Patent Publication Number: US-6990905-B1

Title: Marker projectile

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application claims benefit under 35 U.S.C. 119(e) of provisional application 60/481,041, filed 30 Jun. 2003, the entire file wrapper contents of which provisional application are herein incorporated by reference as though fully set forth at length. 

   FEDERAL RESEARCH STATEMENT 
   The inventions described herein may be manufactured, used and licensed by or for the U.S. Government for U.S. Government purposes. 

   BACKGROUND OF INVENTION 
   The current US military 40 mm M781 marker projectile is fired from the M203 grenade launcher which is attached to the M16 rifle. This projectile is comprised of a plastic windshield, which contains a florescent powder, and a zinc body that attaches to the windshield. 
   The basic function of the M781 is as a training round that marks the target with a fluorescent powder. If the M781 projectile hits a person or a light target, it may be lethal to the person and may severely damage the light target. The M781 fluorescent mark on the target can only be seen during the day. In addition, the M781 does not have a tracer that allows an observer to see the flight of the projectile to the target. The maximum gun launched service velocity of the M781 projectile is approximately 250 ft/sec and has a range of approximately 400 meters. 
   The current US military XM1062 marker munition (as disclosed in U.S. Pat. No. 6,497,181, which is herein incorporated by reference) provides a trace of the projectile travel and a mark of the target with chemiluminescent materials that glow and therefore can be seen at night and in low light settings. The XM1062 projectile is comprised of a plastic windshield and an optional rear plastic windshield. The windshields are attached to a zinc body. In practice, one or more glass or plastic vials, some containing a liquid peroxide and some containing a oxalate liquid, is disposed in the plastic windshield(s). An oxalate powder is then placed between the vials and fills the balance of the space in plastic windshield(s). The windshield employed may either be opaque, transparent or translucent dependent upon the desired use. Thus, one requiring a tracer will employ a transparent or translucent windshield whereas one requiring only a site identification of the target area will employ an opaque windshield. It will be noted that the use of a rear windshield which may be threaded to fit body is an optional feature, which feature is typically used in conjunction with an optional aperture which allows chemlucent or chemiluminescent chemicals (or chemiluminescents) to flow into the rear windshield during activation of the projectile. It will be noted that vials break only on setback impact at which time the peroxide mixes with the oxalate ester to form a slurry which serves to mark the target area. The chemiluminescent materials produce light in all the visible spectrum and some of the IR spectrum. The XM1062 marker munition zinc body can be lethal to people and can do severe damage to light vehicles. Therefore, it is not applicable to marking people or light vehicles or targets. The velocity and range of the XM1062 projectile is the same as that of the M781. 
   Thus, it has been found that there exists a need for a long-range (greater than 70 meters) 40 mm non-lethal marking round with both visible and IR marking capabilities that can be fired from the M203 grenade launcher attached to the M16 rifle. The need is to mark people or light vehicles, with IR and visible light chemiluminescent chemicals, for several minutes to an hour without killing or seriously injuring the person or damaging the vehicle. This is needed by the military, homeland defense and police departments. 
   SUMMARY OF INVENTION 
   In accordance with the present invention, a non-lethal marker projectile that provides site identification capability of a target upon impact with the target is provided. This projectile includes a generally cylindrical rear base which is made of a resilient material and a front end (made of transparent, translucent or opaque, depending on the use, plastic or composite) extending longitudinally from the rear base. The front end includes an outer surface having a rear portion which is attached to the rear base and a nose portion serving as a windshield and which defines a space therein. The front end also includes a breakable container system located in the space which contains separated chemiluminescent reagents which when mixed produce light. The front end further includes a foam filler which surrounds the breakable container system and which fills the space. In addition, an optional plastic donut containing either chemlucent chemical (peroxide or oxalate liquid) or air to cushion impact with objects may be placed in the front end with the foam filler. With this projectile construction, the container system breaks on a setback impact that is exerted during firing and initial launch, causing the chemiluminescent reagents to mix and be absorbed into the foam filler such that upon impact of the projectile with the target, the foam filler marks the target with the mixed chemiluminescent reagents diffused therein. 
   In a preferred embodiment, the rear base is formed of rubber, plastic or composite, and the foam filler is formed of polyethylene or polypropylene foam or any other foam that is compatible with the chemlucent chemicals. Additionally, the rubber, plastic or composite may include a metal filler or glass fibers. Further, the rear base and/or front end may include a foam surface. 
