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We report on the realization of a numerical tool to simulate the three-dimensional fluid flow associated with the interior ballistics problem of propellant based weapon systems. The model is based on a two-phase approach, in which the gaseous and the solid phase, representing the propellant bed, are assumed to be a homogeneously stirred mixture. The ignition and the combustion of the propellant grains are taken into account via heat and mass transfer, respectively, between the two phases. To numerically solve the governing set of equations, a Godunov scheme based on an approximate Riemann solver is applied. Interior ballistics simulations on a 60 mm weapon and experimental findings are compared and it is shown that the presented model, in principle, is also able to predict the muzzle flash after the projectile left the barrel

The naturally aged solid rocket motor is static tested for internal ballistics performance evaluation thus estimating service life. The motor propellant weight is 800 kg and composition is AP/Al/HTPB. After 10 years, propellant samples were cut and taken from motor port region, and test coupons were made from samples; and mechanical properties were evaluated, while ballistic properties determined from static test firing. The mechanical properties test results showed that decrease in tensile strength and elongation and increase in Young’s modulus. The margin of safety on propellant is reduced to 0.3 from 1.0. The aged motor performance was evaluated by full-scale static test firing. The test results show that reduction in ballistics and mechanical properties are due to ageing but no reduction is observed in propellant energy i.e., Isp(delivered). The aged solid rocket motor performed close to lower mission bound and within acceptable limit and the determined motor service life is 10 years.

The paper presents the results of application correctness assessment of a physical burning law in theoretical interior ballistics phenomena modeling. Using the proposed lumped-parameters thermodynamic interior ballistics model, ballistic curves were obtained. In order to validate the used theoretical approach, experimental tests were conducted. Pressure courses, muzzle velocity and temperature courses of the barrel surface were measured and compared with the modeling results. The results obtained with the use of the geometrical burning law model showed a better agreement with the experiment than the results obtained with the physical burning law in which the dynamic vivacity function was estimated using closed vessel tests. The possible reason of this effect is the dependence of the dynamic vivacity function on the loading density, which is confirmed in the literature.

The practical application of bullet penetrating glass is a process of “terminal trajectory to external ballistics to terminal trajectory” essentially. Based on the overall design of the bullet penetrating glass, the numerical simulation of the bullet penetrating glass, the aerodynamic characteristic analysis, the numerical simulating of the transfiguration bullet penetrating the gelatin are carried out, and the feasibility and rationality of the method are compared with the test in each process. This study found within the speed range the impact of penetration speed on mass loss and length loss was basically the same, 5mm glass has little influence on the stable flight, resistance, the rules of roll change and lethality effect in the gelatin of the bullet can be further analyzed. The movement state of a bullet in the whole process of terminal trajectory to external ballistics to terminal trajectory is analyzed to reveal the motion law of the bullet in this process which can provide technical support for the research and development of high precision ammunition.

The fabrication error and assembly error of warhead and fuse will cause the dynamic unbalance of howitzer projectile, which will bring a negative impact on the safety and reliability of fuse. In order to obtain the motion of a certain 155 mm howitzer projectile on the exterior ballistics, the six-dimensional rigid body motion equations of the projectile were studied. The aerodynamic parameters which needed for the six-dimensional rigid body motion equations of the projectile’s exterior ballistics need to be obtained by simulation. Firstly, the credibility of the simulation method is verified in this paper. Then the aerodynamic parameters of the projectile are obtained by numerical simulation of the projectile flow field. When solving the six-dimensional rigid body motion equations of projectile exterior ballistics, the dynamic unbalance of projectile is considered. The calculation results are very important for the safety and reliability of fuze on the projectile under the condition of dynamic unbalance.

The influences of multiple structural parameters on interior ballistics were investigated by using an orthogonal test method. A coupled lumped parameter model was utilized to predict the propellant combustion, and a dynamic finite element method was applied to approximate the mechanical interactions between the projectile and the barrel. In order to reduce the research costs, orthogonal tests were designed to investigate the comprehensive effects of the parameters. According to statistical analysis, the important order of the structural parameters on the launching process was obtained. The results indicate that the influences caused by the width of the rotating band stand out among the studied parameters. This is an extended abstract of a paper published in Defence Technology, 2019.

The main aspiration of gun system is to propel projectile at desired range with high consistency and accuracy. Internal Ballistics (IB) plays a very vital role during design and development of gun systems. Initial temperature of charge system significantly affects gun IB performance. It is not always possible to conduct all gun firings at particular temperature conditions. Design of a temperature invariant charge system for large caliber guns is an important area of research in recent times. In this paper, a method is suggested for compensation of charge temperature effect on IB performance using Combustible Cartridge Case (CCC) physical parameters. A multivariate constrained optimization problem is defined for compensation of initial charge temperature effect on IB performance. The simulation results of this method show that the charge system can be converted into temperature independent by altering CCC physical parameters.

A method for identifying experimental form functions based on the results of interior ballistics modelling using lumped parameters models is presented. The function is defined as the relation between the ratio of the actual burning surface of a whole propellant charge, to the initial global surface of all propellant grains in the charge and the relative burnt mass of the charge. It is approximated by a function depending on several parameters. Values of the parameters are identified by fitting the results of the interior ballistics modelling to the measured maximum pressure value and the projectile muzzle velocity value. The identified experimental form functions are compared to the functions determined in closed vessel tests. The examples analyzed suggest that the use of the experimental form function enables us to take into account the process of ignition in lumped parameters models.

