Patent Publication Number: US-2010107513-A1

Title: Pre-Cured Edge Seal

Description:
BACKGROUND INFORMATION 
     1. Field 
     The present disclosure relates generally to composite components and in particular to a method and apparatus for manufacturing composite components. Still more particularly, the present disclosure relates to a method and apparatus for improving the method of edge sealing. 
     2. Background 
     Aircraft are being designed and manufactured with greater and greater percentages of composite materials. Some aircraft may have more than fifty percent of its primary structure made from composite materials. Composite materials may be used in aircraft to decrease the weight of the aircraft. This decreased weight may improve payload capacities and fuel efficiencies. Further, composite materials may provide longer service life for various components in an aircraft. 
     Composite materials may be tough, light-weight materials, created by combining two or more dissimilar components. For example, a composite may include fibers and resins. The fibers and resins may be combined to form a cured composite material. 
     Composite materials may be used in various portions of an aircraft. These portions include, for example, skin panels, stringers, shear-ties, ribs, fuselage sections, and other suitable components. In manufacturing composite components, it may be desirable to seal the composite component edges. For example, a sealant may be applied to an edge of the composite component such as, for example, an edge of an internal structure within a wing. The sealant may be used to protect the composite part from the environment. The sealant may keep moisture out of an area on which the sealant is applied. The sealant may also be used to contain electro magnetic currents running through the fibers of a composite structure as a result of lightning strike events or static build-up. 
     SUMMARY 
     The different illustrative embodiments provide a method and apparatus for installing an edge seal. In one illustrative example, a pre-cured edge seal is placed on an edge of a composite structure with a sealant to form a placed pre-cured edge seal. The placed pre-cured edge seal is then cured on the composite structure. 
     In another illustrative embodiment, an edge of a structure is prepared with solvent, and a brush coat of sealant is applied to the top and the edge of the structure. A fillet is applied to the base of the edge of the structure. A pre-cured edge seal is applied to the edge of the structure, and the edge is cured. 
     In yet another illustrative embodiment, a mold is identified for a number of dimensions of the pre-cured edge seal. The mold is filled with sealant. The sealant is cured to form the pre-cured edge seal with the number of dimensions. 
     In yet another illustrative embodiment, a sealant is partially cured to form a pre-cured edge seal. The pre-cured edge seal is extruded into a number of shapes and dimensions, and then fully cured. 
     The features, functions, and advantages can be achieved independently in various embodiments of the present disclosure or may be combined in yet other embodiments in which further details can be seen with reference to the following description and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The novel features believed characteristic of the advantageous embodiments are set forth in the appended claims. The advantageous embodiments, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an advantageous embodiment of the present disclosure when read in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is a flow diagram of aircraft production and service methodology in accordance with an advantageous embodiment; 
         FIG. 2  is a block diagram of an aircraft in accordance with an advantageous embodiment; 
         FIG. 3  is a block diagram of an aircraft in accordance with an advantageous embodiment; 
         FIG. 4  is an illustration of an aircraft in accordance with an advantageous embodiment; 
         FIG. 5  is an illustration of a portion of a wing in accordance with an advantageous embodiment; 
         FIG. 6  is an illustration of a portion of an internal wing structure in accordance with an advantageous embodiment; 
         FIG. 7  is an illustration of a pre-cured edge seal applied to the edge of a structure in accordance with an advantageous embodiment; 
         FIG. 8  is an illustration of a cross-section of a pre-cured edge seal applied to the edge of a structure in accordance with an advantageous embodiment; 
         FIG. 9  is a flowchart illustrating a process for applying a pre-cured edge seal in accordance with an advantageous embodiment; 
         FIG. 10  is a flowchart illustrating a process for manufacturing a pre-cured edge seal in accordance with an advantageous embodiment; and 
         FIG. 11  is a flowchart illustrating a process for manufacturing pre-cured edge seal material in accordance with an advantageous embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Referring more particularly to the drawings, embodiments of the disclosure may be described in the context of an aircraft manufacturing and service method  100  as shown in  FIG. 1  and an aircraft  200  as shown in  FIG. 2 . During pre-production, exemplary method  100  may include specification and design  102  of the aircraft  200  and material procurement  104 . During production, component and subassembly manufacturing  106  and system integration  108  of the aircraft  200  takes place. Thereafter, the aircraft  200  may go through certification and delivery  110  in order to be placed in service  112 . While in service by a customer, the aircraft  200  is scheduled for routine maintenance and service  114  (which may also include modification, reconfiguration, refurbishment, and so on). 
