Gun Muzzle Research Articles

Orban’s gun ballistics and assessment of historical evidence concerning the bombardment of Constantinople walls in 1453

In this paper the bombardment of the Constantinople Theodosian Walls by the great cannon of Orban is numerically reproduced with the aid of Structural Mechanics. Overall gun dimensions were assessed based on historical reports, whereby, the gunpowder charge p was estimated at 177 kg, and the gun was placed at a distance of 500 m from the Inner Walls. Gun ballistics and effect on target have been evaluated analytically. The analysis has verified Orban’s gun muzzle velocity, cannonball trajectory and its effect on Constantinople Walls by successfully calculating the length of the breach in the wall, referred to in historical reports, as well as the cannon ball penetration into soil. Finally, a numerical effort was made to assess the sound pressure level inside Constantinople during bombardment confirming the tremendous psychological effect of the cannon’s blast on the City’s population.

Measurement of projectile’s in-bore yaw based on the optical lever principle

The initial disturbance of a projectile emerging from the gun muzzle is a major reason for the projectile dispersion. Therefore, measurements of initial disturbances have a great value in improving the understanding. This paper establishes a mathematical model of the measurement system for the projectile’s in-bore orientation, by utilizing the theory of ray tracing and kinematics. The layout of the optical apparatuses is attributed to an optimization problem, and the genetic algorithm is implemented to acquire an optimal layout scheme, which is further verified by test. Also, the linear time-invariant characteristics of the measurement system are numerically verified in the context of spatial ray. These investigations will provide a technical support for the experiment, the optical apparatuses’ layout and calibration of the measurement system.

Study on Dynamic Burning Rate Equation of Propellant

Aiming at the difficulty that the actual burning law of propellant in the gun bore couldn't be described exactly by static burning rate equation in the closed-bomb, propellant dynamic burning rate equation and its acquisition method were established in the paper, which are based on static burning rate equation and considering burning gas flow and loading density influence factors in bore. A numerical code for interior ballistic two-phase flow was successfully developed. And corresponding firing tests were also carried out. The comparison of simulations with interior ballistic code and firing test results show that the propellant dynamic burning rate equation makes the maximum errors of muzzle velocity and pressure in breech decreased from 2.97 % to 0.75 % and from 6.68 % to 0.38 %, respectively. This method not only improves simulation precision of gun muzzle velocity and pressure significantly, but also provides a means to improve the design accuracy for interior ballistic performance.

Scaling Laws for the Peak Overpressure of a Cannon Blast

For large cannons, blast overpressure can have a detrimental effect on the crew in the near field (i.e., within a distance of 50 tube diameters or calibers from the muzzle center) as well as on the support personnel and equipment in the far field (i.e., at a distance greater than 50 calibers). Therefore, an efficient method to determine the peak overpressure due to a cannon blast is highly desired. In this study, we investigate scaling laws for the peak overpressure, due to the primary blast of a large cannon, with the aim that they can be applied as an efficient method to evaluate the peak overpressure in the far field. We explore two types of scaling laws; each type is based on a power-law model involving a prefactor and an exponent as model parameters. The two types of the power-law models differ in the way they incorporate the polar angle dependence. The first type was proposed by Fansler and Schmidt (1983, “The Prediction of Gun Muzzle Blast Properties Utilizing Scaling,” U.S. Army Ballistic Research Laboratory, Aberdeen Proving Ground, MD, Report No. ARBRL-TR-02504). They developed a muzzle-center based scaling law (MCSL) in which the polar angle dependence was incorporated through a reference length scale to define a nondimensional or scaled radial distance from the muzzle center and the model parameters were independent of the polar angle. They calibrated the parameters by employing least-squares fit to a wide range of experimental data. In this study, we recalibrated or updated the parameters for the current cannon by using the numerical simulation data for the cannon blast in the near field. Additionally, we developed a second type of scaling law in which the radial distance is defined from the blast center (in contrast to the muzzle center) and scaled using the inner tube diameter. In this model, the angular dependence is incorporated directly into the model parameters. For this model too, we calibrated the parameters by using the numerical simulation data. We observe that both the modified version of the muzzle-center based scaling law as well as the blast-center based scaling law (BCSL) show a significantly closer fit to the numerical and experimental data and achieve a similar level of accuracy. This indicates that the current form or structure of the two types of power-law based scaling models is able to fit well with the near-field data; however, the current methodology requires a calibration process for a given cannon of interest. In the future, with far field data, we plan to evaluate predictions in the far field.