In the context of intermediate ballistics, a thorough understanding of the muzzle flow is necessary to optimize the design of muzzle devices and long-range projectiles. However, due to the harsh environment, the extremely short duration, and the transient evolution of the intermediate ballistics phase, both experimental and flow modeling efforts are hampered by the lack of quantitative experimental data. In this study, a Particle Imaging Velocimetry (PIV) experimental set-up is implemented to quantitatively investigate the muzzle flow based on its velocity. This tool has the advantage of obtaining a non-intrusive and whole-field diagnostic, both qualitatively and quantitatively. The first part of the study explains that PIV is suitable for measuring the velocity fields of the muzzle flow. This was achieved by using the naturally present particles in the gas as tracers. We demonstrate that the raw PIV images revealed that the structure of this flow is composed of two regions. The first region is located within the under-expanded jet and consists of spatially dispersed particles. The second region, downstream of the Mach disk, is formed by large structures. We show that cross-correlation and particle tracking velocimetry (PTV) algorithms can determine the flow velocity in both regions. In the second part, we present a quantitative description of the muzzle flow issued from the launch of a subsonic .300 Blackout projectile. The results show that these gases reach a maximum centerline velocity of more than 900 m/s inside the shock bottle. At the barrel exit plane, the gases start to discharge with a velocity close to that of the projectile’s launch velocity, accelerating it. In the third part, we present a detailed comparison between the aforementioned flow and the flow resulting from the launch of a supersonic projectile. Differences and similarities are pronounced and explained. The presented set-up and the description of the whole flow field velocity would serve as valuable improvements toward muzzle devices optimization and numerical code validation.

Cased telescoped ammunition and associated cannon is a proven disruptive technology in medium calibre weapons, allowing increased lethality in a compact, multi role weapon system. From new ammunition development to support of serial production, an internal ballistics model is key to highlight design margins, support design improvement and performance increase. The architecture of the cannon and the ammunition result in a very specific internal ballistics mechanism which makes standard models unsuitable. This paper will detail the different steps of the internal ballistics cycle of the 40 mm cased telescoped ammunition and explain how each steps were studied from both theoretical and experimental point of view and aggregated to achieve the internal ballistics model of the CT cartridge.

The characterization of fragmenting munitions involves conducting arena tests with witness materials (e.g. plywood) to collect fragments. The evaluation of body armour against buried explosives follows a similar process where surrogates made of foam or gel are used to support the armour and capture penetrating soil debris. The manual recovery of the collected fragments is long, tedious and prone to error since small fragments are often not detected. The effectiveness of XCT as a rapid non-destructive technique was evaluated by scanning calibration targets containing various objects of known material types, sizes, and locations. The Fragfinder program was developed to automatically perform 3D images analysis. All fragments were detected and accurately located. For lower density materials (glass, aluminum, titanium), the relative error on the volume of the fragment was within 8%. For higher density materials, (steel, tungsten), larger errors were obtained because of image reconstruction artifacts. Finer reconstruction of target scans using smaller voxel sizes along with artifacts reduction algorithms were explored in order to obtain better precision.

Increasing performance of an armament system often leads to increasing the maximal pressure inside the chamber or increasing the compacity of the system. Telescoped ammunition and the associated weapon (40 CTAS) developed by CTA International is a solution that combines both improvements. With the increase of maximal pressure, the equations of interior ballistics might not be appropriate anymore since the models were established when the pressure was moderated. The aim of this paper is to compare the potential candidates for the equation of state of the combustion gases in a high-pressure system, such as telescoped ammunition. Within this study, the following equations of state are studied: ideal gas equation, Noble-Abel equation, Van der Waals equation and virial equation. The study is divided in two: a first study for air as the coefficients needed are easily accessible in the literature and a second study for combustion products stemming from propellant combustion.

The reports materials on the data presented by the authors earlier in the proceedings of 23rd- 31st International Symposiums on Ballistics are base. The results relate to the field of study of the action of the body on the target. Measuring technology is a set of methodological, technological and software components for tests measuring strikers-probes. Such strikers are equipped with impact accelerometers and original systems for connect with recorder. The difference from the known methods is the realizable range of impact velocities: 100 - 2500 m/s at the stage of action on the target. Theoretical and experimental studies have revealed a new law of medium resistance to penetration. The law allows the application of engineering methods for solving problems. It became possible to solve spatial tasks of penetration with the use of this law.

The motion resistance of projectile in gun barrel has an important influence on the interior ballistic performance. But it is difficult to measure the motion resistance of projectile because there exists high temperature and high pressure gas in the gun barrel. Firstly, this paper designs and manufactures the measurement devices which contains the projectileborne recorder, the shell and the test-projectile. Then the gun launch test is carried out with these devices, and the projectile motion resistance is calculated according to the test data. Secondly, the two-phase flow interior ballistic model is established and solved. Finally, the influence of the projectile motion resistance on the interior ballistics performance, such as pressure wave and projectile muzzle velocity, are simulated and discussed.