   In another preferred embodiment, the rear base is provided with stress grooves so that the rear base shatters upon impact with the target. In addition, the projectile may include a metal insert located somewhere in the rear base. This allows the rear base to have a desired weight but utilizes the rubber, plastic or composite to cushion the impact of the metal insert when the projectile strikes a target. 
   In one preferred embodiment, the outer body surface includes a central portion connecting the rear portion and the nose portion, and wherein the outer surface is a separate member made of plastic. Then, the central and nose portion may be transparent or translucent such that visible light produced by the mixed chemiluminescent reagents is visible therethrough during flight of the projectile. If desired, the nose portion may include stress grooves so that the nose portion shatters upon impact with the target; and also if desired, the outer surface member may include an outermost foam surface. 
   In still another preferred embodiment, the foam filler forms the nose portion, and wherein a remainder of the outer surface is made of plastic and terminates adjacent the nose portion. 
   In yet another preferred embodiment, the breakable container system includes a plurality of breakable vessels. Preferably, the front end also includes a holder for the plurality of vessels. More preferably, the vessels are glass vials, and the foam filler includes a cavity in which the holder including the glass vials is securely located. 
   It is an advantage of the present invention that a long-range (greater than 70 meters) 40 mm non-lethal marking round is provided. 
   It is also an advantage of the present invention that, the non-lethal marking round provided can provide both visible and IR marking capabilities. 
   It is a further advantage of the present invention that the non-lethal marking round is capable of being fired from a standard M203 grenade launcher. 
   It is another advantage that the 40 mm non-lethal marker have the same general appearance and shape of the standard low velocity 40 mm cartridges. 
   Other features and advantages of the present invention are stated in or apparent from detailed descriptions of presently preferred embodiments of the invention found hereinbelow. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
       FIG. 1  is a cross-sectional view of a non-lethal marking projectile in accordance with a first embodiment of the present invention. 
       FIG. 2  is an exploded perspective view of the non-lethal marking projectile depicted in  FIG. 1 . 
       FIG. 3  is a cross-sectional view of a non-lethal marking projectile in accordance with a second embodiment of the present invention. 
       FIG. 4  is a cross-sectional view of a non-lethal marking projectile in accordance with a third embodiment of the present invention. 
       FIG. 5  is a cross-sectional view of a non-lethal marking projectile in accordance with a fourth embodiment of the present invention. 
       FIG. 6  is a cross-sectional view of a non-lethal marking projectile in accordance with a fifth embodiment of the present invention. 
   

   DETAILED DESCRIPTION 
   With reference now to the drawings in which like numerals represent like elements throughout the views, a first embodiment of a marker projectile  10  in accordance with the present invention is depicted in  FIGS. 1 and 2 . It will be appreciated that projectile  10  is designed to provide site identification capability of a target upon impact with the target. Projectile  10  includes a rubber or plastic or composite rear base  12  (such as nylon 12, or nylon 11, or Nylon 6/6 with an optional metal filler and/or optional glass fibers). If desired, an optional soft polypropylene foam surface  14  as shown schematically in  FIG. 1  with a broken line may be provided on rear base  12  to provide additional protection to the target upon impact. While a forward cavity  15  has been depicted in base  12  which serves to reduce the weight of projectile  10 , it will be appreciated that cavity  15  is sized in accordance with the weight and flight characteristics desired for projectile  10 , so that cavity  15  can be of different sizes or not even present as desired. Likewise cavity  36  of rear base  12  can be of different sizes or not even present as desired in accordance with weight and flight characteristics desired for projectile  10 . 
   Projectile  10  also includes a front end  16  which extends longitudinally from rear base  12 . Front end  16  includes an outer surface which in this embodiment comprises a plastic (polyethylene or polypropylene) outer body  18  having a rear end  20  which is attached to rear base  12  and a windshield or nose portion  21 . If desired and similar to foam surface  14 , an optional soft polypropylene foam surface  19  as shown schematically in  FIG. 1  with a broken line may be provided on outer body  18 . It will be appreciated that outer body  18  defines a space  22  therein which is mostly filled as follows. Inside space  22  is a breakable container system  24 . Breakable container system  24  contains separated chemiluminescent reagents which when mixed produce light (as used herein, light includes visible and/or IR wavelengths). In this preferred embodiment, breakable container system  24  includes a plurality of breakable vessels taking the preferred form of plastic or glass vials  26 , though a single vessel with internally separated reagents could be provided. Breakable container system  24  also includes a plastic spider or holder  28  (made of polyethylene or polypropylene) as shown which is used to elastically retain, in the holes thereof, glass vials  26  together as a unit. 
