicing adapter having an elongated cable, according to an embodiment of the invention. 
   

   DETAILED DESCRIPTION 
     FIG. 1  is an exemplary illustration of a system  100  for powering a plurality of aircraft types, according to an embodiment of the invention. The system  100  may be located on an aircraft carrier, or alternatively be located on a land-based airport or hanger, for providing pre-flight and/or general electrical servicing. As shown, the system  100  includes an aircraft electrical servicing adapter  150 , a cablehead  160 , and a cable  165 , which is wound on a cable storage device  166 , such as a spool. The cable  165  is attached to a power supply  175 . 
     FIG. 1  shows aircrafts  101  and  110 . Aircraft  101  includes a standard six pole 115 VAC/400 Hz AC external power receptacle  120 . Aircraft  110  has a 270 VDC power receptacle. The cablehead  160  includes a socket that is structured to mate with the standard six pole external power receptacle  120 , allowing power from power source  175  to be supplied to an aircraft such as  101 , which includes the standard receptacle  120 . However the structure of cablehead  160  does not allow direct mating with 270 VDC power receptacles  130  as included on aircrafts such as  110 . According to the present invention, the cablehead  160  may be connected to the 270 VDC power receptacle via the aircraft electrical servicing adaptor  150 , which is compatible with both the cablehead and the 270 VDC power receptacle. Although  FIG. 1  shows two aircrafts, the illustrated aircrafts  101  and  110  merely represent the types of aircrafts for which the system is applicable. Thus, the system  100  may include more aircrafts or less aircrafts than depicted in  FIG. 1 . As will be outlined below, the system provides a safe and reliable means of ensuring that the correct type of power is applied to each type of aircraft. 
     FIG. 2  is a schematic illustration of a system  200  for powering a plurality of aircraft types, according to an embodiment of the invention.  FIG. 2  shows a system  200  having a power supply system  202 . The power supply system  202  includes power sources  205 ,  210 , and  215 . Power source  205  provides a 28 VDC power supply, power source  210  provides a 270 VDC power supply, and power source  215  provides a 115 VAC/400 Hz AC power supply. The power supply system  202  also includes a power supply controller  220  for controlling the operation of the supply system  202 , as well as the operation of the overall system  200 .  FIG. 2  also shows cablehead  230 . 
     FIG. 2  further illustrates an aircraft electrical servicing adapter  250  and an aircraft  260  having an external power receptacle  262 , a 270 VDC receptacle which is situated on an aircraft such as  110  shown in  FIG. 1 . As shown in  FIG. 2 , and as outlined above, the physical structure of the cablehead  230  is incompatible with the external power receptacle  262 . However, as shown, connection between the abovementioned elements may be achieved via the adapter  250 . 
     FIGS. 3A-3D  are exemplary illustrations of the aircraft electrical servicing adapter  250 , according to an embodiment of the invention. As shown in  FIG. 3A , the adapter  250  includes an adapter body  310 , which primarily includes the adapter circuitry (shown in  FIG. 2 ) including ON and OFF buttons  311  and  312  respectively. The adapter  250  may also include an adapter controller for controlling the operation of the adapter. As shown, the adapter body  310  may be rectangular. However the body  310  may be of any desired shape.  FIG. 3A  shows the adapter body  310  having a back face  315  and a front face  320 , with an aircraft end  330  of the adapter attached to the back face  315  and a power end  340  of the adapter attached to the front face  320 . 
   The aircraft end  330  of the adapter comprises a cable  332  which may comprise an elastomeric material. As shown in  FIGS. 3A and 3B , the aircraft end  330  includes a socket arrangement  335  having six socket openings ( 336 ,  338 ). The socket openings are arranged in two rows, a first row having two socket openings  336  and a second row having four socket openings  338 . As shown, the two socket openings  336  of the first row are larger than the four socket openings  338  of the second row. The socket arrangement  335  represents a mating arrangement for physically mating with a 270 VDC receptacle of an aircraft. 
   As shown in  FIGS. 3A and 3C , the power end  340  of the adapter comprises a six-pin receptacle arrangement  345  surrounded by a protective shield  350 . The six-pin arrangement includes a first row having three pins  355 , and a second row having three pins. The second row includes a two-part F pin  360  having two separate contacts or conducting portions.  FIG. 3D  shows the structure of the two-part F pin  360 . The pin  360  includes a lower portion  365  comprising a conducting material. The pin  360  also includes an upper portion comprising two separate regions, a first region comprising insulating material shown at  366  and a second region comprising conducting material shown at  367 . As shown, the region comprising the insulating material is sandwiched between the conducting material of the lower portion and the conducting material of the upper portion. Additionally, the lower portion  365  has a larger diameter than the upper portion ( 366 ,  367 ). This structure allows the two-part F pin  360  to have two separate contact points when the cablehead is inserted thereon, thereby forming and closing a power recognition circuit, as outlined below. 
     FIG. 3A  shows a length in the z-direction, L 3 , measuring the length of the adapter  250  from the aircraft end to the power end. In order to have a compact apparatus, L 3  is about 8 inches to about 14 inches, preferably from about 9 inches to about 12 inches in length. According to an embodiment of the invention, the adapter body may have a length in the z-direction of about 3 inches to about 5 inches. The shield at the power end may be about 1 inch to about 2 inches in the z-direction, and the cable at the aircraft end may be about 3 inches to about 6 inches in the z-direction. Additionally, the adapter may also have a thickness (x-direction) of about 3 inches to about 6 inches, and a height (y-direction) of about 3 inches to about 5 inches. In another embodiment shown in  FIG. 3E , the cable at the airplane end may have a length L 4  of about 10 ft to about 40 ft to facilitate the attachment of the adapter to an airplane via the airplane receptacle. 
