Note: Descriptions are shown in the official language in which they were submitted.
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ARMOUR PIERCING COMPOSITE PROJECTILE
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to projectiles, and more specifi-
cally to armour penetrating projectiles which contain therein
penetrator cores.
Brief Description of the Prior Art
Heretofore, two main types of armour piercing project-
iles have been utilised. The earlier designs were of a conven-
tional projectile shape and were of full-bore diameter, consisting
of a lightweight material in the nose section and a hardened steel
or high density material core behind the nose section forming the
remainder of the projectile. This type of projectile had limited
ar~our penetration capability. More recently it has been demon-
strated that rod type penetrators fabricated of high density
material are capable of penetrating more armour than the full-bore
deeign. To take advantage of the rod's high ballistic coefficient
and to provide increased initial launch velocities, sabots were
designed to encapsulate the rod penetrator during handling, stor-
age and gun firing, and to dlscard shortly after exiting themuzzle, thus allowing only the rod penetrator to continue in
flight toward the target. The sabot discard process can introduce
trajectory inaccuracies for the rod projectile, as well as repre-
senting a mass-energy loss.
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It is an object of the invention to provide
an armour piercing projectile which overcomes the
problems set forth in detail herein above by
retaining all of the in-bore projectile
components, and which are designed to contribute
to the process of target penetration.
According to the present invention a
composite projectile adapted to be fired from a
gun bore to penetrate armour protected targets
includes a rigid hollow carrier having an open
forward-facing front end and a rear end relative
to the direction of projectile movement toward a
target surface, said carrier having an annular
non-deformable leading edge at said front end, a
penetrator core being adapted to fit in slidable
relationship within said carrier and restrained
within said carrier by a restraining member of
said carrier whereby said penetrator is able to
slide out of said carrier at its front end but not
at its rear end, said core having a front end
which is adapted to penetrate an armoured target
and which, when said projectile is fired, is
situated within said carrier aft of the leading
edge of said carrier.
The projectile according to the present
invention provides improved penetration of
armoured targets, surprisingly without necessarily
requiring the use of discarding components, in the
unique manner described below by which both the
carrier and the penetrator core contribute to the
penetration process.
Preferably, the carrier is elongate and
substantially cylindrical and has a sharp annular
leading edge. The leading edge may be provided by
a bevel on one or both of the inner and outer
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surfaces of the carrier which meet to provide the
leading edge.
The rear end of the carrier may be tapered to
reduce aerodynamic drag. The rear end of the core
may be similarly tapered to be conveniently
accommodated within the carrier.
The said restraining member may be a wall or
collar defining the end of the bore into which the
said penetrator core slidably fits. The rear end
of the carrier may itself be closed and thereby
provide the wall which acts as the restraining
member. The penetrator core may be restrained in
direct contact with the wall or by one or more
intermediate members located between the wall and
the core, e.g. as described further below.
Preferably, the penetrator core has a tapered
front end which desirably terminates in a point.
The taper may be provided as a single conical
section or alternatively as a plurality of conical
sections of different taper angle providing a
gradual convergence to the front of the core of
the profile of the core as seen in cross-section.
The front end of the core may however be an
annular, preferably sharp, non-deforma~le leading
edge. The core may be tubular or partly tubular
and may include within the bore of the tubular
portion a further member, slidably located in the
bore. Such a member may itself provide a
contribution to the target penetration process.
Thus, it may, upon firing, have a front end which
is situated behind the front end of the body of
the core whereby penetration of the target is
provided in a three-stage process by the carrier,
core body and further member slidably fitted in
the core body.
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The further member may have any of the forms
described above which the core itself may have as
a unitary structure.
The front end of the core may, for example,
be situated approximately level with or behind the
beginning of a bevel providing the leading edge of
the carrier when the projectile is fired from a
gun.
The core is preferably made at least in part
of a high density material adapted to penetrate
armour, e.g. of a tungsten alloy or depleted
uranium. Such materials are well known per se to
those skilled in the art. The front end of the
core may be made of the said high density material
although the front end may additionally include a
tip of lighter material, e.g. steel, designed to
provide greater initial penetration of a target
surface as is known to those skilled in the art.