A method for intermediate ballistics modelling is presented. The method is used to study the effect of muzzle brakes with a passing projectile. Pressures, velocities and impulses are computed using a thermodynamic interior ballistics code (lumped parameter code) for projectile travel within the barrel. Then Computational Fluid Dynamics (CFD) simulations are used for gas and projectile travel outside the barrel. CFD simulations are performed both with and without a projectile and the results compared. Three generic muzzle brake geometries are used for simulations. Impulses computed from thermodynamic model and CFD model are combined to evaluate the gun recoil. The CFD model, with initial conditions transferred from the thermodynamic model, can further be used to analyse the influence from the muzzle break on the flow.

Instead of the capillary plasma generator (CPG), a discharge rod plasma generator (DRPG) is used in the 30 mm electrothermal-chemical (ETC) gun to improve the ignition uniformity of the solid propellant. An axisymmetric two-dimensional interior ballistics model of the solid propellant ETC gun (2D-IB-SPETCG) is presented to describe the process of the ETC launch. Both calculated pressure and projectile muzzle velocity accord well with the experimental results. The feasibility of the 2D-IB-SPETCG model is proved. Depending on the experimental data and initial parameters, detailed distribution of the ballistics parameters can be simulated. With the distribution of pressure and temperature of the gas phase and the propellant, the influence of plasma during the ignition process can be analyzed. Because of the radial flowing plasma, the propellant in the area of the DRPG is ignited within 0.01 ms, while all propellant in the chamber is ignited within 0.09 ms. The radial ignition delay time is much less than the axial delay time. During the ignition process, the radial pressure difference is less than 5 MPa at the place 0.025 m away from the breech. The radial ignition uniformity is proved. The temperature of the gas increases from several thousand K (conventional ignition) to several ten thousand K (plasma ignition). Compare the distribution of the density and temperature of the gas, we know that low density and high temperature gas appears near the exits of the DRPG, while high density and low temperature gas appears at the wall near the breech. The simulation of the 2D-IB-SPETCG model is an effective way to investigate the interior ballistics process of the ETC launch. The 2D-IB-SPETC model can be used for prediction and improvement of experiments.

This paper presents high speed video analysis of 11 service caliber lead-free pistol bullets impacting Clear Ballistics Gel® with the dual purpose of assessing the equivalence of Clear Ballistics Gel® and calibrated 10% ballistic gelatin as test media and providing an initial assessment of wounding and incapacitation potential of these 11 service caliber loads. The present study suggests that Clear Ballistics Gel® results in lower retarding forces, erratic expansion, greater variations in penetration depth, and larger average penetration depths than calibrated 10% gelatin. Taken together with other results, testing in Clear Ballistics Gel® should only be used to identify candidates for further testing in calibrated 10% ballistic gelatin; it should not be used for the selection of duty ammunition without further performance testing in calibrated 10% ballistic gelatin. Depending on the wound profile and penetration desired for a given application, several loads analyzed here may warrant additional study. The Liberty Civil Defense 60 grain lead-free hollow point had the largest peak retarding force, temporary cavity, and permanent cavity while meeting the oft-cited minimum penetration requirement of30 cm.

The main objective of this work is to assess the pressure levels obtained over a new designed 155 mm/52-calibre gun-howitzer during a firing sequence. For this design, the barrel muzzle exit is really close to the truck driver’s cab. It is then essential to verify that the wall pressure levels resulting from an artillery firing are compatible with the considered material. For this purpose, the CFD ballistics code FREIN 3D is used to compute the direct coupling between interior, intermediate and exterior ballistics of this new 155 mm/52- calibre gun-howitzer. A simplified geometry is considered for the CFD computation and the computational domain involves only a part of the truck chassis since only the pressure levels over the first part of the truck are of interest. One case is considered, corresponding to an indirect firing.

Small caliber interior ballistic performance can be altered in countless ways. Primer composition, propellant composition and quantity, as well as the interaction between the two play a critical role in determining a cartridge’s performance. This study will focus on the interaction between the primer products and the ignition of the propellant of a 7.62- mm cartridge. To accomplish this a flash tube will be employed to alter the ignition characteristics of the propellant. By employing a flash tube the primer products will be directed into the case at a more forward location in the propellant bed thus altering the ignition and subsequent burning characterization of the propellant. Various length and diameter flash tube configurations will be explored to characterize how the ignition of the propellant influences the interior ballistics of the cartridge.

Aiming at the object of the firing range maximization of the grenade of the cased telescoped ammunition(CTA) gun, a classical interior model was established according to the special charge structure of the CTA and the principle of the sequential combustion with two ignitions. Combined with the particle trajectory model, the optimization design of the integration of the interior and exterior ballistics was carried out using the intelligent optimization algorithm. The results show that, the maximum chamber pressure and the muzzle velocity simulated using the interior model of the CTA gun agree well with the experimental results. The optimal scheme of the projectile mass and the charge design was obtained by means of the optimization design of the ballistic integration. The grenade projectile mass increases 16.4% and the maximum range increases 11.8% compared with the original scheme. The method in the paper can improve the integrated ballistic performance of the CTA and provide an efficient tool for its ballistic and charge design.

