U.S. patent application number 09/280538 was filed with the patent office on 2003-02-20 for enhanced performance insensitive penetrator warhead.
Invention is credited to BROOKS, GEORGE W., ROACH, ERIC E..
Application Number | 20030033954 09/280538 |
Document ID | / |
Family ID | 23073519 |
Filed Date | 2003-02-20 |
United States Patent
Application |
20030033954 |
Kind Code |
A1 |
BROOKS, GEORGE W. ; et
al. |
February 20, 2003 |
ENHANCED PERFORMANCE INSENSITIVE PENETRATOR WARHEAD
Abstract
A warhead assembly includes a penetrating casing having a
forward nose portion and an generally cylindrical aft portion
opposite said nose portion. A closure ring is disposed in said aft
portion, a vent also being provided in said aft portion. The
warhead casing is filled with a predetermined level of explosive
material. Preferably the explosive composition contain reduced
amounts of explosive material and a strong oxidizer. The warhead
assembly possesses superior penetration and blast performance, as
well as superior Insensitive Munitions characteristics.
Inventors: |
BROOKS, GEORGE W.; (ORLANDO,
FL) ; ROACH, ERIC E.; (ORLANDO, FL) |
Correspondence
Address: |
BURNS DOANE SWECKER & MATHIS L L P
POST OFFICE BOX 1404
ALEXANDRIA
VA
22313-1404
US
|
Family ID: |
23073519 |
Appl. No.: |
09/280538 |
Filed: |
March 30, 1999 |
Current U.S.
Class: |
102/481 |
Current CPC
Class: |
F42B 39/20 20130101;
F42B 30/003 20130101 |
Class at
Publication: |
102/481 |
International
Class: |
F41A 009/00 |
Claims
What is claimed is:
1. A warhead assembly comprising: a penetrating warhead casing
having a substantially ogive-shaped nose portion; a substantially
cylindrical aft portion at an end of the warhead assembly opposite
from said nose portion; and a vent disposed along said aft portion
of said warhead assembly.
2. The warhead assembly of claim 1, wherein said warhead assembly
further comprises: a bore formed in said aft portion of said
warhead casing; an aft closure ring fitted within said bore, and a
vent disposed within said aft closure ring.
3. The warhead assembly of claim 1, wherein said vent comprises at
least one opening in said aft closure ring, the total area of said
at least one opening being approximately 21.7 in.sup.2.
4. The warhead assembly of claim 2, wherein said vent comprises a
plurality of circumferentially-spaced openings.
5. The warhead assembly of claim 4, wherein there are three
circumferentially-spaced openings.
6. The warhead assembly of claim 2, wherein said warhead assembly
further comprises an aft closure retaining ring threadably received
within said bore which retains said aft closure ring within said
bore.
7. The warhead assembly of claim 6, wherein a thin layer of
petrolatum sealant is applied along mating surfaces between said
aft closure ring and said casing, and along mating surface between
said retaining ring and said casing and between said retaining ring
and said aft closure ring.
8. The warhead assembly of claim 2, wherein an explosive material
is contained within said warhead casing.
9. The warhead assembly of claim 8, wherein said vent comprises at
least one opening defining a vent opening area, said explosive
defining a total external explosive surface area, and the ratio of
vent opening area to total external explosive area is approximately
0.27.
10. The warhead assembly of claim 8, wherein said explosive
material has a composition comprising:
4 Min. Amount Max. Amount component (weight %) (Weight %) RDX (4
.mu.) 19.0 21.0 RDX Class I 4.0 6.0 Ammonium Perchlorate 29.0 32.0
Aluminum 32.0 35.0 Poly BD 4.44 4.44 Dioctyl Adipate 6.56 6.56
Isophorone Diisocyanate 0.45 0.45 Lecithin 0.30 0.50 Triphenyl
Bismuth 0.01 0.30 Ethyl-702 0.04 0.06
11. A warhead assembly comprising: a penetrating warhead casing
comprising a vented aft end portion; said casing filled to a
predetermined level with an explosive material; and said warhead
assembly constructed such that it will not explode when subjected
to fast cook-off conditions as set forth in MIL-STD-2105.
12. The warhead assembly of claim 11, wherein: said casing
comprises an ogive-shaped end portion, and a substantially
cylindrically-shaped aft end portion at an end of the warhead
assembly opposite from said nose portion, a bore formed in said aft
end portion; and an aft closure ring fitted within said bore, and a
vent disposed within said aft closure ring.
13. The warhead assembly of claim 11, wherein said vent comprises
at least one opening in said aft closure ring, the total area of
said at least one opening being approximately 21.7 in.sup.2.
