Gun Muzzle Research Articles

Empirical Models for Predicting Two-Stage Light Gas Gun Muzzle Velocity

Empirical Models for Predicting Two-Stage Light Gas Gun Muzzle Velocity

Pervasiveness of inorganic gunshot residue (IGSR) in handguns after cleaning and conditioning procedures.

Memory effect in firearms that is, the possibility for a weapon to release inorganic particles whose elemental composition depends on its entire shooting history, is responsible for most of the interpretation difficulties encountered in forensic gunshot residue analysis. The presence of residues chemically inconsistent with the last discharged round, the creation of particles having unusual elemental profiles, and the dependence of residue population composition on the collection point are all manifestations of memory effect. The experimental results reported in this paper highlight the ineffectiveness of a wide number of gun cleaning procedures in reducing memory effect. Moreover, the common alternative of discharging batches of rounds having a "new" primer mixture does not fully eliminate the possibility to recover "old" residues at least from the shooter's hands. Two brand new pistols and ammunition having lead-based, leadless and heavy metal free primers were used. Specimens, collected both from the shooters' hands and from cotton targets set nearby the gun muzzle, were analyzed by SEM-EDS and by ICP-OES. After discharging 10's of new ammunitions, the number of old residues ejected from the gun muzzle indeed showed an asymptotic decrease to zero. In spite of this, the number of old residues recovered from the shooter's hands did not follow any predictable trend. These different behaviors suggest that all internal components of a gun, and not just the barrel, play a role in memory effect.

Numerical Study on the Flow Field Characteristics and Efficiency of Different Underwater Gun Muzzle Brakes

The submerged gun’s mathematical and physical models were established, and an investigation was conducted on the development of the flow field and the recoiling efficiency of three representative muzzle brakes. The study employed the Schnerr-Sauer cavitation model and the k − ω transport turbulence model, both based on the Reynolds-averaged Navier-Stokes method. Numerical simulation of the underwater firing of a 12.7 mm gun’s muzzle flow field was accomplished using a combination of user-defined function (UDF) and overlapping mesh techniques. Detailed analysis was performed on the flow field characteristics encompassing density, velocity, and phase state fields, along with an in-depth examination of the efficiency of the three muzzle brakes. The simulation results demonstrated an enhanced cavitation effect when a brake was incorporated, with the impact muzzle brake exhibiting the highest efficiency, followed by the impact-reaction type, while the reaction type exhibited the lowest performance.

Research on the muzzle vibration displacement test method of large-caliber rifled gun based trinocular vision

To address the problem of inaccurate muzzle vibration displacement measurements caused by the twisting of the barrel at the moment of firing of large-caliber rifled gun, a vibration displacement test method of large-caliber rifled gun based trinocular vision is proposed. A high-precision measurement system for muzzle vibration displacement based on an orthogonal imaging method with three high-speed cameras has been built. Three high-speed cameras are placed at the side and rear of the gun at orthogonal angles to each other to collect two-dimensional digital images of the gun muzzle area. Accurate displacement of the muzzle height, azimuth and recoil direction is derived by image processing techniques and multi-dimensional displacement decoupling methods. In addition, the three cameras can realize the online self-verification of parameters such as ‘recoil’ and ‘twist’. The three-dimensional vibration displacement and torsion parameters of the muzzle of a 155mm gun were obtained by a test of firing range. The test results proved the validity and accuracy of the method for the muzzle vibration displacement of rifled gun.

Research on the Vibration Response of an Aircraft Gun Muzzle Based on Nonlinear Finite Element

The muzzle vibration response of an aircraft gun is one of the key factors affecting the firing accuracy of the aircraft gun. In order to study the muzzle vibration response of an aircraft gun, based on the basic theory of the nonlinear finite element method, the nonlinear finite element dynamics simulation model is established by considering the nonlinear factors which are the contact and collision between the gun aircraft and the cradle, the contact and collision between the elevating gear arc and gear, and the slide clearance between the aircraft gun and the cradle, etc. The muzzle vibration response is characterized by the linear displacement and linear velocity of the center point of the aircraft gun, and its dynamics is obtained through numerical calculation and simulation. The correctness of the dynamics simulation model of the aircraft gun muzzle vibration is verified by setting up verfication bench. The results show that the established nonlinear finite element dynamic simulation model can be used to predict the muzzle vibration response of the aircraft gun, and at the same time, by changing the slide clearance between the aircraft gun and the cradle, the effect of clearance on the muzzle vibration response is investigated. Additionally, it can be seen that reducing the slide clearance can improve the firing accuracy of the aircraft gun while ensuring the machining assembly and mechanism movement.