Several nations have moved to lead free bullets in 5.56x45mm NATO for use as duty ammunition by military personnel. This study reports on the external ballistics and accuracy of two lead free bullet designs that have been fielded to date, the 62 grain lead free hard core bullet manufactured by RUAG and the 62 grain lead free bullet manufactured by ATK at the Lake City Arsenal. Doppler RADAR was used to determine aerodynamic drag curves for each bullet from Mach 1.5 to Mach 3.0 when fired from rifles with twist rates of 1 in 7”, 1 in 8”, and 1 in 9”. Drag coefficients were consistent with claims by the manufacturers when fired from 1 in 7” and 1 in 8” twist barrels; however, drag coefficients varied up to 50% higher when fired from the 1 in 9” twist barrel, suggesting marginal stability. The 1 in 9” twist affects the drag of the ATK bullet more than the RUAG bullet. Accuracy of the RUAG bullet was less than 2 minutes of angle (MOA) when fired from a match grade rifle and less than 4 MOA when fired from a service grade rifle. However, accuracy of the ATK bullet was worse (2 MOA to 4 MOA) from the 1 in 7” twist match grade rifle and poor (6 MOA to 8 MOA) from a service grade rifle with 1 in 9” twist. The original Miller formula for gyroscopic stability of each bullet shows good agreement with experimental data. This formula may be used to estimate gyroscopic stability within 5% for a variety of twist rates, muzzle velocities, and atmospheric conditions.

The following article is a summary of the first step of research on behavior of sniper rifles in calibers .308 Winchester, .300 Winchester Magnum and .338 Lapua Magnum with and without sound suppressor. The paper includes measurements of chosen external ballistics parameters like velocity and accuracy at 300 m (328 yd) with the use of state of the art electronic devices like high speed accuracy light gates and Doppler radar system. The paper includes also a comparison of mentioned parameters registered during testing with two types of silencers and with unsuppressed weapon. The paper is concluded with results analysis that can be used for future work.

To improve the muzzle velocity by a large margin without increasing the gun chamber pressure, a lateral-injection for energy compensation technology was proposed. The principle is installing a regenerative auxiliary chamber with liquid propellant at a proper location in the barrel to compensate the energy in the space behind the projectile. Aiming at the interior ballistic characteristics of the technology, the corresponding model was established and the numerical simulation was carried out for a certain gun. Results show that the location of the auxiliary chamber, the injection area, the differential ratio and the mass of the injection piston have significant effects on the interior ballistic performance. By optimizing these parameters, the muzzle velocity can be increased substantially. The method can provide a new thought for designing the high-speed launcher.

An ordinary gun projectile will, after entry into water, be subject to an extremely high drag and will stop after 50 – 100 calibers of travel through the medium. To avoid such a response, supercavitation must take place. By a specially shaped projectile nose, the flow of water around the projectile may escape contact with the surface of the projectile, except at the nose tip. Under these conditions, the projectile is said to be supercavitating. In such a state, the projectile is unstable, but, the stability is maintained by the oscillation caused by the interaction between the rear part of the projectile and the cavity wall. In order to keep the amplitude of this oscillation as small as possible, the size of the cavity should be just slightly larger than the projectile. The cavity size is, however, determined by the size and shape of the nose tip, by the velocity of the projectile, and by the pressure in the ambient water (i.e. the water depth), through Garabedian’s equations. These parameters will also determine the duration of the cavity which determines how far the projectile will travel before the supercavitation ceases, and the projectile stops. The paper outlines the theory for the size, shape, and duration of the cavity. It discusses also the conditions for designing an optimal design of a supercavitating projectile. Special emphasize is put on how to determine the drag on the projectile by observing the size of the bubble.

Performance evaluation of artillery gun system is carried out during the dynamic firing of armament stores. The recording of different ballistics parameters during dynamic firing plays an important role in assessment of armament stores. For characterization of internal ballistics of a gun and propellant, the velocity-time profile of the projectile and associated chamber pressure inside the barrel are two of the most crucial parameters. This paper presents details of measurement of in-bore velocity-time profile using Doppler radar systems. From the velocity time profile, acceleration-time profile has been obtained and subsequently base pressure and breech pressure time profiles have been calculated. The paper also deals with the effect of charge mass decay profile with time during combustion of propellant on computation of breech pressure-time profile. The average error observed between measured peak breech pressure from piezoelectric transducer and computed peak breech pressure from in-bore radar data is of the order of 2.3%.

