U.S. patent application number 14/761167 was filed with the patent office on 2016-05-26 for explosive composition for use in telescopically expanding non-lethal training ammunition.
This patent application is currently assigned to UTM IP LIMITED. The applicant listed for this patent is UTM IP LIMITED. Invention is credited to Adam COLLINS, Michael Ernest SAXBY, Martin SKEATS, David Martin WILLIAMSON.
Application Number | 20160145166 14/761167 |
Document ID | / |
Family ID | 47843487 |
Filed Date | 2016-05-26 |
United States Patent
Application |
20160145166 |
Kind Code |
A1 |
SKEATS; Martin ; et
al. |
May 26, 2016 |
EXPLOSIVE COMPOSITION FOR USE IN TELESCOPICALLY EXPANDING
NON-LETHAL TRAINING AMMUNITION
Abstract
An explosive composition for use in telescopically expanding
non-lethal training ammunition comprises tetrazene and paraffin
wax. The explosive composition can be used as a primer and/or as a
source of energetic material in a telescopically expanding
non-lethal training cartridge; it can be used to propel a
projectile from a telescopically expanding non-lethal training
cartridge; and/or it can be used to expand telescopically a
non-lethal training cartridge within a host gun.
Inventors: |
SKEATS; Martin; (Mildenhall
Suffolk, GB) ; SAXBY; Michael Ernest; (Eastbourne,
GB) ; COLLINS; Adam; (Los Angeles, CA) ;
WILLIAMSON; David Martin; (Cambridge, Cambridgeshire,
GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
UTM IP LIMITED |
Mildenhall Suffolk |
|
GB |
|
|
Assignee: |
UTM IP LIMITED
Mildenhall Suffolk
GB
|
Family ID: |
47843487 |
Appl. No.: |
14/761167 |
Filed: |
January 15, 2014 |
PCT Filed: |
January 15, 2014 |
PCT NO: |
PCT/EP2014/050720 |
371 Date: |
July 15, 2015 |
Current U.S.
Class: |
102/434 ;
102/464; 149/2; 149/36 |
Current CPC
Class: |
F42B 8/02 20130101; C06B
23/005 20130101; F42B 5/045 20130101; F42B 5/16 20130101; C06B
45/00 20130101; C06B 43/00 20130101 |
International
Class: |
C06B 43/00 20060101
C06B043/00; F42B 8/02 20060101 F42B008/02; F42B 5/045 20060101
F42B005/045; C06B 45/00 20060101 C06B045/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 17, 2013 |
GB |
1300839.6 |
Claims
1. An explosive composition for use in telescopically expanding
non-lethal training ammunition comprising tetrazene and paraffin
wax.
2. The composition of claim 1, wherein the paraffin wax is present
in the form of micro particles.
3. The composition of claim 2, wherein the paraffin wax micro
particles have particle diameters in the range of about 0.5 .mu.m
to about 500 .mu.m in diameter.
4. The composition of claim 3, wherein the paraffin wax micro
particles have particle diameters in the range of about 20 .mu.m to
about 200 .mu.m in diameter.
5. The composition of claim 2, wherein the micro particles have
been prepared by a process of spray-cooling or spray congealing of
molten paraffin wax.
6. The composition of claim 1, further comprising from about 1% to
about 50% of paraffin wax by void less volume.
7. The composition of claim 6, wherein the composition comprises
from about 4.5% to about 5.5% of paraffin wax by void less
volume.
8. The composition of claim 1, wherein the composition is
substantially free from lead.
9. The composition of claim 1, wherein the composition is
substantially free from heavy metals and heavy metal compounds.
10. The composition of claim 1, wherein the composition is
substantially free from metals, semi-metals, metal compounds, and
semi-metal compounds.
11. The composition of claim 1, wherein the composition is
substantially free from perchlorate salts.
