Patent Publication Number: US-2009223402-A1

Title: Pyrotechnic systems and associated methods

Description:
TECHNICAL FIELD 
     The following disclosure relates generally to pyrotechnic systems and associated methods, for example, aircraft decoy flare systems with safe and ignite mechanisms. 
     BACKGROUND 
     Modern aircraft often use decoy flares to defeat infrared-guided weapons. Typically, decoy flares are deployed in flight by ejecting the flare from a tube and then igniting the flare, which emits electromagnetic radiation. The infrared-guided weapon can lock on and track the decoy flare and/or the heat source of the aircraft can be masked by the flare, providing the aircraft with an opportunity to elude the weapon. 
       FIG. 1  is a partially schematic cut-away view of a conventional flare  1  and a deployment tube  2  illustrating a system for igniting the flare  1 , in accordance with the prior art. In  FIG. 1 , a bore rider system  4  is used to ignite the flare  1  after the flare  1  leaves the deployment tube  2 . The bore rider system  4  has a compartment  10  attached to the flare grain  62 . The compartment  10  has a first section  10   a  and second section  10   b . The first section  10   a  has a first opening  12  and the second section  10   b  has a second opening  11 . A flammable material  20  is coupled to a bore rider  50  that has a depressed position and an extended position. As long as the flare  1  is in the deployment tube  2 , the bore rider  50  remains in the depressed position and the flammable material  20  remains in the first section  10   a  of the compartment  10 . 
     When an expulsion charge  5  is fired, hot expanding gases propel the flare  1  out of the deployment tube  2  and penetrate the first section  10   a  of the housing  10 , igniting the flammable material  20 . As the flare  1  leaves the deployment tube  2  (shown by phantom lines), the bore rider is no longer held in the depressed position and a spring  55  moves the flammable material  20  from the first section  10   a  of the compartment  10  to the second section  10   b . In the second section  10   b , the flammable material  20  ignites the flare grain, which burns and emits electromagnetic radiation. 
     A problem with conventional decoy flares is that they can ignite prematurely and/or malfunction so that the flare grain ignites and burns in the deployment tube. For example, combustion can prematurely migrate from the first section of the compartment to the second section and ignite the flare grain before the flare leaves the deployment tube. Additionally, if the flammable material in the compartment ignites before deployment of the flare is commanded, it can cause the flare grain to ignite and burn while the flare is in the deployment tube. Because the deployment tube is not intended to house a burning flare, these conditions can be hazardous to both the aircraft and associated personnel. 
     SUMMARY 
     The present disclosure is directed toward pyrotechnic systems and associated methods. One aspect of the invention is directed toward a pyrotechnic system that includes a package having a combustible material with an aperture proximate to the combustible material. The system further includes a housing having a first portion and a second portion. The first portion has an inlet for receiving combustion products and the second portion has an outlet that is in communication with the aperture to propagate combustion between the second portion of the housing and a combustible material in the package. The system further includes a combustible carrier material movable from the first portion of the housing to the second portion of the housing. The combustible carrier material is ignitable in the first portion of the housing and capable of sustaining combustion while being moved to the second portion of the housing. In a further aspect of the invention, the system can further include a seal positioned to block a migration of combustion products between the first and second portion of the housing when the combustible carrier material is in the first portion of the housing. In another aspect of the invention, the system can further include at least one gasket proximate to the outlet and the aperture to prevent the migration of combustion products through the aperture except from the outlet. In still another aspect of the invention, the system can further include a vent system being located proximate to the first portion of the housing and the inlet. The vent system includes a passageway to allow combustion products to migrate away from the first portion of the housing and/or the inlet. 