14. The warhead assembly of claim 12, wherein said vent comprises a
plurality of circumferentially-spaced openings.
15. The warhead assembly of claim 14, wherein there are three
circumferentially-spaced openings.
16. The warhead assembly of claim 12, wherein said warhead assembly
further comprises an aft closure retaining ring threadably received
within said bore which retains said aft closure ring within said
bore.
17. The warhead assembly of claim 16, wherein a thin layer of
petrolatum sealant is applied along mating surfaces between said
aft closure ring and said casing, and along mating surface between
said retaining ring and said casing and between said retaining ring
and said aft closure ring.
18. The warhead assembly of claim 12, wherein an explosive material
is contained within said warhead casing.
19. The warhead assembly of claim 18, wherein said vent comprises
at least one opening defining an vent opening area, said explosive
defining a total external explosive surface area, and the ratio of
vent opening area to total external explosive area is approximately
0.27.
20. The warhead assembly of claim 18, wherein said explosive
material has a composition comprising:
5 Min. Amount Max. Amount component (weight %) (Weight %) RDX (4
.mu.) 19.0 21.0 RDX Class I 4.0 6.0 Ammonium Perchlorate 29.0 32.0
Aluminum 32.0 35.0 Poly BD 4.44 4.44 Dioctyl Adipate 6.56 6.56
Isophorone Diisocyanate 0.45 0.45 Lecithin 0.30 0.50 Triphenyl
Bismuth 0.01 0.30 Ethyl-702 0.04 0.06
21. A warhead assembly comprising: a penetrating warhead casing,
said casing comprises an ogive-shaped end portion, and a
substantially cylindrically-shaped aft end portion at an end of the
warhead opposite from said nose portion, a bore formed in said aft
end portion; an aft closure ring fitted within said bore, and a
vent disposed within said aft closure ring; and said casing filled
to a predetermined level with an explosive material, said explosive
material having a composition comprising:
6 Min. Amount Max. Amount component (weight %) (Weight %) RDX (4
.mu.) 19.0 21.0 RDX Class I 4.0 6.0 Ammonium Perchlorate 29.0 32.0
Aluminum 32.0 35.0 Poly BD 4.44 4.44 Dioctyl Adipate 6.56 6.56
Isophorone Diisocyanate 0.45 0.45 Lecithin 0.30 0.50 Triphenyl
Bismuth 0.01 0.30 Ethyl-702 0.04 0.06 (% Solids = % RDX + % AP + %
A1
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an improved projectile
construction. In particular, the present invention relates to an
improved penetrator warhead assembly having enhanced
target-defeating capabilities, as well as improved insensitive
munitions characteristics.
[0003] 2. State of the Art
[0004] Implementing an effective penetrating projectile, such as a
warhead, often involves balancing competing factors. A warhead
should have adequate penetration, blast and fragmentation
properties in order to effectively destroy the intended target.
Targets that are difficult to defeat, such as buried or fortified
targets, require a high degree of warhead penetration in order to
be destroyed. The penetrability of a warhead can be increased by
modifying the shape and strength of the nose section, as well as
increasing the overall wall thickness of the warhead. As a result
of such modifications, the payload volume of the warhead is
decreased. Therefore to maintain the same degree of blast
performance in such modified warheads, a smaller quantity of
explosive payload material must be used that is capable of
producing the same explosive performance as larger quantities of
explosive.
[0005] Another important objective in warhead design is the ability
to control detonation of explosive payloads carried by the warhead
so as to avoid accidental of premature explosion of the warhead. In
this regard, the military has increasingly demanded that
contractors develop weapons systems that are less volatile and
therefore less likely to explode unintentionally. These
requirements are often referred to as "Insensitive Munitions" (IM)
requirements and are set forth in military standard
MIL-STD-2105.
[0006] Warheads that have favorable IM characteristics are not only
safer to handle, but are also relatively more effective in
defeating targets that are hard to penetrate since detonation of
the explosive payload of the warhead can be more precisely
controlled, thereby delaying detonation until the warhead has
adequately penetrated the target.
[0007] Accordingly, it would be desirable to provide a warhead
assembly that has good penetrability and blast performance, while
also having enhanced IM characteristics.
SUMMARY OF THE INVENTION
[0008] The present invention is directed to providing warhead
assemblies which are constructed to achieve optimal target
penetration and destruction capabilities, as well as having
favorable IM characteristics which render the warhead assembly
safer and easier to more precisely control detonation. In exemplary
embodiments, a warhead assembly of the present invention has
penetration performance comparable with known warhead
configurations such as the BLU-109 warhead, and blast performance
comparable with the known Mark 83 bomb. The warhead assembly also
conforms with certain IM standards as set forth in
MIL-STD-2105.
