Armor penetrating projectile

An armor penetrator projectile is disclosed that has an elongated rod penetrator core. The core has a central bore therein extending from a rear portion to a front end portion of the core. The front end portion is preferably conically shaped for impact with an armor plate. A self igniting pyrotechnic material such as thermite is packed within the rear portion and in the bore. The thermite is ignited by the frictional heat and pressure generated during projectile impact with a target armor plate. The ignited thermite ejects a molten jet of material through the bore and forwardly out through the impacting front end thus further melting the armor plate about the point of impact and enhancing the behind armor destructive effects of the projectile.

This invention generally relates to a projectile adapted to penetrate armor 
plate and more particularly to a projectile including a hard, heavy metal 
tubular penetrator core containing a pyrotechnic material. 
Various arrangements of armor piercing projectiles have been advanced for 
penetrating heavy metal armor plate. A typical subcaliber penetrator 
arrangement is disclosed in U.S. Pat. No. 4,638,738. These in general 
either utilize a hard penetrator core or an explosive shape charge. Some 
of these further include explosive or incendiary charges within a 
generally tubular penetrator core. 
Examples of conventional incendiary projectiles having generally tubular 
penetrator cores are disclosed in U.S. Pat. Nos. 2,345,619; 2,532,323; 
2,446,082; and 3,208,385. Each of these patents teaches a structure for 
penetrating a metal or other body and igniting an integrally contained 
incendiary to destroy whatever is behind the surface of the body. However, 
the combustion of the incendiary in each of these is generally randomly 
directed and unfocused. In addition, when a generally stable incendiary 
material is used, an explosive ignition charge must be suppled to ensure 
ignition of the incendiary upon target impact. 
Another conventional incendiary projectile, disclosed in U.S. Pat. No. 
4,237,787, utilizes a firmly packed thermite type composition both in 
front of and behind the hollow nose of the penetrator core. The front 
incendiary ignites upon target impact and the incendiary behind the nose 
portion is ignited following penetration of the target to increase behind 
armor destructive effects. This arrangement is effective to ignite fuel 
canisters and thin skinned vehicles, but would be ineffective against 
heavily armored vehicles. The steel casing between the front and rear 
incendiary charge will fracture upon impact to ignite the rear charge, 
thus providing a delay between the burning of the two charges. 
A more effective design to penetrate heavy armor is a combination of both 
penetrator core and an explosive shape charge packaged together in the 
same projectile. One such arrangement is disclosed in U.S. Pat. No. 
4,102,271 issued to Betheman. The Betheman patent discloses a tandem 
arrangement of a conical rod penetrator and a shape charge tandemly 
arranged with the shape charge behind the penetrator rod. A central axial 
bore through the penetrator rod directs the shape charge jet of material 
to the forward end of the penetrator to enhance penetration. This device 
is particularly designed for use against compartmentalized armor and 
reactive armor. Actuation of the shape charge is deliberately delayed so 
as to defeat the main armor beneath an outer armor layer. The penetration 
in armor plate with the conical penetrator portion of this prior art 
design is limited by the kinetic energy of the penetrator core. The 
Betheman arrangement does not improve the after armor lethality capability 
of the penetrator core. Rather, the conical tubular penetrator rod 
primarily shields the path of the shape charge jet so that the jet 
directly impacts and bores into the main armor. If the outer armor 
thickness is substantial then the tandem arrangement of the shape charge 
may not defeat the armor beneath. In addition, the presence of a high 
explosive shape charge in the projectile disclosed in this prior art 
patent, as well as in other conventional arrangements, such as in U.S. 
Pat. Nos. 4,625,650 and 4,497,253, presents an inherently substantial 
handling hazard because of the presence of the explosive. 
Accordingly, there is a need for an armor piercing projectile which 
enhances the after armor effects capability or lethality of the penetrator 
core without containing explosives. There is also a need for a penetrator 
core design which focuses or directs the ignited incendiary or pyrotechnic 
material to the forward path of the projectile. In addition, there is 
always a need for a simple self igniting incendiary projectile design to 
increase armor penetration and after armor effects which inherently 
increases functional reliability. 
The present invention addresses these needs by providing a simple, 
partially hollow, rod penetrator design in conjunction with a self 
igniting pyrotechnic material. The pyrotechnic material used in the 
present invention, preferably a thermite mixture, is extremely stable 
under normal environmental conditions and thus presents a very low 
handling hazard. One preferable pyrotechnic material is disclosed in U.S. 
Pat. No. 3,695,951 issued to Helms et al and is incorporated herein by 
reference. The pyrotechnic material, positioned behind the forward end of 
the penetrator, is ignited by the heat and pressure created as a natural 
result of impact. The burning pyrotechnic material, requiring no external 
oxygen, produces a molten jet of metal and oxides under high gas pressure 
which is directed forward to the impact point to increase after armor 
effects. 
The rod penetrator of the present invention has a partial axial through 
bore in front of the main pyrotechnic charge wherein a portion of the 
pyrotechnic material resides. This portion of the pyrotechnic material, 
when ignited on impact, in turn ignites the main charge of pyrotechnic 
material. The bore acts as a nozzle which directs the flow of burning 
material which forms a jet of molten metal and oxides at high pressure to 
the point of impact, melting the metal of the armor plate at the same time 
that the penetrator core is punching through the armor plate. The 
additional flow of molten metal and oxide material to the impact point 
further spews past the armor plate and substantially enhances the after 
armor effects of the projectile once penetration has been achieved.

