Armor piercing incendiary projectile

Abstract

An improved armor piercing and pyrotechnic projectile for use in .50 military caliber rounds. Such projectiles contain a core, jacket, a base and a hollow nose housing pyrotechnic mixtures composed of sodium periodate and magnalium. The improved projectiles exhibit increased luminosity, and are non-toxic, safer, and environmentally benign compared to current state-of-the-art projectiles.

Claims

1. An improved armor piercing incendiary projectile comprising; a jacket having a tip, a base and a metal core, wherein the tip comprises a hollow nose having a pyrotechnic composition consisting essentially of sodium periodate, magnalium and a flow agent, wherein the sodium periodate is about 30 to about 50 weight percent of the composition, the magnalium is about 50 to about 70 weight percent of the composition, and the flow agent is an additional 0.01 to 0.05 of the total weight of the composition.

2. The projectile of claim 1, wherein the magnalium is a chemical alloy of aluminum and magnesium at a ratio of about 1:1.

3. The projectile of claim 1, wherein flow agent is calcium stearate or fumed silica.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be better understood, and further objects, features, and advantages thereof will become more apparent from the following description of the preferred embodiments, taken in conjunction with the accompanying drawings.

(2) The FIGURE is a cross-section of the armor piercing incendiary projectile of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

(3) Disclosed herein are armor piercing incendiary projectiles containing an incendiary composition that is an improvement over current projectiles as being less toxic and environmentally safe while having enhanced incendiary effects and pyrotechnic flash.

(4) Generally armor piercing incendiary projectiles such as those for M8 API, MK257 APT-DT .50 caliber rounds will disperse incendiary material upon impact to disclose the location of the target as well as causing collateral damage by igniting flammable material.

(5) The FIGURE is an illustration of an exemplary armor piercing incendiary projectile. The projectile contains a core 1, which is typically comprised of a metal such as steel or lead fitted inside a metal jacket 2. The front of the core is shorter than the jacket leaving a space at the tip of the jacket (i.e. hollow nose) when the core is seated inside the jacket. The hollow space 3 at the nose of the jacket houses the incendiary composition 4. At the rear of the jacket and core is the base 5, which may be sealed off to prevent exposure of the powder flame from the cartridge propellant to the incendiary composition. Optionally, a tracer composition may be placed on the rear of projectiles, i.e. on or near the base, to indicate the projectile's path during flight.

(6) The incendiary composition provided herein comprises an oxidizer such as sodium periodate. The composition further comprises magnalium a binary fuel system comprising a chemical alloy of aluminum and magnesium. The incendiary composition may further comprise a flow agent such as fumed silica or calcium stearate.

(7) The current, prior art IM-28 U.S. military incendiary composition formulation is shown in Table 1, below, wherein the Ba(NO.sub.3).sub.2 and the KCIO.sub.4 serve as oxidizers and the 50:50 magnesium-aluminum alloy (magnalium) serves as the fuel.

(8) TABLE-US-00001 TABLE 1 Composition of current in-service US military IM-28 incendiary Weight Component Percentage (%) Ba(NO.sub.3).sub.2 40% KClO.sub.4 10% magnalium 50%

(9) The preferred incendiary embodiment of the present invention is shown in Table 2. As shown in the table below, the preferred weight percentage range for the oxidizer is 30-50 wt. %, 50-70% for the fuel, along with an additional 0.01 to 0.05 percent of a flow agent per the total weight of the composition.

(10) TABLE-US-00002 TABLE 2 Alternative preferred embodiment of the present inventive incendiary composition. Subject Invention 1 Component Weight Percentage (%) NaIO.sub.4 30-50 magnalium 70-50 Flow agent +0.01-0.05

(11) The performance of the alternative preferred embodiments of the present incendiary composition shown in Table 2 is compared to the current state-of-the-art IM-28 incendiary composition in Table 3, below.

(12) TABLE-US-00003 TABLE 3 Laboratory performance of the present invention vs. the current in-service IM-28 incendiary composition Burn Luminous Impact Time Efficiency Sensitivity Formulation (seconds) (cd.Math.s-gm.sup.1) (Joules) Current IM-28 0.109 11,294 2.94 Subject composition 0.185 13,504 9.80

(13) Table 3 illustrates that the subject composition containing NaIO.sub.4 in the formulation exhibits up to about 20% more luminous efficiency vs. the current IM28 formulation. Furthermore, that exhibited brightness will appear to be enhanced because of the spectral emission corresponding to gaseous atomic sodium which gives off a more discernible yellow light than the blueish white light from the current IM-28.