A launching system with novel structure using optimization method is investigated to improve the muzzle velocity of guns in this article. This system has two tandem chambers of which the front one is ignited first and the other is ignited after a while. The launching process of this novel system is modelled and a series of different schemes are simulated, to discover the interior ballistic performance of this novel launching system. In order to obtain the optimal loading conditions, an optimization model combined with the combustion model is established. The optimal schemes can improve the muzzle velocity by 20.6% without changing the parameters of barrel. It means that this novel launch system could improve the interior ballistics performance significantly and it still has considerable potential to be ameliorated. Keywords: Interior ballistics, Mobile chamber, Design optimization

In this research paper, empirical relation between burn rate and pressure index of spherical gun propellant was carried out in the closed bomb. This is double base propellant and used in power cartridge to destroy the suspicious unattended objects. The novelty in this research is that, the author proposed a novel empirical relation among force constant, burning rate coefficient, pressure index and peak pressure. Ballistics properties like burning rate of propellant is depend upon on its shape and size (configuration), chemical composition, temperature, loading density and pressure. The major outcome of this research study has direct relevance for the performance prediction of propellant in the form of powder related to dynamic firings. The peak pressure of the propellant is 235.04 MPa, the rise time 1.95 ms, burn rate coefficient 0.073, pressure index 1.29, flame temperature 2680 0K and force constant 953.2 J/g were obtained during experiment. The burning rate for the spherical gun propellant is experimentally expressed as 1.29

Various experiments were performed on water disruptor to measure the velocity of water and projectile. In these experiments, double base propellants having different physical and chemical properties were utilized to drive the projectile. This projectile was made up of nylon material. Measurement of projectile velocity is significant parameter for disruptor in neutralizing IEDs. An attempt has been made to develop a mathematical model for processes taking place inside the water jet disruptor using internal ballistics model. A code has been developed based on the mathematical model and simulated for various input parameters. The validation of the code has been done by comparing the results with experimental firing. A parametric analysis is carried by varying barrel length of the disruptor, propellant type and projectile mass.

Propellant grain geometry plays a critical role in pressure space behaviours in interior ballistics which are important for operational safety of gun barrel designs. This geometry leads to a burning surface which is tractable to mathematical models only if the grains do not fracture. Complex high fidelity models for situations when grains fracture require significant computational effort. We propose to use instead the conventional lumped model with certain normative assumptions about grain fracture. We demonstrate that with seven perforation grains of two different lengths having different loading mass fractions to mimic fracturing, we can inform design insights concerning peak pressure variation. In particular, our results suggest that hole radius and outer radius could be optimized to provide minimum peak pressure variation on account of grain fracture.

For Gas Generator Internal Ballistics Prediction, Burn rate is important parameter as it determines the mass flow rate of the Gas Generator, which intern determines the canister pressure and ejection velocity of article launched from the canister by cold launch technique. The elemental law and empirical equation to determine the regression rate experimentally is 𝑟=𝑎𝑝c𝑛 , in which burn rate exponent ‘n’ is determined from the experimental measurements on actual propellants, different propellant formulations give different regression rate (Burn rate) verses pressure relationships. The burn rate exponent is independent of propellant grain temperature and describes the influence of chamber pressure on burning rate. High values of ‘n’ gives rapid change of burning rate with pressure, which means that even a small change in pressure will result in a substantial change in hot gas produces by Gas Generator. Since the high regression rate (25 mm/s) propellant is being used in the Gas Generator, chamber pressure varies from 10 to 27 MPa due to high mass flow rate requirement. It is important to note that this high regression rate propellant is particularly sensitive to pressure increase due to variation of burn rate exponent, particularly at high pressures. Mathematical coupling forms among pressure, Burt rate exponent (n) and regression rate, which leads to steep raise in chamber pressure after certain threshold pressure, which depends on propellant composition. This paper attempts to study and present the evaluation of burn rate index variation over pressure range 3 to 23 MPa and corresponding effect on ballistic performance of Gas Generator with high burn rate multi perforated propellant grain, which gives continues progressive mass flow rate.

Based on the available bibliography three types of deterrent concentration profiles were identified. The cumulative distribution function of Gumbel distribution has the ability to reproduce all identified deterrent concentration variation profiles. The relationships between the ballistics characteristics and deterrent concentration can be expressed using the Gumbel function combined with a polynomial function. In order to deal with variability of mean values of burned propellant characteristics the interior ballistic specific equations should by modified accordingly. Based on available experimental data and the calculated variable ballistic characteristics the developed 0D model and the proposed functions are validated.

The modern development of missiles and projectiles that have shown that nonlinearities, usually ignored in traditional ballistics, have a significant impact on the flight performance of projectiles. However, the complexity of the high order terms coupled in the angular equations and the lack of appropriate analytical tools have hampered the investigation of these effects. In this paper, the method of normal forms, featuring transformations that can simplify the dynamical system equations, is applied directly to the angular motion equation to obtain a simplified formulation for the nonlinear angular problem. Analytical solutions are obtained under quantic static moments. Numerical simulations are carried out to demonstrate the efficiency and accuracy of this method. Besides, a criteria identifying the stable region of initial angle of attack is derived and examined feasible and effective. The results of this research can contribute to the studies of more complicated problems related to nonlinear angular motion.

The use of optical imaging is limited at all stages of the ballistic cycle when accelerating probes in launchers. The developed technology of visualization of ballistic processes allows investigation in detail the process of acceleration of the probe in the guiding element of the launcher - in the barrel gun installation. The result of the study was the establishment of ballistic parameters of private versions of the launcher. The values of the ballistic parameters registered in the implemented launcher are used to check the tasks of mathematical modeling and to obtain additional information about the features of physics and the parameters of the process of internal ballistics -the history of changes in the working mixture, about the work of probes elements at stages of the ballistic cycle, about dynamics of the probe acceleration, about dynamics of the gas flow.

