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A Study of Wildfire Ignition by Rifle Bullets

Authors:

Abstract

Experiments were conducted to examine the potential for rifle bullets to ignite organic matter after impacting a hard surface. The tests were performed using a variety of common cartridges (7.62 × 51 [.308 Winchester (The use of tradenames is provided for informational purposes only and does not constitute an endorsement by the U.S. Department of Agriculture.)], 7.62 × 39, 7.62 × 54R, and 5.56 × 45 [.223 Remington]) and bullet materials (steel core, lead core, solid copper, steel jacket, and copper jacket). Bullets were fired at a steel plate that deflected fragments downward into a collection box containing oven-dried peat moss. We found that bullets could reliably cause ignitions, specifically those containing steel components (core or jacket) and those made of solid copper. Lead core-copper jacketed bullets caused one ignition in these tests. Thermal infra-red video and temperature sensitive paints suggested that the temperature of bullet fragments could exceed 800°C. Bullet fragments collected from a water tank were larger for solid copper and steel core/jacketed bullets than for lead core bullets, which also facilitate ignition. Physical processes are reviewed with the conclusion that kinetic energy of bullets is transformed to thermal energy by plastic deformation and fracturing of bullets because of the high-strain rates during impact. Fragments cool rapidly but can ignite organic matter, particularly fine material, if very dry and close to the impact site.
A Study of Wildfire Ignition by Rifle
Bullets
Mark A. Finney and Sara S. McAllister*, Missoula Fire Sciences Laboratory,
USDA Forest Service, 5775 W US Highway 10, Missoula, MT 59808 ,
USA
Trevor B. Maynard, San Dimas Technology and Devel opment Center, USDA
Forest Service, San Dimas, CA, USA
Ian J. Grob, Missoula Technology and Development Center, USDA Forest
Service, Missoula, MT, USA
Received: 10 February 2015/Accepted: 3 July 2015
Abstract. Experiments were conducted to examine the potential for rifle bullets to
ignite organic matter after impacting a hard surface. The tests were performed using
a variety of common cartridges (7.62 9 51 [.308 Winchester (The use of tradenames
is provided for informational purposes only and does not constitute an endorsement
by the U.S. Department of Agriculture.)], 7.62 9 39, 7.62 9 54R, and 5.56 9 45 [.223
Remington]) and bullet materials (steel core, lead core, solid copper, steel jacket, and
copper jacket). Bullets were fired at a steel plate that deflected fragments downward
into a collection box containing oven-dried peat moss. We found that bullets could
reliably cause ignitions, specifically those containing steel components (core or jacket)
and those made of solid copper. Lead core-copper jacketed bullets caused one igni-
tion in these tests. Thermal infra-red video and temperature sensitive paints suggested
that the temperature of bullet fragments could exceed 800°C. Bullet fragments col-
lected from a water tank were larger for solid copper and steel core/jacketed bullets
than for lead core bullets, which also facilitate ignition. Physical processes are
reviewed with the conclusion that kinetic energy of bullets is transformed to thermal
energy by plastic deformation and fracturing of bullets because of the high-strain
rates during impact. Fragments cool rapidly but can ignite organic matter, particu-
larly fine material, if very dry and close to the impact site.
Keywords: Ignition, Hot particles, Rifle bullets, Ballistic impact, Smoldering
1. Introduction
In the United States, outdoor target shooting has been suspected as the source of
numerous wildland fires [1, 2]. Anecdotally, the ammunition involved in most inci-
dents is thought to be of ordinary commercial varietie s with bullets composed of
* Correspondence should be addressed to: Sara S. McAllister, E-mail: smcallister@fs.fed.us
This manuscript was written and prepared by a U.S. Government employee on official time and
therefore is in the public domain and not subject to copyright. The use of tradenames is provided for
informational purposes only and does not constitute an endorsement by the U.S. Department of Agri-
culture.
Fire Technology
Ó 2015 The Author(s). This article is published with open access at Springerlink.com
Manufactured in The United States
DOI: 10.1007/s10694-015-0518-6
1
inert materials including lead, steel, and copper. No scientific studies to date have
specifically addressed projectile behavior or properties related to ignition of wild-
land vegetation or organic material. Thus, the primary focus of this study is whe-
ther inert projectiles fired from commonly available modern firearms can cause
ignition of wildland vegetal matter.
The possible mechanism by which inert projectiles cou ld cause ignitions involves
the conversion of kinetic energy to thermal energy at impac t with a solid object or
target. In general, pistol cartridges are designed to propel a bullet much slower
with less energy than rifle cartridges. Table 1 indicates approximate muzzle energy
for a v ariety of different cartridges. Rifle bullets should thus be the most likely to
have sufficient energy for ignition, and will thus be the focus of the study.
Because modern rifle bullets are accelerated to high velocities, they are typically
covered with a thin layer of a protective metal, called a jacket. All rounds used in
this study used steel or copper jackets. In general, depending on their intended
use, bullets may be designed to achieve immediate expansion within the target (ex-
panding bullets, such as for hunting) or penetration through the target (armor-
piercing rounds). Armor-piercing roun ds typically contain a penetrator con-
structed of steel or another high density metal. The jacket is destroyed on impact,
but the penetrator’s momentum propels it into the target substrate. These different
bullet designs are incorporated into the study.
Ballistic impact has been researched extensively but has been directed princi-
pally toward understanding penetration or perforation of target materials. For a
particular target, projectiles of a given speed will perforate it at higher angles (clo-
ser to normal) and ricochet at lower angles (more oblique) [3 , 4]. The conse-
quences of such impacts most pertinent to ignition are where the impact: (1)
converts a large fraction of kinetic energy to thermal energy, (2) fractures the bul-
let or target into pieces large enough to ignite organic matter, and (3) ejects hot
material into the organic matter. We reasoned that these conditions should occur
most commonly with oblique impacts on a highly resistant target (no penetration
or perforation). The target used in this study is a steel plate angled 20° to 80°
from horizontal.
Because the heating required to initiate smoldering combustion is considerably
lower than flaming combustion and smoldering can transition to flaming combus-
Table 1
Typical Velocity and Kinetic Energy of Common Small Arms Cartridges
[6]
Cartridge Typical firearm used Weight (g)
Muzzle
velocity (m/s)
Kinetic
energy (J)
.22 LR 22 rifle 3 361 195
.45 ACP M1911 Semi-automatic
pistol
15 270 547
5.56 9 45 mm NATO M-16 rifle 4 920 1693
7.62 9 51 mm NATO M-14 rifle 9 840 3175
.50 BMG M2 heavy machine gun 43 850 15,533
Fire Technology 2015
tion when conditions change (creating a ‘‘hazardous shortcut to flaming fires’’ [5]),
a smoldering ignition is considered as much of a concern as direct flaming ignition
in this study.
2. Background
As in-barrel and aerodynamic heating are negligible in terms of bullet temperature
increase, the primary source of heating is interaction between the bullet and tar-
get. The mechanics of this energy dissipation depend on target and bullet con-
struction. A resilient target, such as the steel plate used in this study and other
commonly used targets, requires a large amount of energy to become deformed.
The majority of the kinetic energy of the bullet will thus be used to plastically (ir-
reversibly) deform the bullet. For most metals, almost all energy conversion dur-
ing high strain-rate deformation is manifest as heat [79 ], and because very little
heat is lost during the process, many investigators consider the deformation to be
adiabatic. No empirical studies of bullet fragment temperatures have been found,
but numerical experiments have shown temperature at the impact interface to
increase with velocity [8, 10]. At velocitie s comparable to rifle bullets (700m/s to
1000 m/s) (Table 1), modeled temperatures of impact surfaces exceed 500°C[8,
10].
With sufficient impact velocity and target rigidity, the bullet may fail struc-
turally with only minimal penetration into the target. Xiao et al. [11] identified
four distinct deformation and failure modes for blunt-shaped steel (38CrSi) pro-
jectiles fired at rigid steel plates. The first mechanism, mushrooming, occurred at
relatively low velocities (150 m/s to 250 m/s) and was characterized by the radial
expansion at the nose of the projectile, leading to a mushroom-shaped appear-
ance, but not causing fracture. As impact velocity increased, the second failure
mode, shear cracking, became evident. The mushrooming effect causes stresses to
be localized in the head of the projectile, which can lead to cracks that begin at
the impact face and propagate backwards. Of significance in Xiao et al. [11]
experiments was the bluish discoloration (oxidation) at the head and cracked
interface of the projectile, indicating significant heating. For plain carbon steels,
this occurs at 255°C to 320°C[12].
After shear cracking, the failure modes observed by Xiao et al. [11] were depen-
dent on material hardness. Softer projectiles experienced petalling. Petalling is an
extension of shear cracking but occurs at higher velocity. The shear cracks propa-
gate even farther rearward, giving the projectile a petalled appearance. Significant
discoloration of the petals was evident over much of their length, indicating sus-
tained high temperatures during deformation. Hard projectiles experienced frag-
mentation—the projectiles shattered into many pieces. The number of fragments
increased with projectile velocity. Fragments had some surface discoloration, but
it was less prevalent than with the softer petalled projectiles.
Once hot particles are generated, the next step in the process is the ignition.