(14) As stated above, an important attribute of the present invention, containing NaIO.sub.4 as the oxidizing agent, is the fact that it is non-hygroscopic. The non-hygroscopic nature of this preferred embodiment is demonstrated in Table 4, below, in relation to other common pyrotechnic oxidizers, such as Sr(NO.sub.3).sub.2 and NaNO.sub.3, known as alternatives to Ba(NO.sub.3).sub.2 and KCIO.sub.4 in the present IM-28 composition.

(15) TABLE-US-00004 TABLE 4 Water solubility data for current inventive preferred oxidizer vs. known nitrate oxidizer alternatives. Water Solubility Ingredient [g per 100 g H.sub.2O] NaNO.sub.3 91.2 Sr(NO.sub.3).sub.2 80.2 NaIO.sub.4 14.4

(16) The ballistic performance of the inventive composition exceeds that of the currently specified IM-28 incendiary filler for M8 .50 caliber APIs. Table 5 below compares the performance of the subject composition and IM-28 when each is charged into actual bullets and gun-fired during the Incendiary Flash and Penetration qualification tests. These tests are part of the typical lot acceptance testing and both must be passed with the minimum scores in the Success Criteria column. From Table 5, it is clear that the subject composition, while being free of environmentally objectionable materials, also offers superior performance to the currently specified art.

(17) TABLE-US-00005 Qualification Success Subject Test Reference Criteria IM-28 Composition Incendiary TECP 700-700, >70% 93% 96% Flash Vol. III Penetration TECP 700-700, >87.5% 97.5% 100% Vol. III

(18) The subject preferred inventive incendiary composition was prepared by first oven drying the oxidizer(s), screening the oxidizer(s) through a 60-mesh sieve. The dried and screened oxidizer(s) was then combined with the fuel in a conductive container, and the binary mixture was dry-tumbled therein for a period of up to about 30 minutes to ensure thorough mixing/blending. The thoroughly blended composition therefrom was manually pressed into pellets for static ignition testingto establish the reported burn times and luminous efficienciesor subjected to a variety of physical stimuli as small, loose powder samples (ca. 20 mg)to determine sensitivity dataor alternatively, charged as a loose powder into bullet hardware for ballistic tests. Further, as noted above, a small quantity of hydrophobic fumed silica or calcium stearate (about 0.01 to about 0.05 wt. % per total weight of composition) can be added to the oxidizer after it is screened; but, before it is blended with a metal fuel, to enhance uniformity of the resulting inventive incendiary compositioni.e. the oxidizers ability to be thoroughly mixed with the metal fuel, esp. 50/50 magnalium fuel, is enhanced. And, where the 50/50 magnalium (having a preferred mean particle diameter of about 18.4 m) is available from Magnesium Elektron Powder Products N.A. (Reade Manufacturing Company), Manchester, N.J. 08759.

(19) NaIO.sub.4 oxidizing agent is available from William Blythe, Ltd, Lancashire, England BB5 4PD, or Alfa Aesar, a Johnson Matthey Company, located in Ward Hill, Mass. 01835having a preferred mean particle diameter of about 61.8 m.

(20) The luminous efficiency, the integrated luminous intensity per unit mass, as reported above was established using a single-element photopic light detector. The light detector was manufactured by International Light and is composed of a SED 033 silicon detector (33 mm.sup.2 area silicon detector with quartz window) coupled to a photopic filter (Y-filter) and a field of view limited hood (H-hood). The current output of the detector was converted to a voltage using a DL Instruments 1211 transimpedance amplifier. Voltage output was collected and analyzed form the amplifier using a NI-6115 National Instruments data card and in-house developed Labview based data acquisition and analysis software.

(21) Ballistic test data for the subject composition were obtained by standard methods described in TECP 700-700, Volume III. For incendiary flash, 20 rounds derived from the subject composition were fabricated and gun-fired in a test tunnel. The flash resulting from each shot was recorded by high speed camera and compared to the flash silhouettes on a standard drawing. Scores ranged from 0 (no flash, dud) to 5 (robust, bright flash) and an overall percentage was obtained by simply adding up all 20 individual scores. For .50 caliber rounds, a minimum flash score of 70% is required for lot acceptance. For the penetration tests, 20 more rounds were fabricated and gun-fired at a 1.00 thick steel plate. The terminal effect at the target plate was noted for each shot and only those shots resulting in complete perforation of the plate were credited; other outcomes such as bulge rear no cracks, spall, or partial penetration were not credited. A final penetration score was obtained by adding the number of credited shots and multiplying by five. For .50 caliber rounds, a minimum penetration score of 87.5% is required for lot acceptance.

(22) Although the invention has been described above in relation to preferred embodiments thereof, it will be understood by those skilled in the art that variations and modifications can be effected in these preferred embodiments without departing from the scope and spirit of the invention. Further, while specific weights or ratios may have been used by way of example/specific embodiments, it is also understood by those skilled in the art that quantities of the materials between and about the ratios are equally functional.