Influence of pellet seating on the external ballistic parameters of spring-piston air guns.

In firearm examiners' and forensic specialists' casework as well as in air gun proof testing, reliable measurement of the weapon's muzzle velocity is indispensable. While there are standardized and generally accepted procedures for testing the performance of air guns, the method of seating the diabolo pellets deeper into the breech of break barrel spring-piston air guns has not found its way into standardized test procedures. The influence of pellet seating on the external ballistic parameters was investigated using ten different break barrel spring-piston air guns. Test shots were performed with the diabolo pellets seated 2mm deeper into the breech using a pellet seater. The results were then compared to reference shots with conventionally loaded diabolo pellets. Projectile velocity was measured with a high-precision redundant ballistic speed measurement system. In eight out of ten weapons, the muzzle energy increased significantly when the pellet seater was used. The average increase in kinetic energy was 31% (range 9-96%). To conclude, seating the pellet even slightly deeper into the breech of spring-piston air guns might significantly alter the muzzle energy. Therefore, it is strongly recommended that this effect is taken into account when accurate and reliable measurements of air gun muzzle velocity are necessary.

Characterization of viscoelastic materials for low-magnitude blast mitigation

Recent research indicates that exposure to low amplitude blast waves, such as IED detonation or multiple firings of a weapon, causes damage to brain tissue resulting in Traumatic Brain Injury (TBI) and Post Traumatic Stress Disorder (PTSD). Current combat helmets are not sufficiently protecting warfighters from this danger and the effects are debilitating, costly, and long-lasting. The objective of the present work is to evaluate the blast mitigating behavior of current helmet materials and new materials designed for blast mitigation using a test fixture recently developed at the Naval Surface Warfare Center Dahlgren Division for use with an existing gas gun. The 40-mm-bore gas gun was used as a shock tube to generate blast waves (ranging from 0.5 to 2 bar) in the test fixture mounted on the gun muzzle. A fast opening valve was used to release helium gas from the breech which formed into a blast wave and impacted instrumented targets in the test fixture. Blast attenuation of selected materials was determined through the measurement of stress data in front of and behind the target. Materials evaluated in this research include polyurethane foam from currently fielded US Army and Marine Corps helmets, polyurea 1000, and three hardnesses of Sorbothane (48, 58, and 70 durometer, Shore 00). Polyurea 1000 and 6061-T6 aluminum were used to calibrate the stress gauges.

Scanning electron microscopy and X-ray microanalysis for chemical and morphological characterisation of the inorganic component of gunshot residue: selected problems.

Chosen aspects of examinations of inorganic gunshot particles by means of scanning electron microscopy and energy dispersive X-ray spectrometry technique are presented. The research methodology of particles was worked out, which included a precise and repeatable procedure of the automatic detection and identification of particles as well as the representation of the obtained analytical data in the form of the frequencies of occurrence of particles of certain chemical or morphological class within the whole population of particles revealed in a specimen. On this basis, there were established relationships between the chemical and morphological properties of populations of particles and factors, such as the type of ammunition, the distance from the gun muzzle to the target, the type of a substrate the particles sediment on, and the time between shooting and collecting the specimens. Each of these aspects of examinations of particles revealed a great potential of being utilised in casework, while establishing various circumstances of shooting incidents leads to the reconstruction of the course of the studied incident.

Persistence of biological traces in gun barrels after fatal contact shots

In the majority of cases suicidal shots are put to the head. Typically the gun's muzzle is held against the head. The aim of the present prospective study was to investigate whether victim DNA could reliably be recovered from the inside of the barrels of firearms that were used in 20 cases of homicidal or suicidal close contact shots. Additionally, it was investigated whether such biological traces were eliminated by subsequent firing. After autopsy sterile swabs were used to collect samples from the anterior part of the barrel thereby avoiding the muzzle. In some cases prior endoscopic inspection had revealed traces of blood and soft tissue in the barrel. For 16 cases, another swab was used to also collect sample from the posterior part of the barrel entering from its rear end. Then one shot was fired through the weapon using the same ammunition as in the suicidal shot and the sampling procedure was repeated. DNA was extracted using a magnetic beads based protocol, quantified, and STR-systems were amplified using several commercially available multiplex-STR-PCR-kits. For samples taken after the first shot DNA-analysis yielded STR profiles eligible for reliable individualization in 17 of 20 cases. After a second shot had been fired 8 or more STR systems were amplified successfully in 14 of 20 barrels.