Preferably, the projectile according to the
present invention additionally includes a nose
secured to the carrier at or adjacent to its front
end. Such a nose, which is preferably a fairing
comprising a conical or rounded ogival thin-walled
hollow structure, is adapted to serve as a shield
re~ucing aerodynamic drag of the projectile during
flight toward a target. The nose, which may be
made of a lightweight material such as a plastics
material or an aluminium alloy, is readily
disintegrated upon striking a target. Carried
material, e.g. incendiary or other material, may
be enclosed in the cavity within the nose.
The carrier of the projectile according to
the present invention may be formed of a single
material, e.g. high strength steel, although it
may alternatively comprise a plurality of
dissimilar materials. For example, a forward
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portion including the leading edge of the carrier
may be made of a high strength, high hardness
material, e.g. high strength steel, while a rear
portion may be made of a lighter material such as
an aluminium alloy or a fibre reinforced composite
material. Many such composite materials are well
known to those skilled in the engineering
materials art and may for example comprise fibres
selected from one or more of carbon, boron, glass,
aramid, metal, high strength plastics such as
polyolefin embedded in a suitable matrix such as a
thermosetting or a thermoplastic resin or a
ceramic or metal. The dissimilar portions of the
carrier may be attached together by any suitable
technique well known in the engineering art, e.g.
by screw threads or adhesive bonding. Preferably,
the resulting carrier so formed comprises a single
solid substantially cylindrical hollow mass.
As mentioned above, the penetrator core in
the projectile according to the invention may,
when fitted in the carrier for firing, contact
directly the inner wall of the closed rear end of
the carrier. Alternatively, the rear end of the
carrier and the penetrator core may be separated
by an intermediate member. For example, a slug
may be provided behind the penetrator core. Such
a slug may be made of material which is heavier
than the penetrator core and which provides a
greater impact force to the core when it strikes a
target surface. Alternatively, the slug may
comprise a capsule containing a carried material,
e.g. a chemical agent, an explosive material, an
incendiary material which scatters within a
crew-compartment or the like after penetration.
The outside of such a capsule may for example
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comprise a crushable plastics material or a
composite or metal wall.
The core may conveniently be shaped at its
rear end to receive the slug, e.g. by including a
depression such as a spherical or conical cavity
into which the slug rests.
The carrier, especially in its rear end, may
carry a tracer, e.g. any of the tracers well known
to those skilled in the art.
Unlike the series of Armour Piercing
Discarding Sabot (APDS) projectiles in current
use, the entire armour piercing projectile of this
invention is designed to remain integral when
fired from a gun. Retaining the carrier and
designing it to be utilised to initiate the
penetration process prior to the impact of the rod
core has heretofore never been undertaken and
successfully achieved. The benefit of improved
penetration obtained by the composite projectile
of the invention can however still be achieved
even if the present composite projectile is itself
a sub-calibre component of a larger round which
could, for example, include a discarding sabot or
other component.
In any event, the projectile according to the
invention may be provided with any suitable means
known to those skilled in the art to engage the
rifled barrel of a gun in order to impart to the
projectile rotational torque to provide suitable
in-flight stability.
The gun from which the projectile according
to the present invention is fired may comprise a
small arms weapon, e.g. having a calibre up to
20mm, a medium calibre weapon e.g. in calibres
from 20mm to 60mm, or a heavy weapon e.g. having a
calibre greater than 60mm, although the invention
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is likely to find most use in small arms and
medium calibre applications.