12. A cartridge for use in non-lethal applications comprising, an
anterior portion and a posterior portion, the posterior portion
comprising a recycling mechanism, the recycling mechanism being
initiated on activation of a primer and the anterior portion being
provided with a nose portion which is suitable for receiving a
projectile, and a source of energetic material located in the
anterior portion, the energetic material being initiatable by a
reaction produced on activation of the primer to cause propulsion
of the projectile from the cartridge, wherein either the primer, or
the source of energetic material, or both the primer and the source
of energetic material include an explosive composition having
tetrazene and paraffin wax.
13. Use of the explosive composition of claim 1 as a primer and/or
as a source of energetic material in a telescopically expanding
non-lethal training cartridge.
14. Use of the explosive composition of claim 1 to propel a
projectile from a telescopically expanding non-lethal training
cartridge.
15. Use of the explosive composition of claim 1 to expand
telescopically a non-lethal training cartridge within a host
gun.
16. A combination of a weapon, a telescopically expanding
non-lethal training cartridge, and an explosive composition of
claim 1.
17. (canceled)
18. (canceled)
19. (canceled)
20. The composition of claim 5, wherein the micro particles are
filtered through one or more meshes.
Description
[0001] The present invention relates to an improved explosive
composition, and its use in telescopically expanding non-lethal
training ammunition.
[0002] The applicant's earlier published patent application WO
01/16550 describes telescopically expanding non-lethal training
ammunition.
[0003] A major problem found in the design of this type of
ammunition is that the impact explosives commonly available in
conventional ammunition primers are very energetic and difficult to
control. Most of the commonly available impact explosives used in
conventional ammunition primers are also toxic.
[0004] It has been found that in currently available telescopically
expanding non-lethal training ammunition, the violent expansion of
the currently available impact explosives provides pressures that
can damage the host gun, and yet during cycling of the host gun the
pressure reduces to levels that fail to fully cycle the host gun
causing jammed rounds.
[0005] It has also been found that using the currently available
impact explosives and other conventional propellants for firing low
energy bullets, the velocity of the bullet is difficult to control
and poor standard deviations in the bullets' velocity can cause
either injury at the higher velocities or barrel jams in the gun at
the lower velocities.
[0006] Typical explosives that are sensitive to input stimuli are
often based on heavy metal compounds. In priming mixtures, lead
2,4,6-trinitroresorcinate (commonly referred to as `lead
styphnate`) and lead azide are the most widely used, owing to their
long-term stability, appropriate explosive output and production of
non-corrosive reaction products. Pyrotechnic mixtures often contain
heavy-metal oxidisers, such as barium nitrate, lead dioxide, lead
tetroxide (commonly referred to as `red lead`), and antimony
sulfide (commonly referred to as `stibnite`). However, the toxicity
of these materials and their reaction products is problematic. For
instance, small arms firing ranges are often found to have
unacceptably high levels of lead compounds in the air. The role of
heavy metal compounds in primary explosives and ignition mixtures
is to provide suitably weak-bonding for sensitivity, and provide
reaction products that are hot, lubricating, and non-corrosive. It
is difficult to achieve this level of functionality without
including heavy metal compounds in such explosives.
[0007] As an alternative to heavy metal compounds, perchlorate
salts have also been used in gas-generating mixtures, but concerns
have now been raised about their toxicity. Accordingly, there is a
need to provide alternative gas-generators as a suitable non-toxic
replacement for both perchlorate salts and heavy metal
compounds.
[0008] The present invention seeks to provide an improved impact
explosive such that the gas generated can be controlled to provide
a more reliable velocity and lower standard deviation of the low
energy bullet, in order to reduce the aggressiveness of the
telescopic expansion of the low energy training cartridge so that
it cycles the host gun more reliably. The present invention also
seeks to provide an improved impact explosive that is non-toxic,
being substantially free from perchlorate salts and metal
compounds, particularly heavy metal compounds.
