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Firing accuracy is a critical quantity of interest in the performance analysis of electromagnetic railgun (EMRG) exterior ballistics. Since the simulation technique is always used to simulate the complex physical system at a low cost, it is employed to evaluate the firing accuracy of railgun projectile with uncertainty in this paper. An exterior ballistics simulation model of the railgun, including 3-DOF flight mechanical model, relative kinematic model, and guidance law model, is developed to simulate the ballistics behavior in the missile target intercept mission. The firing accuracy is studied in this paper to compare the capability of EMRG with different ranges and muzzle velocities. In order to explore the firing accuracy of the guided projectile, the guidance precision analysis and ballistics uncertainty quantification are studied. In the guidance precision analysis, the shot range and efficiency are used to make a comparison. In addition, the sensitivity analysis and firing accuracy analysis are also performed in terms of uncertainty quantification. The simulation results illustrate that the simulation of the guided projectile can give some practical guide to the projectile design of EMRG. [ABSTRACT FROM AUTHOR]

Energy efficiency is a critical quantity of interest in the performance of electromagnetic railgun (EMRG). To improve the energy efficiency of EMRG with the presence of uncertainty, a hybrid robust optimization method is proposed. EMRG simulation model is developed to simulate the behavior of exterior ballistics and the corresponding robust optimization issue is formulated. With the help of the impact factor analysis, several significant factors of energy efficiency are selected as the design variables while the insignificant ones are not taken into account. In the robust optimization, the polynomial chaos expansion approach coupled with Latin hypercube design is proposed to propagate the uncertainty for alleviating the computational burden of fitness function (energy efficiency) evaluation. Then, the genetic algorithm is employed to solve the EMRG energy efficiency optimization problem with the constraint of mean miss distance. The optimization results illustrate that the hybrid robust optimization method is an efficient approach to improve the energy efficiency, which can be applied in the practical application of EMRG projectile design. [ABSTRACT FROM AUTHOR]

Electromagnetic railgun (EMRG) is a promising candidate weapon system for the future surface-fire support mission characterized by quick response, hypersonic velocity, and high damage efficiency. Since the huge power consumption during launching, priority should be given to the precise strike. Firing accuracy of EMRG, which refers to the closeness degree of the projectiles’ impact points to the target, is an important performance metric in the EMRG exterior ballistic performance assessment. To provide a systematic solution for the measure of firing accuracy, the assessment factors are formulated in detail. Then, a general framework, including trajectory simulation, data preprocessing, parameters estimation, and hit probability calculation, is proposed to evaluate EMRG firing accuracy. Considering the trajectory simulation experiments may be time consuming, a new multicriteria optimal Latin hypercube design method is presented to maintain the balance between experiment time and sampling performance. Finally, firing accuracy assessment of 16-kg projectiles is performed using the designed framework and proposed experimental design method. The result reveals that the circular error probability is about 5 km under current defined scenarios, which means the initial disturbances may have great impact on the firing accuracy of projectiles without guidance and control units. [ABSTRACT FROM AUTHOR]

This paper describes theoretical and experimental work aimed at the development of a new class of high-speed projectiles with superior penetration performance. Our earlier publications were focused on the finite element analysis of projectile-target interaction over a wide range of impact speeds. The projectiles were made of tungsten or alumina, and the target plates were made of aluminum, steel, or tungsten. Subsequently, finite element modeling was performed for ceramic rods encased in metal shells and launched against reinforced concrete. This paper expands the range of ceramic and ceramic-based composite materials for use in high-speed projectiles. Materials were compared based on their mass density, Hugoniot elastic limit, fracture toughness, deformability, and ability to withstand intense aerodynamic heat during high-speed flight and penetration. Finite element analysis was performed for ceramic and tungsten projectiles impacting metal plates at speeds ranging from 0.5 to 6.0 km/s. Several transient phenomena such as ceramic projectile self-sharpening, multiple impacts, spall, and buckling were observed. The computation results were used for the design and manufacture of high-speed projectiles with superhard tips made of commercially available diamond composites. Experiments involved several projectile configurations. The penetration depth of reference steel projectiles into concrete decreased with increased impact speed, while the penetration depth of the projectiles with diamond tips increased. Clusters of ceramic and metal-ceramic projectiles and fragments can find use against larger and softer targets and in the generation of debris. [ABSTRACT FROM AUTHOR]