     Each of the processes of method  100  may be performed or carried out by a system integrator, a third party, and/or an operator (e.g., a customer). For the purposes of this description, a system integrator may include without limitation any number of aircraft manufacturers and major-system subcontractors; a third party may include without limitation any number of vendors, subcontractors, and suppliers; and an operator may be an airline, leasing company, military entity, service organization, and so on. 
     As shown in  FIG. 2 , the aircraft  200  produced by exemplary method  100  may include an airframe  202  with a plurality of systems  206  and an interior  208 . Examples of high-level systems  206  include one or more of a propulsion system  210 , an electrical system  212 , a hydraulic system  214 , an environmental system  216 , and a fuel system  218 . Any number of other systems may be included. Although an aerospace example is shown, the principles of the disclosure may be applied to other industries, such as the automotive industry, marine industry, space industry, and other industries. 
     Apparatus and methods embodied herein may be employed during any one or more of the stages of the production and service method  100 . For example, components or subassemblies corresponding to production process  106  may be fabricated or manufactured in a manner similar to components or subassemblies produced while the aircraft  200  is in service. Also, one or more apparatus embodiments, method embodiments, or a combination thereof may be utilized during the production stages  106  and  108 , for example, by substantially expediting assembly of or reducing the cost of an aircraft  200 . Similarly, one or more of apparatus embodiments, method embodiments, or a combination thereof may be utilized while the aircraft  200  is in service, for example and without limitation, to maintenance and service  114 . 
     The different illustrative embodiments recognize that some composite materials exhibit a unique characteristic called edge glow when the structure or adjacent structure has a high current attached to the structure. Edge glow results from the current being routed through the fibers of the composite material, which causes the edge of the structure to glow. This condition forms light at a cut edge of the composite structure. Where a composite structure is exposed to fuel and fuel vapor, such as a composite structure internal to the wing, edge glow becomes critical requiring protection of the edge of the composite structure. 
     The different illustrative embodiments recognize that current methods of edge sealing for internal composite structures involve difficult and time consuming processes. Current methods involve the use of wet sealant that is difficult to apply, slumps after application, shrinks when cured, and is time consuming to install due to the sealant slump requiring the sealant to be reapplied to meet the minimum dimension requirements. 
     Therefore, the different illustrative embodiments provide a method and apparatus for improving edge sealing. In particular, these different advantageous embodiments may control, reduce, or minimize time and materials needed to install an edge seal. 
     In one illustrative example, an edge of a structure is prepared with solvent, and a brush coat of sealant is applied to the top and the edge of the structure, as well as to the base of the structure. A fillet is inserted at the base of the edge of the structure. A pre-cured edge seal is applied to the edge of the structure, and the edge is cured. 
     In these examples, a pre-cured edge seal may be fully cured and formed into the required dimensions with the use of a mold, or may be partially cured and then extruded before being fully cured. As a result, the illustrative embodiments improve the installation of the edge seal by decreasing the installation time, eliminating excessive sealant, and assuring the correct dimensions of the edge seal. 
     With reference now to  FIG. 3 , a block diagram of a sealing system is depicted in accordance with an advantageous embodiment. Sealing system  300  is an example in which a method and apparatus for manufacturing and installing a pre-cured edge seal may be implemented. 
     In this illustrative embodiment, sealing system  300  has edge seal mold  302  and edge seal extrusion system  304 . Pre-cured edge seal  306  may be manufactured using either of edge seal mold  302  or edge seal extrusion system  304 . In an illustrative embodiment, sealant may be inserted into edge seal mold  302  and fully cured to form pre-cured edge seal  306 . In another illustrative embodiment, sealant may be inserted into edge seal extrusion system  304  and partially cured to form pre-cured edge seal  306  that may be extruded and fully cured. A sealant may be any type of viscous material that may change states to become solid once applied. A sealant is used to prevent the penetration of various materials such as, for example, without limitation, air, gas, noise, liquid, or some other material. 