However, ignition by contact with hot particles is not well understood [13]. There
are relative ly few well-controlled experimental studies examining this mode of
Study of Wildfire Ignition
ignition and even fewer practical theoretical models. Based on what little research
has been done in this area, however, a few general trends have been noted. In
general, the hot particle must be at a substantially higher temperature than the
ignition temperature measured under radiant or convective heating [1416]. Addi-
tionally, higher temperatures are requ ired to initiate both smoldering and flaming
ignition as the particle size decreases [ 1622]. By performing experiments with
steel and aluminum ball bearings in conjunction with a theoretical model,
Gol’dshleger et al. [20] showed that increasing the conductivity of the hot particle
lowered the required particle temperature. Studies with firebrands indicate that a
higher flux of particles will increase the probability of ignition [ 23 ]. Increasing the
moisture content of both sawdust and pine needle beds has been shown to
increase the required particle temperature [16] and thus decrease the ignition prob-
ability [24]. The density or physical structure of the receptive fuel was also shown
to influence the probability of ignition, with fluffy cotton much easier to ignite
than tightly woven cotton [25].
As a worse-case scenario, dry fluffy commercially available peat moss was cho-
sen in this study as the receptive material. The density, moisture co ntent, and min-
eral (or ash) content of peat has been shown to affect its ignitability. In general, it
is more difficult to ignite peat when the density or moisture content increases [26,
27]. However, the minimum ignition energy of Russian peat was shown by
Grishin and others [27] to have an optimum level of both density and moisture
content. For the lowest density tested (0.38 9 10
3
kg/m
3
), an increase in the igni-
tion energy was seen. A similar increase in ignition energy was seen with extre-
mely low values of moisture content (<1% MC). The combined effect of mineral
content and moisture content was examined by Frandsen [28, 29] where it was
shown that as the mineral content increases the maximum moisture content for
ignition decreases.
3. Theoretical Model
As a first approximation, the maximum temperature rise due to impact can be
estimated by assuming that all kinetic energy is converted into plastic deformation
heating. This approximation is crude and will yield an overestimate of tempera-
ture rise, since energy is also dissipated by other mechanisms (sound/pressure
waves, fragmentat ion, deformation and heating of the target). By equating the
kinetic energy to the change in internal energy, a simplified estimate of tempera-
ture rise is given by:
DT ¼
v
2
2c
ð1Þ
where DT is the increase in tempe rature (K), v is the velocity of the projectile (m/
s), and c (J/kg K) is the specific heat. Of significance in Eq. 1 is the lack of depen-
dence of temperature rise on mass. In our experiments, all bullets deformed to the
point of fracture, resulting in individual fragments rather than a single mass. All
Fire Technology 2015
the heating was assumed due to plastic deformation that occurred prior to frag-
mentation. Assuming the bullet was a uniform temperature throughout just prior
to fragmentation, all the fragments should be the same temperature and equal to
the temperature of the whole.
The temperature rises predicted by Eq. 1 for monolithic projectiles of lead, cop-
per, and steel are shown in Figure 1. The specific heats were calculated using the
specific heat at the midpoint of ambient and final temperature (dete rmined using
an iterative procedure). As an example, the velocity of a Winchester 7.62 9 54R
180-grain soft point bullet is approximately 750 m/s , which yields temperature
increases of 2233°C, 660°C, and 502°C for lead, copper, and steel projectiles,
respectively. One method of validating this prediction is by observing the condi-
tion of recovered fragments. Lead melts near 320°C, copper near 1100°C, and car-
bon steels between 1400°C and 1500°C. Some lead fragments recovered during
our experiments appeared to have melted and re-solidified, but this was not evi-
dent for any copper or steel fragments. This observation, though rudimentary, is
in agreement with the calculated values.
The simple model described above does not account for the mechanical proper-
ties of materials subject to impact loading. The amou nt of heating caused by plas-
tic deformation depends on strain rate, the type of loading, and the mate rial itself.
Currently, there is no accepted theoretical model that completely describes the
Figure 1. Temperature rise versus impact velocity for an idealized
projectile impact (Eq. 1).
Study of Wildfire Ignition
heating of objects as they undergo plastic deformation. Though dynamic stress–
strain data are limited for high strain rate experiments (due to the difficulty of
measurement), we can make some qualitative arguments about the effect of differ-
ent materials. Brittle materials have limited ductility and do not undergo much
plastic deformation before fracturing, while very ductile materials (like copper)
can experience significant plastic deformation [30] which should result in a greater
temperature rise.
After impact, fragments are reflected from the target surface and trave l some
distance before reaching the ground. During flight, fragments will lose heat
through convective and radiative heat trans fer to the surroundings. A simple cal-
culation shows that the radiation heat losses are negligible compared to the con-
vective heat losses. Though their time of flight was not measured, high speed
video indicated that fragments in our experiments were airborne for only a frac-
tion of a second before landing on the surface. To estimate the effect of heat loss
during this time, the particles are considered thermally thin [31] and treated as cir-
cular cylinders in cross flow [32]. Determining the Reynolds number requires the
ricochet velocity be known. Experimental data on the ricochet velocity of frag-
ments is scarce, primarily due to the difficulty of measurement. However, intuition
leads us to expect that it will be proportional to the impact velocity. Using the
initial fragment temperatures obtained by Eq. 1, and assuming cylindrical frag-
ments with a ricochet velocity of 50% of the impact velocity, the time required to
reach 275°C (fragments below this temperature would be unlikely to act as igni-
tion pilot s) is shown in Table 2. Since even very small fragments take more than
0.1 s to cool to 275°C, it seems likely that fragments reach the grou nd at tempera-
tures high enough to transfer significant amounts of heat to the surface, particu-
larly because fragments would require only 0.0025 s at 400 m/s to travel
approximately 1 m between impact and resting position in our experimental appa-
ratus.
Table 2
Time Required for a Thermally-Thin Cylindrical Fragment to Reach
275°C
Diameter (cm) Length/diameter
Time to reach 275°C (s)
Steel (T
i
= 614°C) Copper (T
i
= 767°C)
0.5 0.25 0.09 0.12
0.5 0.18 0.23
0.75 0.28 0.35
1.0 0.37 0.46
1.5 0.55 0.69
2.0 0.73 0.92
3.0 1.10 1.38
5.0 1.84 2.31
Initial temperature estimated by Eq. 1 Lead is not shown, as it would be in a liquid phase above 230°C
Fire Technology 2015
4. Experimental Methods
The study was designed to principally evaluate effects of bullet construction on
ignition by bullet fragments themselves (not pieces of the target). Different calibers
were used because these varied the velocity and bullet mass as well as constituent
materials. Cartridges selected were based on the availability to the general public
and the variety of bullet materials available (Table 3; Figure 2). Steel core ammu-
nition was only widely obtainable for the 7.62 9 54R and the 5.56 9 45. Ammu-
nition with steel jacketed bullets (referred to as Bi-metal) has thin copper gilding
on the outside surface but is mostly made of soft steel. Copper jacketed and lead
core bullets are the most common and come in many brands and varieties of
jacket style.
The target used for most tests was a steel bullet trap consisting of a deflector
and a collector box (Figure 3a). The deflector was a 1.91 cm thick Abrasion
Resistant (AR-500) steel plate 0.91 m wide by 1.22 m long. The bottom edge of
the de flector was connected by a hinge to the middle of the rim of a collector box
with dimensions 0.91 m by 1.52 m by 0.3 m made of 0.64 cm thick soft steel. The
hinge allowed the deflector angle to be adjusted between 0 and 90 from horizon-
tal by means of a cable and winch. Angle-iron was bolted to the edges of the
deflector to redirect fragments into the collector.
Shooting took place in the laboratory from a distance of about 32 m. The
sound from the muzzle blast was lessened by use of an external plyw ood suppres-
sor box (0.91 m 9 0.91 m 9 1.21 m) fitted with internal vertical plywood baffles
spaced 15 cm apart and covered by carpet on both fore and aft surfaces. The
muzzle of the rifle was inserted into a rectangular hole (7.5 cm horizontal by
15 cm vertical) cut through the baffles to allow sighting of the target downrange.
The bullet trap was housed inside a plywood shell to prevent fragments from
damaging cameras or laboratory equipment (Figure 3b). Further details and pho-
tographs of the apparat us can be found in [33]. The following tests were con-
ducted:
Peat ignition tests on the steel target at combinations of cartridge, bullet type,
and deflection angle (20°,30°,40°,60°, and 80° from horizontal). Five shots
fired for each combination.
Excelsior ignition test (Barnes TSX only). Three shots fired.
Bullet fragment temperature with empty collector box (IR camera).
Bullet fragment temperature (‘‘birdhouse’’ attachment to deflector plate, see
Figure 4).
Bullet fragment size distribution with deflector set to 30 (water filled collector).
Two shots fired.