Active electromagnetic (EM) armor is a new type of active defense system, which can intercept invading objects effectively. When hit by interception projectiles, the invading object will deviate from its trajectory or be destroyed totally. A steerable EM launcher system using two separate pancake coils is introduced in this paper, and its 3-D model is built. With finite element analysis code, acceleration process of the interception projectile is simulated, and laws of acceleration force acting on the projectile, its velocity, and displacement versus time are also investigated. Experimental installation is introduced, and experimental data are well matched with simulation results. [ABSTRACT FROM AUTHOR]

This paper deals with experiments and calculations performed in order to investigate the influence of the electromagnetic hardening of payloads in a railgun. This is a complex task: besides the large amplitudes of the in-bore magnetic fields due to the pulsed current, the exit of the projectile from the muzzle and the consequences of plasma arcs have to be considered. At the muzzle the magnetic induction can drop from several Teslas to zero within some microseconds, leading to very high induced voltages and electric fields in the metallic parts of the projectile. On the other hand, the electric contact established by solid armatures tends to develop into electric arcs at high velocities during the launch. These plasma arcs as well as the closing switch transients of the railgun circuit are a source of electromagnetic radiation in a broad spectral range. Some electronic devices were selected and tested with static setups corresponding to the previous conditions. In a first phase a series of static railgun experiments (no projectile movement) was performed. In a second phase, static experiments simulating the muzzle exit conditions were carried out. Finally, the influence of electromagnetic waves emitted during railgun experiments on electronic devices was investigated, using a static setup with a conventional spark gap. [ABSTRACT FROM AUTHOR]

Projectiles in coil gun usually make one-way movement and move at a very high speed. The device would be fit for the application of oil pumping unit, as long as the projectiles can make reciprocating movement and move slower by adopting proper control methods. At present, during the production process of petroleum, the efficiency of the system is rather low. Energy dissipation takes a considerable ratio in the total cost of oil production. Moreover, beam pumping-unit system suffers from long driving chain, poor flexibility, a quite huge capacity and weight under long length of stroke, and low efficiency. Aiming at the earlier problems, linear electromagnetic oil pumping unit is presented in this paper, which is essentially a multiphase coil launcher. Analysis is made about the advantages and disadvantages of three~phase and multiphase structures, as well as the practical structure. Simulation studies are made; meanwhile, experimental investigations are carried out on a small-scale-model machine system. Further simulation studies of coil launching system are carried through the mechanical and mathematical models of rod string in a sucker-rod pumping-unit system. Theoretical analysis and experimental results verify the feasibility and the validity of the proposed system. Thus, a new path to solve the problem of high energy dissipation in oil production is explored. [ABSTRACT FROM AUTHOR]

The main motivation of this work is to clarify whether the hopes of significantly improving the performance of the conventional guns by using plasma ignition have a realistic basis. We assessed the possibility of improving the whole interior ballistic process, its repeatability and safety, through a uniform propellant ignition. In addition, we planed to improve the gun performance [the projectile muzzle energy (velocity)] by "forcing" "cold" charges to perform as "hot" ones (achieving "temperature compensation"). All of these goals are intended to be accomplished by using reasonable electrical energies (which would allow the reduction of the mass and volume of the power supply). We also avoided any significant changes in the conventional gun topography in order to prevent unacceptable costs. The presented research program proved that by using a standard 105-mm gun (concerning its barrel length and charge chamber volume) and a standard propellant, improved performances (more than 28% in the projectile muzzle energy) can be achieved while dense charges are used. In addition, significant reduction of the important effect, the "temperature gradient," is obtained. The capacity of plasma as the ignition factor to provide ballistic gain has also been demonstrated. [ABSTRACT FROM AUTHOR]

