Title:
FUZELESS TARGET PRACTICE CARTRIDGE
United States Patent 3645208
Abstract:
A fuzeless target practice cartridge to produce a flash and smoke signal, on impact of the projectile with the target. This is accomplished by the use of a controllably sensitized pyrotechnic composition, reactive on impact or abrasion, and an ogive-anvil-spike configuration designed to easily rupture upon a low-force impact. The system is made functional by a proper balancing of the sensitivity of the composition and the design of the ogive-anvil-spike configuration depending on the impact force available.
US Patent References:
Incendiary projectile
Ciccone - August 1959 - 2900914
Fire cartridge
Allen - September 1968 - 3401633
Incendiary projectile
Ciccone - August 1959 - 2900914
Fire cartridge
Allen - September 1968 - 3401633
Inventors:
Weinssen, John (Dover, NJ)
Carrazza, James A. (Dover, NJ)
Kaye, Seymour M. (Dover, NJ)
Hoerter, John (Chatham, NJ)
Weingarten, Garry (Morris Plains, NJ)
Carrazza, James A. (Dover, NJ)
Kaye, Seymour M. (Dover, NJ)
Hoerter, John (Chatham, NJ)
Weingarten, Garry (Morris Plains, NJ)
Application Number:
05/011989
Publication Date:
02/29/1972
Filing Date:
02/17/1970
View Patent Images:
Export Citation:
Primary Class:
International Classes:
F42B8/02; F42B12/40; F42B8/00; F42B12/02; F42B13/44; F42B13/14
Field of Search:
102/1M,41,87,92.7
Primary Examiner:
Stahl, Robert F.
Claims:
We claim
1. A fuzeless target practice cartridge for at least a low-force impact comprising: a projectile body; a hollow ogive mounted on said projectile body; means for breaking said ogive upon impact mounted on said projectile body within said ogive; said breaking means being of such configuration as to form a forwardly disposed tearing edge and a space between said breaking means and said ogive; signalling means placed within said ogive in the space between said breaking means and said ogive to provide a flash and smoke signal upon impact and breaking of the ogive said signalling means being sensitive to impact and frictional forces and means for propelling said target practice cartridge.
2. A cartridge as defined in claim 1 wherein said means for breaking the ogive upon impact comprises:
3. A cartridge as defined in claim 2 wherein said cap has a cross-sectional area greater than the cross-sectional area of said body.
4. A cartridge as defined in claim 1 wherein said signalling means comprises a controllably sensitized pyrotechnic composition consisting of about 25 to 45 percent by weight of magnesium, about 25 to 45 percent by weight of red phosphorous and about 10 to 50 percent by weight of barium nitrate.
5. A cartridge as defined in claim 4 wherein said signalling means is in loose homogeneous condition.
6. A cartridge, as defined in claim 1, wherein said means for breaking the ogive upon impact comprises:
7. A cartridge as defined in claim 1 wherein said means for breaking the ogive upon impact comprises:
8. A cartridge as defined in claim 1 wherein said means for breaking the ogive upon impact comprises:
9. A cartridge as defined in claim 1 wherein said means for breaking the ogive upon impact comprises:
1. A fuzeless target practice cartridge for at least a low-force impact comprising: a projectile body; a hollow ogive mounted on said projectile body; means for breaking said ogive upon impact mounted on said projectile body within said ogive; said breaking means being of such configuration as to form a forwardly disposed tearing edge and a space between said breaking means and said ogive; signalling means placed within said ogive in the space between said breaking means and said ogive to provide a flash and smoke signal upon impact and breaking of the ogive said signalling means being sensitive to impact and frictional forces and means for propelling said target practice cartridge.
2. A cartridge as defined in claim 1 wherein said means for breaking the ogive upon impact comprises:
3. A cartridge as defined in claim 2 wherein said cap has a cross-sectional area greater than the cross-sectional area of said body.
4. A cartridge as defined in claim 1 wherein said signalling means comprises a controllably sensitized pyrotechnic composition consisting of about 25 to 45 percent by weight of magnesium, about 25 to 45 percent by weight of red phosphorous and about 10 to 50 percent by weight of barium nitrate.