[0009] In accordance with the present invention, there is provided
an improved explosive composition for use in telescopically
expanding non-lethal training ammunition which comprises tetrazene
and paraffin wax.
[0010] The explosive composition of the present invention has been
found to have a number of advantages, including providing a more
consistent gas production process, which results in more consistent
propulsion velocities and reliable cycling of the host gun. The
explosive composition and its decomposition products are also
non-toxic.
[0011] The invention will be described with reference to the
following figures in which:
[0012] FIG. 1 shows a microscope image of synthesised tetrazene
crystals.
[0013] FIG. 2 shows the approximate particle size distribution of
the synthesised tetrazene crystals.
[0014] FIG. 3 shows a schematic of the equipment for producing
paraffin wax powder by spray-condensation.
[0015] FIG. 4 shows a microscope image of the paraffin wax micro
particles used in the explosive composition, prepared by
spray-cooling of molten paraffin wax.
[0016] FIG. 5 shows a schematic of the packaged explosive
composition for pressure measurement.
[0017] FIG. 6 shows a cross-sectional schematic of the experimental
arrangement for pressure measurement.
[0018] FIG. 7 shows the mean values of ten of ten pressure-time
profiles of pure tetrazene and the explosive composition of the
invention. The pure tetrazene peak mean pressure is 704 bar, with
the peak mean pressure of the explosive composition of the
invention slightly lower at 694 bar. The time to peak pressure for
pure tetrazene is 37 .mu.s and 39 .mu.s for the explosive
composition of the invention.
[0019] FIG. 8 shows the standard deviation of ten pressure-time
profiles of pure tetrazene and the explosive composition of the
invention.
[0020] FIG. 9 shows the mean, and the mean.+-.1 standard deviation
(.sigma.), of ten pressure-time profiles of the explosive
composition of the invention and a commercial lead styphnate based
primer composition.
[0021] The present invention provides an explosive composition for
use in telescopically expanding non-lethal training ammunition
which comprises tetrazene and paraffin wax.
[0022] The following definitions shall apply throughout the
specification and the appended claims.
[0023] Embodiments have been described herein in a concise way. It
should be appreciated that features of these embodiments may be
variously separated or combined within the invention.
[0024] Within the context of the present specification, the term
"comprises" is taken to mean "includes" or "contains", i.e. other
integers or features may be present, whereas the term "consists of"
is taken to mean "consists exclusively of".
[0025] Within the present specification, the term "about" means
plus or minus 20%; more preferably plus or minus 10%; even more
preferably plus or minus 5%; most preferably plus or minus 2%.
[0026] In the present specification, the term "substantially free
from" in relation to a certain substance means at most 1% of that
substance, more preferably at most 0.1% of that substance, even
more preferably at most 0.01% of that substance, most preferably at
most 0.001% of that substance.
[0027] Tetrazene (or tetracene) is the common name for
1-(5-tetrazolyl)-3-guanyl tetrazene hydrate, the compound of
formula (I) shown below.
##STR00001##
[0028] The chemical compound was discovered in 1910, and has been
widely used as an ignition sensitiser in priming mixtures for many
years. Tetrazene's high nitrogen content and high sensitivity to
impact, friction and heat encourages its use in devices that
require energetic output from a small stimulus. Tetrazene derives
its sensitivity from the relatively long and weak C--N bond between
the tetrazole ring and the 3-guanyltetrazene chain. With the
high-nitrogen content of tetrazene, its decomposition products are
nitrogen-rich, allowing it to be a good gas-generator. Tetrazene is
known to have good ageing characteristics, e.g. with 99.9% purity
over 8 years. However, tetrazene's low explosion temperature and
high gas-generating ability as the major gas generating component
of an explosive composition can only be fully utilised if its high
sensitivity can be mitigated.