The three-year line of sight/beyond line of sight (LOS/BLOS) electrothermal chemical (ETC) launcher program, funded by the U.S. Army's Armament Research, Development and Engineering Center (ARDEC), Picatinny Arsenal, is a comprehensive effort to advance ETC launcher technologies. The program includes development of ETC plasma injectors for 120-mm M829A2s, build of a 100-kJ pulsed power supply small and robust enough to be realistically integrated into a combat vehicle, improvement of power connections to the gun to allow electromagnetic field containment and automated connection to the round, and tests of the completed ETC system with various chemical propellants and electrical energy levels. As part of the LOS/BLOS program, a new, coaxial version of BAE Systems' Basepad plasma injector has been developed and tested successfully in XM36, XM291, and M256 cannons. The Basepad's coaxial design effectively insulates the gun breech, thus preventing any part of the gun from being part of the high-voltage discharge circuit. A compact electrothermal ignition pulsed power supply (ETIPPS) has been designed, built, and tested. Including its own high-voltage charger, actuation circuitry, safety systems, and peripherals, ETIPPS's low weight and volume make it easily small enough for vehicle integration, as was demonstrated in a concurrent effort that included ETC firings from a combat vehicle. Test firings, currently ongoing, have validated the system architecture and performance and continue to supply data on performance at different temperatures, electrical energy levels, propellant loading, and propellant type. These tests demonstrate many of the benefits of ETC launchers including improved accuracy from precision ignition; maximum performance potential across all temperatures ranges (temperature compensation); and reliable ignition of new, high-energy, high-density, and in some cases low-vulnerability propellants. The system-wide approach of the LOS/BLOS electrothermal launcher program has advanced ETC technology significantly towards field readiness. [ABSTRACT FROM AUTHOR]

This paper is based upon the observation that, when a bullet is fired, it creates characteristic markings on the cartridge case and projectile. From these markings, over 30 different features can be distinguished, which, in combination, produce a ‘fingerprint’ for a firearm. By analyzing features within such a set of firearm fingerprints, it will be possible to identify not only the type and model of a firearm, but also each and every individual weapon just as effectively as human fingerprint identification. A new analytic system based on the fast Fourier transform for identifying projectile specimens by the line-scan imaging technique is proposed in this paper. This paper develops optical, photonic, and mechanical techniques to map the topography of the surfaces of forensic projectiles for the purpose of identification. Experiments discussed in this paper are performed on images acquired from 16 various weapons. Experimental results show that the proposed system can be used for firearm identification efficiently and precisely through digitizing and analyzing the fired projectiles specimens. [ABSTRACT FROM AUTHOR]

This paper describes the design of an 8-MJ base-pushed launch package for railgun launch. Extensive interior ballistics and flight dynamic analyses were performed. The launch package was designed to withstand a peak acceleration of 57 k-gees, and a substantial amount of lateral load. The lateral load was of prime importance for this launch package to ensure survivability of subprojectile joints present inside. Even though the launch was by a base-push method, a sabot was necessary to carry the bore-riders. Sabot separation dynamics and projectile aerodynamic coefficients were evaluated to ensure a successful flight. The package was successfully tested at the 32-MJ U.K. EM Gun Facility, Kirkcudbright, Scotland, at 7-MJ muzzle energy. [ABSTRACT FROM AUTHOR]

One of the main issues of railguns is the ablation of the rails due to the existence of a plasma arc occurring at high currents. To avoid the heat load on the rails, it is necessary to reduce the current intensities. The use of a parallel augmented railgun is one method of lowering the current without reducing the electromagnetic force on the projectile. One- and two-brush projectiles have been fired in a parallel augmented railgun with a 15 mm × 15 mm caliber and with a barrel length of 1.5 m. These experiments have shown that the maximum kinetic energy at the muzzle-without the transition of the solid contact between the rails and the brush to a plasma contact-can be significantly increased in an augmented railgun. The maximum kinetic energy has increased by a factor of 5 for one-brush projectiles and by a factor of 9 for two-brush projectiles. A model for the electromagnetic force in the augmented railgun and a friction model for the brush projectile are presented. The kinematics of the projectile in the gun are simulated with these models and are compared to the measured velocity. A good agreement is obtained. [ABSTRACT FROM AUTHOR]

Presents information on a study which examined long-range ballistics to highlight the launch parameters of importance to electromagnetic gun designers. Atmospheric effects; Launcher energy limitations; Subcaliber projectiles; Conclusions.

Researchers at the Weapons and Materials Research Directorate of the Army Research Laboratory (ARL) have recently completed experimental testing with a G-hardened gun-launched miniature instrumentation package that fits within the projectile fuze cavity for obtaining realistic in-bore, deceleration, and projectile impact data. This device consists of an accelerometer and a digital recorder that is designed for the reliable capture of ballistic data during projectile launch, flight, and target impact. During recent flight test evaluation at the ARL, Aberdeen Proving Ground, projectiles containing this device were tested with a telemetry link as well as recovery and direct downloading of onboard recorded data. For projectile impact studies both concrete and bunker targets were successfully engaged. This methodology of onboard data recording has been shown to provide a reliable and high-fidelity characterization of projectile in-bore and impact events critical for advanced munitions designers. [ABSTRACT FROM AUTHOR]