     Another aspect of the invention is directed toward a method for making a pyrotechnic system that includes providing a package having a combustible material with an aperture proximate to the combustible material. The method includes coupling a housing to the package, wherein the housing has a first and a second portion. The first portion has an inlet for receiving combustion products and the second portion has an outlet. The outlet is in communication with the aperture to propagate combustion between the second portion of the housing and the combustible material in the package. The method further includes installing a combustible carrier material that is movable from the first portion of the housing to the second portion of the housing. The combustible carrier material is ignitable in the first portion of the housing and capable of sustaining combustion while being moved to the second portion of the housing. In a further aspect of the invention, the method can include positioning a seal to block a migration of combustion products between the first and second portions of the housing when the combustible carrier material is in the first portion of the housing. In another aspect of the invention, the method can further include positioning at least one gasket proximate to the outlet and the aperture to prevent the migration of combustion products through the aperture except from the outlet. In still another aspect of the invention, the method can further include locating a vent system proximate to the first portion of the housing and the inlet. The vent system includes a passageway to allow combustion products to migrate away from the first portion of the housing and/or the inlet. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a partially schematic cut-away view of a conventional flare and a deployment tube illustrating a method for igniting the flare, in accordance with the prior art. 
         FIG. 2A  is a partially schematic cut-away view of a pyrotechnic system with a deployable component positioned in a launcher, in accordance with an embodiment of the invention. 
         FIG. 2B  is a partially schematic cut-away view of the pyrotechnic system shown in  FIG. 2A  where an expulsion charge has begun to deploy the deployable component. 
         FIG. 2C  is a partially schematic cut-away view of the pyrotechnic system shown in  FIG. 2B  where the deployable component has been deployed from the launcher. 
         FIG. 2D  is a partially schematic cut-away view of the pyrotechnic system shown in  FIG. 2C , having a package with a combustible material that has been ignited. 
         FIG. 3  is a partially schematic cutaway view of the pyrotechnic system shown in  FIG. 2A  illustrating a vent system. 
         FIG. 4A  is a partially exploded schematic illustration of the combustible material of the pyrotechnic system shown in  FIG. 2A  prior to tape being applied to the combustible material. 
         FIG. 4B  is a partially exploded schematic illustration of the combustible material of the pyrotechnic system shown in  FIG. 4A , with the tape partially applied. 
         FIG. 4C  is a partially exploded schematic illustration of the package shown in  FIGS. 4A and 4B  with a gasket and a housing positioned to be coupled to the package to form a portion of the deployable component. 
         FIG. 4D  is a partially exploded schematic illustration of the package, the gasket, and the housing shown in  FIG. 4C  being coupled together by the application of a second portion of tape. 
         FIG. 4E  is a partially exploded schematic illustration of the package, gasket, and housing, and second portion of tape shown in  FIG. 4D , at another point during the process of applying the second portion of tape. 
         FIG. 4F  is a partially exploded schematic illustration of the package, gasket, and housing shown in  FIG. 4E , coupled together by the second portion of tape. 
         FIG. 5  is a schematic illustration of a vehicle including a pyrotechnic system in accordance with embodiments of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure is directed toward pyrotechnic systems and associated methods, for example, aircraft decoy flare systems having safe and ignite mechanisms. Several specific embodiments are set forth in the following description and in  FIGS. 2A-5  to provide a thorough understanding of certain embodiments of the invention. One skilled in the art, however, will understand that the present invention may have additional embodiments, and other embodiments of the invention may be practiced without several of the specific features explained in the following description. 
       FIG. 2A  is a partially schematic cut-away view of a pyrotechnic system  200  with a deployable component  201  positioned in a launcher  202 , in accordance with an embodiment of the invention. The deployable component  201  includes a package  260  and a housing  210 . The package  260  has a combustible material  262  and an aperture  265  proximate to the combustible material  262 . The pyrotechnic system  200  includes at least one feature that ignites the combustible material  262  once the deployable component  201  is clear of the launcher, and several other features that, singularly or in combination, can prevent premature ignition of the combustible material  262 . These features, which are described in detail below with reference to  FIGS. 2A-5 , can provide an effective ‘safe and ignite’ mechanism for the pyrotechnic system  200 . Common reference numbers refer to common elements in  FIGS. 2A-5 . 