Knowledge of impact conditions is critical to evaluating the terminal impact performance of a projectile. For a small caliber bullet, in-flight velocity has been precisely measured for decades using detection screens, but accurately quantifying the orientation of the bullet on a target has been more challenging. This report introduces the Automated Small-Arms Photogrammetry (ASAP) analysis method used to measure, model, and predict the orientation of a small caliber bullet before reaching an impact surface. ASAP uses advanced hardware developed by Sydor Technologies to record a series of infrared digital photographs. Individual images (four orthogonal pairs) are processed using computer vision algorithms to quantify the orientation of the projectile and re-project its precise position and orientation into a three-dimensional muzzle-fixed coordinate system. An epicyclic motion model is fit to the measured data, and the epicyclic motion is extrapolated to the target location. Analysis results are fairly immediate and may be reviewed during testing. Prove-out demonstrations have shown that the impact-angle prediction capability is less than six hundredths of a degree for the 5.56 mm ball round tested. Keywords: Yaw, Terminal ballistics, Exterior ballistics, Test & evaluation, Computer vision, Image processing, Angle of attack

In order to get the different muzzle velocity in large caliber artillery gun systems, the propellant charge usually have several charge zones. When these charge zones been fired, the different chamber pressure and projectile velocity will happen which can influence the burning rate of propellants. It is very important for getting the burning rate of propellants in different charge zone when predicted the performance of interior ballistics. Usually we can get the burning rate of propellant from experiment results of closed bomb, but these results cannot be directly used in numerical simulation of interior ballistics processes for all charge zones. Now, we use a serial experiment of gun firing for different charge zone to get the performance of interior ballistics. On the basis of the simulation for performance by the IB code, we can get the real burning rate of propellant in IB processes. By using the methods, we can get the accurate results for predict the interior ballistics performance when different charge zones were used. So in this paper, an approach has been developed for getting the real characteristic of burning rate of propellant at different charge zone for large caliber artillery gun systems.

Body armour is the only protection a dismounted soldier has against the 7.62x39 mm rifle projectile threat. While body armour protects against such threats, weight limitations challenge helmet manufacturers to make a helmet withstand a direct rifle projectile impact. However, an oblique projectile impact on a helmet has the highest probability. This work promotes the 7.62x39 mm projectile ricochet off helmets to increase the likelihood of projectile deflection and the survivability of the wearer. Also, a deflected projectile causes severe deformation on the helmet shell. Optical measurement systems capture the deformation, and this data is transferred to numerical models. Numerically achieved BFD data in a LS-DYNA® Finite element (FE) head model is used to evaluate the blunt trauma using a head injury criteria (HIC) in the advanced SUFEHM model.

Kinetic Energy (KE) projectiles are major threat to armour fighting vehicles (AFVs). Penetration can be greatly reduced by detonation of a HE charge in the vicinity of the projectile. This can be greatly reduced by transferring momentum from a blast due to detonation of a High Explosive Charge in close vicinity of KE projectile. This blastwill causes a deflection on the KE projectile. The blast can cause deflection of the projectile. The study aims to investigate the effect of explosive quantity, miss distance and intercept distance on the angular deflection of free flying KE projectile. An existing analytical theory based on ideal momentum transfer is available for predicting the deflection of KE projectile using High Explosive charge. The theory is extended and used to estimate the explosive quantity, miss distance, intercept distance and time of initiation of explosive charge, for providing required deflection in KE projectile. Different combination of these parameters are simulated and a set of solutions are discussed and optimised under realistic design space.

Ballistic performance of Artillery projectiles are generally characterized by maximum range and dispersion. Launch angle at which maximum range is achieved by a projectile for a given combination of weapon and charge has been a long intriguing aspect for Ballisticians. Although in ideal conditions, vacuum, trajectory case maximum range of a projectile is achieved at an elevation of 450, below which the range decreases monotonically with decreasing elevation and beyond which the range reduces with increasing elevation. But in actual scenario, presence of air, which offers drag to projectile motion largely affects this value. A review of theoretical considerations and computational verification of the same with various projectiles have been carried out to establish the relationship between various factors that characterize and determine maximum ranges. This plays a vital role for computational purposes like Fire Prediction and Firing Tables compilation. Termination conditions of most of these Ballistic algorithms essentially built around these data. For the sake of brevity and want of completeness a few projectiles were only studied. Projectile classes considered have been varying in their sizes from 0.303cal Bullets to 305mm Artillery shells, masses from few grams to few 100s of Kgs, with L/D ratios from 3 to 25 and fineness varying from blunt noses to highly Ogival shells. Detailed trajectory computations based on Point mass trajectory model has been attempted to answer and to offer plausible explanations for the not so obvious problem.

This paper investigated the effect of mid-wall water cooling for the gun barrel under continuous firing. A 2D cross-section model of the gun barrel is adopted and the cooling channel is circular. An interior ballistics code is used to determine the inner wall convection boundary condition, providing gas temperature and heat transfer coefficient. Results of temperature histories of the inner wall and outer wall and temperature distributions are presented. The results show that this cooling method can slow down growth rate of the peak temperature of the inner wall.