5. A cartridge as defined in claim 4 wherein said signalling means is in loose homogeneous condition.
6. A cartridge, as defined in claim 1, wherein said means for breaking the ogive upon impact comprises:
7. A cartridge as defined in claim 1 wherein said means for breaking the ogive upon impact comprises:
8. A cartridge as defined in claim 1 wherein said means for breaking the ogive upon impact comprises:
9. A cartridge as defined in claim 1 wherein said means for breaking the ogive upon impact comprises:
Description:
The invention described herein may be manufactured, used and licensed by or for the Government for Governmental purposes without the payment to us of any royalty thereon.
This invention relates to a new fuzeless target practice cartridge for the production of a flash and smoke signature, visible both day and night, upon impact of the projectile with a number of different substrate compositions.
Target practice cartridges are used for familiarizing personnel with a weapon system. These cartridges function by giving off a flash or smoke signal upon impact with the target, thus enabling the personnel using the weapon to determine its range and accuracy. In the past, target practice cartridges, with few exceptions, were either fuzed high explosive or used high-explosive mixture in the ogive to give a signal when impacted upon the target. A few of these used a pyrophoric mixture in the ogival aperture which ignited upon tearing the ogive and contacting the mixture with atmospheric oxygen.
The use of fuzed, high explosive cartridges for target practice is prohibitively expensive and necessarily limits the number of cartridges that can be used to familiarize the personnel with their weapon system. Detonating and pyrophoric mixtures in the ogive are extremely dangerous as they may easily explode or ignite when dropped, these characteristics making this type of cartridge very hazardous to handle. In addition, previous target practice cartridges using a detonating or a pyrophoric mixture in the ogive depended on either a high velocity or a large mass to give the cartridge enough force to cause initiation, tearing of the ogive, and subsequent signaling by the projectile. In particular, a number of standard size projectiles do not have enough mass or a high enough velocity to easily tear the ogive to expose the signalling composition. Also, if a detonating mixture is sensitive enough to explode on a low force impact, it is much too hazardous to be used in the ogive. Further, depending on the type of terrain or substrate the projectile is fired into, the composition in the ogive may or may not initiate, for example, initiation being very difficult to achieve on sand.
As a result, target practice cartridges were frequently nonexistent for certain sizes of rounds and if they did exist, were either too expensive to use to completely familiarize personnel with their weapon system, or too dangerous to handle.
The subject invention, the combination of a specially designed ogive-anvil-spike configuration and a controllable sensitized pyrotechnic composition for use with the new configuration overcomes all the disadvantages of the prior art. This is accomplished with the advantage that such target practice cartridges are rendered capable of signalling upon a low-force impact, yet are safe for handling, and inexpensive to manufacture.
An object of this invention is to provide a new fuzeless target practice cartridge which will provide a signal upon a low-force impact.
A further object of the invention is to provide a new fuzeless target practice cartridge with a controllably sensitized pyrotechnic composition in the ogive to give both a flash and smoke signal, visible both day and night, upon impact.
Another object of this invention is to provide a new fuzeless target practice cartridge, which is economical to produce and safe for handling while providing maximum reliable functionality upon a low-force impact, for familiarizing personnel with a weapon system.
Other objects and many of the attendant advantages of this invention will be readily appreciated as the same become better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
FIG. 1 is a cross-sectional view of the cartridge assembly.
FIG. 2 is a perspective view of the anvil-spike-ogive assembly.
FIGS. 3 through 7 are perspective views of other embodiments of our invention.
Similar numerals refer to similar parts throughout the several views.
The entire cartridge assembly, as shown in FIG. 1, is provided with a projectile body 10 on which is mounted an anvil 12. A capped spike 16 is inserted into the mounted anvil 12 so that it extends forwardly. A rotating band 14 is circumferentially attached to the projectile body 10 by a suitable magniforming or a suitable forging method, and an O-ring 18 is slipped around one end of the projectile body 10 to provide a weatherproof seal. A hollow ogive 20, suitably aluminum, is loaded with a preweighed amount of signalling composition 22. For example, in the case of a 40 mm. projectile, the composition would suitably be 40/40/20 magnesium, red phosphorous, barium nitrate. The assembled projectile body components are then lowered into the ogive 20 until the ogive 20 seats against the projectile body 10, the spike 16 then being in close proximity to the end of the ogive 20. The loaded ogive 20 is then crimped around the projectile body 10. After assembly, the signalling composition 22 is located in the space remaining between the mounted anvil 12 and spike 16 and the projectile body 10 to provide a weatherproof seal. A cartridge case assembly 24, used to propel the projectile, is then placed on the loaded projectile over the O-ring 23 against the rotating band 14 and crimped to form the final assembled practice cartridge.
