System and method for facilitating aerial refueling

A refueling system and method for use with a refueling tanker aircraft. The system and method involves the use of a camera system to provide imaging information concerning a receiver aircraft to the processor. The processor uses the imaging information to derive closure rate and distance information for the receiver aircraft as it approaches a refueling envelope prior to contact with a refueling boom. The processor also makes use of information from a look-up table to generate commands that are tailored to the specific type of aircraft being refueled. The commands are applied to a pilot's director lights display that generates visual commands or signals (e.g., “UP”, “DOWN”, “LEFT”, “RIGHT”) that assist the pilot of the receiver aircraft in guiding his/her aircraft toward and into the refueling envelope at a desired closure rate. The system and method eliminates potential error in the pre-contact phase of a refueling operation by eliminating judgment decisions by a boom operator when generating the commands for the pilot's director lights display.

FIELD

The present disclosure relates to aerial refueling systems and methods, and more particularly to a system and method of guiding a fuel receiving aircraft into a predetermined spatial envelope behind a refueling tanker aircraft through the use of visual display signals presented to a pilot of the fuel receiving aircraft.

BACKGROUND

Aerial refueling tanker aircraft may be equipped with a “pilot's director light” system. The function of this system is to enable the air refueling boom operator (i.e., typically known as the “Boomer”) to provide visual commands to the receiver aircraft pilot during a pre-contact phase of alignment between the refueling tanker aircraft and the fuel receiving aircraft (the “receiver” aircraft). The pilot's director light system displays commands to the pilot of the receiver aircraft (e.g., “fast”, “slow”, “up”, “down”, “left”, “right”) that helps the pilot of the receiver aircraft to guide his/her aircraft into a predetermined spatial refueling envelope behind the refueling aircraft where contact with a refueling boom can be made. These commands from the pilot's director light system may also complemented by voice communications from the boom operator (except where a radio silence condition is required).

The boom operator uses judgmental distance and the closure rate between the receiver fuel receptacle on the receiver aircraft and the boom tip for providing the commands to the pilot's director light system. The closure rate is the rate that the receiver aircraft moves toward and into the predetermined refueling envelope. When the receiver aircraft is within the refueling envelope, the pilot of the receiver aircraft steadies his/her aircraft so that the boom hook-up begins and fuel is delivered. If the boom operator determines the receiver aircraft is not moving into the refueling envelope properly during this pre-contact phase of alignment, he/she may give a “break-away” command to abort the operation. In this instance, the pilot of the receiver aircraft will then need to break-away from the refueling aircraft and then repeat the approach in an effort to enter the spatial refueling envelope at a suitable approach angle and suitable closure rate.

As will be appreciated, the experience and judgment of the boom operator plays a significant role in providing the commands to the pilot's director light system that enables the pre-contact phase of receiver aircraft positioning, and thus the overall refueling operation, to be successfully carried out. Misjudgment or human error (position, closure rate, command errors, etc.), may necessitate repeated attempts before the receiver aircraft is properly guided into the spatial refueling envelope where contact with the boom tip can be made. The time needed to perform repeated refueling attempts can potentially adversely impact a mission.

SUMMARY

The present system and method is directed to an aerial refueling system and method for assisting in guiding a fuel receiving aircraft into a refueling envelope behind a refueling aircraft. In one embodiment, the system includes a subsystem associated with the re-fueling aircraft for real time monitoring of a position of the receiver aircraft, relative to the refueling aircraft. The subsystem generates signals representing needed flight adjustments by the receiving aircraft as the receiving aircraft approaches and enters the spatial envelope. A visual indicator system is responsive to the signals from the subsystem and generates visually perceptible information that an operator of the receiving aircraft can see to assist the operator in guiding the receiving aircraft towards and into the refueling envelope.

In one embodiment the visual indicator system includes a pilot's director lights system that is carried on the refueling aircraft, and the subsystem includes a camera system for real time imaging of the receiver aircraft. The output of the camera system is fed into a processor that uses the imaging information, and also information on the specific type of aircraft being refueled, to generate the signals that drive the pilot's director lights system.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is not intended to limit the present disclosure, its application or uses.

Referring toFIG. 1, there is shown an environmental view of a tanker refueling aircraft12that carries a system10in accordance with one embodiment of the present disclosure for assisting in performing an aerial refueling operation. More, specifically, the system10is used to help guide a fuel receiving aircraft (hereinafter “receiver aircraft”)14into a spatial refueling envelope16behind and slightly below the refueling aircraft12. A boom18controlled by a boom operator on the refueling aircraft12can then be extended into a refueling receptacle20on the receiver aircraft14. An aerial refueling operation can be carried out between the refueling aircraft and the receiver aircraft14.

The system10, in this embodiment, includes one or more cameras22located at an aft end of the refueling aircraft12that can be used to image the receiver aircraft14as the receiver aircraft14approaches the refueling envelope16. A pilot's director lights display24is also located on an exterior surface of the fuselage of the refueling aircraft12so that it can be viewed by a pilot of the receiver aircraft14as the pilot guides the receiver aircraft14towards and into the refueling envelope16. It is important that the receiver aircraft14approach and enter the refueling envelope16at a suitable predetermined rate of speed, typically termed a “closure rate”. The system10enables information concerning the type of receiver aircraft and a suitable closure rate for the receiver aircraft to be used to generate command signals that can be used to illuminate the pilot's director lights display24. The commands may include, for example, “FAST”, “SLOW”, “UP”, “DOWN”, “LEFT”, “RIGHT”, “BREAK AWAY”, etc. that visually cue the pilot in to needed adjustments in the approach and/or closure rate of the receiver aircraft14as it enters the refueling envelope16. The system10eliminates judgment errors by the boom operator located in an operator station26on the refueling aircraft12that may complicate the hook up process between the boom tip18aof the boom18and the refueling receptacle20of the receiver aircraft14. The system10thus enables known characteristics of the receiver aircraft14, in addition to real time imaging information provided by the camera (or cameras)22, to be used to generate the commands that drive the pilot's director lights display24, thus removing any possible error by the boom operator in judging the distance, closure rate or position of the receiver aircraft14.