CFD analysis of sound pressure in tank gun muzzle silencer

The high pressure waves generated due to muzzle blast flow of tank gun during firing is a critical issue to examine. The impulsive noise from the gun has various negative effects such as damage of human bodies, damage of structures, creating an environmental, social problem and also military problems such as exposure of location of troops. This high pressure impulsive sound, generated during the blast flow, was studied and attenuated. An axisymmetric computational domain was constructed by employing Spalart Allmaras turbulence model. Approximately 90% of pressure and 20 dB of sound level are reduced due to the use of the three baffle silencer at the muzzle end of the gun barrel, in comparison with the tank gun without silencer. Also, the sound pressure level at different points in the ambient region shows the same attenuation in results. This study will be helpful to understand the blast wave characteristics and also to get a good idea to design silencer for large caliber weapon system.

Wounding capacity of muzzle-gas pressure

Suicidal gunshot wounds that are caused by ammunition fired from a 9-mm Luger pistol, with direct contact between the gun muzzle and the victim's head, present a serious injury pattern even with full metal jacket bullets. Wound ballistic experiments were performed to clarify whether muzzle gases from the firearm have an additional wounding potential. Fifteen head models were prepared as follows: an acryl sphere measuring 14 cm in diameter was completely covered with a layer of silicon that was 3 mm thick. These spheres were filled with 10% gelatine. At 4°C, these models were fired at with a 9-mm Luger pistol, loaded with Quick Defense 1 expanding bullets. Five shots were fired with direct muzzle contact, one shot was fired from a distance of 10 cm, four shots were fired from a distance of 2 m, and five shots were fired from a distance of 4 m. Each projectile penetrated the model; all but one projectile deformed regularly. Each acryl sphere shattered into comminuted pieces but was held together by the silicon cover. The gelatine filling was then cut into slices 1 cm thick, and each slice was optically scanned. An evaluation was performed following both Fackler's Wound Profile method and the polygon procedure method. The pattern of gelatine disruption did not differ in shots from intermediate ranges, but the amount of gelatine destruction was always more extended in the case of muzzle contact shots. Depending on the section of the bullet path, crack lengths were 31% to 133% longer in contact shots. The first centimetre and the second half of the bullet path showed the greatest increase. The experimental findings prove the wounding capacity of muzzle gases.

Variation of the chemical contents and morphology of gunshot residue in the surroundings of the shooting pistol as a potential contribution to a shooting incidence reconstruction

A study of the chemical contents and sizes of gunshot residue originating from 9×18mm PM ammunition, depositing in the vicinity of the shooting person was performed by means of scanning electron microscopy and energy dispersive X-ray spectrometry. Samples of the residue were collected from targets placed at various distances in the range 0-100cm as well as from hands and clothing of the shooting person. Targets were covered by fragments of white cotton fabric or black bovine leather. In the case of cotton targets microtraces were collected from circles of 5 and 10cm in radius. Results of the examinations in the form of numbers of particles, proportions of their chemical classes and dimensions revealed a dependence on the distance from the gun muzzle, both in the direction of shooting and in the opposite one, i.e., on the shooting person. The parameters describing gunshot residue differed also depending on the kind of the target substrate. The kind of obtained information gives rise to understanding the general rules of the dispersion of gunshot residue in the surroundings of the shooting gun. Thus, it may be utilised in the reconstruction of shooting incidences, especially in establishing the mutual positions of the shooter and other participants of the incident.

Analytical Approach to Ballistic Dispersion of Projectile Weapons Based on Variant Launch Velocity

This study quantifies the contribution of variant projectile velocity at a gun muzzle to its dispersion at an aim point from an analytical approach. The dispersion was formulated on the basis of stochastic physical conditions including potential crosswind effect. As a result, the statistical quantities of projectile impact distribution could be obtained from the stochastic formulation. In addition, this research proposes correction factors that may be needed when comparing dispersion in angular mil at multiple downrange distances. The significance of the correction factors was demonstrated through a few application examples.