   Front end  16  also includes a polyethylene or polypropylene foam filler  30  which is shaped with a rear opening cavity  32 . To construct front end  16 , glass vials  26  are first placed into the holes of the holder  28  to hold them in place, and outer body  18  is filled with foam filler  30 . Glass vials  26  and spider  28  are then inserted inside of outer body  18  and pressed to a snug fit in cavity  32  of foam filler  30 , at which time additional foam filler  30 ″ (depicted with common cross-hatching with filler  30 ) to complete the enclosure of container system  24  can be injected or inserted in place. To complete construction of projectile  10 , epoxy  34  is placed on the inside surface and the mating shoulder of rear end  20  of outer body  18  as shown in  FIG. 1 . Next, outer body  18  is pressed onto rear base  12 , and any excess epoxy is wiped away. Projectile  10  is then held in a fixture or the like (not shown) until epoxy  34  has set in accordance with the epoxy directions. An adhesive  40  will be applied to base  12  for cartridge assembly, as shown in  FIG. 2 . The location of this adhesive is shown in  FIG. 1  and is placed behind the obturator  45 . Obturator  45  prevents propellant gases from blowing past the projectile  10  during gun launch and is a standard feature from the M781 and is needed on all 40 mm projectiles including the present non-lethal projectile  10 . 
   As shown in  FIG. 2 , projectile  10  is received in a cartridge case  38 , having a primer (not shown) pressed into a rear thereof. Standard primers and cartridge cases, such as plastic cartridge case  38  depicted in  FIG. 2 , from the M781 are conveniently used for the present invention. The primer is used to create propellant gases that propel projectile  10  through the grenade launcher and to the target. Thus, to produce a finished cartridge assembly, projectile  10  is removed from the holding fixture and an RTV (such as a standard RTV used for the M781) adhesive  40  is applied to projectile  10  in the location as shown in FIG.  1 . Projectile  10  is pressed into the plastic cartridge case  38  until it reaches the obturator  45 . Excessive adhesive  40  is wiped away, and the cartridge assembly is placed in a holding fixture until adhesive  40  is cured. The cartridge assembly is then ready for ballistic testing or shipping to a needed location. 
   In a preferred embodiment, rear base  12  is provided with stress grooves  42  (shown with an exaggerated size for clarity) so that rear base  12  shatters upon impact with the target to reduce the chance of injury or damage to the target. In addition, outer body  18  is also provided with stress grooves  44  (also shown with an exaggerated size for clarity) so that outer body  18  also shatters upon impact. 
   In operation, the assembled cartridge is chambered in the M203 grenade launcher or the like that is typically attached to the M16 rifle. The assembled cartridge is chambered in the same way as all other ammunition that is fired in the M203. The M203 chamber is closed and non-lethal projectile  10  is fired in the same manner as all other ammunition. When fired, the primer is set off and the gases ignited by the primer propel projectile  10  down the gun tube. The force exerted on projectile  10  as projectile  10  begins to move at firing is called a set-back force. This set-back force is designed to break glass vials  26  in projectile  10 , so that the chemiluminescent chemicals previously separately contained in glass vials  26  mix and the mixed chemicals give off light. If the mixed chemicals are IR producing, then IR light is given off; while if the mixed chemicals are a visible formulation, then visible light is given off. 
   Fired projectile  10  continues down the gun tube and engages the rifling, which spins up the projectile to 3,600 rpm. The chemiluminescent chemicals thus become well mixed, and get absorbed onto and into foam filler  30  located inside outer body  18 . With the M203, projectile  10  leaves the grenade launcher at a maximum velocity of 76 mps (250 fps). If outer body  18  is designed to be clear or a color that light may pass through, then the chemiluminescent light produced by the mixed chemicals provides a trace of the flight path of projectile  10  to the target. This means that the shooter or an observer can follow the flight of projectile  10  by eye. It will be appreciated that projectile  10  is spin stabilized all the way to the target. 
   Upon impact with the target, thin plastic windshield  21  shatters (with preferable stress grooves  44  causing it to easily shatter into non-lethal pieces with minimal force) and the foam filler  30 , now acting much as a sponge saturated with the chemiluminescent chemical mixture, gently marks the person or target impacted. Foam filler/sponge  30  also takes up the impact force of the plastic composite rear base  12  so that the impacted person is not injured or the impacted target is not severely damaged. Plastic composite rear base  12  is also preferably designed with stress grooves  42  as noted above to cause it to shatter into non-lethal pieces with minimal force as well. After this impact, the target is now well marked for up to 2 hours—depending on the chemical formulation of the chemiluminescent mixture (for example, the prior art chemicals as described in U.S. Pat. No. 6,497,181 and the references cited therein). Projectile  10  is designed to fly up to 400 meters in a similar manner as the M781 to provide this marking capability. 