[0009] Generally speaking, exemplary embodiments are directed to a
warhead assembly including a warhead casing having a substantially
ogive-shaped nose portion, a substantially cylindrical aft portion
at an end of the warhead opposite from the nose portion, and a vent
disposed along said aft portion of said warhead assembly.
[0010] Other exemplary embodiments of the present invention are
directed to a warhead assembly having a warhead casing including a
vented aft end portion, the casing being filled to a predetermined
level with an explosive material, and the warhead assembly being
constructed such that it will not explode when subjected to fast
cook-off conditions.
[0011] Further exemplary embodiments of the present invention are
directed to a warhead casing which comprises an ogive-shaped end
portion, and a substantially cylindrically-shaped aft end portion
at an end of the warhead opposite from a nose portion, a bore
formed in the aft end portion, an aft closure ring fitted within
the bore, and a vent disposed within the aft closure ring. The
casing is filled to a predetermined level with an explosive
material, the explosive material having a composition
including:
1 Min. Amount Max. Amount component (weight %) (weight %) RDX (4
.mu.) 19.0 21.0 RDX Class I 4.0 6.0 Ammonium Perchlorate 29.0 32.0
Aluminum 32.0 35.0 Poly BD 4.44 4.44 Dioctyl Adipate 6.56 6.56
Isophorone Diisocyanate 0.45 0.45 Lecithin 0.30 0.50 Triphenyl
Bismuth 0.01 0.30 Ethyl-702 0.04 0.06 (% Solids = % RDX + % AP + %
Al
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Other objects and advantages of the present invention will
become more apparent to those skilled in the art from reading the
following detailed description of preferred embodiments in
conjunction with the accompanying drawings, wherein like elements
have been designated with like reference numerals, and wherein:
[0013] FIG. 1 is a longitudinal cross-sectional view of a warhead
assembly constructed according to an exemplary embodiment of the
present invention;
[0014] FIG. 2 is a longitudinal cross-sectional view of the warhead
casing of FIG. 1;
[0015] FIG. 3 is an enlarged partial cross-sectional view of the
aft closure ring assembly of FIG. 1;
[0016] FIG. 4 is an end view along line 4-4 of FIG. 3;
[0017] FIG. 5 is a plan view of a vent opening seal member; and
[0018] FIG. 6 is an end view of the vent opening seal member along
line 6-6 of FIG. 5.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0019] FIG. 1 illustrates an exemplary warhead assembly 100
constructed according to principles of the present invention. The
warhead assembly 100 has a longitudinal axis A and includes a
forward end portion 102. An aft end portion 104 is located at the
end of the warhead assembly 100 opposite the forward end portion
102. The warhead assembly 100 includes warhead casing 200 which
contains an explosive material payload 106. The aft end portion 104
of the warhead assembly 100 includes an aft closure ring assembly
300.
[0020] Referring to FIG. 2, the warhead casing 200 comprises a
substantially ogive-shaped nose portion 202 having a forward
exterior end surface 218, a cylindrical body portion 204, and an
aft end portion 206.
[0021] A bore 208 is formed in the aft end portion 206. The bore
208 forms a large opening in the aft end portion 206 of the warhead
casing 200, thereby facilitating filling of the interior or payload
section of the warhead casing 200 with explosives or other payload
materials. A rear exterior end surface is also defined at the aft
end portion 206.
[0022] An interior surface 210 of the warhead casing 200 defines
the payload section. In one embodiment, the interior surface 210 is
coated with an asphaltic compound 211. One such suitable compound
is specified in military standard MIL-C-3301. A forward interior
end surface 212 is also defined along the interior surface 210.
[0023] The weight and dimensions of the warhead casing can vary,
depending upon the target scenario against which the warhead is
intended to be utilized, among other factors. In one embodiment of
the present invention, the warhead has a weight on the order of 650
lbs. Exemplary dimensions are as follows:
2 Dimension Approximate Value (inches) 216-Longitudinal length
between 64.61-64.08 forward interior end surface 212 and rear
exterior end surface 214. 220-Longitudinal distance between
6.53-5.94 forward interior end surface 212 and forward exterior end
surface 218. 222-Longitudinal distance between 70.61-70.55 forward
exterior end surface 218 and rear exterior end surface 214.
224-Outer diameter of warhead 12.65-12.35 casing at aft end portion
206. 226-Internal radius of curvature 60.01-59.99 along
ogive-shaped nose portion 202. 228-External radius of curvature
81.01-80.99 along ogive-shaped nose portion 202.