Research on simulation of gun muzzle flow field empowered by artificial intelligence

Artificial intelligence technology is introduced into the simulation of muzzle flow field to improve its simulation efficiency in this paper. A data-physical fusion driven framework is proposed. First, the known flow field data is used to initialize the model parameters, so that the parameters to be trained are close to the optimal value. Then physical prior knowledge is introduced into the training process so that the prediction results not only meet the known flow field information but also meet the physical conservation laws. Through two examples, it is proved that the model under the fusion driven framework can solve the strongly nonlinear flow field problems, and has stronger generalization and expansion. The proposed model is used to solve a muzzle flow field, and the safety clearance behind the barrel side is divided. It is pointed out that the shape of the safety clearance under different launch speeds is roughly the same, and the pressure disturbance in the area within 9.2 m behind the muzzle section exceeds the safety threshold, which is a dangerous area. Comparison with the CFD results shows that the calculation efficiency of the proposed model is greatly improved under the condition of the same calculation accuracy. The proposed model can quickly and accurately simulate the muzzle flow field under various launch conditions.

Numerical study of the influence of different water depths on the muzzle flow characteristics of machine gun

The mathematical and physical models of the underwater submerged gun are established to study the flow field distribution characteristics of the gun muzzle at different water depths. The Schnerr–Sauer cavitation model and the realizable k–ω transport turbulence model based on the Reynolds-averaged Navier–Stokes method are employed. The muzzle flow field for the 12.7 mm gun that is submerged launched underwater is numerically simulated by combining user-defined functions and overlapping mesh technology. The flow characteristics of the density, velocity, and pressure fields at the gun muzzle at different water depths are analyzed in detail. The results show that the muzzle flow morphology depends mainly on the pressure at different water depths. The muzzle flow field distribution in deep water is more flat due to the high value of water pressure, which limits the expansion of the muzzle gas, and the range of the velocity field of the muzzle flow field at 100 m is one time smaller than that at 1 m.

Effect of active cooling on the thermal effect of electromagnetic rail under single launch mode

In order to investigate the influence of active cooling on the rail thermal effect of electromagnetic gun under single launch mode, characteristics of the peak temperature, cross-section current density and temperature distribution, axial temperature distribution of rail with and without active cooling are simulated. In addition, the time-varying characteristics of the rail axial temperature distribution, the temperature time-varying characteristic in different temperature parts on the rail and the influence of the cooling water flow velocity on the temperature in different temperature parts are experimentally studied. The results show that during the launch, there is almost no difference between the rail peak temperature and its location with and without active cooling, and the peak temperature is basically located at the initial position of the armature. Without active cooling, the rail axial temperature distribution shows a trend of higher at the gun tail and lower at the gun muzzle. The current density and temperature distribution of rail cross-section show a trend of higher on the rail inner side and lower on the rail outer side, and the diffusion of heat lags behind the diffusion of current. Under the action of active cooling, the rail peak temperature will move to the muzzle along the armature moving direction, and there is a “thermal inversion” phenomenon. The rail cross-section temperature drops faster, and the lowest temperature region appears near the middle cooling channel. Active cooling has different effects on rail temperature in different temperature parts. In the high-temperature part, the rail temperature decreases monotonically with the increase of cooling water flow velocity, increasing the water velocity can accelerate the decline of rail temperature. In the middle-temperature parts, the variation trend of rail temperature is different with different water flow velocities. At low water velocity, the rail temperature increases gradually. When the water flow velocity is greater than 0.75 m/s, the phenomenon of “thermal inversion” will occur. i.e., the rail temperature increases first and then decreases. In the low-temperature part, “thermal inversion” will occur at different flow velocities, that is, the rail temperature increases first and then decreases. When the water flow velocity is greater than 1.0 m/s, the improvement of rail cooling effect will no longer be obvious. It is suggested that the appropriate water flow velocity is 0.75–1.0 m/s under the present experimental conditions.