     Structure  308  is a component of a vehicle, such as, without limitation, an aircraft, a submarine, a spacecraft, a surface ship, and other suitable vehicle. Structure  308  may be, for example, a component of a fuel tank, hydraulic system, or some other system exposed to humidity, moisture, light, electrical currents, or vapors. Pre-cured edge seal  306  may be applied to the surface, and in particular the edge of the surface, of structure  308 . Pre-cured edge seal  306  may be, for example, without limitation, an acryl sealant, polysulfide sealant, polyurethane sealant, silicone sealant, WKT sealant, firestop, or some other suitable material. Fillet  310  may be used to fill any gap left between structure  308  and pre-cured edge seal  306 . Fillet  310  is a sealant applied in its un-cured, or wet, form to the base of the edge of structure  308 . Fillet  310  may be any type of viscous material that changes state to become solid and is appropriate for the edge of the structure being sealed, such as, without limitation, acryl sealant, polysulfide sealant, polyurethane sealant, silicone sealant, WKT sealant, firestop, or some other suitable material. 
     The different components illustrated for sealing system  300  in  FIG. 3  are not meant to provide architectural limitations to the manner in which different embodiments may be implemented. The different illustrative embodiments may be implemented in a sealing system including components in addition to or in place of those illustrated for sealing system  300 . Other components shown in  FIG. 3  can be varied from the illustrative examples shown. 
     With reference now to  FIG. 4 , an illustration of an aircraft is depicted in accordance with an advantageous embodiment. Aircraft  400  is an example of a vehicle in which a method and apparatus for installing a pre-cured edge seal may be implemented. In this illustrative embodiment, aircraft  400  has wings  402  and  404  attached to body  406 . Aircraft  400  includes wing mounted engine  408 , wing mounted engine  410 , and tail  412 . 
     In particular, the different advantageous embodiments may be used to install pre-cured edge seals to structural components in wings  402  and  404  and body  406 . For example, the different advantageous embodiments may be used along the edges of the internal structures, such as spars, stringers, shear-ties, ribs, and other composite structures with cut edges. In one example, wing spar to body joints are used to attach the wing spars for wings  402  and  404  to a structural component in body  406 , which may be located at points  414  and  416 . 
     Wing spars are structural components that are used to form wings  402  and  404 . In particular, ribs are attached to these wing spars and to wing skins. A spar is a main structural member of the wing. A spar runs the length of the wing and is typically around or about a right angle to the body or fuselage. Upper and lower wing skins form the aerodynamic surfaces and are separated by the spars. Together with the spar, ribs and skins form the wing box, which typically carries the majority of the forces of both lift and the weight of the wings when the aircraft is on the ground. Other structural and forming members such as ribs are attached to a spar. 
     With reference now to  FIG. 5 , an illustration of a portion of a wing is depicted in accordance with an advantageous embodiment. Wing  500  is an example of wing  404  in  FIG. 4 . 
     In these illustrative examples, wing skin  502  represents the bottom portion of a wing. Forward wing spar  504  and aft wing spar  506  separate wing skin  502  and the top portion of the wing skin not depicted in this illustration. Forward wing spar  504  and aft wing spar  506  are separated by ribs  508  and  510 . Forward wing spar  504 , aft wing spar  506 , rib  508 , and rib  510  are examples of internal structures that may require edge sealing. Other internal structures may include, without limitation, stringers, shear-ties, and other composite components. Forward wing spar  504 , aft wing spar  506 , ribs  508 , rib  510 , and wing skin  502  may be formed from different materials. For example, aluminum, titanium, or composite materials may be used. Composite materials may include, for example, graphite combined with epoxy resin, titanium, and other graphite composites. Carbon fiber reinforced polymer (CFRP) is another example of a composite that may be used. 
     With reference now to  FIG. 6 , an illustration of a portion of an internal wing structure is depicted in accordance with an advantageous embodiment. Wing portion  600  is an example forward wing spar  504  in  FIG. 5 . 
     Wing spar  602  includes bottom flange  604  and top flange  606 . Top flange  606  and bottom flange  604  represent a sealed edge. Bottom flange  604  of wing spar  602  is sealed with pre-cured edge seal  608 . Fillet  610  is applied to the base of bottom flange  604  to fill in the gap between the bottom of pre-cured edge seal  608  and bottom flange  604 . 