Located immediately downrange of the suppressor box, a chronograp h (PACT
Professional XP) was used to measure the muzzle velocity of each shot. Most igni-
tion tests were conducted with commercial peat moss that was oven dried at
approximately 90°C for 2 days and poured into the collector box to a depth of
approximately 10 cm. Given the uncontrol lability and uncertainty of bullet frag-
Study of Wildfire Ignition
Table 3
Rifles, Cartridges, and Bullets Used for the Study
Rifle, Cartridge Manufacturer
Bullet
weight (g, gr)
Muzzle
velocity (m/s)
Muzzle
energy (J)
Internal
construction Jacket, bullet style
Colt M4, 5.56 9 45
a
Remington UMC 3.563 (55) 884 2785 Lead Copper, FMJ
Lake City, M855 4.018 (62) 914 3359 Hard steel penetrator,
lead
Copper, FMJ
Federal, Barnes TSX 3.563 (55) 869 2689 Copper, solid None
Wolf WPA 3.563 (55) 853 2596 Lead Steel, FMJ Bimetal
Arsenal SA-M7, AK-47,
7.62 9 39
Barnaul, Silver Bear 7.970 (123) 701 3917 Lead Steel, FMJ Bimetal
Fiocchi 7.970 (123) 746 4445 Lead Copper, FMJ
Mosin-Nagant, M91/30,
7.62 9 54R
Hungary (head stamp 21 74) 11.664 (180) 792 3681 Steel, soft Steel, FMJ
Russia (188 head stamp, 1989) 9.525 (147) 853 7032 Steel, hardened Steel, FMJ
Barnaul, Silver Bear 11.275 (174) 777 6811 Lead Steel, FMJ Bimetal
Winchester 11.664 (180) 808 7610 Lead Copper, soft point
Springfield Armory M1A,
7.62 9 51
b
Federal, American Eagle 9.720 (150) 860 7181 Lead Copper, FMJ
Federal, Barnes TSX 9.720 (150) 869 7335 Copper, solid None
Federal, Sierra SMK 10.886 (168) 808 7102 Lead Copper, OTM
Nosler, Partition 10.692 (165) 853 7787 Lead Copper, soft point
gr grains, FMJ full metal jacket
a
The designation 5.56 9 45 includes cartridges labeled as .223 Remington
b
The designation 7.62 9 51 includes cartridges labeled as .308 Winchester
Fire Technology 2015
ment properties (velocity, size, temperature, etc.), an ignition-sensitive material
such as peat was thought necessary to allow ignition diff erences between bullet
types to be distinguished. In other words, if ignitions were very rare, our limited
set of tests may not be able to detect ignitions or make comparison among bullet
materials. Peat was chosen because it is a partially decomposed organic substance
similar to upper soil layers with large fractions of incorporated organic material.
The ground surface would be a likely resting location for bullet fragments. Also,
Figure 2. Cross-sections of bullets used in this study. Photograph by
J. Kautz.
Figure 3. (a) Sketch of the bullet trap designed with an angle-ad-
justable deflector plate mounted in the middle of a steel collector box
for bullet fragments deflected downward after impact, (b) photograph
shows the bullet trap and white deflector plate visible between the
doors of a plywood shell with cutouts for cameras and lighting.
Study of Wildfire Ignition
peat is composed of fine particles that would increase surface contact with small
bullet fragments.
Dryness of the peat became an important factor, so controls were put in place
to maintain moisture conditions of the peat. The dryness of the peat was main-
tained after removing it from the drying oven by heating the collector box under-
neath with heat tape and aiming halogen heat lamps along the sides. Measured
temperatures of the box remained at approximately 55°C, similar to soil surface
temperatures on sunny summer days. The environment of the laboratory was sus-
tained at temperatures of 38°Cto43°C and approximately 7% to 10% relative
humidity. This preserved moisture content of the peat between 3.0% and 4.5%
(dry weight basis). Moisture sampling of the peat was perfor med approximately
every 15 min to 30 min using a Computrac MAX 2000XL automatic balance.
Ignitions were recorded after shooting each set of bullets by first observing the
peat for smoldering spots. When observed, each spot was excavated with a small
trowel to remove it from the collector before the ignition spread throughout the
box. The volume of peat containing the smoldering spot was sifted on the pave-
ment to attempt to find the fragment responsible. The number of smoldering spots
was co unted for each set of sho ts (‘‘Appendix’’ section) and once all visible igni-
tions had been removed, the trowels were used to thoroughly overturn the peat in
the collector box in preparation for subsequent tests. We noted that it often took
several minutes before all ignitions were found—some being buried near the bot-
tom of the peat. Once satisfied that no residual burning material was present, the
next series of bullets was fired.
Measurement of bullet fragment temperatures was attempted by remote methods
using a calibrated thermal IR video camera (Cincinnati TVS-8500) and directly by
use of temperature sensitive paints. To capture IR images, the bullet collector box
was emptied and the camera aimed to focus on the bottom surface with the deflector
angle set to 30° from horizontal. IR video taken at 30 fps was analyzed by tabulat-
ing maximum temperature of the pixels in the image over time to obtain cooling
rates. The direct measurement of the approximate fragment temperature was
attempted using a ‘‘birdhouse’’ attachment to the deflector/collector (Figure 3). The
bullet was fired through the 7.6 cm hole in the front plate. Fragments were con-
tained inside the birdhouse and ricocheted off a series of baffles arranged to indi-
rectly funnel them downward to rest upon a steel plate (0.16 cm thick) coated with a
Figure 4. Photographs of the ‘‘birdhouse’’ attachment to the deflec-
tor plate on the bullet trap that allowed collecting and concentrating
fragments onto plates painted with temperature sensitive paints.
Fire Technology 2015
temperature sensitive paint. Two tests were conducted at each paint temperature
(300°C, 40 0°C, 500°C, 600°C, 700°C, 800°C) consisting of a single shot of 7.62 9 51
Barnes TSX. This bullet and cartridge was selected because ignitions consistently
resulted during the peat tests and the fragments were not as damaging to the appara-
tus as steel-core bullets, which also readily produced ignitions.
Video in the visible portion of the spectrum was recorded for bullet impacts
with a Photron Apex high speed video camera. Various recording rates were used,
ranging from 8000 fps to 100,000 fps, to attempt to capture impact fragmentation
and impact flash. The various recording speeds were a result of the trade-off
between resolution, aperture (for depth of field), and frame rate.
We statistically examined the pairwise relationship between cartridge type and
both ignition occurrence and number of ignitions via the Bonferroni method [34]
and the less conservative Tukey’s HSD test. In no case was there a statistically
significant difference in the effe ct of cartridge types. We then examined the rela-
tionship between other predictors and ignition response via the use of Generalized
Linear Mixed Modeling (GLMM) Poisson regression. The purpose of the regres-
sion analysis was to distinguish and characterize responses rather than to produce
a predictive model since the data collected reflect the particulars of the laboratory
testing such as number of shots and target distance. Although the number of sep-
arate ignitions in each set was recorded, the GLMM used only the binary respon-
ses of ignition or no-ignition. The dummy variables of bullet core material (lead,
steel, copper) and jacket material (steel, copper) were specified in the model.
5. Results
A total of 433 rounds were fired against the steel target. The impact of rifle bullets
consistently produced ignitions in dry peat, especially for the solid copper and steel
core/steel jacketed bullets (for a full table of results, see ‘‘Appendix’’ section). Igni-
tions were detected visibly as smoldering spots in the peat. Sometimes several separate
ignitions were produced from the multiple fragments produced for a particular test (5
shots). Sometimes several minutes went by before all ignitions were detected. This was
interpreted as a function of the depth that a hot fragment was buried in the peat layer
which required time for the ignition or smoke to become visible. A single test for igni-
tion of dry excelsior by the solid copper bullets (3 bullets) produced ignitions.
Fragments found by excavating ignitions in the peat suggested that bullet frag-
ments were responsible for the ignition rather than steel eroded from the target.
For steel jacketed bullets, very small (only a few millimeters across) fragments of
jacket material were often found inside the incipient ignition. Particles of this size
have been reported to require temperatures of 1100°C or above to cause ignitions
in dry cellulose [17]. At low target angles, little cratering of the target occurred
regardless of bullet type, limiting alternative sources of hot materials other than
bullet fragments themselves. At high target angles using bullets with hardened
steel penetrators, cratering of the steel target could have liberated steel fragments
and contributed to the ignitions. The process of deformation and fragmentation of
the target would produce hot particles in the same way as discussed for bullet
Study of Wildfire Ignition
fragments. We did observe in one place where the sharp edge of a crater rim on
the target had chipped from subsequent impacts and could have contributed hot
material for ignition.
Statistical analysis of the ignition results by Poisson regression revealed signifi-
cant differences among bullet materials (Figure 5). The regression model (Table 4)
represented separately the effects of core material and the jacket material com-
pared to the base model that represented solid copper bullets.
5.1. Bullet Material
Bullet construction materials were important factors in producing ignition. The
only type of bullet that co nsistently did not produce ignitions was made with a
lead core and copper jacket, although a single ignition was observed from a Nos-
ler partition bullet (see Figure 2). Solid copper bullets were the most consistent in
producing ignitions at all angles and all targets. Fragments of the solid copper
bullets appeared larger than fragments of other bullet types. Fragments recovered
from the water-filled collector box supported this observation with solid copper
bullets having the most combined weight of recovered fragments (Figure 6;
Table 5). Bullets with lead core and copper jacket produced the smallest frag-
Figure 5. Graph showing statistical regression model of laboratory
data on probability of ignition as a function of bullet-type variables.
Probability of ignition applies to 5-shot groups in oven dried peat.
Fire Technology 2015
ments with the least recovered weight. Bullets with steel components were found
to produce ignitions but not as consistently as the solid copper bullets.
The regression model suggested that impact angle should also play a role in
ignition probability, with more oblique angles more likely to produce an ignition.
However, when the target was set at higher angles (60° to 80°) we suspected that
more bullet fragments were escaping the collector box. The effect of angle on igni-
tion would, therefore, involve more than effects on fragment properties (size or
Table 4
Regression Estimates for Poisson Model of Ignition Probability as a
Function of Bullet Core and Jacket Materials
Equation & coefficients SE z value Pr (>|z|)
Ignition probability = 1/(1 + exp(-(2.57971
- 3.90678 steelcore - 2.35951 Leadcore
- 1.66653 steeljacket - 0.03522 angle)))
0.58514 4.409 1.04e-05
0.66442 -5.880 4.10e-09
0.65998 -3.575 0.00035
0.57410 2.903 0.00370
0.01209 -2.912 0.00360
Core and jacket variables are set either to zero or one. If both are set to zero then regression produces results for
solid copper bullets. All coefficients were statistically significant at least to the 0.001 level
Figure 6. Photographs of bullet fragments collected after impact
from water-filled collector tank.