Referring toFIG. 2, a simplified block diagram of one embodiment of the system10as illustrated. It will be appreciated that the system10is carried on the refueling aircraft12, even though the refueling aircraft12is not illustrated diagrammatically onFIG. 2. The system10may include the camera system22which may comprise one or more cameras for imaging the receiver aircraft14. The camera system22provides electrical signals that are fed into a distance and closure measuring subsystem28. The distance and closure measuring subsystem28may include a suitable distance and closure rate algorithm for providing distance and closure rate signals to a processor30. One suitable distance and closure rate system algorithm is disclosed in U.S. Pat. No. 6,752,357, assigned to The Boeing Company, hereby incorporated by reference into the present application. It will be appreciated, however, that any suitable subsystem or mechanism for providing signals relating to the distance and closure rate of the receiver aircraft14could be incorporated for use with the present system10.

With further reference toFIG. 2, the distance and closure measuring subsystem28provides signals to the operator station26of the refueling aircraft12and also to the processor30. This enables the operator to visually monitor the signals being generated by the distance and closure measuring subsystem28, in the event the operator wishes or needs to take over manual control of the boom18. Additional information may optionally be obtained from an altimeter32and/or an airspeed sensor34of the refueling aircraft12, and outputs from such sensors also fed to the processor30. Sensors associated with the boom18, as designated by box36, may be used to control a boom load alleviation subsystem38. The boom load alleviation subsystem38assists in alleviating a load experienced by the boom18to thus make the boom18essentially weightless as it is coupled to the receptacle20of the receiver aircraft14.

With further reference toFIG. 2, the processor30uses the above-described inputs to generate command signals to a light driver subsystem40. The light driver subsystem40generates signals to the pilot's director lights display24. The output signals from the light driver subsystem40enable the pilot's director lights display24to be illuminated with the various above-described signals or commands that the pilot of the receiver aircraft14can use to guide the aircraft14into the refueling envelope16at a desired closure rate. Optionally, the boom operator can apply inputs to a manual light driver subsystem42to manually produce commands on the pilot's director lights display24if needed. Thus, the system10, in this embodiment, enables the processor30to control the generation of command signals for providing the commands to the pilot's director lights display24or, alternatively, the boom operator can be provided with this capability, via the processor30, based on his/her visual observation of the receiver aircraft14as it approaches the refueling envelope16. It will be appreciated that the system10could also be applied to a probe/drogue refueling device in which the receiver aircraft14includes a probe that engages with a drogue at a distal end of a flexible refueling hose. Such a system is well known in the art and will not be described in detail here.

In one embodiment, the system10may make use of a look-up table44that includes specific information about the type of receiver aircraft and the desired closure rate for the particular type of receiver aircraft that is being refueled. It will be appreciated that different types of aircraft have different optimal closure rates when approaching the refueling envelope16shown inFIG. 1. Thus, the processor30accesses the look-up table44and uses the information pertinent to the specific type of aircraft being refueled, when generating the commands used to drive the pilot's director lights display24.

Referring toFIG. 3, a flowchart illustrating a plurality of operations that may be performed by the system10will now be described. At operation50, real time imaging information concerning the receiver aircraft14is obtained from the camera system22. At operation52, the processor30accesses the look-up table44to retrieve specific distance and closure rate information for the specific type of aircraft being refueled. At operation54, the needed algorithms to extrapolate distance and closure rate information from the output signals of the camera system22are executed. This provides electrical signals that represent distance and closure rate information for the specific type of receiver aircraft that is being refueled. At operation56, the processor30uses the information from the distance and closure measuring subsystem28, as well as the look-up table44, to generate commands for driving the pilot's director lights display24. At operation58, the output of the processor30is applied to an input of the pilot's director lights display24to generate the needed commands (e.g., “FAST”, “SLOW”, “UP”, “DOWN”, “LEFT”, “RIGHT”, “BREAK AWAY”). At operation60, the processor30makes a determination if the boom18has engaged the receiver aircraft14after the receiver aircraft has moved into the refueling envelope16. If so, the system10refueling operation is complete, and the processor30terminates the commands to the pilot's director lights display24. If the answer to this inquiry is “No”, further information is acquired from the camera system22and operations52-60are repeated. It will be appreciated that operations50-60are performed in real time. Thus, the system10is able to provide virtually instantaneous signals to the pilot of the receiver aircraft14via the pilot's director lights display24to assist the pilot of the receiver aircraft14in guiding the receiving aircraft14into contact with the tip18aof the refueling boom18.

The system10thus eliminates any potential error that could be introduced by the boom operator as a result of misjudgment by the boom operator as to the distance, position or closure rate of the receiver aircraft14as the receiver aircraft14approaches the boom envelope16. This allows refueling to be accomplished quickly and efficiently, which helps to insure that the mission being performed by the receiver aircraft14is not compromised because of difficulty encountered during a refueling operation. The system of the present application can be implemented with a limited number of additional component subsystems and also makes use of preexisting components on a typical refueling tanker aircraft (i.e., the camera system and a pilot's director lights display).