In FIG. 3 is shown a truncated conically shaped anvil 12 mounted on the projectile body 10 and having a plurality of pointed members 26 attached thereto, the members being of such size as to fit within the hollow ogive 20. The signalling composition is placed within the space left between the ogive 20 and the anvil 12 with members 26 attached. This embodiment is used for a practice cartridge having a low- or high-force impact.
In FIG. 4 is shown a cylindrically shaped anvil 28 mounted on the projectile body 10. The signalling composition is placed in the space left between the ogive 20 and the anvil 28. This embodiment is for use with a practice cartridge having a high-force impact.
In FIG. 5 is shown an anvil comprised of two truncated conically shaped wafers 30 axially connected by a cylindrical member 32 and mounted on the projectile body 10, the wafers being of such size as will fit within the hollow ogive 20. The signalling composition is placed within the space left between the ogive 20 and the attached wafers 30. This embodiment is for use with a practice cartridge having a low or high impact force.
In FIG. 6 is shown a conically shaped anvil 34, of such size as will fit within the hollow ogive 20, coated with any suitable abrasive material 36 to assist in initiation of the signalling composition. The composition is placed in the space left between the ogive 20 and the coated anvil 34. This embodiment is for use with a practice cartridge having a low or high force impact.
In FIG. 7 the target practice cartridge is shown in operation. As shown in FIG. 1, upon impact, the ogive 20 crushes inwardly towards the projectile body 10, and the controllably sensitized signalling composition 22, sensitive to both impact and friction, is initiated. The ogive 20 continues to be crushed throughout the duration of the impact and subjects the sensitized pyrotechnic composition to frictional forces between the ogive 20 and the anvil 12. On a low- or high-force impact, the spike 16 will tear the ogive 20, thereby exposing the sensitized pyrotechnic composition to atmospheric oxygen, which is necessary to complete combustion of the composition. This completed combustion produces the maximum signalling effect. The frictional forces imposed on the composition by the rushed ogive 20 impinging on the anvil 12 also assist in initiating and completing the combustion of the composition.
In the alternative embodiments of our invention as shown in FIGS. 3 through 6, the operation is essentially the same as described for FIG. 1.
As shown in FIG. 3, the pointed members 26 tear the ogive 20 on a low- or high-force impact and frictional forces generated between the ogive 20 and the anvil 12 assist in initiating and completing the combustion of the composition 22.
As shown in FIG. 4, the elongated shape of the anvil 28 with its sharp edges tear the ogive 20 on a high-force impact and the frictional forces between the ogive 20 and the anvil 12 assist in initiating and in completing the combustion of the composition 22.
In FIG. 5, on a low- or high-force impact, the ogive 20 tears on the sharp edges of the wafers 30. The wafers 30 then bend inwardly towards the projectile body 10 subjecting the signalling composition 22 to additional impact force. Frictional forces between the wafers 30 and the ogive 20 assist in initiating and completing the combustion of the composition 22.
In FIG. 6, the ogive 20 tears on the sharp point of the cone on a low- or high-force impact. The frictional forces then generated between the ogive 20 and the abrasive coating 36 on the anvil 34 assist in initiating and completing combustion of the composition 22.
A number of signalling compositions have been evaluated with the ogive-anvil-spike configuration to ascertain the optimal sensitivity and efficiency for use in the finished practice cartridge.
We have found that the use of a homogeneous mixture of magnesium, red phosphorous and barium nitrate provides an excellent method of producing a smoke and flash signature upon impact of a low-force projectile with a variety of substrate compositions, when used in conjunction with our ogive-anvil-spike configuration.
A simple mixture of red phosphorous and magnesium will ignite without the addition of barium nitrate only on a high force impact. The force generated by the impact must be great enough to cause shock initiation of the mixture and to tear the ogive as atmospheric oxygen is require d to complete combustion and cause the terminal signal.