Turning now to the drawing, a saboted subcaliber armor penetrating 
projectile assembly 10 in accordance with the present invention is shown 
in FIG. 1 and indicated generally by the reference numeral 10. The 
projectile assembly 10 includes a penetrator core body 12 and a sabot 14 
around core body 12. The core body 12 has a rear portion 16, a mid portion 
18 and a front end portion 20. A stabilizing fin assembly 22 is fixed to 
the rear portion 16 of the penetrator core body 12 and a streamlined 
plastic nose cone 24 is secured to the forward end portion 20. The fin 
assembly 22 and nose cone 24 provide aerodynamic stabilization and 
improved flight accuracy of the penetrator core body 12 after separation 
of the sabot 14. 
The presence of sabot 14, fin assembly 22, and nose cone 24 is not required 
for the functioning of the projectile according to the present invention 
as set forth below. These components are merely illustrative of a 
preferred embodiment of the invention in a subcaliber kinetic energy 
projectile configuration. 
The penetrator core body 12 is an elongated generally cylindrical rod of a 
heavy, extremely hard metal for penetrating armor plate, preferably 
tungsten, a tungsten alloy, depleted uranium, or other typical penetrator 
material. Penetration is maximized by concentrating the kinetic energy of 
impact over a small area of the target armor plate. Accordingly, the front 
end portion 20 of the penetrator core 12 has an approximately truncated 
cone shape. The plastic nose cone 24 is in turn fixed to the forward end 
of front end portion 20 giving an overall smooth pointed shape to the 
projectile. 
Specifically in reference to FIG. 2, the rear portion of penetrator core 
body 12 has a central, axially aligned, generally cylindrical cavity 26 
therein forming a housing for a plurality of compacted pyrotechnic pellets 
28 preferably disc shaped and stacked axially. These pellets are a 
pyrotechnic mixture such as Pyronol which is a thermite-like mixture of 
nickel, aluminum iron oxide, and a flurocarbon binder. Since thermite is 
self oxidizing, the reaction does not require external support of oxygen. 
When initiated, the exothermic reaction generates extreme heat, high gas 
pressure, and a molten mass of metal and oxides. 
In the middle portion 18 of penetrator core 12 is a narrow central axial 
bore 30 connecting cavity 26 with front end portion 20. The bore 30 
preferably has a diameter about 1/10 that of the cavity 26. The bore 30 
houses an initiating powder 32. This initiating powder 32 is also a self 
oxidizing pyrotechnic mixture such as a thermite material. The initiating 
powder 32 is preferably Pyronol in powder form. 
When penetrator core 12 impacts a target armor plate, the impact creates a 
substantial amount of heat, well in excess of 660.degree. C., and 
liquifies a part of the front end portion 20. The powder 32 ignites when 
it reaches the melting point of aluminum, about 660.degree. C. Once 
initiated, the thermochemical reaction in bore 30 propagates 
spontaneously, igniting the thermite pellets 28 in cavity 26. The burning 
pellets 28 create a molten stream of metal and metal oxide products at a 
temperature of about 2800.degree. C. This stream is forced, by the gas 
pressures of the reaction, in a molten jet through the narrow nozzle 
formed by the narrow bore 30 through the mid portion 18 into and through 
the front end portion 20. 
The molten jet burns forwardly into and through the armor virtually 
simultaneously with the kinetic energy dissipation of the penetrator core 
12. If the core 12 penetrates entirely through the armor, the Pyronol burn 
continues, enhancing the potential for complete ignition and destruction 
of any material behind the armor in the generally forward path of the 
penetrator core 12. 
Thus the penetrator core 12 of the present invention combines the features 
of a kinetic energy round with a self initiating pyrotechnic charge to 
increase the after armor effects. Since the pyrotechnic material, a 
thermite mixture such as Pyronol, requires an initiation temperature of at 
least 660.degree. C., there is very little danger of ignition during 
normal handling. No explosive is utilized and therefore there is virtually 
no personnel hazard associated with handling the projectile assembly. Only 
the heat generated during impact of the core 12 with a target armor is 
sufficient to generate the required initiation temperatures. 
Although the penetrator projectile according to the invention has been 
described with a certain degree of particularity it is to be understood 
that the present disclosure has been made only by way of example. For 
example other pyrotechnic materials may be used so long as they are self 
sustaining, requiring no external oxygen to support the exothermic 
reaction. Numerous changes in the details of construction and the 
combination and arrangement of parts of the projectile illustrated in the 
preferred embodiment may also be resorted to without departing from the 
spirit and scope of the invention as set forth in the following claims.