[0029] Passivation is a common technique for reducing the
sensitivity and reaction rates of many explosives. However, until
now, passivating agents for use with tetrazene have not been
investigated to establish a suitable agent which could potentially
reduce tetrazene's ignition sensitivity and fast decomposition
rate, and thereby enable its use in various new applications.
[0030] It has now surprisingly been found that mixing paraffin wax
with tetrazene effectively passivates tetrazene, thus reducing its
ignition sensitivity and fast decomposition rate. The passivated
tetrazene accordingly has utility as an effective explosive
composition for use in telescopically expanding non-lethal training
ammunition.
[0031] Paraffin wax typically has a melting point of around
65.degree. C., and a heat capacity of 2.14-2.9 kJ kg.sup.-1
K.sup.-1. Its high heat capacity is exploited in applications such
as insulation systems, where it is used to absorb and release heat
slowly.
[0032] The paraffin wax performs a number of functions within the
explosive compositions of the invention. Firstly, it binds the
tetrazene crystals together, allowing the mixture to be pressed
into shape. Secondly, the lubricating paraffin wax fills the
boundaries between tetrazene crystals, reducing contact friction
between the crystals, and thus reducing mechanical sensitivity.
Thirdly, the paraffin wax, when mixed with tetrazene, acts to
reduce large thermal gradients and thus inhibit hotspot formation,
which is thermal in origin. Fourthly, during tetrazene
decomposition, the paraffin wax acts to absorb heat from the
decomposition reaction, and hence reduces the gas-production rate.
Finally, following the decomposition reaction, unburned paraffin
wax can also act as a lubricant, which is useful for continuous
functioning of a projectile-launching system.
[0033] Preferably, the paraffin wax is present in the form of micro
particles. Micro particles are used herein to mean particles of
between 0.5 and 500 .mu.m in diameter. Such micro particles can
conveniently be prepared by spray-cooling or spray congealing of
molten paraffin wax. Micro particles prepared by such processes may
additionally be sieved through a mesh of an appropriate size,
removing those particles that do not pass through the mesh, in
order to ensure a maximum particle diameter. For example, the micro
particles may be sieved through a 300 .mu.m mesh, a 250 .mu.m mesh,
a 200 .mu.m mesh, a 150 .mu.m mesh, or a 100 .mu.m mesh. In a
preferred embodiment, the micro particles are sieved through a 200
.mu.m mesh. The micro particles may also optionally be sieved
through a mesh of an appropriate size, removing those particles
passing through the mesh, in order to ensure a minimum particle
diameter.
[0034] The paraffin wax micro particles typically have particle
diameters in the range of about 5 .mu.m to about 300 .mu.m. For
example, the particle diameters of the paraffin wax micro particles
may be from about 5 .mu.m, about 10 .mu.m, about 15 .mu.m, about 20
.mu.m, about 30 .mu.m, or about 50 .mu.m. For example, the particle
diameters of the paraffin wax micro particles may be up to about
100 .mu.m, about 150 .mu.m, about 200 .mu.m, about 250 .mu.m, or
about 300 .mu.m. In a preferred embodiment, the micro particles
have particle diameters in the range of about 20 .mu.m to about 200
.mu.m.
[0035] Accordingly in one aspect, the present invention provides an
explosive composition for use in telescopically expanding
non-lethal training ammunition which comprises tetrazene and
paraffin wax, wherein the paraffin wax is in the form of micro
particles having particle diameters in the range of about 20 .mu.m
to about 200 .mu.m.
[0036] The explosive composition may comprise the tetrazene and
paraffin wax components in any amounts such that the tetrazene is
effectively passivated and the resultant composition displays an
appropriate pressure-time profile to give acceptable consistency of
gas production. The amounts of the tetrazene and paraffin
components required to display an appropriate pressure-time profile
to give acceptable consistency of gas production may vary dependent
on the type of low energy training cartridge in which the
composition is to be used.