     With reference now to  FIG. 7 , an illustration of a pre-cured edge seal applied to the edge of a structure is depicted in accordance with an advantageous embodiment. Structure  700  is an example of forward wing spar  504  in  FIG. 5  and wing spar  606  in  FIG. 6 . The pre-cured edge seal may be applied using sealing system  300  in  FIG. 3 . 
     Wing spar  702  is an example of an internal structure of a wing. Wing spar  702  may be comprised of composite materials including fibers that may conduct electrical currents. Wing spar  702  may be exposed to fuel or fuel vapors within the wing. Wing spar  702  is positioned on wing skin  704 , and sealed with pre-cured edge seal  706 . 
     Pre-cured edge seal  706  may be manufactured using edge seal mold  302  in  FIG. 3 , edge seal extrusion system  304  in  FIG. 3 , and/or with some other suitable system. A sealant may be any type of viscous material that may change states to become solid. A sealant is used to prevent the penetration of various materials such as, for example, without limitation, air, gas, noise, liquid, or some other material. In this example, pre-cured edge seal  706  may provide corrosion resistant and or resistance to various environments, such as, for example, exposure to fuel or fuel vapors. Pre-cured edge seal  706  may be, for example, without limitation, an acryl sealant, polysulfide sealant, polyurethane sealant, silicone sealant, WKT sealant, firestop, or some other suitable material. 
     Pre-cured edge seal  706  is manufactured in the required dimensions to fit a variety of wing spar thicknesses, that may be adjusted further with the application of additional fillet seal. The required dimensions may be, for example, a degree of thickness, a shape, a degree of flexibility, and the like. 
     Fillet  708  is a sealant applied in its un-cured, or wet, form to the base of the edge of wing spar  702 , where wing spar  702  meets wing skin  704 , to fill in any gap left between pre-cured edge seal  706  and wing skin  704 . Fillet  708  may be any type of viscous material that changes state to become solid and is appropriate for the edge of the structure being sealed, such as, without limitation, acryl sealant, polysulfide sealant, polyurethane sealant, silicone sealant, WKT sealant, firestop, or some other suitable material. Fillet  708  may be the same type of sealant used to manufacture pre-cured edge seal  706 , or may be a different type of sealant. Fillet  708  fills any gap that may remain once pre-cured edge seal  706  is applied to the edge of wing spar  702 . 
     Once fillet  708  and pre-cured edge seal  706  have been applied, a final curing process may occur to bond pre-cured edge seal  706  to fillet  708  and wing spar  702 , and finish the edge sealing process. Curing refers to the process of toughening or hardening a viscous material into a solid state. Curing may be brought about by chemical additives, a reaction to water or heat, or by exposure to ambient or elevated temperature per the seal material requirements. 
     With reference now to  FIG. 8 , an illustration of a cross-section of a pre-cured edge seal applied to the edge of a structure is depicted in accordance with an advantageous embodiment. Cross-section  800  is an example of a cross-section of a portion of a structure sealed with a pre-cured edge seal, such as the portion represented by line A in  FIG. 7 . 
     Spar  802  is positioned against wing skin  804 . Spar  802  is an example of spar  702  in  FIG. 7 . Spar  802  is sealed with pre-cured edge seal  806 . Fillet  808  is applied to the base of spar  802  and pre-cured edge seal  806 . 
     With reference now to  FIG. 9 , a flowchart illustrating a process for applying a pre-cured edge seal is depicted in accordance with an advantageous embodiment. This process may be implemented during component and subassembly manufacturing  106  and maintenance and service  114  of production and services method  100  in  FIG. 1 , and in sealing system  300  in  FIG. 3 . The process begins by preparing an edge of a structure using a solvent (step  902 ). The solvent may be any type of cleaner or solvent used to clean and/or remove sealant from a structure, such, for example, methyl polyketone (MPK) solvents. The process inspects the preparation (step  904 ) to ensure the area is ready for an edge seal. The process then applies a brush coat of sealant along the top and edge of a structure (step  906 ). In another illustrative embodiment, a brush coat of sealant may be applied to the pre-cured edge seal before the edge seal is applied to the structure. The brush coat of sealant is an application of sealant in its un-cured, or wet, form. The sealant may be any type of viscous material that changes state to become solid and is appropriate for the edge of the structure being sealed, such as, without limitation, acryl sealant, polysulfide sealant, polyurethane sealant, silicone sealant, WKT sealant, firestop, or other suitable material. 
