Hose-and-drogue in-flight refueling system
An in-flight hose-and-drogue refueling system composed of: a refueling hose-and-drogue unit extending from a refueling aircraft for engaging with a refueling probe of an aircraft to be refueled and; a drogue steering assembly for steering the drogue, the drogue steering assembly including a plurality of individually controllable, compressed air driven thrusters, and a compressed air supply line extending along the hose for supplying compressed air to the thrusters, wherein the hose and the supply line form a unit having a circular outline.
This is a division of application Ser. No. 10/226,134, filed on Aug. 23, 2002, the disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTIONThe present invention relates to automatic hook-up of a hose-and-drogue aerial refueling apparatus to a receiver aircraft probe and, more particularly, to apparatus and methods for in-flight hose-and-drogue refueling using electrooptical technology.
The usefulness of air refueling became apparent to the military almost as soon as they started using aircraft. The main advantage of air refueling is obvious: it enables aircraft to stay airborne longer. Since most aircraft are incapable of taking off with maximum fuel and full payload, without in-flight refueling there is always a balance to be struck between range, payload, and fuel. Air refueling is more than just a range stretcher: it allows one to carry out missions with a smaller number of sorties, or alternatively, fewer aircraft.
One approach to in-flight refueling is the hose-and-drogue system, in which a drogue attached to a fuel hose is extended from the refueling aircraft's belly or wings. The receiver aircraft is equipped with a fixed or retractable probe and the receiving aircraft's pilot flies the probe into the drogue.
The advantages of the hose-and-drogue system are the following: (a) up to three receivers can take fuel simultaneously; (b) if one hose/drogue unit (HDU) becomes unserviceable, the tanker still can offload its fuel; (c) the HDU is inherently safer than the heavy, rigid boom, which is restricted in its movements; (d) it is easier to install on non-purpose-built aircraft; and (e) it is compatible with most receivers, e.g., fixed wings, as well as rotorcraft.
There were, however, two disadvantages to early hose and drogue system: it has lower fuel transfer rates than the boom system, and the drogue is uncontrollable and is susceptible to winds and gusts. In bad weather conditions and particularly in low level refueling situations the hookup process was very difficult and demanded excessive receiving aircraft pilot maneuvers. Since the aircraft &o be refueled was likely to be already low on fuel, excessive maneuvering could result in the necessity to abandon the aircraft.
U.S. Pat. No. 5,326,052, which issued to Krispin et al. on Jul. 5, 1994 (hereinafter the '052 patent), and the entire disclosure of which is incorporated herein by reference, discloses a system designed to overcome the problem of drogue instability by providing a system with means for both drogue steering and drogue motion measurement, thus enabling either stabilization of the drogue or, alternatively, fully automatic hookup.
Specifically, the system disclosed in the '052 patent includes a plurality of miniature, pressurized gas thrusters mounted, preferably equally spaced, on the perimeter of a drogue in such way that activation of any thruster generates a force in a direction perpendicular to the fuel outlet nozzle. In principle, four thrusters are sufficient. Two are required to control the drogue in up-and-down motion and two in the sideways motion. The position of the drogue is measured by electrooptical position-sensing devices.
The measurement system consists of a plurality of light sources (LS) such as Light Emitting Diodes (LEDs) or Laser Diodes (LDs) mounted at a certain distance from the end of the receiving fuel probe, a plurality of sensors each comprising a lens and a position-measuring photodetector that is mounted on the perimeter of the drogue with its sensitive area directed toward the receiving aircraft, and a processing electronic circuit for calculating the position of the light-source assembly relative to the detector assembly and computing the control commands to the thrusters.
In accordance with one preferred form of the invention disclosed in the '052 patent, the measured position of the drogue relative to the probe of the receiving aircraft is used to determine the control commands to the thrusters so that the drogue will track the position of the probe in order to achieve automatic hookup. In such an arrangement the pilot of the receiver aircraft is required to approach the vicinity of the tanker aircraft; once the two aircraft have closed to a certain distance, the automatic control system of the drogue is activated and guides the drogue until contact with the incoming probe has been achieved.
In accordance with an alternative form of the invention disclosed in the '052 patent, measurements are made of the drogue position relative to the tanker aircraft, either belly or wings, and are used to control the motion of the drogue so as to stabilize or, equivalently, to minimize the motion of the drogue relative to the tanker aircraft. In such an arrangement, the pilot of the receiver aircraft is required to track the drogue, which has been stabilized relative to the tanker. The tanker is much less susceptible to wind gusts and turbulence.
BRIEF SUMMARY OF THE INVENTIONThe present invention provides a number of improvements to the systems disclosed in the '052 patent.
Specifically, the invention provides an in-flight hose-and-drogue refueling system comprising, in combination: a refueling hose-and-drogue unit extending from a refueling aircraft for engaging with a refueling probe of an aircraft to be refueled; and a drogue steering means for steering the drogue, said drogue steering means comprising a plurality of individually controllable, compressed air driven thrusters, and a compressed air supply line extending along the hose for supplying compressed air to said thrusters, wherein said hose and said supply line form a unit having a circular outline.
The invention further provides a refueling hose-and-drogue unit for airborne refueling of an aircraft, said unit comprising a hose, a drogue, an infitting that attaches said hose to said drogue, and a plurality of thrusters secured to said infitting and operable to control the position of said drogue in flight.