Study of Wildfire Ignition
Table 5
Summary of Bullet Fragment Tests Using a Water-Filled Collector Box
Cartridges and bullets tested for fragmentation
Weight of fragments (g)
Number of
fragments
Total weight Core Jacket
Core Jacket
Cartridge Num. fired Bullet wt, g (grains) Jacket Core Weight recovered %Original weight Max Min Max Min
7.62 9 51 2 9.720 (150) Solid Copper 16.597 85.375 5.715 0.011 41
7.62 9 51 2 9.720 (150) Copper Lead 6.865 35.314 0.103 0.007 0.412 0.004 62 126
7.62 9 39 2 7.970 (123) Steel Lead 6.800 42.658 0.076 0.008 0.784 0.006 50 54
7.62 9 54R 2 9.525 (147) Steel Steel/lead 12.924 67.838 1.782 0.010 0.601 0.001 49 58
Fire Technology 2015
number). At high impact angles, fragments flying farther from the point of impact
will experience more cooling before finally resting on potential ignitable substrate
(Table 2) and may be less likely to cause ignitions.
High speed video (20,000 fps) captured the impact and trajectory of splatter
as well as an ‘‘impact flash’’ (Figure 7) that was visible for most bullets. Impact
flash is not visible to the naked eye in daylight but is clearly visible in the videos.
Bullets having a steel core displayed the greatest and longest-lasting flash. Smaller
flash was visible from impact of bullets with lead core and of solid copper. Impact
flash has been described as the burning of metal spall (oxidizing metal dust from
the target and/or projectile) at temperatures of about 3000 K [35 , 36]. Its duration
is very short and was visible in high speed video for less than 1/2000th of a sec-
ond (<10 frames at 20,000 fps).
5.2. Temperatures of Bullet Fragments
The thermal camera captured 30 fps and recorded the movements and approxi-
mate temperatures of the fragments as they bounc ed around in the collector.
Assuming fragment emissivity to be 1.0, the thermal images recorded peak tem-
peratures of 550°C to 793°C. We attribute little significance to the apparent vari-
ability among bullets or shots because there was no control over fragment
numbers, sizes, or locations in the field of view. Also, for several reasons discussed
below, these estimated temperatures must be considered conservative values that
may be affected by factors beyond the control of the experiments. Even without
confidence in the actual fragment temperature, these data are indicative of high
Figure 7. Frame sequence from high speed video (20,000 fps) of
147 g 7.62 3 54R steel core-steel full metal (steel) jacket bullet
impacting steel plate at 20° angle (from horizontal) shows the ‘‘im-
pact flash’’ produced by oxidation or burning of metal spall and hot
glowing particles deflected downward.
Study of Wildfire Ignition
thermal energy of the particles and the rapid cooling rates following impact.
Higher cooling rates of the steel-components were indicated compared to frag-
ments of the solid copper bullets. The steel components cooled within several sec-
onds to temperatures near the minimum setting for the camera (375°C) but copper
took approximately three times longer. This may be caused by higher initial tem-
peratures or partially a function of the larger sizes of the copper bullet fragments
because more rapid cooling of copper (for equivalent mass) would be expected
from the higher thermal conductivity compared to steel (almost 10 times greater).
Examination of the temperature-sensitive plates from the ‘‘birdhouse’’ tests
revealed discoloration from contact points with hot fragments at all temperature
levels, including the maximum of 800° C. The density of discolored places
decreased with increasing temperature threshold for the paints , suggesting that
most particles cool too rapidly to discolor the paint or are not raised to higher
temperatures initially. Given the single temperature threshold of each paint and
the thermal conductivity and limited contact on flat steel plates, these results are
necessarily conservative estimates of actual fragment temperature. They are con-
sistent with both the theory and the thermal camera data, which reveal fragment
temperatures sufficient for ignition.
6. Discussion
No previous studies have been devoted to the particular problem of ignition by
metal fragments he ated upon ballistic impac t. The physical processes and factors
involved throughout the sequence of impact, fragmentation, and ignition are, never-
theless, interpretable from studies of related phenomena. In general, high velocity
impacts produce heat in the rapidly deformed projectile (and possibly the target)
that must quickly come to rest on a dry ignitable material. The rapid cooling of frag-
ments, their small sizes, and odd shapes mean that fine-grained substrates such as
peat provide more opportunity for direct contact and ignition. The toughness of dif-
ferent metals determines how much energy is required for deformation and fractur-
ing, and thus, how much heat is generated when the particle material ultimately
fails. This is why bullet construction is important to heating and ignition.
Our study focused on laboratory testing of different bullets load ed in commer-
cial ammunition. We observed that bullet material did affect fragment sizes and
ignitions, with steel components and solid copper bullets producing the largest
fragments and the most likely ignitions in peat. Despite similar maximum temper-
atures recorded on thermal images, larger fragments from solid copper bullets
seem to be the most plausible explanation for the slower rates of temperature
decline compared to steel seen in the image sequences. The opposite trend would
be expected ba sed only on the greater thermal conductivity of copper than steel,
meaning that heat loss rates should be greater for equivalent fragment mass. Both
copper and steel are much ‘‘tougher’’ metals compared to lead, meaning that a
greater amount of energy is required for plastic deformation at a particular strain
rate. Lead therefore deforms with relatively little energy, and due to its relatively
low melting temperature, will probably melt.
Fire Technology 2015
The actual bullet fragment temperatures remain unknown, but they are consis-
tent with the physical theory of plastic deformation under high strain rates. Maxi-
mum temperatures of about 550°C to nearly 800°C were recorded on thermal
images for several bul let types and were consistent with the discoloration reaction
by fragment contact with the temperature-sensitive paints. Both must be consid-
ered conservative estimates of the true fragment temperatures because:
(1) The thermal camera was operated at 30 fps and could miss high temperatures
of shorter duration.
(2) There is an unknown and uncontrolled ratio of bullet fragment size relative to
the pixel area in an image, which can lead to under-representing temperature
due to partial pixel coverage by the fragment.
(3) The emissivity of the bullet fragments is not known but assumed to be 1.0 for these
calculations and which must therefore underrepresent the actual temperature.
(4) Irregular particle geometry offers few contact points on a flat steel plate for
discoloring the paints.
(5) Thermal properties of the steel plate may diminish the paint response to small
fragments.
This study intentionally did not address ignition by target material dislodged by
the impact. Most ballistic impact studi es are concerned with perforation or pene-
tration of the target, often metal, which may break away. Loose pieces of target
metal have been fractured by similar deformation physics as described for the pro-
jectile, and it is possible that fires could ignite from them as well.
From this study, an understanding of wildfire ignitions from field reports begins
to emerge, but also involves other processes not encompassed by this work. The fol-
lowing is a discussion of linkages to field-scale wildfire ignitions, given that the pre-
sent study was confined to a laboratory apparatus and limited to detection of
smoldering ignition very close to the target (<1 m). First, target materials that are
highly resistant to damage would be similar to the steel plate tested here, such as
boulders, rocks, or thick metal such as silhouettes. Oblique angles of impact may be
important, regardless of target material, to producing larger fragments that would
cool more slowly after contacting organic matter. Second, bullet materials clearly
affect ignition potential, with steel components and solid copper having the greatest
chance of producing hot fragments. We observed only one ignition from lead-core
copper jacketed bullets. Third, the very rapid particle cooling means the ignitions
are more likely nearer the target. Fragment size distribution was not known or con-
trolled, but smaller pieces cool so quickly that they must contact the suitable sub-
strate very rapidly. The distances from a target that ignitions can occur are not
determined by the present study. Four th, ignitions are observed in the field only
when the fire begins to spread. This is probably not when or where ignition actually
takes place. The original ignition likely occurs in a material similar to peat, meaning
partially decomposed organic matter incorporated in the surface horizons of the
soil—not the vegetation or fuel which carries the spreading fire with visible fla mes.
The process of transition from smoldering incipient ignition to spreading fire may
take some time (minutes to days, even weeks) depending on the fuel types and the
Study of Wildfire Ignition
weather and fuel conditions. Where the target is exposed to wind, a smoldering igni-
tion in litter or duff may be ventilated easily and ignite grasses or surface litter and
become visible more quickly than an area sheltered by trees or terrain.
Consistent with previous research on particle ignition, bullet fragments can be
very small and still effective in producing ignitions. The multiple ignitions observed
in this experiment from small fragments of a single bullet means that it may be diffi-
cult to identify the exact piece of bullet material that causes an ignition under field
conditions. The limited testing using dry excelsior revealed that other material
besides decayed organic matter can also be ignited by bullet fragments but further
testing beyond this study will be required. As with all fire behavior and ignition
research, moisture content of the organic material will be an important factor in
ignition. Peat moisture contents of 3% to 5%, air temperatures of 34°Cto49°C,
and relative humidity of 7% to 16% were necessary to reliably observe ignitions in
the experiments. Peat moisture contents above this (perhaps 8%) did not produce
ignitions. Field conditions matching the experimental range would imply summer-
time temperatures, as well as solar heating of the ground surface and organic matter
to produce a drier and warmer microclimate where bullet fragments are deposited.
Acknowledgments
Conducting this study depended on the support and ingenuity of many people.
Chuck Harding constructed the bullet trap. Jack Kautz, Randy Pryhorocki, and
Andrew Gorris built and designed the laboratory shooting range apparatus includ-
ing external sound suppressor and birdhouse attachment to the deflector. Mark
Vosburgh, Amanda Determan, and Dan Jimenez took responsibility for video ima-
gery. Jay Fronden and Jason Forthofer assisted in all phases of the shooting tests.