The barium nitrate of our invention increases the shock sensitivity of the mixture and is necessary to provide initiation of the signalling composition upon a low-force impact. The impact sensitivity can be adjusted by varying the amount of barium nitrate used, thus providing a highly efficient signalling composition for both low- and high-force impacts.
One of the effects of this invention is to provide a much more economical method of familiarizing personnel with their weapon system. Previously, fuzed high explosive cartridges were used for familiarization, since these cartridges were expensive, the number of rounds available for practice was necessarily small. Our invention, since it is fuzeless, is much more economical, and hence, a much greater number of rounds will be available for practice resulting in greatly enhanced familiarity with the weapon system. Another effect is that the reliability of initiation on substrate compositions such as sand has been shown to be excellent, so only a small number of misfires have been encountered. Yet another effect is that out pyrotechnic composition provides a maximum amount of smoke and flash while requiring only a minimum amount of composition, thereby making recovery of the few projectiles that do misfire much less hazardous. Any duds in the area are safe and cannot be ignited by being moved or disturbed, thus permitting clearing an area with complete safety to personnel. A further effect is that by adjusting the amount of Ba (NO 3 ) 2 in our composition the projectile can be made more or less sensitive so that the composition may be made suitable for a large variety of rounds with both low- and high-force impacts.
A number of test compositions have been evaluated for impact sensitivity by dropping a 2-kilogram steel weight on them from a specified height. The lower the height which causes initiation, the more impact sensitive the composition. This evaluation was performed using a test described by A. J. Clear, Standard Laboratory Procedures for Sensitivity, Brisance and Stability of Explosives, Picatinny Arsenal Technical Report 3278, December 1965.
Friction tests were also performed by placing about 7 grams of the test composition on a metal anvil, then attaching a specified type of shoe on the end of a weighted pendulum and allowing the pendulum to swing against the composition and abrade it against the metal block. The pendulum swings approximately 18 times for each test. Results were obtained with both a fiber and a steel shoe. In each of the cases there was either complete burning designated by "CB" or complete detonation designated by "CD." This evaluation was performed using a test described by J. H. McIvor, Friction Pendulum, Picatinny Arsenal Manual 7-1, May 1950.
The materials used were atomized magnesium 200/325 mesh, commercial red phosphorous 7±3 microns and ground barium nitrate 1 to 100 microns.
Results of test performed on various mixtures of the materials are reported in Table 1. ------------------------------------------------------------ --------------- TABLE 1
Impact and Friction Sensitivity Test
Composition No. 1 2 3 4 5 6 7 ____________________________________________________________ ______________ Magnesium-weight % 50 45 40 35 30 25 -- Red Phosphorous-- weight % 50 45 40 35 30 25 50 Barium Nitrate-- weight % -- 10 20 30 40 50 50 Height of 2 kg. 28 23 20 12 11 9 6 weight in inches, necessary for detonation Friction Pendulum Fiber Shoe *CB CB **CD CD CD CD CD Friction Pendulum Steel Shoe CB CB CB CD CD CD CD ____________________________________________________________ ______________ *CB represents complete burning **CD represents complete detonation
Test composition Number 2 as described in Table 1, consisting of 45/45/10 magnesium/red phosphorous/barium nitrate was tested in conjunction with the various ogive-anvil configurations described in FIGS. 3 through 6. Results of 40 mm. round test firings at about 500 meters onto sand are reported in Table 2. ------------------------------------------------------------ --------------- TABLE 2
Experimental Firing Test Anvil Configuration Percent Functioning ____________________________________________________________ ______________ a FIG. 1 85 FIG. 3 63 FIG. 4 35 FIG. 5 69 FIG. 6 45 ____________________________________________________________ ______________ a The test conducted with the ogive-spike-anvil configuration of FIG. 1 was performed with Test Composition Number 3.
It is evident from the results set forth in Tables 1 and 2 that a modified signalling composition is necessary to achieve functional reliability with a low-impact round such as a 40 mm. projectile. It is also evident that a specially designed anvil increases this reliability.