   In operation, if an aircraft having a 270 VDC receptacle is to be connected to the power supply system  202 , the aircraft electrical servicing adapter  250  must be an intermediary between the components. According to this embodiment, with reference to  FIGS. 2 ,  3 A,  3 B,  3 C, and  3 D, the adapter  250  is connected at the adapter&#39;s power end  340  to the cablehead  230  of the power supply system  202 . As shown in  FIG. 3C , the power end  340  includes a receptacle arrangement having six pins including the two-part pin  360 . See also  FIG. 3D . When the cablehead  230  and the adapter  250  make a proper electrical connection, a power recognition circuit is completed. As shown in  FIG. 2 , the power recognition circuit comprises a first power recognition circuit segment  233  located within the power supply system  202 , and a second power recognition circuit segment  253  in the adapter  250 . The first power recognition circuit segment may include a power supply independent of supplies  205 ,  210 , and  215 . The second power recognition circuit segment, illustrated in  FIG. 2 , includes contacts F 1  and F 2  of the two-part contact, and a diode connected across the contacts. When the single power recognition is completed between the first and second segments, the diode allows current to flow in only one direction. This unidirectional current flow communicates to the controller  220  that the adapter  250  is connected to the power supply system  202 . In response to this information, the controller  220  closes the coils in the 28 VDC power source  205  and the 270 VDC power source  210 , allowing the supply of power from the aforementioned sources to the adapter  250 , and preventing the supply of potentially damaging power from the 115 VAC/400 Hz AC power source  215 . 
   As shown in  FIG. 2 , the adapter  250  includes a first relay  251  and a second relay, contactor  252 , as well as an electrical switch for switching ON and OFF the current flow through the second relay  252 . When the power from sources  205  and  210  are supplied to the adapter  250 , the current from the 28 VDC supply  205  is allowed to flow through the adapter via the first relay  251 . As a safety measure, the 270 VDC current is prevented from automatically flowing through the adapter  250 . The 270 VDC current is only allowed through the adapter  250  if the electrical switch is turned ON. 
   After the current from the 28 VDC supply  205  is allowed to flow through the adapter  250 , the current flows through to the aircraft  260  via the receptacle  262 , if the aircraft is electrically connected to the adapter  250 . If the aircraft is electrically connected to the adapter  250 , the 28 VDC current flows through to the aircraft and back towards the adapter.  FIG. 2  shows the current flowing from pin I and jumping back to the adapter via pin  2 . When this current flows back to the adapter, it flows towards the ON/OFF switch, thereby energizing the switch and allowing a user to close the switch (into the ON position). In the ON position, current from the 270 VDC source is allowed to flow through the second relay through the adapter to the aircraft, thereby fully powering the aircraft. This arrangement where the switch  253  can only be turned ON if the 28 VDC current first flows to an electrically connected aircraft, protects a user from the hazardous effects of a 270 VDC power surge when the adapter is not connected to an aircraft. In other words, according to this arrangement, the 270 VDC power is only supplied through the adapter if an aircraft is properly attached to the adapter. It should be noted that if there is some sort of system error, and the 115 VAC/400 Hz supply is applied to the adapter  250 , the relays  251  and  252  would not allow the alternating current to flow through the adapter  250 , thereby preventing potential hazard to a user or to a connected 270 VDC aircraft.  FIG. 2  also shows a thermal switch within the second power recognition circuit segment, which protects against overheating in the adapter. 
   It should be noted that an aircraft  275  having a 115 VAC/400 Hz six pin receptacle  277 , as shown in  FIG. 2 , may be connected directly to the power supply system  202  via the complementarily mating cablehead  230  and aircraft receptacle  277 . In this arrangement, as opposed to a two-part F-pin  260 , the aircraft receptacle includes a solid F-pin, similar to pin  355  shown in  FIG. 3C . The solid F-pin showed schematically in  FIG. 2 , at least partially forms a third power recognition circuit segment. Together with the first power recognition circuit segment  233 , the third segment forms a single power recognition circuit. When the solid F pin is inserted into the socket arrangement of the cablehead, the single power recognition circuit between the aircraft receptacle and the power supply system is completed. Because this arrangement does not include a diode, the current flow in the completed recognition circuit is not limited to one direction. The resulting bidirectional current flow signals to the power supply system controller  220  that a 400 Hz receptacle is attached to the cablehead  230 , and that the 115 VAC/400 Hz AC power source is required. In response to this information, the controller  220  closes the coils in the 115 VAC/400 Hz power source  215 , allowing only the supply of power from source  215  to the aircraft  275 , and preventing the supply of potentially damaging power from the 28 VDC and 270 VDC power sources. 
   What has been described and illustrated herein are preferred embodiments of the invention along with some variations. The terms, descriptions and figures used herein are set forth by way of illustration only and are not meant as limitations. Those skilled in the art will recognize that many variations are possible within the spirit and scope of the invention, which is intended to be defined by the following claims and their equivalents, in which all terms are meant in their broadest reasonable sense unless otherwise indicated.