     The housing  210  has a first portion  210   a  and a second portion  210   b . The first portion  210   a  has an inlet  212  for receiving combustion products and the second portion  210   b  has an outlet  211 , proximate to the aperture  265 , and positioned to propagate combustion between the second portion  210   b  of the housing  210  and the combustible material  262 . The housing can be formed from any single or combination of materials, including metal, plastic, silicone, and/or a composite material. A combustible carrier material  220  is movable from the first portion  210   a  of the housing  210  to the second portion  210   b . The combustible carrier material  220  can be ignited in the first portion  210   a  of the housing  210  and is capable of sustaining combustion while being moved from the first portion  210   a  of the housing  210  to the second portion  210   b  where combustion can propagate through the outlet  211  and the aperture  265  to the combustible material  262 . 
     The launcher  202  includes a launch platform  207  that includes a platform portion  207   a  on which the deployable component  201  rests and piston portion  207   b . The piston portion  207   b  is received in a recessed portion of the launcher  202 . The launcher  202  also receives an expulsion charge  205  proximate to the piston portion  207   b . The expulsion charge  205  can include any type of charge that releases an expanding gas and combustion products (e.g., an impulse charge that uses gun powder). When the expulsion charge  205  is detonated, the resulting expanding gases and combustion products (e.g., flames, hot gases, and sparks) will cause the launch platform  207  to propel the deployable component  201  out of the launcher  202 . The launch platform  207  also includes a port  208  that allows a portion of the combustion products produced by the expulsion charge  205  to migrate through the piston portion  207   b , the platform portion  207   a , and into the first portion  210   a  of the housing  210 . The combustion products can ignite the combustible carrier material  220  when the combustible carrier material  220  is in the first portion  210   a  of the housing  210 . 
     A biasing mechanism  255  is positioned to urge the combustible carrier material  220  toward the second portion  210   b  of the housing  210 . A device  250  movable between a first position and a second position is located proximate to the combustible carrier material  220  and the biasing mechanism  255 . When the deployable component  201  is in the launcher  202 , the device is held in the first position. In the first position, the device  250  restricts the biasing mechanism  255  from moving the combustible carrier material  220  from the first portion  210   a  of the housing  210  to the second portion  210   b . The device  250  can move to the second position when the deployable component  201  leaves the launcher  202 . When the device  250  is in the second position, it does not prevent the biasing mechanism  255  from moving the combustible carrier material  220  to the second portion  210   b  of the housing  210 . For example, when the deployable component  201  is clear of the launcher  202 , a single biasing mechanism  255  can simultaneously urge the combustible carrier material  220  to move to the second portion  210   b  of the housing  210  and the device  250  to move to the second position, as shown in the illustrated embodiment. In other embodiments, separate biasing devices  255  can be used to move the combustible carrier material  220  and the device  250 . 
       FIG. 2B  is a partially schematic cut-away view of the pyrotechnic system  200  shown in  FIG. 2A  where an expulsion charge  205  has been detonated and the expanding gases and combustion products indicated as arrows C have begun to deploy the deployable component  201 . The expanding gases and combustion products are causing the launch platform  207  to push the deployable component  201  out of the launcher  202 . Additionally, a portion of the high-temperature combustion products are migrating through the port  208  in the launch platform  207 , through the inlet  212 , and into the first portion  210   a  of the housing  210  igniting the combustible carrier material  220 . Because the deployable component  201  is still in the launcher  202 , the device  250  is held in the first position, preventing the combustible carrier material  220  from moving out of the first portion  210   a  of the housing  210 . A seal  225  is positioned to block the migration of combustion products between the first and second portions  210   a  and  210   b  of the housing  210  when the combustible carrier material  220  is in the first portion of the housing  210 . Accordingly, combustion products do not migrate from the first portion  210   a  of the housing, to the second portion  210   b , so the seal  225  blocks the combustion products from migrating through the outlet  211  to the combustible material  262 . The seal can be formed from any single or combination of suitable materials (e.g., a silicone material and/or a composite material). 