Since there are a number of competing variables inherent in the design of a target practice cartridge such as maximum functionality, maximum safety in handling and minimum cost the proper composition and anvil-spike-ogive design can be chosen to provide the desired result for either a low or high impact force cartridge.
We wish it to be understood that we do not desired to be limited to the exact details of construction shown and described for obvious modifications will occur to a person skilled in the art.
This invention relates to a new fuzeless target practice cartridge for the production of a flash and smoke signature, visible both day and night, upon impact of the projectile with a number of different substrate compositions.
Target practice cartridges are used for familiarizing personnel with a weapon system. These cartridges function by giving off a flash or smoke signal upon impact with the target, thus enabling the personnel using the weapon to determine its range and accuracy. In the past, target practice cartridges, with few exceptions, were either fuzed high explosive or used high-explosive mixture in the ogive to give a signal when impacted upon the target. A few of these used a pyrophoric mixture in the ogival aperture which ignited upon tearing the ogive and contacting the mixture with atmospheric oxygen.
The use of fuzed, high explosive cartridges for target practice is prohibitively expensive and necessarily limits the number of cartridges that can be used to familiarize the personnel with their weapon system. Detonating and pyrophoric mixtures in the ogive are extremely dangerous as they may easily explode or ignite when dropped, these characteristics making this type of cartridge very hazardous to handle. In addition, previous target practice cartridges using a detonating or a pyrophoric mixture in the ogive depended on either a high velocity or a large mass to give the cartridge enough force to cause initiation, tearing of the ogive, and subsequent signaling by the projectile. In particular, a number of standard size projectiles do not have enough mass or a high enough velocity to easily tear the ogive to expose the signalling composition. Also, if a detonating mixture is sensitive enough to explode on a low force impact, it is much too hazardous to be used in the ogive. Further, depending on the type of terrain or substrate the projectile is fired into, the composition in the ogive may or may not initiate, for example, initiation being very difficult to achieve on sand.
As a result, target practice cartridges were frequently nonexistent for certain sizes of rounds and if they did exist, were either too expensive to use to completely familiarize personnel with their weapon system, or too dangerous to handle.
The subject invention, the combination of a specially designed ogive-anvil-spike configuration and a controllable sensitized pyrotechnic composition for use with the new configuration overcomes all the disadvantages of the prior art. This is accomplished with the advantage that such target practice cartridges are rendered capable of signalling upon a low-force impact, yet are safe for handling, and inexpensive to manufacture.
An object of this invention is to provide a new fuzeless target practice cartridge which will provide a signal upon a low-force impact.
A further object of the invention is to provide a new fuzeless target practice cartridge with a controllably sensitized pyrotechnic composition in the ogive to give both a flash and smoke signal, visible both day and night, upon impact.
Another object of this invention is to provide a new fuzeless target practice cartridge, which is economical to produce and safe for handling while providing maximum reliable functionality upon a low-force impact, for familiarizing personnel with a weapon system.
Other objects and many of the attendant advantages of this invention will be readily appreciated as the same become better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
FIG. 1 is a cross-sectional view of the cartridge assembly.
FIG. 2 is a perspective view of the anvil-spike-ogive assembly.
FIGS. 3 through 7 are perspective views of other embodiments of our invention.
Similar numerals refer to similar parts throughout the several views.
The entire cartridge assembly, as shown in FIG. 1, is provided with a projectile body 10 on which is mounted an anvil 12. A capped spike 16 is inserted into the mounted anvil 12 so that it extends forwardly. A rotating band 14 is circumferentially attached to the projectile body 10 by a suitable magniforming or a suitable forging method, and an O-ring 18 is slipped around one end of the projectile body 10 to provide a weatherproof seal. A hollow ogive 20, suitably aluminum, is loaded with a preweighed amount of signalling composition 22. For example, in the case of a 40 mm. projectile, the composition would suitably be 40/40/20 magnesium, red phosphorous, barium nitrate. The assembled projectile body components are then lowered into the ogive 20 until the ogive 20 seats against the projectile body 10, the spike 16 then being in close proximity to the end of the ogive 20. The loaded ogive 20 is then crimped around the projectile body 10. After assembly, the signalling composition 22 is located in the space remaining between the mounted anvil 12 and spike 16 and the projectile body 10 to provide a weatherproof seal. A cartridge case assembly 24, used to propel the projectile, is then placed on the loaded projectile over the O-ring 23 against the rotating band 14 and crimped to form the final assembled practice cartridge.