Mike Bonzano ensured range safety for the laboratory tests. Dave Ball of the Mis-
soula County Sheriff’s Department graciously helped with the access and use of the
outdoor range. Isaac Grenfell provided data processing and statistical advice and
analysis. Shari Kappel and Corrie Kegel oversaw safety and security plans for the
indoor testing. This report was greatly impr oved from the review comments pro-
vided by Don Latham, Vytensis Babrauskas, Steve Mates, and John Fehr.
Open Access
This article is distributed under the terms of the Creative Commons Attribution
4.0 Internationa l License (http://creativecommons.org/licenses/by/4.0/), which per-
mits unrestricted use, distribution, and reproduction in any medium, provided you
give appropriate credit to the original au thor(s) and the source, provide a link to
the Creative Commons license, and indicate if chan ges were made.
Appendix
See Table 6.
Fire Technology 2015
Table 6
Data Obtained from Shooting Tests
Date
Test
number
Target
material Cartridge Manufacturer
Bullet type
Angle
Material
Number
of rounds
Number of
ignitions
Avg muzzle
velocity (m/s) CommentsWeight (g) Core Jacket Deg
Preliminary
outdoor tests
9/21/2012
98 Steel 5.56 9 45 m855 4.02 FMJ Steel/lead Copper 30 Peat 11 0
9/21/2012
99 Steel 7.62 9 54R Hungarian
Surplus
11.7 FMJ Steel/lead Steel 30 Peat 5 2
9/21/2012
910 Steel 7.62 9 54R Hungarian
Surplus
11.7 FMJ Steel/lead Steel 20 Peat 5 5
9/21/2012
911 Steel 7.62 9 39 Silver Bear 7.97 FMJ Lead Steel 20 Peat 7 7
Rifle: Russian
Mosin-Nagant
91/30
1/22/2013
1 Steel 7.62 9 54R Russian
Surplus
9.5 FMJ Steel Steel 20 Peat 5 4 857
1/22/2013
2 Steel 7.62 9 54R Russian
Surplus
9.5 FMJ Steel Steel 30 Peat 5 2 557
1/22/2013
3 Steel 7.62 9 54R Russian
Surplus
9.5 FMJ Steel Steel 40 Peat 5 2 857
1/22/2013
4 Steel 7.62 9 54R Russian
Surplus
9.5 FMJ Steel Steel 60 Peat 5 4 846
1/22/2013
5 Steel 7.62 9 54R Russian
Surplus
9.5 FMJ Steel Steel 80 Peat 5 1 855
1/22/2013
6 Steel 7.62 9 54R Silver Bear 11.3 FMJ Lead Steel 20 Peat 5 4 791
1/22/2013
7 Steel 7.62 9 54R Silver Bear 11.3 FMJ Lead Steel 30 Peat 5 0
1/22/2013
8 Steel 7.62 9 54R Silver Bear 11.3 FMJ Lead Steel 40 Peat 5 0
1/22/2013
9 Steel 7.62 9 54R Silver Bear 11.3 FMJ Lead Steel 60 Peat 5 0 790
1/22/2013
10 Steel 7.62 9 54R Silver Bear 11.3 FMJ Lead Steel 80 Peat 5 0 793
1/23/2013
11 Steel 7.62 9 54R Winchester 11.7 JSP Lead Copper 20 Peat 5 0 805
1/23/2013
12 Steel 7.62 9 54R Winchester 11.7 JSP Lead Copper 30 Peat 5 0 810
1/23/2013
13 Steel 7.62
9 54R Winchester 11.7 JSP Lead Copper 40 Peat 5 0 804
1/23/2013
14 Steel 7.62 9 54R Winchester 11.7 JSP Lead Copper 60 Peat 5 0 807
Study of Wildfire Ignition
Table 6
continued
Date Test
number
Target
material
Cartridge Manufacturer Bullet type Angle Material Number
of rounds
Number of
ignitions
Avg muzzle
velocity (m/s)
Comments
Weight (g) Core Jacket Deg
1/23/2013
15 Steel 7.62 9 54R Winchester 11.7 JSP Lead Copper 80 Peat 5 0 803
Rifle: AK47,
Arsenal
SA-M7A1R
1/23/2013
16 Steel 7.62 9 39 Silver Bear 7.97 FMJ Lead Steel 20 Peat 5 0 709
1/23/2013
17 Steel 7.62 9 39 Silver Bear 7.97 FMJ Lead Steel 30 Peat 5 0 705
1/23/2013
18 Steel 7.62 9 39 Silver Bear 7.97 FMJ Lead Steel 40 Peat 5 0 707
1/23/2013
19 Steel 7.62 9 39 Silver Bear 7.97 FMJ Lead Steel 60 Peat 5 1 710
1/23/2013
20 Steel 7.62 9 39 Silver Bear 7.97 FMJ Lead Steel 80 Peat 5 0 708
1/24/2013
21 Steel 7.62 9 39 Fiocchi 7.97 FMJ Lead Copper 20 Peat 5 0 744
1/24/2013
22 Steel 7.62 9 39 Fiocchi 7.97 FMJ Lead Copper 30 Peat 5 0 753
1/24/2013
23 Steel 7.62 9 39 Fiocchi 7.97 FMJ Lead Copper 40 Peat 5 0 747
1/24/2013
24 Steel 7.62 9 39 Fiocchi 7.97 FMJ Lead Copper 60 Peat 5 0 745
1/24/2013
25 Steel 7.62 9 39 Fiocchi 7.97 FMJ Lead Copper 80 Peat 5 0 750
Rifle: AR15,
Colt M4
LE6940
1/24/2013
26 Steel 5.56 9 45 Lake City 4.02 FMJ Steel/lead Copper 20 Peat 5 1 913
1/24/2013
27 Steel 5.56 9 45 Lake City 4.02 FMJ Steel/lead Copper 30 Peat 5 0 913
1/24/2013
28 Steel 5.56 9 45 Lake City 4.02 FMJ Steel/lead Copper 40 Peat 5 1 910
1/24/2013
29 Steel 5.56 9 45 Lake City 4.02 FMJ Steel/lead Copper 60 Peat 5 0 913
1/24/2013
30 Steel 5.56 9 45 Lake City 4.02 FMJ Steel/lead Copper 80 Peat 5 0 921
1/24/2013
31 Steel 5.56 9 45 Wolf 3.6 FMJ Lead Steel 20 Peat 5 0 879
1/24/2013
32 Steel 5.56 9 45 Wolf 3.6 FMJ Lead Steel 30 Peat 5 0 879
1/24/2013
33 Steel 5.56 9 45 Wolf 3.6 FMJ Lead Steel 40 Peat 5 0 873
1/24/2013
34 Steel 5.56 9 45 Wolf 3.6 FMJ Lead Steel 60 Peat 5 0 865
1/24/2013
35 Steel 5.56 9 45 Wolf 3.6 FMJ Lead Steel 80 Peat 5 0 874
1/25/2013
36 Steel 5.56 9 45 Remington 3.6 FMJ Lead Copper 20 Peat 5 0 897
1/25/2013
37 Steel 5.56 9
45 Remington 3.6 FMJ Lead Copper 30 Peat 5 0 891
1/25/2013
38 Steel 5.56 9 45 Remington 3.6 FMJ Lead Copper 40 Peat 5 0 891
Fire Technology 2015
Table 6
continued
Date Test
number
Target
material
Cartridge Manufacturer Bullet type Angle Material Number
of rounds
Number of
ignitions
Avg muzzle
velocity (m/s)
Comments
Weight (g) Core Jacket Deg
1/25/2013
39 Steel 5.56 9 45 Remington 3.6 FMJ Lead Copper 60 Peat 5 0 905
1/25/2013
41 Steel 5.56 9 45 Federal 3.6 Barnes TSX Copper Copper 20 Peat 5 2 915
1/25/2013
42 Steel 5.56 9 45 Federal 3.6 Barnes TSX Copper Copper 30 Peat 5 1 923
1/24/2013
43 Steel 5.56 9 45 Federal 3.6 Barnes TSX Copper Copper 40 Peat 5 1 915
1/25/2013
44 Steel 5.56 9 45 Federal 3.6 Barnes TSX Copper Copper 60 Peat 5 0 930
Rifle: M1A,
Springfield
Armory
1/25/2013
51 Steel 7.62 9 51 Federal 9.72 FMJ Lead Copper 20 Peat 5 1 880 Probable
hold-over
ignition
from test 44
1/25/2013
52 Steel 7.62 9 51 Federal 9.72 FMJ Lead Copper 30 Peat 5 0 879
1/25/2013
53 Steel 7.62 9 51 Federal 9.72 FMJ Lead Copper 40 Peat 5 0 852
1/25/2013
54 Steel 7.62 9 51 Federal 9.72 FMJ Lead Copper 60 Peat 5 0 864
1/25/2013
57 Steel 7.62 9 51 Federal 9.72 Barnes TSX Copper Copper 30 Peat 5 12 888
1/25/2013
58 Steel 7.62 9 51 Federal 9.72 Barnes TSX Copper Copper 40 Peat 5 7 885
1/25/2013
59 Steel 7.62 9 51 Federal 9.72 Barnes TSX Copper Copper 60 Peat 5 6 863
1/25/2013
60 Steel 7.62 9 51 Federal 9.72 Barnes TSX Copper Copper 80 Peat 5 0 863
1/25/2013
61 Steel 7.62 9 51 Federal 10.9 SMK OTM Lead Copper 20 Peat 5 0 807
1/25/2013
62 Steel 7.62 9 51 Federal 10.9 SMK OTM Lead Copper 30 Peat 5 1 806 Probable
hold-over
ignition
from test 60
1/25/2013
63 Steel 7.62 9 51 Federal 10.9 SMK OTM Lead Copper 40 Peat 5 0 803
1/25/2013
66 Steel 7.62 9 51 Nosler 10.7 Partition Lead Copper 20 Peat 5 1 876
1/25/2013
67 Steel 7.62 9 51 Nosler 10.7 Partition Lead Copper 30 Peat 5 0 872
1/25/2013
68 Steel 7.62 9 51 Nosler 10.7 Partition Lead Copper 40 Peat 5 0 849
1/23/2013
76 Steel 7.62 9
54R Russian
Surplus
9.5 FMJ Steel Steel 40 Peat 5 0 864
Study of Wildfire Ignition
Table 6
continued
Date Test
number
Target
material
Cartridge Manufacturer Bullet type Angle Material Number
of rounds
Number of
ignitions
Avg muzzle
velocity (m/s)
Comments
Weight (g) Core Jacket Deg
1/23/2013
77 Steel 7.62 9 54R Russian
Surplus
9.5 FMJ Steel Steel 40 Peat 5 0 862
1/23/2013
78 Steel 7.62 9 39 Silver Bear 7.97 FMJ Lead Steel 40 Peat 10 0 707
1/24/2013
79 Steel 7.62 9 54R Russian
Surplus
9.5 FMJ Steel Steel 30 Peat 5 6 863
1/24/2013
80 Steel 5.56 9 45 Lake City 4.02 FMJ Steel/lead Copper 40 Peat 10 0
1/24/2013
6 Steel 7.62 9 54R Silver Bear 11.3 FMJ Lead Steel 20 Peat 5 1 799
1/24/2013
7 Steel 7.62 9 54R Silver Bear 11.3 FMJ Lead Steel 30 Peat 5 0 799
1/24/2013
8 Steel 7.62 9 54R Silver Bear 11.3 FMJ Lead Steel 40 Peat 5 2 802
1/24/2013
16 Steel 7.62 9 39 Silver Bear 7.97 FMJ Lead Steel 20 Peat 5 4 709
1/24/2013
17 Steel 7.62 9 39 Silver Bear 7.97 FMJ Lead Steel 30 Peat 5 0 713
1/24/2013
18 Steel 7.62 9 39 Silver Bear 7.97 FMJ Lead Steel 40 Peat 5 1 718