Based on the research of large caliber modular charge howitzer and electrothermal-chemical (ETC) launch technology, the application advantages and prospects of ETC launch technology in a 155mm modular charge howitzer are discussed from the perspective of the technology development and actual applications, respectively. The analysis and discussion results show that the ETC launch technology will effectively improve the chamber combustion stability and interior ballistics consistency of the modular charge howitzer. It also will enhance the whole operational effectiveness including both firing range and accuracy. The ETC launch technology is an important development route for the future modular charge howitzer.

An optimization method is introduced to design the aerodynamic parameters of a dual-spin two-dimensional guided projectile with the canards for trajectory correction. The nose guidance kit contains two pairs of canards which can provide lift and despinning with a projectile for stability. An optimal design algorithm is developed to decide the profiles of the steering and spinning canards, and their deflection angles are also simulated to meet the needs of trajectory correction capabilities. Finally, the aerodynamic efficiency of the specific canards is discussed according to the CFD simulations. The simulation and analysis results can be further applied to the exterior ballistics design.

In the field of experimental small arms ballistics there has always been a large amount of energy put into how a test weapon is secured. Various philosophies exist; however, this is largely left to experience and is more of an artistic approach rather than a scientific approach. Many experimentalists leverage physical understanding of the firing event to reduce motion or vibration. However, in most cases, there is no direct measurement of the performance of the mounting technique. Often the dispersion performance of a weapon system when fired from a specific mount is used as a gauge, ignoring the fact that dispersion is comprised of many sources. Through complex jump testing, the US Army Research Laboratory has shown the ability to dissect the relative contribution of individual dispersion sources. This work showed that it is possible to mount a weapon system in a way that barrel motion does not affect the dispersion or jump behavior. This effort employs an easy-to-use modern measurement technique to characterize barrel motion of a commercial AR-15 weapon during dispersion testing. High speed digital micrometers were used to measure barrel motion before, during, and after firing in order to establish the pointing angle and crossing velocity variability as a function of mounting configuration. Ten mounting configurations were examined for a single weapon type firing match grade ammunition with the intention of isolating the barrel motion effects.

The science of “Internal Ballistics” have extensively studied the pressure generated within the cartridge and clearly indicate that maximum generated pressure (Peak Pressure) is not to exceed the yield strength of the material of which the cartridge case is made of [1]. Failure to ensure this could result in catastrophic accidents that may lead to death or serious injuries. Different test standards (SAAMI, C.I.P, MIL-STD and NATO EPVAT) were established to ensure the safety of the ammunition in terms of pressure. These standards differ in many aspects from the test procedure to the equipment used to the acceptance criteria. The main motive behind this study was understanding the need to establish a scientific correlation between pressure measurements obtained by different test standards in order to save cost, time and effort as well as ensuring that a specific type of ammunition that was pressure tested according to one standard is safe to use in a specific weapon that was tested according to another. The main aim of this study was to investigate the possibility of finding a scientific correlation between the mean peak pressure values obtained by the NATO EPVAT and CIP test standards for 7.62 x 51mm NATO Ball Reference Ammunition through derived and validated equations with fixed conversion factors in order to convert “actual” Mean Peak Pressure (MPP) and Standard Deviation (SD) values obtained by NATO EPVAT test to predict those values in the C.I.P equivalent and calculate the Average Maximum Pressure (Ptmax).Thirty 7.62 x 51mm NATO BALL reference ammo were tested according to NATO EPVAT and C.I.P and the mean peak pressure conversion factor (FMPP) was found to be 0.974, while the standard deviation conversion factor (FSD) was 1.381. Both conversion factors were used to convert the MPP and SD values obtained by EPVAT testing of the reference ammunition, to their C.I.P Equivalent. These C.I.P converted values were then used to calculate (Predict) the Maximum Average Pressure Ptmax which was 3540.26 bar. Validation of this result was achieved by conducting an actual C.I.P pressure test on the same amount of reference ammunition which resulted in a Ptmax of 3422.40 bar with an error percentage between actual and predicted Ptmax of 3.54%.

Separation of sabot petals is a critical procedure in intermediate ballistics affecting accuracy of the final hit of the penetrator of the fired ammunition round. Design of sabot petals has been an important concern supported by modeling and simulation studies of sabot separation. Computational fluid dynamics studies of the same have hitherto addressed feasibility of coupled fluid dynamics and 6 DOF simulations employing fixed sabot designs. The use of dynamical meshes for supersonic air flow is in its infancy as each simulation run for a given sabot geometry is highly computationally intensive. Good support can still be offered to sabot petal design by using analytical models, like the one by Reinecke and Guillot and its subsequent improvements. We present and study an improved model which better captures the role of the sabot petal scoop. In particular, we study how changes in the shape of the scoop affects the sabot separation kinematics. The sabot assembly assumed to be axisymmetric in shape and other major design parameters are kept the same when the scoop shape is changed.