       FIG. 2C  is a partially schematic cut-away view of the pyrotechnic system  200  shown in  FIG. 2B  where the deployable component  201  has been deployed from (e.g., cleared or exited) the launcher  202 . As the deployable component  201  clears the launcher  202 , the biasing device  255  moves the device  250  from the first position to the second position and slides the combustible carrier material  220  from the first portion  210   a  of the housing  210  to the second portion  210   b . Once the combustible carrier material  220  has moved to the second portion  210   b  of the housing  210 , combustion propagates (shown by arrows C) from the combustible carrier material  220  through the outlet  211  and the aperture  265  to the combustible material  262 . The propagation of combustion can be aided by at least one combustible intermediary material  280  (e.g., a fuse) positioned proximate to (e.g., inside) the outlet  210  and the aperture  265  and/or between the combustible carrier material  220  and the combustible material  262 , as shown in  FIG. 2C . In other embodiments, combustion can propagate between the combustible carrier material  220  and the combustible material  262  without the aid of a combustible intermediary material  280 . 
       FIG. 2D  is a partially schematic cut-away view of the pyrotechnic system  200  shown in  FIG. 2C , having a package  260  with a combustible material  262 , that has been ignited (the resulting combustion being shown by arrows C). In certain embodiments, as the combustible material  262  begins to burn, the housing  210  separates from the combustible material  262  as shown in  FIG. 2D . The combustible material  262  can perform various functions once ignited. For example, the combustible material  262  can be flare grain and once ignited can emit electromagnetic radiation (shown as arrows L). In other embodiments, the combustible material  262  can include other types of devices, for example, an expulsion device. 
     In still other embodiments, the combustible material  262  can simply be coupled to the housing without any additional packaging and/or without the aperture  265  described above. For example, in certain embodiments, the combustible material  262  can simply be placed on top of the housing  210  and the outlet  211  can be in communication with a portion of the combustible material  262 . In other embodiments, the packaging surrounding the combustible material  262  can be flammable and/or a portion of the packaging can act as a combustible intermediary material  280 . In still other embodiment, the package can contain multiple combustible materials  262 . 
     A feature of foregoing embodiments discussed above with reference to  FIGS. 2A-2D  is that the seal  225  prevents the migration of combustion products from the first portion  210   a  of the housing  210  to the second portion  210   b  when the combustible carrier material  220  is in the first portion  210   a . This prevents the ignition of the combustible material  262  until the deployable component  201  has cleared the launcher  202  and the device  250  allows the combustible carrier material  220  to move to the second portion  210   b . An advantage of this feature is that the combustible material  262  does not prematurely ignite and burn until clear of the launcher  202 , allowing the pyrotechnic system  200  to function more reliably and with better safety than conventional systems (e.g., conventional aircraft decoy flares). This feature can be especially important for decoy flares installed on commercial aircraft and other vehicles. 
       FIG. 3  is a partially schematic cutaway view of the pyrotechnic system  200  shown in  FIG. 2A  illustrating a vent system  270  that carries combustible products away from at least a portion of the deployable component  201  in the unlikely event of a malfunction. For example, the combustible carrier material  220  and/or the expulsion charge  205  can be inadvertently ignited even though the deployable component  201  is jammed in the launcher  202  and/or not being deployed. If the combustion products produced by the burning combustible carrier material  220  and/or the expulsion charge  205  can be kept away from the combustible material  262 , for example by the vent system  270 , the combustible material can be prevented from being ignited. This in turn can prevent having the combustible material  262  (e.g., the flare grain in a flare) from burning while the deployable component  201  is still in the launcher. 
     In the illustrated embodiment, the vent system  270  is located proximate to the first portion  210   a  of the housing  210  and the inlet  212 . The vent system  270  includes at least one passageway  272  to allow combustion products to migrate away from the first portion  210   a  of the housing  210  and/or the inlet  212 . In  FIG. 3 , two passageways  272  are shown, however, as illustrated in  FIGS. 2A and 4F  the housing  210  includes two additional passageways  272  (not shown in the present illustration). The two additional passageways  272  are in the front and rear of the housing  210  proximate to where the port  208  in the launch platform  207  communicates with the first portion  210   a  of the housing  210 . Other embodiments can have more or fewer passageways  272 . 