Embodiments of the present invention will now
be described with reference to the accompanying
drawings, in which:
Figure l is a cross-sectional view of one
embodiment of this invention;
Figure 2 is a cross-sectional view of a
second embodiment of this invention;
Figure 3 is a cross-sectional view of a prior
art non-saboted high density core .50 inch calibre
(12.7mm) projectile currently used;
Figure 4 is a cross-sectional view of the
currently used prior art Air Force GAU-8 30mm high
density core projectile;
Figure 5 is a cross-sectional view of the
prior art Armour Piercing Discarding Sabot (APDS)
Projectile as currently used in gun systems such
as the 20mm Phalanx;
Figure 6 is a longitudinal view schematically
illustrating the initiation of the penetration
process as the projectile embodying the invention
impacts the target;
Figure 7 is a longitudinal view schematically
illustrating the continuation of the penetration
process shown in Figure 6;
Figure 8 i8 a cross-sectional view of a third
embodiment of this invention;
Figure 9 is a cross-sectional view of a
fourth embodiment of this invention
Figure 10 is a longitudinal view illustrating
the initiation of the penetration process as the
prior art currently used non-saboted high density
core projectile impacts a target;
Figures 11 to 15 are cross-sectional views of
various penetrator cores in further alternative
embodiments of the invention.
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DESCRIPTION OF THE PREFERRED EMBODIMENTS
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AS shown in Figure 1, a full-calibre
projectile embodying the present invention has an
outward shape and symmetry very similar to those
of conventional projectiles, providing an
advantage not heretofore obtained with known
discarding sabot projectiles. Major components or
parts of this new projectile 10 include an
elongate carrier 11, which may be made of steel,
an elongate rod penetrator core 12, made of high
density material such as tungsten alloy or
depleted uranium, and a thin ogival nose shield 13
attached to the forward end of the carrier 11.
The nose shield 13 may be made of plastics or
aluminium, but in any case is preferably light in
weight. It will be noted in Figure 1 that the
core 12 has a front end in the form of a pointed
nose 14 which is not aligned in a vertical plane
with a beveled leading edge 15 of the carrier 11.
Rather, the core nose 14 is deliberately placed
aft or behind the leading edge 15 of carrier 11
with reference to the travel direction 25 of
projectile 10. Preferably, the front of the nose
14 is approximately level with the start of the
bevel providing the sharp leading edge 15 upon
firing from a gun (not shown). This relative
positioning is done to produce the foliowing
sequence of events and is based on the phenomena
of interaction between the projectile 10 and the
surface of impact.
Upon target impact, the sharp, annular
beveled leading edge 15 of the carrier 11 produces
a stress field in a target 50 as shown in Figure
6. As the stress waves meet in the target
material, they combine and result in a wave
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amplitude increase (Figure 6) which is
significantly larger than that produced by a
conventional armour piercing projectile (Figure
10). This stress field in the target 50 material
is then further increased or reinforced by the
core 12 at the centre impacting the target 50
shortly after the initial impact by the sharp
leading edge 15 of the carrier 11. The target
material cannot resist the sudden or rapid stress
loading and fails. In contrast, a conventional
projectile penetrator 20 such as seen in Figure 3,
upon initial impact with the target, will produce
a series of non-reinforcing stress waves through
the target as shown in Figure 10.
When the projectile embodying this invention
is fired from a gun, the expanding propellant
gases exert a positive force on the projectile
base, which keeps the rod penetrator core 11 set
back to the rear of the carrier 11 in the position
shown in Figure 1. Upon target impact, the thin
aerodynamic shield 13 is readily disintegrated.
As the beveled leading edge 15 makes contact with
the target 50, the projectile 10 is rapidly
decelerated during the initial penetration process
and the abrupt arresting of momentum causes the
higher density rod penetrator core 12 which can
slide inside the carrier ll to be moved violently
forward to add a second generation of impact
stresses as shown in Figure 7. The stress field
initiated by the beveled leading edge 15 of the
carrier 11 is thereby supplemented by a second
series of shock loading stresses concentrated in
the same field, the overall effect being in the
manner of a ~one-two punch~ which is far more
damaging than a single punch by either penetration
mechanism acting alone.
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The projectile shown in Figure 2 is similar
in geometry to the projectile of Figure l, except
that the Figure 2 embodiment has been adapted to
include an incendiary material 16 located inside
the shield 13 and enclosed by the rod penetrator
core 12 and the forward section of the carrier
ll. It will be recognised that either embodiment,
Figure l or Figure 2, could readily include a
known tracer (not shown) in the base of the
carrier body as will be readily apparent to those
skilled in the art.