1/24/2013
19 Steel 7.62 9 39 Silver Bear 7.97 FMJ Lead Steel 60 Peat 5 0
1/24/2013
20 Steel 7.62 9 39 Silver Bear 7.97 FMJ Lead Steel 80 Peat 5 0
1/25/2013
8 Steel 7.62 9 54R Silver Bear 11.3 FMJ Lead Steel 40 Peat 5 0
1/26/2013
6 Steel 7.62 9 54R Silver Bear 11.3 FMJ Lead Steel 20 Peat 5 2 816
1/26/2013
7 Steel 7.62 9 54R Silver Bear 11.3 FMJ Lead Steel 30 Peat 5 1 803
1/26/2013
8 Steel 7.62 9 54R Silver Bear 11.3 FMJ Lead Steel 40 Peat 5 1 800
1/26/2013
16 Steel 7.62 9 39 Silver Bear 7.97 FMJ Lead Steel 20 Peat 5 1 715
1/26/2013
17 Steel 7.62 9 39 Silver Bear 7.97 FMJ Lead Steel 30 Peat 5 0 710
1/26/2013
18 Steel 7.62 9 39 Silver Bear 7.97 FMJ Lead Steel 40 Peat 5 0 711
1/26/2013
31 Steel 5.56 9
45 Wolf 3.6 FMJ Lead Steel 20 Peat 5 0 883
1/26/2013
32 Steel 5.56 9 45 Wolf 3.6 FMJ Lead Steel 30 Peat 5 2
1/26/2013
33 Steel 5.56 9 45 Wolf 3.6 FMJ Lead Steel 40 Peat 5 0 873
1/26/2013
57 Steel 7.62 9 51 Federal 9.72 Barnes
TSX
Copper Copper 30 Excelsior 3 3 886
Values in italics indicates tests where ignitions were observed. Values in bold shading indicates ambiguous result (see comments)
Fire Technology 2015
References
1. Guns blamed for starting some wildfires in the west. CBS News, July 4th, 2012.
http://www.cbsnews.com/news/guns-blamed-for-sparking-some-wildfires-in-west/
2. Gunfire blamed for some wildfires; target shooting limited. USA Today, July 3, 2012.
http:// cont ent.usa toda y.com/communiti es/ondeadline/post/2012/07/gunfire- blamed-for-
some-wildfires- states-consider-limits/1#.UCF4202PXwk
3. Johnson W, Sengpta AK, Ghosh SK (1982) High velocity oblique impact and ricochet
mainly of long rod projectiles: an overview. Intl J Mech Sci 24(7):425–436
4. Goldsmith W (1999) Non-ideal projectile impact on targets. Intl J Impact Eng 22:95–
395
5. Rein G (2009) Smouldering combustion phenomena in science and technology. Int Rev
Chem Eng 1:3–18
6. U.S. Army (1994) Army ammunition data sheets: small caliber ammunition—FSC
1305. Technical Manual TM 43-0001-27. Washington, DC: U.S. Government Printing
Office. 1994-546-043:80742
7. Rogers HC (1979) Adiabatic plastic deformation. Annu Rev Mater Sci 9(1):283–311
8. Yildirim B, Muftu S, Gouldstone A (2011) Modeling of high velocity impact of spheri-
cal particles. Wear 270:703–713
9. Kapoor R, Nemat-Nasser S (1998) Determination of temperature rise during high
strain rate deformation. Mech Mater 27(1):1–12
10. Molinari JF, Ortiz M (2002) A study of solid-particle erosion of metallic targets. Intl J
Impact Eng 27:447–458
11. Xiao X, Zhang W, Wei G, Mu Z (2010) Effect of projectile hardness on deformation
and fracture behavior in the Taylor impact test. Mater Des 31(10):4913–4920
12. Oberg E, Jones FD, Horton HL (1990) Machinery’s handbook, 23 edn. Industrial
Press, New York
13. Babrauskas V (2003) Ignition handbook (Ch. 7, pp 238–239; Ch. 7, pp 287–289; Ch.
11, pp 500–509; and Ch. 14, pp 842–844). Fire Science Publishers, Issaquah
14. Setchkin NP (1949) A method and apparatus for determining the ignition characteris-
tics of plastics. J Res NBS 43:591–608
15. Kuchta JM, Furno AL, Martindill GH (1969) Flammability of fabrics and other mate-
rials in oxygen-enriched atmospheres. Part 1. Ignition temperatures and flame spread
rates. Fire Technol 5:203–216. doi:10.1007/BF02591517
16. Tanaka T (1977) On the inflammability of combustible materials by welding spatter.
Rep Natl Res Inst Police Sci 30(1):51–58
17. Hadden RM, Scott S, Lautenberger C, Fernandez-Pello AC (2011) Ignition of com-
bustible fuel beds by hot particles: an experimental and theoretical study. Fire Technol
47:341–355. doi:10.1007/s10694-010-0181-x
18. Rowntree GWG, Stokes AD (1994) Fire ignition by aluminum particles of controlled
size. J Electr Electron Eng Aust 14(2):117–123
19. Stokes AD (1990) Fire ignition by copper particles of controlled size. J Electr Electron
Eng Aust 10(3):188–194
20. Gol’dshleger UI, Barzykin VV, Ivleva TP (1973) Ignition of condensed explosives by a
hot spherical object. Combust Explos Shock Waves 9(5):642–647
21. Urban JL, Zak CD, Fernandez-Pello C (2014) Cellulose spot fire ignition by hot metal
particles. Proc Comb Inst. doi:10.1016/j.proci.2014.05.081
22. Zak CD, Urban JL, Fernandez-Pello C (2014) Characterizing the flaming ignition of
cellulose fuel beds by hot steel spheres. Combust Sci Technol 186(10–11):1618–1631
Study of Wildfire Ignition
23. Manzello SL, Cleary TG, Shields JR, Maranghides A, Mell W, Yang JC (2008) Experi-
mental investigation of firebrands: generation and ignition of fuel beds. Fire Saf J
43:226–233
24. Ellis PF (2000) The aerodynamic and combustion characteristics of eucalypt bark—a
firebrand study, Ph.D. dissertation, Australian National University, Canberra
25. McGuire JH, Law M, Miller JE (1956) Domestic fire hazard created by flying coals
and sparks (FR note 252). Fire Res Station, Borehamwood
26. Hartford RA (1989) Smoldering combustion limits in peat as influenced by moisture,
mineral content, and organic bulk density. In: MacIver DC, Auld H, Whitewood R
(eds) Proceedings of the 10th conference on fire and forest meteorology, April 1989,
Ottawa. Forestry Canada, Petawawa National Forestry Institute, Chalk River, pp 282–
286
27. Grishin AM, Golovanov AN, Sukov YV, Preis YI (2006) Experimental study of peat
ignition and combustion. J Eng Phys Thermophys 79(3):563–568
28. Frandsen WH (1987) The influence of moisture and mineral soil on the combustion
limits of smoldering forest duff. Can J For Res 17:1540–1544
29. Frandsen WH (1997) Ignition probability of organic soils. Can J For Res 27:1471–1477
30. Rittel D, Osovski S (2010) Dynamic failure by adiabatic shear banding. Int J Fract
162(1–2):177–185
31. Incropera FP, DeWitt DP (2002) Introduction to heat transfer. Wiley, New York
32. Churchill SW, Bernstein M (1977) A correlating equation for forced convection from
gases and liquids to a circular cylinder in crossflow. ASME Trans J Heat Transf
99:300–306
33. Finney MA, Maynard TB, McAllister SS, Grob IJ (2013) A study of ignition by rifle
bullets. Res Pap RMRS-RP-104. US Department of Agriculture, Forest Service, Rocky
Mountain Research Station, Fort Collins, CO, 31p
34. Christiensen R (1998) Analysis of variance, design, and regression (Chap. 62). Bonfer-
onni adjustments Chapman & Hall, Boca Raton, FL
35. Abernathy JB (1968) Ballistic impact flash. Masters Thesis. School of Engineering of
the Air Force Institute of Technology, Air University. Wright-Patterson Air Force
Base, Ohio. 50p
36. Mansur JW (1974) Measurement of ballistic impact flash. Masters Thesis. School of
Engineering of the Air Force Institute of Technology, Air University. Wright-Patterson
Air Force Base, Ohio, 51p
Fire Technology 2015
... It is particularly dangerous in the case of such shooting in built-up areas, where the projectiles ricochetting on the metal structures, as well as building elements (stone, concrete, granite, etc.), may not only injure people, but also destroy the surrounding infrastructure-buildings and technical installations [1][2][3][4][5][6][7]. In addition, ricochetting projectiles in dry and warm terrain can cause ignition and fire of the area, such as mulch and peat [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. The most dangerous is ricochetting of projectiles on sensitive and dangerous materials, i.e., tanks and installations (refineries, gas and oil transfer stations, etc.) with flammable gases such as propane−butane and methane or with flammable liquids with gasoline, acetone, solvents, etc. (installations, warehouses and stores) or when ricochetting projectiles hit the above tanks and installations. ...