     Additionally, in certain embodiments, the passageway(s)  272  can be configured (e.g., the number and size adjusted) so that it/they can accommodate a higher flow rate than the port  208  in the launch platform. The higher flow rate capability of the passageway(s)  272  can provide a capability to quickly vent combustion products during certain malfunctions, while the lower flow rate of the port  208  can prevent the expanding gases from the expulsion charge  205  from being vented to quickly during deployment, allowing the gases to apply sufficient pressure/force to the piston portion  207   b  of the launch platform  207  to provide suitable launch characteristics. Furthermore, if during a malfunction the combustible carrier material  220  is ignited and the expulsion charge  205  is not, the combustion products will be more likely to migrate through the passageway(s)  272  than through the port  208  to the expulsion charge  205 , reducing the probability that the expulsion charge  205  will ignite. Other embodiments can have different configurations with different comparative flow rates. 
     The passageways  272  vent combustion products, shown as arrow C in  FIG. 3 , to a portion  203  of the launcher  202 . For example, the passageways  272  can vent the combustion products into the launch tube in which the deployable component  201  is located. In certain embodiments wherein the launch tube of the launcher  202  may be sealed, however, the tube is large enough to accept a significant amount of combustion products without breaching the seal. In other embodiments, the combustion products can be vented from the portion  203  of launcher  202  and/or the passageways  272  can be coupled to passageways in the launcher  202 , carrying the combustion products away from the deployable component  201  and the launcher  202 . 
     Because the combustion products are carried away from the first portion  210   a  of the housing  210  and/or the inlet  212 , the combustion products will not substantially migrate to the second portion  210   b  of the housing  210 . Additionally, the seal  225 , discussed above, can further aid in preventing combustion products from migrating between the first and second portions  210   a  and  210   b  of the housing  210  while the combustible carrier material  220  is in the first portion  210   a  of the housing  210 . Accordingly, even if the combustion products are vented into a portion  203  of the launcher  202 , ignition of the combustible material  262  can be prevented during certain malfunctions provided that other areas of the combustible material  262  are protected from the combustion products. For example, the combustible material  262  is sealed except for the aperture  265  that is proximate to the outlet  211  of the second portion  210   b  of the housing  210 . When the combustion products are carried away from the launcher  202 , the necessity to seal or protect the other areas of the combustible material  262  can be reduced. 
     A feature of embodiments discussed above with reference to  FIG. 3  is that because the combustion products are carried away from the inlet  212  and the first portion  210   a  of the housing  210 , the combustible material  262  can be prevented from prematurely igniting. This in turn can prevent the first combustible material  262  from burning in the launcher  202 . An advantage to this feature is that safety can be increased because even during a malfunction the first combustible material  262  can remain unignited. This can be especially important for use on commercial airliners, other aircraft, and/or other vehicles where the deployable component  201  can be sealed in the launcher  202  (e.g., behind a door) until it is intentionally deployed. 
     As discussed above, in some cases it can be desirable to seal or protect the combustible material  262  from combustion products/sources other than those intended to be propagated from the second portion  210   b  of the housing  210 . Accordingly, as shown in  FIGS. 4A-4F , at least one gasket  230  can be positioned proximate to the outlet  211  of the housing  210  to prevent the migration of combustion products to the combustible material  262 , except from the outlet  211 . The gasket can be made of any single or combination of suitable materials (e.g., a silicone material and/or a composite material).  FIGS. 4A-4F  is a partially exploded schematic illustration of the deployable component  201 , shown in  FIG. 2A , during different stages of assembly. For the purpose of illustration, many of the elements shown in  FIGS. 4A-4F  were not shown in  FIGS. 2A-3 , however, like reference numbers refer to like elements in  FIGS. 2A-4F . 