~ Figure 3 depicts a prior art .50 inch calibre
(12.7mm) conventional anti-armour projectile 20 in
current use. It consists of a high density
material core 21 placed within an aluminium base
carrier 22. The forward section of the projectile
incorporates either a filler material such as a
plaster or an incendiary material 23. The entire
structure is encased by a thin gilding metal
envelope 24. In contrast to the present
invention, the only element of prior art
projectile 20 involved in the target penetration
process is the core 21.
As noted above, it is intended that the
invention may be utilised in a wide range of guns,
from handguns through to larger calibre guns and
the projectile shape and size will vary according
to the application. Elowever, the same beneficial
penetration phenomena discussed above with
reference to Figures 6 and 7 will apply in the
case of the geometric envelope of each specific
projectile size or configuration. As an example
of the range of different projectiles in current
use, although the current .45 inch calibre
(11.4mm) round has a short projectile length to
diameter ratio, it is primarily intended for
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personnel who may be wearing armour vest type
clothing; by contrast, the c~rrent 30mm GAU-8
projectile envelope, shown in Figure 4, allows for
a much greater projectile length to diameter
ratio, which then provides for a longer rod core,
giving more mass and a higher ballistic
coefficient for target penetration. This is
entirely appropriate as the larger calibre
projectiles are intended for anti-material
purposes. The present GAU-8 anti-armour
projectile 30 shown in Figure 4 consists of a high
density material rod core 21 surrounded by an
aluminium material 32 which forms the projectile
configuration. Upon target impact, an aluminium
windscreen 33 is readily broken up leaving the
high density rod 31 to penetrate the target. This
action produces only a single stage penetration
stress pattern and is not capable of defeating
heavy armour plate systems. The projectiles
embodying the present invention may have an
overall shape similar to that of these known
projectiles.
Figure 5 represents a form of the current
discarding sabot projectile as patented by Feldman
(United States Patents Nos. 3,714,900 and
3,905,299). Note that sabot elements 42, 43 and
windshield 44 must be discarded after leaving the
gun muzzle (not shown) in order to allow the
sub-calibre core 41 to continue toward the target
without the considerable ballistic drag which
would result from failure to discard such
components. Besides the expense of producing
sabot sub-assembly components instead of a single
unitary sabot, there is a relatively greater risk
of compromising performance in multiple-component
sabots. Thus, the sabot must totally discard all
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its parts in a matter of micro-seconds,
immediately when the round exits the gun muzzle,
and without any angular or lateral non-symmetrical
forces applied to the core 41 such as would
disrupt its uninhibited trajectory even slightly.
Any such aerodynamic perturbations during discard
could cause the penetrator to miss the distant
target or to alter its angularity at impact, which
degrades its penetration effectiveness away from
optimum design conditions. In contrast, the
projectiles embodying this invention need not have
discarding dead-weight, high drag masses or
parasitic elements which do not contribute to the
penetration process, and their accuracy need not
be compromised by highly sensitive and unreliable
sabot-discarding mechanisms.
Referring to Figure 8, a further embodiment
of the present invention is seen for use where gun
recoil and barrel forces are limited within a
narrow performance force envelope, and excessive
impulse loading could destroy the weapon by using
projectiles having a higher mass than that the gun
is designed to fire. To accelerate a projectile
for armour piercing capability without exceeding
gun total impulse design limitations, a decrease
in projectile mass may be desirable. Therefore,
in the embodiment shown in Figure 8, this is
accomplished by forming the carrier 11 in two
parts instead of a single unitary mass as shown in
Figure 1. The Figure 8 modification shows carrier
ll comprising two structurally joined portions 26
and 18 made from two dissimilar materials.
Forward portion 26 formed with the forward sharply
beveled leading edge 15 is made of undeformable
and high-hardness material such as high-strength
steel, while aft or rear portion 18 is made of
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lighter weight material such as aluminium,
reinforced plastics or strong and lightweight
composite fiberglass or filament laminates of
metallic, ceramic and non-metallic materials.
Elements 26 and 18 are securely joined at their
interface 19 by any suitable means such as
screw-threads, various high-strength epoxy based
adhesives, or any other assembly techniques known
to the prior art and widely used in industry.