Rail Gun Muzzle Velocity Control With High Accuracy

A rail gun can be used as an experimental tool to accelerate small-mass specimens up to 300 m/s to study impact phenomena. In order to obtain comparable and reproducible results, it is desirable to achieve a low statistical deviation of the final velocity. To decrease the deviation during the launch for a railgun, the movement of the projectile is observed along the barrel and the difference between the desired and the measured velocity is calculated. The driving current is then adjusted dynamically by triggering the capacitor modules earlier or later than planned. This paper presents initial experimental results within this study. A light barrier system has been set up to monitor the projectile's position in real time. The special design of the system prevents disturbances caused by magnetic fields and electromagnetic radiation. This is reported in detail. A series of shots was performed under constant conditions to measure the deviation of the final velocity. Launches were performed using the French-German Research Institute Saint Louis's augmented railgun (caliber 15 mm × 15 mm, length 1.6 m), which was supplied by a 38-kJ capacitor bank. The bank consisted of four energy modules, each module containing one capacitor and a thyristor as a switch. The modules could be triggered independently from each other. In the second series of shots, the trigger-time of the last module was varied to investigate the effect on the final velocity. The experimental results are analyzed and discussed.

Acoustical analysis of an indoor test facility for aircraft Gatling guns

An indoor test facility for 20-mm and 30-mm aircraft Gatling guns was recently constructed at Hill Air Force Base in Layton, UT. In designing the range, the primary concerns were that the 30-mm gun muzzle blast overpressures were large enough to a) cause significant spallation of the concrete walls during the anticipated 20-year building usage, and b) potentially pose an auditory risk for personnel working elsewhere in the test range building. This project consisted of three phases. First, levels, directivity, and geometric spreading of the 30-mm gun blast were characterized in outdoor measurements. Second, range impulse response estimates generated by a commercial room acoustics package were used to discover potential problem areas within the range and explore the effectiveness of treatments. Finally, data were collected on gun blasts in the completed range to confirm that the test facility meets all acoustical and occupational safety requirements

Comparison of cartridge case and airborne GSR—a study of the elemental composition and morphology by means of SEM‐EDX

AbstractA comparative study of the properties of gunshot residue (GSR) collected from shooter's hands and from inside the case of the same cartridge used in a shooting experiment was performed. Three types of popular Luger 9 mm ammunition were chosen with primer mixtures based on different types of detonators: mercury fulminate, lead styphnate or lead azide and an organic one, e.g. diazodinitrophenol. Two modifications of lead‐free ammunition, with copper and tin plated projectiles were used. Samples of GSR were examined by means of scanning electron microscopy and energy dispersive X‐ray spectrometry. Both, similarities and differences in the chemical composition and morphology of GSR secured from the hands of the shooting person and from the appropriate cartridge case were observed. The chemical composition of the characteristic gunshot particles originating from the primer may be influenced by the chemical composition of other parts of the cartridge case, especially the core and the jacket of the projectile. Thus, the distribution of the chemical elements in GSR strongly depends on the direction of the reaction path starting in the primer cup placed at the bottom of the cartridge case, moving along the cartridge case and finishing when the projectile leaves the gun muzzle. A reliable comparison of the airborne residue to these taken from cartridge case for forensic purposes requires some experience based on laboratory experiments performed under controlled conditions. Copyright © 2007 John Wiley & Sons, Ltd.

장축 실린더의 열변형 최소화를 위한 차열관 효과 해석 및 실험 연구

A barrel is a high length-to-diameter ratio cylinder that is influenced by environmental factors such as sunlight, precipitation, wind and clouds. Cross-barrel temperature differences caused by uneven heating or cooling lead to thermal deformation that degrades accuracy. Therefore, a barrel is covered by thermal shrouds to minimize the type of thermal deformation, fall-of-shot. In this paper, an analytical and experimental study is presented to design the thermal shrouds for a gun barrel and to evaluate the thermal shroud effect. First, an analytical study on the thermal shroud effect to minimize thermal deformation of a gun barrel by sunlight and wind is performed. The coupled analysis of thermal fluid dynamics of the air flow between a barrel and thermal shrouds and thermal stresses of a barrel Is performed to clarify both the thermal shroud effect and the drift in gun muzzle orientation by thermal deformation. Second, experiments are carried out to test and evaluate the thermal shroud effect on the performance of a gun barrel. The drift in gun muzzle orientation against the solar radiation is confirmed by the experiments, and the results well agree with the analytical estimation. Third, three principal design factors that are presumed to have an effect on the performance of the thermal shrouds are also analyzed; sorts of shroud materials, wall-thickness of thermal shrouds, and distance of the gap between a barrel and thermal shrouds.