     Next, the process applies a fillet of sealant at the base of the edge of the structure (step  908 ). The sealant may be the same type of sealant used for the brush coat and to manufacture the pre-cured edge seal, or may be a different type of sealant. The process then applies a pre-cured edge seal (step  910 ) to the edge of the structure, such as the edge of wing spar  702  in  FIG. 7 . The prior brush coat application of sealant acts as a bonding agent for the pre-cured edge seal and the structure. The process then cleans up the application area (step  912 ) and cures the edge of the structure (step  914 ). This curing process solidifies the bond created by the brush coat of sealant between the pre-cured edge seal and the structure. The process then inspects the seal and cure (step  916 ), with the process terminating thereafter. 
     Current methods involve more time and additional steps to achieve an edge seal. For example, the area is prepared and cleaned using a solvent, the preparation is inspected to ensure the area is ready for a seal, and a brush coat of sealant is applied. These steps take approximately five minutes, similar to the first few steps in the illustrative embodiment, which also take about five minutes. However, after these steps, current methods next apply a first application of sealant as both a fillet and edge seal, which takes approximately fifteen minutes. That application must then be cured, taking approximately another ten minutes, before a second application of sealant to both the fillet and edge seal areas can be applied. The second application of sealant takes approximately another ten minutes, and is required in order to achieve the required dimensions of thickness. Due to multiple applications of sealant being applied, more sealant is used than may be necessary to achieve the desired degree of thickness. This is in part due to the shrinkage and slumping of sealant during the curing process, and in part due to the lack of tools for measuring the thickness of an edge seal once it is applied to a structure. As a result, excessive sealant is used to achieve a minimum degree of required thickness. This leads to more cleanup, excessive hazardous waste, and additional time. Cleanup in current methods may take approximately ten minutes, before the final cure to solidify the second application. All together, the time expended on the steps of the current method for edge sealing total forty-five minutes or more. 
     In the illustrative embodiments, once the brush coat of sealant is applied, the pre-cured edge strip is applied to the structure, taking little time as compared to current processes. In these examples the time may be approximately five minutes. A small fillet is applied to the base of the seal, taking approximately another five minutes. This process is more efficient because the only sealant applied in wet form is the brush coat and the fillet. The majority of the seal, which makes of the bulk of the sealant used, is pre-cured and in a solid, yet flexible, state that makes it easier to apply. 
     Additionally, the pre-cured edge seal requires less clean up time, again due to the minimum amount of wet sealant being applied to the structure, and cleanup in the illustrative embodiments can take approximately five minutes, as compared to the current methods which require ten minutes or more. 
     Thus, the illustrative embodiments provide a method that allows for efficient edge sealing in approximately twenty minutes, half the time of current methods. In addition to the more efficient time frame, the illustrative embodiments provide a method that eliminates excessive hazardous waste, and reduces the weight of the edge seal by minimizing the dimensions to the exact requirements. 
     With reference now to  FIG. 10 , a flowchart illustrating a process for manufacturing a pre-cured edge seal is depicted in accordance with an advantageous embodiment. This process may be implemented during component and subassembly manufacturing  106  and maintenance and service  114  of production and services method  100  in  FIG. 1 , and in sealing system  300  in  FIG. 3 . 
     A number, as used herein, refers to one or more items. The process begins by identifying a mold for a number of dimensions of a pre-cured edge seal (step  1002 ). The dimensions may be, for example, without limitation, a degree of thickness, a shape, a degree of flexibility, or another suitable dimension requirement. In an illustrative embodiment, common dimensions for the pre-cured edge seal may be, without limitation, a dome height of 0.10 inches, a thickness of leg 0.10 inches, and a length of leg 0.20. Dome height refers to the dome shape of the edge seal as it overlaps the edge of the structure, such as, for example, the flange of a wing spar. The process fills the mold with sealant (step  1004 ). The sealant may be any type of viscous material that changes state to become solid and is appropriate for the edge of the structure being sealed, such as, without limitation, acryl sealant, polysulfide sealant, polyurethane sealant, silicone sealant, WKT sealant, firestop, or other suitable material. 