[0037] Compositions of tetrazene and paraffin wax of varying
amounts may be prepared. The compositions may then be characterised
by calculating the void-less fraction of paraffin wax, i.e. the
fraction of the volume occupied by wax if the composition were
pressed to the theoretical maximum density (TMD), an impractical
solution because the powders have a lower pouring density.
Therefore, the following conversion for volume to
mass-fill-fraction was devised. For a percentage .epsilon. of wax,
by void less volume, and a total mixture mass, M, the mass of wax
and tetrazene in the mixture are:
m .omega. = .rho. .omega. .rho. .omega. + ( 100 - ) .rho. t M , and
##EQU00001## m t = ( 100 - ) .rho. t .rho. .omega. + ( 100 - )
.rho. t M ; ##EQU00001.2##
[0038] Where m is mass, .rho. is density and subscripts .omega. and
t refer to paraffin wax and tetrazene respectively.
[0039] Crystal density of Tetrazene=1.63 mg mm.sup.-3.
[0040] Density of paraffin wax=0.84 mg mm.sup.-3.
[0041] For example, the explosive composition may comprise from
about 2% to about 35% of paraffin wax by mass of tetrazene. Thus,
the explosive composition may comprise from about 1% to about 50%
of paraffin wax by void less volume. In compositions containing
more than about 50% of paraffin wax by void less volume, the
tetrazene is not able to function as a gas generator. In
compositions containing less than about 1% of paraffin wax by void
less volume, the tetrzene is not sufficiently passivated and gas
production is too rapid for the desired application in non-lethal
training ammunition, leading to faster and/or less controlled
velocities
[0042] For example, the composition may comprise from about 1%,
about 2%, about 2.5%, about 3%, about 3.5%, about 4%, or about 4.5%
of paraffin wax by void less volume. The composition may comprise
up to about 5.5%, about 6%, about 7%, about 8%, about 10%, about
15%, about 20%, about 30%, about 40%, or about 50% of paraffin wax
by void less volume.
[0043] Accordingly, in one aspect, the present invention provides a
composition comprising from about 2% to about 40% of paraffin wax
by void less volume. Preferably, the composition comprises from
about 2.5% to about 20% of paraffin wax by void less volume, from
about 3% to about 15% of paraffin wax by void less volume, or from
about 3.5% to about 10% of paraffin wax by void less volume. More
preferably, the composition comprises from about 4% to about 8% of
paraffin wax by void less volume. Most preferably, the composition
comprises from about 4.5% to about 5.5 of paraffin wax by void less
volume.
[0044] In one preferred aspect, the present invention provides a
composition comprising about 5% of paraffin wax by void less
volume. Such a composition is particularly effective for use in
conjunction with a 9 mm man marker round.
[0045] As mentioned above, the compositions of the present
invention are designed to be non-toxic. Accordingly, in one aspect,
the present invention provides a composition that is substantially
free from lead. In another aspect, the present invention provides a
composition that is substantially free from heavy metals and heavy
metal compounds. As used herein, heavy metals are understood to
mean metals and semimetals (metalloids) that have been associated
with contamination and potential toxicity or ecotoxicity, and
includes lead, barium, antimony, arsenic, cadmium, cobalt,
chromium, copper, mercury, manganese, nickel, tin, thallium,
beryllium, selenium, zinc, and compounds thereof. In a further
aspect, the present invention provides a composition that is
substantially free from metals, semi-metals, metal compounds, and
semi-metal compounds. In another aspect, the present invention
provides a composition that is substantially free from perchlorate
salts.
[0046] The tetrazene crystals and the paraffin wax micro particles
may be combined using any conventional method of mixing or
blending. Conveniently, the tetrazene crystals and the paraffin wax
micro particles may be combined using a powder mixer.
[0047] The composition of the present invention may additionally
contain amounts of other conventional additives that are commonly
used in explosive compositions. Such additives may include binders,
lubricants and/or dyes.