... The United States Department of Agriculture carried out research on the capability of various flammable substrates to ignite from ricochetting projectiles [8]. For the tests, the following ammunitions were used: 7.62 × 39 mm, 5.56 × 45 mm, 7.62 × 51 mm and 7.62 × 54R, with a steel core, lead core and solid copper and with a steel and copper jacket. ...
... The conducted literature review reveals a deficit of this type of studies. Similar studies were carried out in the work [8], but no thermal energy calculations were performed as in this paper. ...
Article
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This paper presents the results of a study of the hazards of ground ignition and/or explosion when various small-calibre projectiles struck various solid materials placed on a test stand in environments at risk of ignition (fire) or explosion (ricochets and projectile penetration of obstacles). For projectile ricochetting tests, the following were used: an armour plate, concrete, sidewalk and granite slabs, etc., and various small-calibre projectiles: 7.62 × 51 mm SWISS PAP, 7.62 × 51T, 7.62 × 51 mm M80, 7.62 × 54R B-32, 7.62 × 54R LPS and .308 Win. Norma Ecostrike. Projectiles impacts were recorded with a high-speed camera (50,400 fps) and thermal cameras (660 fps) and (2615 fps). The ignition capability of solid flammable materials during projectile ricochetting was studied, and the temperatures and surface areas of isotherms were measured as a function of time. From the spherical distribution of thermal energy radiation in space, their volumes, masses of air occupying the studied area, masses of projectile disintegrating into fragments (after impact), thermal energies during projectile ricochetting, histograms of area temperatures and temperatures were calculated. This energy was compared with the minimum ignition energy of the selected gases and liquid vapours, and the ignition temperature were determined. The probabilities of some of the selected gases and liquid vapours which can ignite or cause an explosion were determined. The thermal energies of the 7.62 × 54R B-32 (3400–9500 J) and 7.62 × 51T (2000–3700 J) projectiles ricochetting on the Armox 600 plate was sufficient to ignite (explode) propane−butane gas. The thermal energy of 7.62 × 54R B-32 projectiles ricochets on the non-metallic components (800–1200 J) was several times lower than that of projectiles ricochets on an Armox 600 plate (3400–9500 J). This is due to the transfer of much of the kinetic energy to the crushing of these elements.
... Numerous papers on ignition and fire have been published [6][7][8][9][10][11][12][13][14][15], but the available sources show a shortage of references on fire ignition from ricocheting projectiles [16]. ...
... Research on the ability of various flammable substrates to ignite from ricocheting projectiles was carried out by the United States Department of Agriculture/Forest Service [16]. For the tests, intermediate ammunition: 7.62 × 39 mm, 5.56 × 45 mm and rifle ammunition: 7.62 × 51 mm, 7.62 × 54R was used. ...
... This article focuses on the 5.56 × 45 mm SS109 projectile hitting a steel plate at an angle of 45 degrees ( Figure 1). Contrary to the work of [16], we decided to support the experimental research with FE analyses. Hence, it would be possible to recognise the phenomenon in more detail and calculate the ricochet temperatures, which will eventually help to determine if ignition of a given substance is possible. ...
Article
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This paper describes the process of creating a numerical FEM (finite element method) model of the 5.56 × 45 mm SS109 projectile. The model was used to calculate the temperatures occurring in the projectile materials during the impact on the steel plate at an angle of 45°. The purpose of the investigation is to estimate the ability of a ricocheting projectile to cause ignition. For the same projectile, experimental tests were also carried out under the conditions adopted for the numerical investigation in order to validate the FEM model. During the experiment, temperature was measured with a thermal camera; the phenomenon was also recorded with a colour high-speed camera.
... Further, Rogers [17] revealed that the expeditious plastic deformation is adiabatic, and no heat loss takes place during the deformation. Several numerical simulations [17,21] proved that impacted surface temperature increases with an increase in impact velocities of the bullet. According to Yildirim et al. [18], Molinari et al. [20], Finney et al. [21], and Rosenberg et al. [22], bullets with a velocity range of 700-1000 m/s could rise the impacted surface temperature from 623 to 773 K. ...
... Several numerical simulations [17,21] proved that impacted surface temperature increases with an increase in impact velocities of the bullet. According to Yildirim et al. [18], Molinari et al. [20], Finney et al. [21], and Rosenberg et al. [22], bullets with a velocity range of 700-1000 m/s could rise the impacted surface temperature from 623 to 773 K. An approximate estimation of bullet impact against solid objects predicted that bullet energy increased the bullet temperatures beyond 1273 K after impact under ideal conditions. ...
Article
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In the present investigation, a comparative study of ballistic impact behavior of Armox 500T (base metal) and its weldments prepared by low hydrogen ferrite (weldment-1) and austenitic stainless steel (weldment-2) consumables against 7.62 AP bullet has been performed with the help of finite element analysis code Abaqus 2017. Further, the result is validated with the experimental results. The experiment has been performed on the base metal, weldment-1, and weldment-2 against 7.62 AP bullet. Further, a two-dimensional explicit model has been developed for given purpose to simulate the bullet penetration at such high strain rate (103 s−1). Both bullet and plate are considered as deformable. Experimental results revealed that the depth of penetration in the base metal, weldment-1, and weldment-2 is 10.93, 13.65, and 15.20 mm respectively. Further computational results revealed that the depth of penetration of base metal, weldment-1, and weldment-2 is 10.11, 12.87, and 14.60 mm, respectively. Furthermore, weldment-1 shows more resistance against 7.62 AP bullet than weldment-2 in experimentation as well as FEA results. The percentage difference between experimental and FEA results are less than 10% which shows the prediction capability of FEA models. A feasibility analysis has been presented for using the welding consumables to weld the Armox 500T plate. Finally, in terms of ballistic resistance, the low hydrogen ferrite consumables are more appropriate than austenitic stainless-steel electrodes.
... RT value of IMR propellant ¼ 1.54 Â 10 6 (ft-lbs/lbs) [2]. W c ¼ 2.98 gm ¼ 0.0066 lbs [4,5]. W p ¼ 4 gm (62 grain) ¼ 0.0089 lbs [4,5]. ...
... W c ¼ 2.98 gm ¼ 0.0066 lbs [4,5]. W p ¼ 4 gm (62 grain) ¼ 0.0089 lbs [4,5]. ...
Article
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This research work deals with the design of a tunable muzzle brake [10] for a rifle chambered in 5.56 × 45 NATO ammunition. It proposes to solve the problem of handling differences from shooter to shooter by incorporating the feature of tunability. Beside this, it also solves the problem of requirement of optimum recoil in short recoil weapons. This innovation gives this design an edge over its already existing counterparts in the market. The product is designed using the internal ballistics calculations and the investigations been performed using solidworks flow simulation tool and ANSYS static structural to check the parameters like velocity distribution, pressure growth, and muzzle brake force along the series of ports and comparison of the so found results with those devised by the authors of the documents mentioned in references. This assures the market adaptability of the product for satisfactory performance, when brought among its already existing counterpart, though with a slight edge over them due to tunability. The results so found shall be concluded satisfactory regarding the performance of muzzle brake.
... Such causes may be more sensitive to the specific ambient conditions and have attracted considerable theoretical, experimental and statistical work, e.g. smoking (Countryman 1983;Kohyo et al. 2003;Butry et al. 2014), powerline arcs (Mitchell 2013;Miller et al. 2017) or rifle bullets (Finney and McAllister 2016). ...
Article
Several large Swedish wildfires during recent decades were caused by forestry machinery in operation, fires for which there is still no characterisation. We combined 18 years of data on dispatches, weather and fire danger and interviewed forestry workers to understand the spatial, temporal and weather distributions of these fires, and their underlying mechanisms. We estimate the average annual number of ignitions from forestry machinery in Sweden at 330–480 (2.0±0.4 ignitions per 1000ha clear-felling) of which 34.5 led to firefighter dispatches, constituting 2.2% of all forest fire dispatches and 40% of area burnt. Soil scarification causes the most ignitions and the main mechanism is likely high-inertia contact between discs and large stones, causing sparks igniting dry humus or moss, countering reports suggesting that such metal fragments cannot fulfil ignition requirements. We found a spatial relationship between forestry machine ignitions and abundance of large stones, represented by a Boulder Index generated from a nationwide dataset. Further, 75% of the dispatches occurred on days with relative humidity <45%, Duff Moisture Code (Canadian system) >26 and Fire Weather Index >12. 75% of the area burned when Fire Weather Index was >20. Results suggest machine-caused forest fires can be largely avoided by cancelling operations in stony terrain during high-risk weather.