In FIG. 3 is shown a truncated conically shaped anvil 12 mounted on the projectile body 10 and having a plurality of pointed members 26 attached thereto, the members being of such size as to fit within the hollow ogive 20. The signalling composition is placed within the space left between the ogive 20 and the anvil 12 with members 26 attached. This embodiment is used for a practice cartridge having a low- or high-force impact.
In FIG. 4 is shown a cylindrically shaped anvil 28 mounted on the projectile body 10. The signalling composition is placed in the space left between the ogive 20 and the anvil 28. This embodiment is for use with a practice cartridge having a high-force impact.
In FIG. 5 is shown an anvil comprised of two truncated conically shaped wafers 30 axially connected by a cylindrical member 32 and mounted on the projectile body 10, the wafers being of such size as will fit within the hollow ogive 20. The signalling composition is placed within the space left between the ogive 20 and the attached wafers 30. This embodiment is for use with a practice cartridge having a low or high impact force.
In FIG. 6 is shown a conically shaped anvil 34, of such size as will fit within the hollow ogive 20, coated with any suitable abrasive material 36 to assist in initiation of the signalling composition. The composition is placed in the space left between the ogive 20 and the coated anvil 34. This embodiment is for use with a practice cartridge having a low or high force impact.
In FIG. 7 the target practice cartridge is shown in operation. As shown in FIG. 1, upon impact, the ogive 20 crushes inwardly towards the projectile body 10, and the controllably sensitized signalling composition 22, sensitive to both impact and friction, is initiated. The ogive 20 continues to be crushed throughout the duration of the impact and subjects the sensitized pyrotechnic composition to frictional forces between the ogive 20 and the anvil 12. On a low- or high-force impact, the spike 16 will tear the ogive 20, thereby exposing the sensitized pyrotechnic composition to atmospheric oxygen, which is necessary to complete combustion of the composition. This completed combustion produces the maximum signalling effect. The frictional forces imposed on the composition by the rushed ogive 20 impinging on the anvil 12 also assist in initiating and completing the combustion of the composition.
In the alternative embodiments of our invention as shown in FIGS. 3 through 6, the operation is essentially the same as described for FIG. 1.
As shown in FIG. 3, the pointed members 26 tear the ogive 20 on a low- or high-force impact and frictional forces generated between the ogive 20 and the anvil 12 assist in initiating and completing the combustion of the composition 22.
As shown in FIG. 4, the elongated shape of the anvil 28 with its sharp edges tear the ogive 20 on a high-force impact and the frictional forces between the ogive 20 and the anvil 12 assist in initiating and in completing the combustion of the composition 22.
In FIG. 5, on a low- or high-force impact, the ogive 20 tears on the sharp edges of the wafers 30. The wafers 30 then bend inwardly towards the projectile body 10 subjecting the signalling composition 22 to additional impact force. Frictional forces between the wafers 30 and the ogive 20 assist in initiating and completing the combustion of the composition 22.
In FIG. 6, the ogive 20 tears on the sharp point of the cone on a low- or high-force impact. The frictional forces then generated between the ogive 20 and the abrasive coating 36 on the anvil 34 assist in initiating and completing combustion of the composition 22.
A number of signalling compositions have been evaluated with the ogive-anvil-spike configuration to ascertain the optimal sensitivity and efficiency for use in the finished practice cartridge.
We have found that the use of a homogeneous mixture of magnesium, red phosphorous and barium nitrate provides an excellent method of producing a smoke and flash signature upon impact of a low-force projectile with a variety of substrate compositions, when used in conjunction with our ogive-anvil-spike configuration.
A simple mixture of red phosphorous and magnesium will ignite without the addition of barium nitrate only on a high force impact. The force generated by the impact must be great enough to cause shock initiation of the mixture and to tear the ogive as atmospheric oxygen is require d to complete combustion and cause the terminal signal.
The barium nitrate of our invention increases the shock sensitivity of the mixture and is necessary to provide initiation of the signalling composition upon a low-force impact. The impact sensitivity can be adjusted by varying the amount of barium nitrate used, thus providing a highly efficient signalling composition for both low- and high-force impacts.