Vibration control of a military vehicle weapon platform under the influence of integrated ride and cornering dynamics

The present study is focussed upon vibration control of the weapon elevation and azimuth dynamics mathematical model under influence of the 20 degree of freedom integrated ride and cornering dynamics non-linear mathematical model of a military vehicle with trailing arm suspension. The PID, LQR and Backstepping control techniques are applied in the weapon dynamics model in order to achieve the desired level of gun stabilisation over different manoeuvring situations. The control methods are initially implemented in the weapon elevation dynamics mathematical model which is subjected to vehicle ride response inputs only. In the later section, the control methods are incorporated in the azimuth dynamics mathematical model which is subjected to the integrated ride and cornering dynamic response inputs from different manoeuvres. The control forces are incorporated in the governing equations of motion for the weapon elevation and azimuth dynamics. The equations of motion for the weapon elevation and azimuth dynamics with incorporated control parameters, are transformed into state space matrix domain and solved by using Matlab. The elevation and azimuth dynamic responses are observed over the random terrain and with variable track velocities, respectively and compared with the corresponding passive models. It is observed that adequate attenuation of the vehicle dynamic inputs could be attained with the control techniques which led to desired weapon stabilisation in both elevation and azimuth directions. Compared to other controllers, backstepping control strategy is observed to provide the maximum attenuation in weapon responses by directly considering the Lyapunov stability criterion in its formulation. Therefore, the basic focus is to evaluate the gun muzzle response reduction by implementing different control techniques under the influence of a non-linear vehicle dynamic platform. These studies would provide the motivation and foundation behind design and development of gun control system for the military vehicles with All Electric Drive.

Dynamic Compensation of Piezoresistive Pressure Sensor Based on Sparse Domain

In the process of transient test, due to the insufficient bandwidth of the pressure sensor, the test data is inaccurate. Firstly, based on the projection of the shock tube test signal in the sparse domain, the feature expression of the signal sample is obtained. Secondly, the problem of insufficient bandwidth is solved by inverse modeling of sensor dynamic compensation system based on swarm intelligence algorithm. In this paper, the method is used to compensate the shock tube test signals of the 85XX series pressure sensors made by the Endevco company of the United States, the working bandwidth of the sensor is widened obviously, the rise time of the pressure signal can be compensated to 12.5 μs, and the overshoot can be reduced to 8.96%. The repeatability of dynamic compensation is verified for the actual gun muzzle shock wave test data, the results show that the dynamic compensation can effectively recover the important indexes such as overpressure peak value and positive pressure action time, and the original shock wave signal is recovered from the high resonance data.

SUBSTANTIATION OF PERSPECTIVES OF USING THE LIBRARY OF COMPUTER VISION OpenCV IN THE DEVELOPMENT OF SOFTWARE FOR PROCESSING VIDEO INFORMATION TESTS

The article highlights the practicability of developing our own software for processing video information obtained during testing of weapons and military equipment (WME) specimens. To obtain measurement information of processes which are distributed in space and time, namely: motion trajectories, velocity, acceleration of the object, propagation of gun muzzle blast ejection, dynamics of explosion of ammunition of various purposes.
 The basic operations of video information processing were outlined:
 1) perspective correction;
 2) compensation (correction) of distortion (optical effect "fish eye”);
 3) scale determination of the video material’s frame;
 4) conducting of static measurements;
 5) position determination of the image object in a sequence of video stream’s frames.
 A brief overview of major open-access computer libraries (Accord.NET, VXL (Vision-something-Libraries), OpenCV (Open Source Computer Vision Library)) were conducted.
 To demonstrate how the above operations were performed by the OpenCV library, examples of the results of using it in Kinovea program were presented.
 An analysis of the popularity of computer vision libraries was conducted, which made it possible to assess the prospects for their further development and information support.
 The rationale for using OpenCV in software was fulfilled, that can be developed to process the video information obtained during testing of weapons and military equipment specimens.

Gun Source and Muzzle Head Detection

There is a surging need across the world for protection against gun violence. There are three main areas that we have identified as challenging in research that tries to curb gun violence: temporal location of gunshots, gun type prediction and gun source (shooter) detection. Our task is gun source detection and muzzle head detection, where the muzzle head is the round opening of the firing end of the gun. We would like to locate the muzzle head of the gun in the video visually, and identify who has fired the shot. In our formulation, we turn the problem of muzzle head detection into two sub-problems of human object detection and gun smoke detection. Our assumption is that the muzzle head typically lies between the gun smoke caused by the shot and the shooter. We have interesting results both in bounding the shooter as well as detecting the gun smoke. In our experiments, we are successful in detecting the muzzle head by detecting the gun smoke and the shooter.