[0024] By constructing a warhead casing having a shape according to
the present invention a high degree of penetration of the target
can be achieved. Target penetration of the warhead of the present
invention is comparable with, for example, a conventional BLU-109
warhead.
[0025] Warhead casing 200 can be constructed of any suitable high
strength material. In preferred embodiments, the warhead casing 200
is constructed of a high strength steel alloy. By way of example,
one such alloy is AISI 4335 steel alloy.
[0026] As illustrated in FIGS. 3 and 4, the aft end portion 206 of
the warhead casing 200 is closed by an aft closure ring assembly
300 that is received within bore 208. The aft ring closure assembly
300 comprises an aft closure ring 301 and an aft closure retaining
ring 312.
[0027] Aft closure ring 301 includes a central bore 302 and fuze
liner 304. A fuze (not shown) of any suitable conventional
construction is inserted into central bore 302 and housed by fuze
liner 304. In the illustrated embodiment, aft closure ring 301
includes a solid hub portion 306 with vent openings 308 disposed
therein. Three such openings 308 are illustrated, each opening
defining an open area A.sub.1, A.sub.2, and A.sub.3. Aft closure
ring 301 further includes an outer mounting flange 310 that is
received on a shoulder 311 of the bore 208.
[0028] Aft closure retaining ring 312 is threadably received within
the bore 208 and is tightened so as to engage outer mounting flange
310 and thereby retain aft closure ring 301 in its proper
position.
[0029] When assembling the aft closure ring 301 and aft closure
retaining ring 312, it is desirable to cover the mating surfaces of
the warhead casing 200, closure ring 301 and retaining ring 312
with a petrolatum sealant in order to prevent unwanted leakage from
the payload section of the warhead casing 200.
[0030] The aft closure ring assembly 300 of the present invention
provides several key advantages. Providing the aft closure ring
assembly with a structure for venting the interior explosive
payload section of the warhead assembly 100 allows the explosive
material 106 to "cook-off" in the event that the warhead is exposed
to heat or flame. In other words, instead of being trapped inside
warhead casing 200, reacted explosive material can be expelled from
the interior of the warhead casing 200. In this manner the warhead
is less prone to accidental or unintentional explosions, and the IM
performance is improved.
[0031] In the illustrated embodiment, the venting structure is in
the form of oblong circumferentially spaced openings 308. However,
several alternative venting structures are comprehended by scope of
the present invention.
[0032] For example, the openings may be differently shaped and in
different numbers than the illustrated embodiment. Where venting is
to be provided by openings formed in the aft closure ring 301, the
size, shape, and number of such openings are determined based upon
potentially competing factors.
[0033] First, the required amount of venting is affected by the
rate at which the explosive material 106 reacts when subjected to
heat and/or flame. Clearly, a larger total venting area will be
advantageous in satisfying this first factor. One way of
characterizing this first factor is with the ratio of total venting
area over the total exposed exterior surface area of the explosive
(VA.sub.T/XSA.sub.T). This ratio can be referred to a the ratio of
vent area to burn area. By way of example, in the illustrated
embodiment the open area of each individual vent opening 308 is
7.24 in.sup.2, thereby giving a total venting area of
(A.sub.1+A.sub.2+A.sub.3)=21.7 in..sup.2. The total exposed
external surface area of the explosive contained within the warhead
casing 200 is 79.49 in.sup.2. The ratio VA.sub.T/XSA.sub.T=0.273
and provides beneficial venting performance.
[0034] A second competing factor that must be considered in the
design of the aft closure ring assembly 300 is the structural
integrity that must be possessed by the aft closure ring 301 in
order to survive impact with target. Structural integrity is
required so that penetration and detonation is not adversely
effected. Clearly, the larger the total vent area opening in the
aft closure ring 301, the more the structural integrity is
adversely effected. While the appropriate structural integrity may
be determined through impact testing, the use of commercially
available software such as SAMPLL.TM. or NASTRAN.TM. may also be
used to analyze the structural strength of a particular aft
retainer ring assembly 300 design mounted in case 200.
[0035] By providing an aft ring assembly 300 constructed in
accordance with the principles of the present invention, both
adequate venting and structural integrity can be achieved thereby
improving overall warhead performance and IM characteristics.
[0036] In one embodiment of the present invention, the vent
openings 308 are each sealed or covered by an appropriate sealing
member. One such member 500 is illustrated in FIGS. 5-6. Vent seal
500 is constructed as a thin strip that has a shape roughly the
same as the vent openings 308. Vent seal 500 is sized so as to be
somewhat larger in area than each of the vent openings 308. Vent
seal 500 can be formed of any suitable material, such as an
insulative polymeric material. One such material is described in
military specification MIL-I-23053/5. The vent seal members 500 are
preferably fitted over each vent seal opening 308, then adhesively
bonded to solid hub potion 306 of aft closure ring 301. Upon
exposure to sufficient amounts of heat and/or flame, vent seals 500
thermally degrade thereby clearing the vent seal openings 308 to
permit "cook-off" or venting from the interior of the warhead
casing 200.