One of the effects of this invention is to provide a much more economical method of familiarizing personnel with their weapon system. Previously, fuzed high explosive cartridges were used for familiarization, since these cartridges were expensive, the number of rounds available for practice was necessarily small. Our invention, since it is fuzeless, is much more economical, and hence, a much greater number of rounds will be available for practice resulting in greatly enhanced familiarity with the weapon system. Another effect is that the reliability of initiation on substrate compositions such as sand has been shown to be excellent, so only a small number of misfires have been encountered. Yet another effect is that out pyrotechnic composition provides a maximum amount of smoke and flash while requiring only a minimum amount of composition, thereby making recovery of the few projectiles that do misfire much less hazardous. Any duds in the area are safe and cannot be ignited by being moved or disturbed, thus permitting clearing an area with complete safety to personnel. A further effect is that by adjusting the amount of Ba (NO 3 ) 2 in our composition the projectile can be made more or less sensitive so that the composition may be made suitable for a large variety of rounds with both low- and high-force impacts.
A number of test compositions have been evaluated for impact sensitivity by dropping a 2-kilogram steel weight on them from a specified height. The lower the height which causes initiation, the more impact sensitive the composition. This evaluation was performed using a test described by A. J. Clear, Standard Laboratory Procedures for Sensitivity, Brisance and Stability of Explosives, Picatinny Arsenal Technical Report 3278, December 1965.
Friction tests were also performed by placing about 7 grams of the test composition on a metal anvil, then attaching a specified type of shoe on the end of a weighted pendulum and allowing the pendulum to swing against the composition and abrade it against the metal block. The pendulum swings approximately 18 times for each test. Results were obtained with both a fiber and a steel shoe. In each of the cases there was either complete burning designated by "CB" or complete detonation designated by "CD." This evaluation was performed using a test described by J. H. McIvor, Friction Pendulum, Picatinny Arsenal Manual 7-1, May 1950.
The materials used were atomized magnesium 200/325 mesh, commercial red phosphorous 7±3 microns and ground barium nitrate 1 to 100 microns.
Results of test performed on various mixtures of the materials are reported in Table 1. ------------------------------------------------------------ --------------- TABLE 1
Impact and Friction Sensitivity Test
Composition No. 1 2 3 4 5 6 7 ____________________________________________________________ ______________ Magnesium-weight % 50 45 40 35 30 25 -- Red Phosphorous-- weight % 50 45 40 35 30 25 50 Barium Nitrate-- weight % -- 10 20 30 40 50 50 Height of 2 kg. 28 23 20 12 11 9 6 weight in inches, necessary for detonation Friction Pendulum Fiber Shoe *CB CB **CD CD CD CD CD Friction Pendulum Steel Shoe CB CB CB CD CD CD CD ____________________________________________________________ ______________ *CB represents complete burning **CD represents complete detonation
Test composition Number 2 as described in Table 1, consisting of 45/45/10 magnesium/red phosphorous/barium nitrate was tested in conjunction with the various ogive-anvil configurations described in FIGS. 3 through 6. Results of 40 mm. round test firings at about 500 meters onto sand are reported in Table 2. ------------------------------------------------------------ --------------- TABLE 2
Experimental Firing Test Anvil Configuration Percent Functioning ____________________________________________________________ ______________ a FIG. 1 85 FIG. 3 63 FIG. 4 35 FIG. 5 69 FIG. 6 45 ____________________________________________________________ ______________ a The test conducted with the ogive-spike-anvil configuration of FIG. 1 was performed with Test Composition Number 3.
It is evident from the results set forth in Tables 1 and 2 that a modified signalling composition is necessary to achieve functional reliability with a low-impact round such as a 40 mm. projectile. It is also evident that a specially designed anvil increases this reliability.
Since there are a number of competing variables inherent in the design of a target practice cartridge such as maximum functionality, maximum safety in handling and minimum cost the proper composition and anvil-spike-ogive design can be chosen to provide the desired result for either a low or high impact force cartridge.
We wish it to be understood that we do not desired to be limited to the exact details of construction shown and described for obvious modifications will occur to a person skilled in the art.