Comparative study of positive and negative pulsed discharge plasma characteristics of coaxial gun

The coaxial gun plasma generated by pulsed discharge possesses the characteristics of high speed and high density, and has potential application value in the field of fusion, space propulsion and astrophysics. In this paper, the effect of positive and negative pulsed discharges on plasma characteristics are investigated and a theoretical model for analyzing the morphology of positive and negative pulsed current sheets is proposed. Positive and negative pulsed discharges are realized by changing the direction of the rectifier diode in the pulse power supply to change the direction of the recharging current. Through theoretical analysis, and measurements by using photodiode, Pearson probe, magnetic probe, HD camera, fast-framing camera and RGB image processing, the plasmas generated by positive and negative pulsed discharges are compared and investigated. Most of experimental diagnoses concentrate on investigating the plasma behavior in the coaxial gun muzzle on a microsecond-order time scale. Because radial and axial transport characteristics of plasma change little, we think, the plasma characteristics in the muzzle still depend on the characteristics of plasma in the coaxial gun. Therefore, the conclusion of the theoretical analysis of the current sheet in the coaxial gun is still valid for the plasma in the muzzle. The theoretical analysis shows that the positive pulsed current sheet presents a parabolic shape and the negative pulsed current sheet displays a convex shape, which makes the negative pulsed current sheet sweep more efficiently and a large amount of plasma is concentrated near the inner electrode, namely the cathode, so the negative pulsed plasma is denser. For the positive pulsed plasma, near the inner electrode the plasma is thin and the magnetic pressure is powerful, and near the outer electrode, the plasma is dense and the magnetic pressure is weak. Therefore, the positive pulsed plasma is faster in movement speed but easier to split, and because of its dispersion, its transport stability is not so good as that of the negative pulsed plasma. The experimental results accord with the theoretical analyses. The final conclusion shows that under the same discharge parameters, the positive pulsed discharge produced plasma is faster in movement speed but more likely to split, and the negative pulsed discharge created plasma is denser in density and more stable. Therefore, for obtaining a higher density plasma, the negative pulsed discharge is recommended, and for achieving a high-speed plasma source, the positive pulsed discharge is advised to be adopted.

Gunshot Airborne Surveillance with Rotary Wing UAV-Embedded Microphone Array.

Unmanned aerial vehicles (UAV) are growing in popularity, and recent technological advances are fostering the development of new applications for these devices. This paper discusses the use of aerial drones as a platform for deploying a gunshot surveillance system based on an array of microphones. Notwithstanding the difficulties associated with the inherent additive noise from the rotating propellers, this application brings an important advantage: the possibility of estimating the shooter position solely based on the muzzle blast sound, with the support of a digital map of the terrain. This work focuses on direction-of-arrival (DoA) estimation methods applied to audio signals obtained from a microphone array aboard a flying drone. We investigate preprocessing and different DoA estimation techniques in order to obtain the setup that performs better for the application at hand. We use a combination of simulated and actual gunshot signals recorded using a microphone array mounted on a UAV. One of the key insights resulting from the field recordings is the importance of drone positioning, whereby all gunshots recorded in a region outside a cone open from the gun muzzle presented a hit rate close to 96%. Based on experimental results, we claim that reliable bearing estimates can be achieved using a microphone array mounted on a drone.

Damage and failure of Orban’s gun during 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 deploying 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 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 in historical reports, as well as the cannon ball penetration into soil. The evaluated sound pressure level inside Constantinople, produced by the bombard, con­firmed the tremendous psychological effect of the cannon’s blast on the City’s population. A numerical effort was made to assess the combined effect of powder chamber internal pressure with associate temperature produced by powder ignition.

Effect of the firing position on aiming error and probability of hit

This is an extended abstract of a paper to be published in Defence Technology, 2019. Sources of dispersions that contribute to delivery error and reduce the soldier performance in terms of hit probability are numerous. In order to improve the warfighter performance, the source of the errors contributing to the inaccuracy and dispersion of the weapon systems must be understood. They include ammunition dispersion error, gun dispersion, aerodynamic jump and the aiming error. The aiming error or gun pointing error is defined as the angle between the gun muzzle at the instant the trigger is pulled and the line of fire that corresponds to the intendent aim point. This is a round-to-round error. In weapons systems that include the rifle, the ammunition, a sight and a gunner, the aiming error was shown to be the single most important source of dispersion for the regular infantryman. In other words, for the general purpose rifle weapon system, the weak link is often the human. In order to verify and quantify this assertion, an experimental investigation was carried out to determine the aiming error associated with general purpose rifle fired by infantryman. The aiming error was evaluated for various firing positions and scenarios using infantryman for ranges varying between 100 m and 500 m. The results show that the aiming error is the main contributor to dispersion for the general purpose rifle fired by a non-specialized infantryman. The aiming error induced dispersion for unstressed and rested gunners is shown to be at best equivalent to that of the weapon fired from a bench rest by a marksman.