Gun accuracy is influenced by several parameters during the in-bore projectile travel. The aim of this study is to determine the influence of gun barrel straightness on projectile exit conditions, in order to understand how to improve weapon accuracy. A tridimensional numerical model is created in order to vary this parameter and to study its influence on the ammunition behavior during internal ballistics. The model will be validated using experimental firings, particularly with accelerometers embedded in the ammunition. These firings have required the development of an optoelectronic system to transmit accelerations in real time. The good correlation of the experimental and numerical results proves the representativeness of the model. The model can then be used now to perform parametric analysis and to determine the most penalizing straightness shapes for gun accuracy.

The development of high accuracy rifle has uncovered a need for understanding the movement of the bullet in muzzle flow. Recent researches have always been focused on computational fluid dynamics (CFD) and experimental research on the muzzle flow, which released many data, such as velocity and base pressure drop of projectile. Due to CFD tests are timeconsuming, a dynamic model for spatial motion of projectile is established. In this model an empirical relationship is utilized for the base pressure of projectile, and the model is assumed that the base pressure is along the axis of barrel which applied on the tail cone of the bullet; The spatial motion equations deduced from the mass center motion equations and Euler equations of motion are solved with Runge-Kutta method. A 7.62 caliber bullet is tested to verify the dynamic model. The result agrees with the CFD and experimental data, which shows that the model is applicable in predicting the translational motions, besides the angular motion of projectile is also presented, which can be the initial condition of exterior ballistics to analyses the firing accuracy.

To avoid gas escaping from the gap between tube and projectile in mortar, some seal grooves structures are designed. The blow-by phenomena should be considered in the simulation of interior ballistics. In order to investigate the gas leakage, computational fluid dynamic study of seal groove during the mortar interior ballistic process is presented in this paper. By the seal groove, the pressure near the outlet decreases directly. The mass flow rate of the structures without seal groove and with seal groove at the inlet are similar. However, the mass flow rate of the structure without seal groove at the outlet is obviously bigger than that of structures with different seal grooves. The results show that the seal groove such as trapezoid seal groove can decrease the gas leakage and improve the interior ballistic performance. The further study on structure optimization will be a reference for the mortar design.

Current military operations often comprise urban scenarios. Thus, masonry objects offer protection and shielding against weapon effects. To effectively engage enemy forces and targets the munitions applied must be capable of perforating masonry materials and of delivering lethal force behind structures. Building structures may consist of soft materials like clay or adobe as well as of hard materials like brick or (reinforced) concrete. They might be set up of double or triple layers in combination with mortar opposing a very inhomogeneous target compared to classic armored vehicles. The penetration of these structures by small and medium caliber projectiles results in projectile deflection and tumbling. Also large shot to shot scatter of residual velocities is associated with these nonlinear trajectories, as has been observed in penetration testing and high-fidelity numerical simulations (such as FEM). The prediction of weapon effects with standard accredited vulnerability tools, like UniVeMo (Universelles Verwundbarkeitsmodell) in Germany, has to consider the observed effects but also has to provide results in acceptable time frames. Therefore fast-running methods have to be developed. This presentation will demonstrate the IABG approach deriving regression functions and/or look-up tables for small and mid-caliber penetration processes in masonry materials. Based on numerous simulation and experimental results the phenomena observed will be described, the way to fast running modules including the application of analytical tools will be explained, and final results and samples will be demonstrated.

The main goal of this research is to create a new ballistic helmet concept able to defeat high velocity rifle bullets, specifically the 7.62 x 39 M43 round. The current design consists of four layers, where the first layer is responsible for the deformation and breaking up of the projectile, the second layer for stopping the projectile, the third layer for reducing the back face deformation, and the fourth and last layer for absorbing the shock wave send into the helmet shell, next to the back face deflection of the latter. Whereas previous research gave possible solutions for the first three layers, this work focuses on the feasibility of the fourth, shock-absorbing layer. A finite element model approach was used to see the influence of the shock-absorbing layer on the risk on behind-helmet blunt trauma and to determine a suitable standoff based on a maximum force injury criterion.

Most spacecraft have at least one pressurized vessel on board. For robotic spacecraft, it is usually a liquid propellant tank. In some satellite or spacecraft designs, the fuel tank or some other pressurized vessel is necessarily exposed to the hazards of space, including the micro-meteoroid and orbital debris (MMOD) environment. Because of the potential of serious mission-threatening damage that might result following an on-orbit MMOD impact, a primary design consideration of such spacecraft is the anticipation and mitigation of the possible damage that might occur in the event of such an impact. While considerable energy and effort has been expended in the study of the response of non-pressurized spacecraft components to MMOD impacts, technical and safety challenges have limited the number of tests that have been conducted on pressurized elements of such spacecraft. As a result, several investigators have taken to modelling pressurized vessels as flat plates under uniaxial or bi-axial tensile loading conditions. This paper presents the development of a data-driven equation for initially stressed flat composite material plates that differentiates between impact conditions which, given a plate perforation, would result in only a hole or crack from those which would cause catastrophic plate failure / rupture. If this equation were subsequently shown to also model the rupture/no-rupture behavior of actual COPVs, then it could also be used to appropriately tailor the design parameters and/or operating conditions of a pressurized tank. Tank designs could be adjusted so that if that tank were to be struck and perforated by the impact of an MMOD particle, then only a hole would occur and additional sizable debris would not be created as a result of that impact.