The invention further provides a refueling probe installable in an aircraft for engaging a drogue to enable the aircraft to be refueled in flight, said probe comprising a light source and electrical wires or optical fibers for supplying lighting energy to said light source, wherein said probe comprises a tube having a wall and said electrical wires or optical fibers are embedded in said wall.
The invention further provides an in-flight hose-and-drogue refueling system comprising: a housing configured to be housed in a weapons bay of a military aircraft or to be suspended below an aircraft; and a refueling hose-and-drogue unit installed in said housing.
BRIEF DESCRIPTION OF THE DRAWINGS
Light sources 26 are supplied with lighting energy via electrical wires or optical fibers. According to a feature of the invention, probe 24 is constituted by a tube having the electrical wires or optical fibers embedded in its wall. This tube may be made of a suitable composite material.
Light sources 26 can be IR sources and PSDs 22 can be IR sensors.
The light source on the refueling aircraft can be an IR source and PSDs 38 can be IR sensors.
Coupler assembly 16 includes a ball joint 40 that couples assembly 16 to drogue 18 in a manner to permit limited pivotal movement of drogue 18 about two axes perpendicular to longitudinal axis 28 of the drogue. Coupler assembly 16 further includes a joint 42 that forms a rotatable coupling with infitting 14. This rotatable coupling allows coupler assembly 16 and drogue 18 to rotate about longitudinal axis 28 without twisting hose 12 or infitting 14, so that the relative orientations of nozzles 34 are not varied and hose 12 is not subject to damage.
As described in the '052 patent, suitable circuitry is connected between PSDs 38 and the thrusters to allow the position of the drogue to be controlled to maintain the drogue relatively stationary relative to the refueling aircraft.
PSDs 22 can be constituted by self-contained wireless transmitting devices that transmit signals to wireless receivers (not shown) in infitting 14 to provide information about the position of light sources 26 relative to longitudinal axis 28. Each transmitting device can have a different carrier frequency or can be digitally coded to be receivable only by a respective one of the wireless receivers. Thus, each wireless receiver produces position signals associated with only one PSD 22. The wireless receivers have outputs that are supplied to signal processing circuitry in the refueling aircraft. The wires coupling the receivers to the circuitry can be embedded in hose 12.
Since coupler assembly 16 and drogue 18 are subject to rotation about axis 28 when being dragged through the air, provision must be made to identify the angular positions of PSDs 22, and thus of drogue 18, associated with position signals produced by the wireless receivers.
One possible arrangement for effecting such identification is shown in
In
In the embodiment of
In the embodiment shown in
In all of the illustrated embodiments of the invention, because the air hose is filled with air at a high pressure, for example in the range 340-455 psi, the air hose has a rigidifying effect on the fuel hose, thereby reducing the magnitude of transverse movements of the fuel hose while being dragged through the air.
With regard to the embodiment shown in
According to one feature of the invention, pressure vessel 52 may be either clad or lined with a suitable composite material to prevent the vessel from exploding and from being penetrated by at least some projectiles. Any known composite material that is suitable for this purpose may be used.
Heretofore, in-flight refueling has been performed by refueling aircraft that are specially equipped to perform this function. This limits the number of aircraft available to perform this function. According to a further feature of the present invention, a refueling system is installed in a vessel, or housing, that can be mounted on or in a variety of aircraft that are configured to be used for other purposes. Two embodiments of such a housing are illustrated in
The pod is open at its rear end and hose 12, containing hose 47, would be deployed out of the open rear end of the pod.
In the embodiments shown in
While the description above refers to particular embodiments of the present invention, it will be understood that many modifications may be made without departing from the spirit thereof. The accompanying claims are intended to cover such modifications as would fall within the true scope and spirit of the present invention.
The presently disclosed embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims, rather than the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
Claims
1. A refueling probe installable in an aircraft for engaging a drogue to enable the aircraft to be refueled in flight, said probe comprising a light source and electrical wires or optical fibers for supplying lighting energy to said light source, wherein said probe comprises a tube having a wall and said electrical wires or optical fibers are embedded in said wall.
2. The probe of claim 1 wherein said tube is made of a composite material.
3. A refueling hose-and-drogue unit for airborne refueling of an aircraft, said unit comprising a hose, a drogue carried by, and rotatable relative to, said hose, and a plurality of thrusters attached to, and nonrotatable relative to, said hose, said thrusters being operable to control the position of said drogue in flight.
4. An in-flight hose-and-drogue refueling system comprising:
- a housing configured to be carried by an aircraft and including a cowl mounted to pivot downwardly from a closed position; and
- a refueling hose-and-drogue unit stored in said housing and deployable out of said housing when said cowl is pivoted downwardly,
- wherein said cowl is disposed below said unit when said cowl is in the closed position and said cowl is pivoted downwardly when a refueling operation is to be performed in order to provide aerodynamic stabilization during deployment of said unit.
Type: Application
Filed: Jan 28, 2005
Publication Date: Mar 30, 2006
Inventors: Eric Enig (Bethesda, MD), Julius Enig (Calverton, MD)
Application Number: 11/044,199
International Classification: B64D 39/00 (20060101);