Passive CMOS Single Photon Avalanche Diode Imager for a Gun Muzzle Flash Detection System

We present the architecture and design of a novel $64\times64$ CMOS single-photon avalanche diode (SPAD)-based imager for gun muzzle flash detection. The imager is fabricated in a standard front side illuminated $0.18~\mu \text{m}$ CMOS image sensor process. Each pixel comprises a $25~\mu \text{m}$ diameter SPAD, a variable-load passive quenching circuit implemented with 1.8 V PMOS, an 8-bit counter, an 8-bit latch register, and digital processing electronics, and feeds an 8-bit output bus. The array delivers two-dimensional intensity data through photon counting, with integration time as low as $5~\mu \text{s}$ over the full dynamic range. Per-pixel digital memory enables fully parallel processing and global-shutter mode readout. The imager can acquire fast optical events at high frame rate (up to 200 kfps) and at single-photon sensitivity. The imager has an 8-pixel (64-bit) parallel output bus. This imager enables for the first time the detection and arrival-direction determination of individual muzzle flashes in real time, and even in the case of bursts of flashes, at a moderate cost and size. The presented results confirm the feasibility of gun muzzle flash online detection in the visible or NIR spectrum by uncooled silicon SPAD detectors using standard CMOS technology.

CMOS Single-Photon Avalanche Diode Pixel Design for a Gun Muzzle Flash Detection Camera

We present the architecture and design of a CMOS single-photon avalanche diode (SPAD) pixel that was selected to be the basis for a gun muzzle flash detection camera. The SPAD sensor and auxiliary circuitry are fabricated in a standard $0.18-\mu \text{m}$ CMOS image sensor technology. The pixel integrates a $25-\mu \text{m}$ pitch SPAD, a variable-load quenching circuit implemented with a 1.8-V pMOS, and digital processing electronics providing an 8-bit output bus. The SPAD is low noise (around 100-Hz dark count rate at 1.8-V excess voltage) and has a real peak photon detection efficiency (not averaged on pixel pitch) of 9.2% at 450 nm (1.8-V excess voltage). The pixel delivers intensity information through photon counting, up to 256 counts per frame with down to $5-\mu \text{s}$ integration time for the full dynamic range. The pixel memories enable parallel processing and global-shutter readout, preventing motion artifacts and partial exposure effects. The pixel can acquire very fast optical events at a high frame-rate (up to 200 kilo frames/s) and at a single-photon level. The pixel has an 8-bit parallel output bus.

Numerical analysis of the influence of water/air medium on the muzzle flow field characteristics of machine gun

The mathematical and physical model for underwater sealed gun is established to investigate the flow field distribution characteristics for gun muzzle in different mediums. The muzzle flow field for the 12.7 mm gun which is sealed launched underwater is numerically simulated by combining User-Defined Functions (UDF) and dynamic grid technique. The predicted results show that, the muzzle flow field for gun launched underwater is significantly different with that for in air. Unlike that the initial air forming bottle shock wave at the muzzle for gun launched in air, it hits the gas-liquid interface with forming series cylindrical compressed wave in the area before the projectile for gun sealed launched underwater. As the gunpowder gas sprays out, Mach disk appears at 60μs after the projectile shot into water. Meanwhile, the shape of shock waves is fusiform and then turns into a peach heart gradually. However, the bow shock for gun launched in air, which is affected by the projectile base with its structure being bowl-shaped, fails to develop into the Mach disk at even 160μs. Compared with gun launched in air, the muzzle shock wave area for gun launched underwater is obviously smaller.

CMOS-Based Gunshot Optical Detection Systems Performance Prediction Model

Detection of gunshots is a challenging mission which has many different engineering and sensing approaches. In this paper, we describe the system performance model for gun muzzle detection systems which are based either on complementary metal–oxide–semiconductor (CMOS) image sensors or on CMOS (as well as non-CMOS-based) single-photon avalanche diode image sensors. The principle of detection which was explored in this paper is based on the emission of photons from alkali atoms which are found in the projectiles’ gunpowder. This paper describes the model of electro-optical performance and its sensitivities to its various parameters. This paper also describes how the model may be used to derive requirements for the system’s optical design. This paper ends with a description of the model’s experimental validation, which reassures its correctness and applicability.