   Depicted in  FIG. 3  is an alternate 40 mm non-lethal chemiluminescent tracer/marker projectile  50  which is similar to projectile  10 . Projectile  50  differs from projectile  10  primarily in the shape of The rubber, plastic or composite rear base  52  as shown. In addition, projectile  50  includes an optional metal insert  54  or the like located imbedded in the composite base  52 . For visual purposes the metal insert is shown between a forward end of rear base  52  and a rearward end of foam filler  30 . Insert  54  adds weight to projectile  50  for better/longer flight characteristics (and thus no equivalent to cavity  15  of projectile  10  is provided in rear base  52 ). Imbedding the metal insert  54  allows the rubber, plastic or composite base  52  to absorb the impact force with the target instead of the target being contacted by a hard metal. Further, foam filler  56  has a better defined cavity in which container system  24  is located such that mostly only holder  28  is resiliently held in contact with foam filler  56 . In order to close the area behind container system  24 , a piece of foam filler  56 ″ (depicted with common cross-hatching with filler  56 ) is added behind foam filler  56  in this embodiment. All other features of projectile  50 , such as assembly ballistics and tracer/marker features, are the same as projectile  10  and thus the same reference numerals as used with projectile  10  are used with projectile  50  as well with such similar features not being discussed further. 
   Depicted in  FIG. 4  is a second alternate projectile  60  which differs primarily from projectile  10  by having plastic windshield  21  of outer body  18  replaced by a simple cylindrically shaped plastic outer body  62  with no nose portion. It will be appreciated that outer body  62  includes an expanded portion  63  which engages holder  28  to hold container system  24  in place. Instead of a plastic nose portion  21  formed integral with outer body  12 , a similarly shaped nose portion  64  of foam filler  30  is provided, so that foam filler  30  thus now continues into a foam tip windshield as shown and outer body  62  and nose portion  64  constitute the outer surface of the front end of projectile  60 . Foam filler  30  is placed around container system  24 . Stress grooves  42  (not shown in  FIG. 4 ) are also part of rear base  12  as shown in  FIG. 2 . A foam pad  66  is placed behind container system  24 . As with projectile  50 , all other features of projectile  60 , such as assembly ballistics and tracer/marker features, are the same as projectile  10  and thus the same reference numerals as used with projectile  10  are used with projectile  60  as well with such similar features not being discussed further. 
   In this alternative embodiment, foam nose portion  64  contacts the person or target to be marked and provides an even softer impact. Projectile  60  is assembled by gluing foam pad  66  to rear base  12 . Plastic outer body  62  is glued with epoxy to composite rear base  12 . Glass vials  26  inside holder/spider  28  are then pressed into plastic outer body  62  until plastic spider  28  snaps into groove  67  of plastic outer body  62 . Alternate foam filler  30  may be added between outer body  62  and glass or plastic vials  26 . Foam nose  64  is pressed into outer body which contains epoxy (not shown) at contact points to ensure adhesion. After curing, projectile  60  is pressed into the cartridge case with the primer already inserted until the cartridge case  38  reaches the obturator  45  as previously described. This alternate cartridge design is now assembled. The ballistics projectile  60  of this alternate embodiment are the same as the other non-lethal projectile designs of projectiles  10  and  50 . 
   Depicted in  FIG. 5  is a third alternate projectile  70  which differs from projectile  60  by having outer surface  62  and nose portion  64  formed by a single body  72  formed of foam. With this embodiment, impact on the target is very soft. As with projectile  50 , a piece of foam filler  74 ″ (depicted with common cross-hatching with filler  74 ) is added behind foam filler  74 . In this preferred embodiment, for even greater protection for the target, a foam surface  76  is also provided on the rear base, as well as optional stress grooves as described above. 
   Depicted in  FIG. 6  is a fourth alternative projectile  80  which differs from projectile  10  by having a donut shaped member  82  located behind glass vials  26  as shown. Member  82  forms an enclosed space which is filled with air or a liquid so that member  82  serves as an impact cushion for rear base  12  when the target is impacted to better insure that no damage is inflicted on the target by rear base  12 . 
   As will be appreciated that by those of ordinary skill in the art, the mix of features of the various disclosed embodiments of the projectile of the present invention can be varied by adding from thereto or subtracting therefrom the features of other embodiments, to make additional embodiments with the scope and spirit of the invention. 
   Further, while the present invention has been described with respect to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that other variations and modifications can be effected within the scope and spirit of the invention.