Aeronautics and astronautics – Aircraft structure – Fuel supply
Reexamination Certificate
2000-05-04
2001-01-23
Eldred, J. Woodrow (Department: 3644)
Aeronautics and astronautics
Aircraft structure
Fuel supply
C244S13500B, C280S830000, C280S831000
Reexamination Certificate
active
06176452
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to fuel tanks, or fuel containment areas, formed within a vehicle structure, such as an aircraft wing or fuselage.
BACKGROUND OF THE INVENTION
This invention relates to a device and processes for joining and sealing sections of flexible material, such as material used to make up removable bladder tanks used to contain fuel or other liquids in aircraft or land vehicles, to aircraft or vehicle structure interior elements such as skins, ribs or bulkheads, for in-situ formation of a fluid tight container in the aircraft or vehicle.
Fuel containers for applications such as an aircraft typically face stringent weight and space requirements. Voids in structures such as fuselage and wing cavities are reserved to serve as fuel storage areas capable of storing substantial volumes of fuel. However, the voids are not simply filled with flammable fuel. Instead, various techniques have been developed for accommodating fuel storage requirements within such voids.
In one technique, the area within an aircraft fuselage or wing, is provided with an impervious bladder, formed outside of the aircraft and custom designed to accommodate the structural arrangement within the fuselage or wing. Various techniques have been proposed in relation to the construction of the bladder, the means for supporting the bladder within the structure, and the means for attaching the bladder to the structural members. While such bladder constructions are useful in that they provide a well-defined fuel containment area, they suffer from several generic technical and cost disadvantages. One such disadvantage relates to the need to custom design the bladder, outside of the aircraft or vehicle, to accommodate the specific structural arrangement and aircraft subsystems that must penetrate the structure and bladder. Abrasion of the bladder against protruding structural members may also be a concern, as well as the need to closely mate any support for the bladder about irregular structural features. Still further, mechanisms for securing the bladder to a structure may be cumbersome and expensive, particularly about irregular surface areas.
Another general technique for forming fuel compartments within an aircraft or vehicle is referred to as an integral construction technique. In that technique, no separate bladder is formed. Instead, interior cavities formed by structure surfaces of the fuselage or wing are sealed with hand applied or sprayed sealing materials which define a fluid chamber within the aircraft or vehicle (spaced from wing outersurface portions). The layers of sealing material may be formed in various ways, and in various configurations. Areas about irregular structural features may be sealed from the fluid chamber by selective placement of spacing material, with sealing material disposed upon the surface of the spacing material.
Such integral construction techniques have an advantage in that they do not require the external construction of a customized bladder, and avoid the difficulties that can be associated with subsystem penetrations and locating and securing such bladders. However, such integral construction techniques do not capitalize on the advantages of the bladder constructions, such as the additional containment integrity and fuel containment advantages associated with bladders. Moreover, such integral construction techniques may require tedious assembly insofar as the containment area is typically not complete until the fuselage and wing body is fully assembled, and containment integrity may be difficult to assure.
The present invention is directed to a structure and technique of forming hybrid fuel containers which capitalize on the advantages of both bladder construction and integral construction. By the present invention, a fuel container is constructed wherein certain portions are formed using an integral construction technique, particularly in areas where surface irregularities may make bladder construction cumbersome and less reliable. Other portions of the fuel container are defined by a section of flexible material, which is secured and sealed to the integrally-formed portion by a flexible transition joint to facilitate the definition of a continuous fuel container area. The flexible material may be conveniently joined to the integrally-formed portion prior to complete construction of the wing body such that the fuel container may be defined and inspected prior to complete assembly of the wing. The flexible material may be arranged in areas less subject to structural irregularity to multiple disadvantages associated with contemporary bladder constructions.
SUMMARY OF THE INVENTION
A fuel containment area, and method of forming the same are disclosed herein. A fuel containment area is defined in part by a vehicle interior structure, such as an aircraft wing or fuselage. Portions of the fuel containment area are provided with elastomeric appliqu{acute over (e)}s or partial bladders to bridge sections of the vehicle interior structure, to provide additional container integrity, and/or to segregate fuel from certain areas of the vehicle interior, e.g., about electrical components, mechanical linkages, or fluid critical areas such as high temperature areas. The appliqu{acute over (e)}s or partial bladders, in some cases having edge portions of raw uncoated textile cloth, are sealed to the vehicle interior by flexible transition joints to define a continuous, hybrid fuel container.
In the disclosed embodiments, the vehicle interior structure is provided with an integral sealant liner formed on the vehicle interior surface. In certain areas, support material, such as foam, with the sealant layer formed thereon, may be used to form a regular continuous surface for convenient joining of the partial bladder or appliqu{acute over (e)} to the integral liner construction with the flexible transition joint.
Unlike the transition joints disclosed in application Ser. No. 09/246,606, the flexible transition joint may be formed in several ways. In one embodiment, the flexible transition joint disclosed in this first embodiment herein is formed from uncoated textile cloth strip which may have peel-off TEFLON tape applied thereon to selectively prevent adhesion of the joint during in-situ installation. Flexible transition joints arranged about border regions of the appliqu{acute over (e)}s or partial bladder material, bridge, join and seal the appliqu{acute over (e)}s or partial bladder material to the vehicle innersurface having the sealing layer formed thereon. In this embodiment, after installation of the joint to seal and bond the partial bladder or applique to the integral liner, additional elastomeric layers are applied to the transition joint strip to provide fluid integrity to the transition joint area. This may include a diffusion barrier layer of various materials, for example, nylon, such as used in fuel bladder constructions.
In another embodiment, a second textile crotch strip, set in a 180 degree fold, is sewn or fused midpoint to the back of the textile joining strip to facilitate additional strength integrity to the in-situ joint installation. In the same manner as in the first embodiment, elastomeric layers may be applied to the joining strip for fluid integrity after the strip is installed. The crotch strip remains uncoated raw cloth and may include application of TEFLON tape on multiple surfaces.
The broad concepts of the invention permit insight to formation of the fuel containment area by placement of bladder appliqu{acute over (e)}s or partial bladders as convenient in the course of fabricating the vehicle structure. The partial bladders are preformed to fit specific structure arrangements and the bladder appliqu{acute over (e)}s may be preformed or cut and fit on sight. Both the partial bladder and appliqu{acute over (e)}s may be manufactured with uncoated, raw textile edge portion extensions of the textile reinforcement used in bladder material construction. The uncoated textile extension of the bladder material functions to enhanc
Anderson Terry J.
Eldred J. Woodrow
Hoch, Jr. Karl J.
Northrop Grumman Corporation
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