[0048] The present invention also provides a combination of a
telescopically expanding non-lethal training cartridge, and an
explosive composition of the invention. Suitable cartridges include
those disclosed in WO 01/16550, which include two independent
energetic sources, namely a primer and a source of energetic
material. One of the energetic sources acts to initiate cycling of
the reload mechanism and the other propels a projectile from the
casing. In such cartridges, the explosive composition of the
invention may advantageously be used as either the primer, or the
source of energetic material, or both the primer and the source of
energetic material.
[0049] Accordingly, the present invention provides a cartridge for
use in non-lethal applications comprising an anterior portion and a
posterior portion, the posterior portion comprising a recycling
mechanism, the recycling mechanism being initiated on activation of
a primer and the anterior portion being provided with a nose
portion which is suitable for receiving a projectile, characterised
by a source of energetic material located in the anterior portion,
the energetic material being initiatable by a reaction produced on
activation of the primer to cause propulsion of the projectile from
the cartridge, wherein either the primer, or the source of
energetic material, or both the primer and the source of energetic
material comprise the explosive composition of the invention.
[0050] The present invention also provides the use of the explosive
composition of the invention as a primer and/or as a source of
energetic material in a telescopically expanding non-lethal
training cartridge.
[0051] The present invention also provides the use of the explosive
composition of the invention to propel a projectile from a
telescopically expanding non-lethal training cartridge.
[0052] The present invention also provides the use of the explosive
composition of the present invention to expand telescopically a
non-lethal training cartridge within a host gun.
[0053] The present invention also provides a combination of a
weapon, a telescopically expanding non-lethal training cartridge,
and an explosive composition of the present invention.
[0054] The following Examples illustrate the invention.
EXAMPLE 1
Tetrazene Synthesis
[0055] A solution of sodium nitrite (1.68 g) and dextrin (6 mg) in
distilled water (40 ml) was heated to 50-55 C..degree. with
stirring. Tetrazene was synthesised by slow addition (control flow
rate of 0.15 ml/min) of an acidified solution (pH control to 2.2
with nitric acid) of aminoguanidine Hemisulfate (6.28 g) in
distilled water (80 ml) to the sodium nitrite solution, with
stirring. At this scale, the process time was 4 to 6 hours.
[0056] A precipitate of tetrazene formed, which was filtered,
washed with distilled water, with a final rinse of alcohol, and
oven dried at 50.degree. C. for 8 hours to afford tetrazene
crystals. The product was confirmed as tetrazene by single crystal
X-ray diffraction. The synthesised crystals were small
(approximately 1 .mu.m diameter), and agglomerated readily. A
microscope image of the synthesised tetrazene crystals is shown in
FIG. 1, while FIG. 2 shows the approximate particle size
distribution of the synthesised tetrazene crystals.
EXAMPLE 2
Preparation of Paraffin Wax Micro Particles
[0057] Paraffin wax micro particles were prepared by spray-cooling
of molten paraffin wax (melting point .about.65.degree. C.). The
paraffin wax used in these experiments was supplied by Sigma
Aldrich as 20.times.10.times.5 cm bricks with a melting point of
53-57.degree. C.
[0058] The equipment used for preparing the paraffin wax micro
particles is shown in FIG. 3. The paraffin wax bricks are placed
into a small glass beaker (1) sealed with a sealing lid (2) with
two tubes (3, 4) in the lid, one of which (4) reaches into the wax.
The beaker is heated to around 80.degree. C. Once the wax has
melted to form liquid paraffin wax (5), air jet (7) is forced into
the beaker through tube (3), this in turn forces out a jet of
liquid paraffin wax (6) through tube (4). The jet of hot liquid
paraffin is disrupted sideways with another air jet (8) resulting
in small particles of paraffin wax condensing in the air. The small
particles of wax spray (9) are caught in a large glass beaker (10).
The obtained paraffin wax micro particles were sieved through a 200
.mu.m mesh to afford micro particles with a maximum particle
diameter of 200 .mu.m.