[0037] While the above description of venting has centered around
openings formed in the aft closure ring 301, other constructions
are contemplated by the present invention to achieve this result.
For example, at least one closure could be provided in the aft
closure ring assembly 300 which is opened automatically upon
exposure to a predetermined temperature, in essence acting as a
thermally activated valve.
[0038] As previously noted the warhead casing 200 is filled to a
predetermined level "L" (see FIG. 3) with an explosive material
106. Consistent with the principles of the present invention, any
explosive material which possesses both good blast performance as
well as good IM characteristics could be utilized. By way of
example, one such explosive shown to possess the desired properties
is designated as Air Force explosive AFX-757. In one embodiment of
the present invention, a somewhat modified form of the nominal
AFX-757 is used as explosive material 106 and has the following
approximate composition:
3 Exemplary Min. Amount Max. Amount Component Amount (wt. %)
(weight %) (Weight %) Function RDX* (4 .mu.) 20.00 19.0 21.0 High
Explosive RDX* Class I 5.00 4.0 6.0 High Explosive Amonium
Perchlorate 30.00 29.0 32.0 Oxidizer (AP-200 .mu.) Aluminum (17
.mu.) 33.00 32.0 35.0 Metal Fuel Polybutadiene, Liquid, 4.44 -- --
Polymer Hydroxl-Terminated, Type II (Poly BD) Dioctyl Adipate (DOA)
6.56 -- -- Plasticizer Isophorone Diisocyanate 0.45 -- --
Crosslinker (IPDI) Lecithin (Liquid) 0.40 0.30 0.50 Wetting Agent
Triphenyl Bismuth (TPB) 0.10 0.01 0.30 Catalyst Ethyl-702 0.05 0.04
0.06 Antioxidant (* = as set forth in military specification
MIL-R-398)
[0039] An explosive having the above composition uses a reduced
amount of explosive component in order to improve IM
characteristics and prevent premature explosion upon impact with
the target, but includes a strong oxidizer, which drives the
explosive to a very complete reaction, thereby increasing blast
performance. The above composition also provides for acceptable
cure times and processing characteristics. In terms of performance,
the above explosive composition has shown an increase in blast
performance on the order of 38%, and a reduction in materials costs
on the order of 20%, when compared with other standard explosive
compositions, (e.g.--TRITONAL and PBXN-109), while also providing
enhanced IM characteristics.
[0040] By providing the warhead assembly 100 with the combination
of features set forth above, superior IM characteristics, as well
as target destruction capabilities, are obtained.
[0041] The requirements for certification under the military's
Insensitive Munitions guidelines are set forth in military standard
MIL-STD-2105. One indicator of Insensitive munitions
characteristics is performance during a "fast cook-off" test. Under
this test a warhead assembly loaded with an explosive is subjected
to high temperatures over a specified period of time. The test is
"passed" if the explosive material does not explode.
[0042] A loaded warhead assembly 100 constructed according to the
above description was suspended 36 inches above a container 28 ft.
in diameter and 4 inches deep housing 1200 gallons of JP-8 fuel
with 40 gallons of high-octane gasoline. The gasoline was ignited
at four different locations. The temperature rose to approximately
1600.degree. F. in about 12 seconds, rapidly rose to approximately
1800.degree. F., then fell again to approximately 1600.degree. F.
for the remainder of the test. The fuel burned for approximately 35
minutes. No evidence of explosion was observed.
[0043] In terms of target destruction capabilities, a warhead
assembly 100 constructed according to the present invention
achieves superior penetration and blast performance. For example, a
warhead assembly of the present invention can be configured with
penetration performance comparable with the BLU-109 warhead or
better, and blast performance comparable with the Mark 83 bomb or
both.
[0044] The invention has been described above in terms of specific
embodiments merely for the sake of elucidation. No statement above
is intended to imply that the above embodiments are the only
fashion in which the invention may be embodied or practiced, and no
statement above should be so construed. To the contrary, it will be
readily apparent to one of ordinary skill in the art that it is
possible to conceive of many embodiments not described above which
nevertheless embody the principles and teaching of the invention.
The invention should therefore not be limited to what is described
above, but instead should be regarded as being fully commensurate
in scope with the following claims.
* * * * *