... As well as possibly causing fracture into larger particles, the kinetic energy of a bullet is partly converted, upon striking the target animal's flesh, into a permanent change in shape of the projectile and into heat. The heat may cause some of the lead to melt or vaporize (Finney et al. 2016). On cooling, very small nanoparticles of solid lead may form from the melt. ...
Article
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It has been known for centuries that lead is toxic to humans. Chronic exposure to lead, even at low levels, is associated with an elevated risk of cardiovascular and chronic kidney disease in adults and of impaired neurodevelopment and subsequent cognitive and behavioural development in the foetus and young children. Health agencies throughout the world have moved from assuming that there are tolerable levels of exposure to lead to a recognition that valid ‘no-effect’ thresholds cannot currently be defined. Formerly, the most important exposure pathways were occupational exposure, water from lead plumbing, paints, petrol additives and foods. Regulation of products and improved health and safety procedures at work have left dietary lead as the main remaining pathway of exposure in European countries. Ammunition-derived lead is now a significant cause of dietary lead exposure in groups of people who eat wild game meat frequently. These are mostly hunters, shoot employees and their families, but also some people who choose to eat game for ethical, health or other reasons, and their children. Extrapolation from surveys conducted in the UK and a review of studies of game consumption in other countries suggest that approximately 5 million people in the EU may be high-level consumers of lead-shot game meat and that tens of thousands of children in the EU may be consuming game contaminated with ammunition-derived lead frequently enough to cause significant effects on their cognitive development.
... Spot ignition typically is considered to consist of three steps: the generation of sparks, their transport and coupled thermo-chemical change, and finally the potential ignition of the target fuel. There are a significant number of experimental studies examining the effect of single hot metal particle properties (material, size, and temperature), fuel properties (fuel material, morphology, and moisture content) [7][8][9][10][11][12][13] and some studies have examined the ability of spark fragments from bullet and heavy equipment impacts [14,15]. There have also been some studies examining the spot ignition of fuels by showers of sparks, and it was found that if the fuel is exposed to a continuous spray of sparks ignition can be achieved with lower temperature sparks [16,17]. ...
Article
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The temperature, velocity, and size of hot metal sparks are essential to understanding their ability to ignite flammable materials. However, existing measurement methods have limitations to achieve detailed, in situ measurements of these parameters. This paper describes a methodology that combines color-ratio pyrometry and particle streak tracing velocimetry, together with digital image processing to obtain non-intrusive measurements of the temperature, velocity, and size of multiple sparks in a spray. Furthermore, these measurements can be performed using a properly calibrated commercially available color digital camera. The principle of the measurement is firstly introduced, and the repeatability and accuracy of the method are validated via a designed experiment. Then the method is performed to measure the temperature and velocity of metal (steel) sparks in sprays generated by abrasive cutting. Measurements of initial spark temperatures and velocities are reported, as well as the evolution of the temperature and velocity along the flight path of the sparks. Observed initial spark temperature in this work mostly ranged within 1500°C to 1700°C. Results show evidence of both melting and oxidation of the sparks. Different blade speeds are used to understand their effect on spark velocity and temperature. The results of this study can be used as input parameters for spark oxidation and transport models, which in turn can be used to assess the hazards of spark sprays in wildland spot fires, ignition, explosions of flammable gaseous mixtures and dust clouds, and for monitoring and optimizing the material processes such as thermal-spray coating. © 2019, Springer Science+Business Media, LLC, part of Springer Nature.
... In Australia, some of the wild fires of the Black Saturday fires of February 2009 were also allegedly started by sparks and the fires propagated extremely fast by ember spotting [12]. Particles and sparks produced by welding, grinding and various forms of hot work have also been involved in several other notable incidents, and the established literature discusses many potential hot particle sources [1,5,[13][14][15][16][17][18][19]. ...
Article
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The ignition of combustible material by contact with hot metal particles is an important pathway by which wildland and urban spot fires are started. This work examines how fuel characteristics such as density, morphology and chemical composition effect the ability of the fuel to be ignited by a hot metal particle. Fuels were prepared out of three materials: alpha-cellulose, a barley/wheat/oat grass blend, and pine needles. Each material was prepared as a powder and as larger, long pieces: strips of cellulose paper, loose grass, and pine needles. These fuels are representative of thermal insulation (cellulose strips), dry grasses (grass blend), forest litter (pine needles) and duff (powders). Aluminum particles ranging from 2 mm to 8 mm in diameter heated to temperatures between 575°C and 1100°C were dropped onto these fuels. The particle temperature required for ignition becomes higher as the particle size decreased. The results show that the required temperatures for ignition of powders were lower, with this trend particularly pronounced for the alpha-cellulose fuels. The biomass fuels required higher temperature particles to ignite, indicating that the presence of other ligno-cellulosic materials make ignition more difficult.
Article
Despite Federal Bureau of Investigation Laboratory announcing the discontinuation of bullet lead examinations, knowledge of the composition of the bullets has been used as an alternative means of identifying their origin, achieving success in some case studies. In this work, wavelength dispersion X-ray fluorescence (WDXRF) and chemometrics were used for the analysis of rifle bullets, in order to identify the spectral similarities of these samples. For this purpose, 54 lead core fragments from 7.62 mm rifle bullets from 5 different manufacturers were obtained: Companhia Brasileira de Cartuchos (CBC), Israel Military Industries (IMI), Federal Cartridge (FC), Fray Luiz Beltrán (FLB) and Zavod Vlasim (ZV). Principal components analysis (PCA) discriminated the five groups of bullets according to their manufacturers in a three-dimensional scores graph, where 3 principal components accounted for >99% of the variability between the samples. The spectral region for Sb and the scattering region together proved to be determinant for discrimination of the groups. The dendrogram presented in the hierarchical cluster analysis (HCA) showed the formation of five groups. The k-nearest neighbor algorithm (k-NN) and soft independent modeling of class analogy (SIMCA) correctly classified all samples of the test set. X-ray scattering spectrum were used for the first time in the analysis of the fragments and contributed to the grouping of samples from the same manufacturers. The results indicate that the WDXRF technique is suitable for forensic purposes in case studies, as, besides being quick and relatively simple, it has the advantage of preserving evidence.
Technical Report
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A Natural England evidence review on the occurrence, causes, prevention and management of wildfires on open, semi-natural habitats in the UK, with a particular focus on heathlands and peatlands in England. This reflects Natural England’s role and interest in relation to maintaining and restoring the structure and function of semi-natural habitats, including supporting ecosystem services and related government environment objectives and policies. Supporting information and summary data are given in 12 appendices.
Book
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This is the only authoritative treatise to encompass the entire field of ignition. The 1116-page handbook was published in cooperation with the Society of Fire Protection Engineers, under whose auspices the peer review was performed.
Article
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The ignition of natural combustible material by hot metal particles is an important fire ignition pathway by which wildland and urban spot fires are started. There are numerous cases reported of wild fires started by clashing power-lines or from sparks generated by machines or engines. Similarly there are many cases reported of industrial fires caused by grinding and welding sparks. In this work, the effect of metal type on the ability of hot metal particles to cause flaming ignition of powdered cellulose fuel beds is studied experimentally. The materials studied are stainless steel, aluminum, brass and copper. These metals are representative of clashing conductors (aluminum and copper) and those involved in machine friction and hot work such as welding (stainless steel and brass). Cellulose powder is used as a surrogate for natural fuel beds. Particles of various sizes from 2 to 11 mm in diameter are heated to various temperatures between 575 and 1100 ° C and dropped onto the fuel bed. The results show a hyperbolic relationship between particle size and temperature, with the larger particles requiring lower temperatures to ignite the cellulose than the smaller particles. For large particles of all the metals, the ignition boundary is not very sensitive to particle size. For small particles the ignition boundaries are similar for the different metals and sensitive to both energy and temperature. The thermal properties of the metal play a lesser role in determining ignition with exception of the energy release from melting when it occurs. It also appears that the controlling ignition mechanisms by large particles are different than those from the small particles. The former appears to be determined primarily by the particle surface temperature while the later by the particle energy and temperature.
Thesis
The process of spotting whereby burning firebrands are transported by convection and wind to ignite new fires ahead of the source fire is significant both economically and in terms of exposure of fire crews to dangerous situations. Spotting behaviour recorded in Australia is the worst in the world in terms of spotfire distance and concentration and this has been attributed to features of eucalypt bark types. This thesis is the first comprehensive firebrand investigation of any bark. It briefly examines selected firebrand characteristics of Eucalyptus diversicolor, E. marginata and E. bicostata and examines in detail the aerodynamic and combustion characteristics and fuel bed ignition potential of Eucalyptus obliqua...
Article
The aim of this work was to determine the smallest size of copper emission which could pose a significant fire risk in normal environments. Results are given for the fire ignition tendency of a selection of naturally occurring fuels exposed to incandescent copper droplets of controlled size.
It is recognised that aluminium particles, released by electric arcing, present a severe bushfire hazard. Results are presented showing the fire ignition tendency for a selection of naturally occurring fuels exposed to incandescent aluminium particles of controlled size.
Book
This book explains the physical concepts and methodologies of heat and mass transfer. It uses a systematic method for problem solving and discusses the relationship of heat and mass transfer to many important practical applications through examples and problems. It also presents the extensive use of the First Law of thermodynamics.