       FIGS. 4A-4B  illustrate a first portion of tape  240   a  (e.g., laminated aluminum-fiber tape) being used to completely surrounds the first combustible material  262 , to produce the package  260  shown in  FIG. 2A . Once the tape  240   a  has been applied, only a portion of the combustible material  262  remains exposed by the aperture  241  in the first portion of the tape  240   a . The aperture  241  in the first portion of the tape  240   a  thereby forms at least a portion of the aperture  265 , which is proximate to the combustible material  262 , in the package  260  (discussed above with reference to  FIG. 2A ). In  FIG. 4C , a gasket  230  with a gasket aperture  232  is positioned proximate to the aperture  265  of the package  260 . The housing  210  is positioned so that the outlet  211  of the second portion  210   b  of the housing  210  is proximate to the aperture  265  and the gasket aperture  232 , so that combustion can propagate from the second portion of the housing  210  to the combustible material  262 . As discussed above with reference to  FIGS. 2A-2D , in certain embodiments at least one combustible intermediary material can be positioned proximate to the second portion  210   b , the outlet  211 , the gasket aperture  232 , the aperture  265 , and/or the combustible material  262 . 
       FIGS. 4D-4F  illustrate a second portion of tape  240   b  being applied to surround a portion of the housing  210 , a portion of the at least one gasket  230 , and a portion of the package  260 , securing the gasket  230  in place. The gasket  230 , when secured in place, can prevent combustion products from migrating to the combustible material  262 , except through the outlet  211  of the housing  210 . The second portion of tape  240   b  can also aid in preventing the migration of combustion products through the aperture  265 , except from the outlet  211 . Additionally, as shown in the illustrated embodiment, the second portion of tape  240   b  can couple the housing  210  to the package  260  and to the first combustible material  262 , and can serve to apply a compressive force to the gasket  230  making the gasket  230  seal more effective. 
     In other embodiments, multiple gaskets can be located proximate to the outlet  211  of the housing  210  and/or the combustible material  262 . For example, a gasket with a gasket aperture can also be positioned between the combustible material  262  and the first portion of tape  240   a . In other embodiments, the housing  210  can be coupled to the package  260  and/or the first combustible material  262  in other ways (e.g., an outer housing that holds both the housing  210  and the first combustible material  262 ). Additionally, in other embodiments, the at least one gasket  230  can be used without any tape (e.g., a strap can secure the package  260  to the housing  210  with the gasket  230  between the two). In still other embodiments, different types of gaskets or seals can be used. For example, a liquid gasket material can be applied proximate to the intersection of the housing  210  and the combustible material  262  to prevent the migration of combustion products to the combustible material  262 , except from the outlet  211  of the housing  210 . Additionally, the liquid gasket material can serve to couple the housing  210  to the package  260  (e.g., acting as a cement or adhesive when the liquid gasket material cures and/or hardens). 
     A feature of embodiments discussed above with reference to  FIGS. 4A-4F  is that the migration of combustible products to the first combustible material  262  can be prevented, except from the outlet  211  of the housing  210 . An advantage of this feature is that premature ignition of the first combustible material  262  (e.g., during deployment of the deployable component  201 ) and/or ignition of the first combustible material  262  can be prevented. This can make the carriage and operation of the pyrotechnic device more reliable and safer. Additionally, this feature can be particularly important in preventing the inadvertent ignition of the combustible material  262  when the vent system, discussed above with reference to  FIG. 3 , vents combustion products into a portion of the launcher during certain malfunctions. 
     Embodiments discussed above with reference to  FIGS. 2A-4F  can be particularly suited for operations near or on a vehicle.  FIG. 5  is a partially schematic illustration of a vehicle  595  (e.g., an aircraft) having a pyrotechnic system  200  in accordance with embodiments of the invention. Additionally, many of the features discussed above can be used singularly or in combination to tailor the pyrotechnic system  200  for a particular use. For example, several of the features discussed above can be suitable for a pyrotechnic system  200  used on commercial aircraft, for example, a pyrotechnic system configured as a flare on a commercial airliner. 
     From the foregoing, it will be appreciated that specific embodiments of the invention have been described herein for purposes of illustration, but that various modifications may be made without deviating from the spirit and scope of the invention. For example, features described in the context of particular embodiments can be combined or eliminated in other embodiments. Accordingly, the invention is not limited except as by the appended claims.