When thus joined, elements 26 and 18 form a single
solid, substantially cylindrical hollow mass which
is dimensioned so as to grasp snugly the heavier
and higher density penetration core 12 in the same
manner that carrier 11 embraces and retains the
core 12 in Figure 1.
Figure 9 shows a further modification of the
inventive structure. In this case, wherein the
mass slidably located inside the carrier 11
instead of being a simple homogeneous core 12 as
in Figure 1, is composed of plural elements
consisting of a front core 12 and a rear element
17. The core 12 has a generally conical pointed
nose 14 and is made from high density,
non-deforming material which may be the same as
the materials discussed above for the core 12
shown in Figure 1. Element 17 behind the core 12
is of material different from the core 12,
however, and may be heavier or lighter, depending
upon the combat needs which the round is designed
to fulfil. Thus, for example, the element 17 may
be an elongate slug of material heavier than core
12, and may be positioned so as to add greater
impact force to assist the core 12 at the time
projectile 10 strikes a target surface. The core
12 shown in Figure 9 is provided with a depression
such as a spherical or conical cavity at its aft
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or base end opposite from the nose 14. The
element 17 has either a spherical or conical
forward end portion which nests or bears against
the aft cavity in core 12 as shown in Figure 9 in
a symmetrical pattern of surface bearing contact.
The element 17 may, alternatively, comprise a
crushable plastics, composite, or metallic capsule
containing a carried material. The precise
composition of the carried material will depend
upon the combat need to be served. Thus, the
element 17 may for example comprise a chemical
agent, an explosive material, or an incendiary
material which scatters within a crew compartment
or the like after penetration is achieved by the
carrier 11 and the core 12.
In each of the above described embodiments of
the present invention the penetrator core 12 has a
pointed nose 14. The nose 14 is shown in each
case as being of the same material as the body of
the core 12 although it could have a tip of
different material, e.g. steel where the core 12
body is of tungsten alloy or depleted uranium.
In the embodiments shown in Figures 11 to lS
various alternative forms of the penetrator core
12 only are shown in which the front of the core
12 is provided in each case by a sharp annular
leading edge 64 instead of the pointed nose 14
shown in Figure 1.
In Figure 11 the core 12 is tubular and the
leading edge 64 is provided by beveled surfaces 65
on the inside and outside of the tube.
In Figure 12 the shape of the core 12 is
similar to that shown in Figure 11 except that
only a front portion 66 of the core 12 is
tubular. The core 12 in this case has a rear
portion 67 which is solid. As shown, the rear
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portion 67 may be of different material, e.g.
heavier material, than that of the front portion
66.
In Figure 13 the shape is similar to that
shown in Figure 11. However in this case the
tubular core 12 additionally contains a rod 68
slidably fitted within the core 12. The rod 68
is, upon firing of the projectile/ set back within
the bore of the core 12 in the same manner that
the core 12 is itself set back within the carrier
11 as described with reference to Figure 1. Thus,
the carrier 11, tubular core 12 and rod 68 serve
in this case to provide a three stage target
penetration process instead of the two stage
process described with reference to Figure 7.
In Figure 14 the annular leading edge 64 is
provided at the front of a conical portion 69, the
edge 64 being sharply formed by a slot 61 machined
in the front of the core 12.
The embodiment shown in Figure 15 is similar
to that shown in Figure 14 except that in Figure
15 the body of the core 12 is tubular. In a
similar alternative embodiment (not shown) to that
shown in Figure 15 the rear end only of the core
12 may be tubular.
In each of the embodiments shown in Figures
11 to 15 the core 12 is to be fitted in its
carrier 11 in the manner shown in Figure 1 and a
nose 13 is to be fitted on the front of the
carrier 11, also as shown in Figure 1.
In all embodiments of this invention, the
cav~ity inside the nose 13 may be used for loading
useful carrier material other than incendiary
material (as mentioned).
Any of the projectiles according to the
present invention fired from the bore of a gun are
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spin stabilised in flight. The carrier (e.g.
carrier 11) may include any suitable means to
engage the rifled barrel of a gun to impart the
necessary rotational torque, e.g. a driving band
or pusher/obturator may be used as will be
apparent to those skilled in the art.