[0059] A microscope image of the paraffin wax micro particles is
shown in FIG. 4. The particles are of a similar approximate size to
the agglomerations of tetrazene crystals.
EXAMPLE 3
Preparation and Packaging of the Composition
[0060] The tetrazene crystals (300 mg) as prepared in Example 1 and
the paraffin wax micro particles (7.92 mg--equivalent to 5% wax by
void less volume) as prepared in Example 2 were weighed out, and
combined in a powder mixer. The resulting TW5 composition was
packaged as a percussion primer for measurement. A plan view of the
packaged TW5 composition is shown in FIG. 5a and a section view of
the packaged TW5 composition is shown in FIG. 5b. A controlled
quantity of the TW5 composition was weighed out, and pressed into a
nickel-plated brass primer cup (11) to form the charge (11). A
paper foil (13) was placed on top of the mixture, and the cup was
sealed with a brass anvil (14). The anvil provides a crush-point
for reliable ignition of the mixture.
EXAMPLE 4
Pressure Measurement
[0061] A diagram of the experimental arrangement for the pressure
measurement is shown in FIG. 6. The packaged TW5 composition (15)
was placed in a sample mount (16). A Kistler 6215 pressure gauge
(17) was mounted on a gauge mount (18) aligned faceon to the open
face of a primer cup holding the packaged TW5 composition. The
packaged TW5 composition was ignited by impact, and its
gas-generating ability was measured in a closed cavity, with the
mechanically shielded Kistler 6215 pressure gauge. The expansion
volume was 32.65 mm.sup.3.
[0062] Pressure measurements were taken of the TW5 composition and
of the same mass of pure tetrazene packaged identically. The TW5
composition was also compared against the pressure-time profile of
a commercial lead styphnate based primer composition. Pressure-time
profiles were evaluated by peak pressure, pressure rise-time and
repeatability of the pressure profile.
[0063] Ten pressure-time profiles of pure tetrazene and the TW5
composition were recorded. The resulting mean and standard
deviation pressure-time profiles are shown in FIGS. 7 and 8
respectively.
[0064] FIG. 7 show that the addition of paraffin wax has slightly
reduced the peak pressure and gas-production rate. FIG. 8 show that
the TW5 composition has a consistently lower standard deviation
pressure than that of pure tetrazene. The addition of paraffin wax
has resulted in more consistent gas-production, likely due to the
reduced gas-production rate. A smaller quantity of the TW5
composition, packaged as before, was compared against a commercial
lead styphnate primer composition. The mean of ten pressure-time
profiles of both the TW5 composition and the commercial primer
composition are shown in FIG. 9. The standard deviation about the
mean is also shown.
[0065] The similarity of the mean pressure-time profiles in FIG. 9
shows that the TW5 composition can be used as a direct replacement
for the lead styphnate based primer composition in a propulsion
system. The standard deviation pressure of the TW5 composition is
much smaller than the lead styphnate based primer composition,
indicating that the gas-production process is more repeatable,
resulting in more consistent propulsion speeds. Table 1 below
summarises the mean and standard deviation velocities for a 270 mg
projectile launched down a barrel by a lead styphnate based primer
composition and the quantity of the TW5 composition shown in FIG.
9. As shown in Table 1, the mean velocities are almost the same,
but the TW5 composition provides better repeatability.
TABLE-US-00001 TABLE 1 Mean and standard deviation muzzle
velocities for a 2.7 g projectile down a barrel Mean muzzle
Standard deviation muzzle Propellant velocity/ms.sup.-1
velocity/ms.sup.-1 Commercial lead 106 6.1 styphnate primer
composition TW5 composition 105.6 .+-. 0.8 5.6
[0066] It is to be understood that the above Examples are merely
exemplary of specific embodiments of the invention and that
modifications can be made to those embodiments without departing
from the scope of the invention.
* * * * *