     The process then fully cures the sealant to form a pre-cured edge seal (step  1006 ) in the number of dimensions for the structure to which the edge seal will be applied. The pre-cured edge seal is still flexible although in a solid state, and can be glued onto the edge of a structure using a brush coat of wet sealant to adhere the pre-cured edge seal to the edge of the structure. A final curing process will bond the pre-cured edge seal to the edge of the structure by curing the application of wet sealant used as a bonding agent. Then the process stores the pre-cured edge seal on a roll or package (step  1008 ), with the process terminating thereafter. In an illustrative embodiment, a roll on which the pre-cured edge seal may be stored is large enough in diameter to prevent the seal from kinking or twisting. In another illustrative embodiment, a package in which the pre-cured edge seal may be stored is a flat package similar to a plastic bag. 
     With reference now to  FIG. 11 , a flowchart illustrating a process for manufacturing pre-cured edge seal material is depicted in accordance with an advantageous embodiment. This process may be implemented during component and subassembly manufacturing  106  and maintenance and service  114  of production and services method  100  in  FIG. 1 , and in sealing system  300  in  FIG. 3 . 
     The process begins by partially curing a sealant to form a pre-cured edge seal (step  1102 ). Partially curing a sealant may be performed by using a curing process, such as chemical additives, water, heat, or exposure to ambient temperature, to bring the sealant from its viscous state to a partially cured state, dependent upon material requirements, without letting the curing process complete. The partially cured edge seal will not be in a fully cured state, but will still be in a wet or semi-solid state and solid enough to extrude into a shape. The process then extrudes the pre-cured edge seal into a shape (step  1004 ). The shape may be, for example, a shape in the required dimensions for the edge of a particular structure. The process then cures the seal (step  1006 ), and stores the pre-cured edge seal as a roll or package (step  1108 ), with the process terminating thereafter. The roll, which is large enough in diameter to prevent the pre-cured edge seal from kinking or twisting, or the flat package like a plastic bag may be a type of housing that stores the pre-cured edge seal until it is ready to be applied to a structure. 
     The flowcharts and block diagrams in the different depicted embodiments illustrate the architecture, functionality, and operation of some possible implementations of apparatus, methods and computer program products. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of a process for installing and edge seal. In some alternative implementations, the function or functions noted in the block may occur out of the order noted in the figures. For example, in some cases, two blocks shown in succession may be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. 
     Therefore, the different illustrative embodiments provide a method and apparatus for improving edge sealing. In particular, these different advantageous embodiments may control, reduce, or minimize time and materials needed to install an edge seal. 
     In one illustrative example, an edge of a structure is prepared with solvent, and a brush coat of sealant is applied to the top and the edge of the structure. A fillet is inserted at the base of the edge of the structure. A pre-cured edge seal is applied to the edge of the structure, and the edge seal is cured. 
     In these examples, when cured, the pre-cured edge seal may be formed into the required dimensions with the use of a mold. In another illustrative example, sealant may be partially cured into pre-cured edge seal material and then extruded into shape before being fully cured. As a result, the illustrative embodiments improve the installation of the edge seal by decreasing the installation time, eliminating excessive sealant, and assuring the correct dimensions of the edge seal. 
     The illustrative embodiments eliminate the need to apply a second application of fillet or edge seal, and provide for a more efficient method of installing the edge seal by brush coating the surface and then installing the pre-cured edge seal. The illustrative embodiments provide a method for installing a pre-cured edge seal that greatly reduces the waste of excess sealant, thereby reducing the weight of the vehicle, decreasing hazardous waste, and reducing cleanup time required to install the edge seal. 
     The description of the different advantageous embodiments has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the embodiments in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. Although the different advantageous embodiments in the illustrative examples are describe with respect to an aircraft, one or more the different advantageous embodiments may be applied to other vehicles other than aircraft, such as, for example, without limitation, a submarine, a spacecraft, a surface ship, and other suitable vehicles. Further, different advantageous embodiments may provide different advantages as compared to other advantageous embodiments. The embodiment or embodiments selected are chosen and described in order to best explain the principles of the embodiments, the practical application, and to enable others of ordinary skill in the art to understand the disclosure for various embodiments with various modifications as are suited to the particular use contemplated.