Acoustic methods for measuring bullet velocity

This article describes two acoustic methods to measure bullet velocity with an accuracy of 1% or better. In one method, a microphone is placed within 0.1 m of the gun muzzle and a bullet is fired at a steel target 45 m away. The bullet’s flight time is the recorded time between the muzzle blast and sound of hitting the target minus the time for the sound to return from the target to the microphone. In the other method, the microphone is placed equidistant from both the gun muzzle and the steel target 91 m away. The time of flight is the recorded time between the muzzle blast and the sound of the bullet hitting the target. In both cases, the average bullet velocity is simply the flight distance divided by the flight time.

Sustained spheromak coaxial gun operation in the presence of an n=1 magnetic distortion

The Sustained Spheromak Physics Experiment (SSPX) [E. B. Hooper, L. D. Pearlstein, and R. H. Bulmer, Nucl. Fusion 39, 863 (1999)] uses a magnetized coaxial gun to form and sustain spheromaks by helicity injection. Internal probes give the magnetic profile within the gun. An analysis of these data show that a number of commonly applied assumptions are not completely correct, and some previously unrecognized processes may be at work. Specifically, the fraction of the available vacuum flux spanning the gun that is stretched out of the gun is variable and not usually 100%. The n=1 mode that is present during sustained discharges has its largest value of δB∕B within the gun, so that instantaneously B within the gun is not axisymmetric. By applying a rigid-rotor model to account for the mode, the instantaneous field and current structure within the gun are determined. The current density is also highly nonaxisymmetric and the local value of λ≡μ0j∣∣∕B is not constant, although the global value λg≡μ0Ig∕ψg closely matches that expected by axisymmetric models. The current distribution near the gun muzzle suggests a cross-field current exists, and this is explained as a line-tying reaction to plasma rotation.

기총 폭발 하중에 대한 모델 수립과 구조 해석에 관한 연구

총구로부터 방출되는 폭발파에 대한 수학적 모델(GUNBLAST)을 수립하였으며, 폭발 하중에 대한 구조 응답 해석을 수행하였다. 폭발파는 자유영역 폭발파와 반사 폭발파로 구분되어질 수 있다. 본 연구에서는 스케일 기법을 이용하여 자유영역 폭발파 모델을 수립하였으며, 경사 충격파 이론과 전산유체역학(Computational Fluid Dynamics) 계산을 통하여 반사 충격파를 계산하였다. GUNBLAST는 두 가지의 구조 모델에 적용되었으며 구조 표면으로부터의 총구거리 변화에 따른 폭발파 특성을 파악하기 위하여 평판에 대한 적용을 통하여 균일하중조건과의 비교를 수행하였다. 또한 MSC/NASTRAN을 이용하여 12.7mm 기총을 장착한 비행기 날개 모델의 과도 응답 해석을 수행하였다. 결과적으로 이러한 폭발파는 랜덤진동과 항공기에 탑재된 장비에 고주파의 손상을 일으킬 수 있음을 확인하였다. A mathematical model, GUNBLAST, of blast waves emitted from a gun muzzle is established, and structural response analyses for the blast load are performed. The blast wave can be divided into two kinds of waves, free field and reflected blast waves. In this research, the free field blast wave model is established by the use of a scaling approach, and the reflected blast wave is calculated by using the oblique shock theory and computational fluid dynamic calculation. GUNBLAST is applied to two kinds of structural models. To investigate the effect of the muzzle distance from a structural surface, the blast waves on a plate for various muzzle distances are compared to uniform loads. Moreover, the transient response analysis of an aircraft wing model with a 12.7mm gun is carried out by using MSC/NASTRAN. From the results, it can be shown that the blast wave can cause broad random vibration and high frequency damage to equipments mounted in the aircraft.

Heating and Transport of Metal Plasma in a Vacuum-Arc Rail Gun

Arc coupled nonlinear LCR circuit equations were solved simultaneously with the Newtonian arc motion to describe the under-critically damped high arc current and resulting _J /spl times/ _B propulsion in a vacuum-arc rail gun. Heating of plasma owing to the direct coupling by arc through magneto-hydrodynamic, ion-acoustic, Coulomb, and neutral interactions is formulated in a three-component electron continuity regime including major loss by radiation. The plasma density (n/sub e/) so deduced in arc was around 10/sup 22/-10/sup 23/m/sup -3/, temperature (T/sub e/) over hundreds of electronvolts, and attained final velocity /spl sim/2/spl times/10/sup 6/cm/s. The launched plasma on emerging from the gun muzzle, rapidly equilibrated through radiative re-combinations and three-body collisions has n/sub e//spl sim/5/spl times/10/sup 21/m/sup -3/ and T/sub e//spl sim/80-90 eV at 50 cm away from the breech as shown through experiments.