Johan Gallant

Design Considerations for an Electromagnetic Railgun Firing Intelligent Bursts to Be Used Against Antiship Missiles

Railguns can reach higher muzzle velocities and fire rates than conventional guns. Muzzle velocities up to 2400 m/s and fire rates of more than 50 Hz have already been demonstrated with projectiles having a mass of 140 g and a square caliber of 25 mm. We investigated if a close-in weapon system (CIWS) based on a railgun performs better against incoming antiship missiles than a conventional CIWS such as the goalkeeper and propose solutions to optimize the performance of such a railgun. CIWSs are operational systems that defend a ship against incoming subsonic antiship missiles. However, the future antiship missiles will be supersonic and more difficult to defeat with conventional gun systems. Railguns are expected to perform better against these future threats thanks to their higher muzzle velocity and fire rate. Furthermore, the muzzle velocity within a single burst can be varied easily from shot to shot, generating a so-called intelligent burst. It allows varying the velocity of each projectile such that all projectiles arrive on the target at the same time. The number of projectiles, and thus the electrical energy required to achieve a target kill with an intelligent burst is expected to be lower than for railguns firing at constant muzzle velocity. In the first part, the performance of an electromagnetic CIWS is discussed using simulation models calculating the hit probability of a burst of projectiles fired with muzzle velocities ranging from 1200 to 2400 m/s and fire rates ranging from 75 to 300 rounds/s. The geometry of the target is that of a typical antiship missile, its velocity ranges from subsonic (300 m/s) to supersonic (600 m/s). The influence of the projectile mass on the performance of the system and the required electric energy was also investigated. We confirmed that the concept of intelligent burst reduces the required electric energy, especially against supersonic targets. The second part deals with some technical aspects of high fire rate railguns. We have shown experimentally that an automatic loading system allows increasing the fire rate of a medium caliber railgun from 50 to 75 Hz.

A Review of Smart Clothing in Military

Wearable technologies are now pervading many applications in several fields. The aim of this review paper is to collect and summarize the actual smart clothing in the space and military field where conditions could be critical for health and safety, and outline the innovation trend for innovative services to police and soldiers.

Design considerations for an electromagnetic railgun firing intelligent bursts to be used against anti-ship missiles

Railguns can reach higher muzzle velocities and fire rates than conventional guns. Muzzle velocities up to 2400 m/s and fires rates of more than 50 Hz have already been demonstrated with projectiles having a mass of 140 g and a square calibre of 25 mm. We investigated if a Close In Weapon System (CIWS) based on a railgun performs better against incoming anti-ship missiles than a conventional CIWS such as the Goalkeeper and propose solutions to optimize the performance of such a railgun. CIWS are operational systems that defend a ship against incoming subsonic anti-ship missiles. However, future anti-ship missiles will be supersonic and more difficult to defeat with conventional gun systems. Railguns are expected to perform better against these future threats thanks to their higher muzzle velocity and fire rate. Furthermore, the muzzle velocity within a single burst can be varied easily from shot to shot, generating a so-called intelligent burst. It allows varying the velocity of each projectile such that all projectiles arrive on the target at the same time. The number of projectiles and thus the electrical energy required to achieve a target kill with an intelligent burst is expected to be lower than for railguns firing at constant muzzle velocity. In the first part, the performance of an electromagnetic CIWS is discussed using simulation models calculating the hit probability of a burst of projectiles fired with muzzle velocities ranging from 1200 m/s to 2400 m/s and fire rates ranging from 75 rounds per second to 300 rounds per second. The geometry of the target is that of a typical anti-ship missile, its velocity ranges from subsonic (300 m/s) to supersonic (600 m/s). The influence of the projectile mass on the performance of the system and the required electric energy was also investigated. We confirmed that the concept of intelligent burst reduces the required electric energy, especially against supersonic targets. The second part deals with some technical aspects of high fire rate railguns. We have shown experimentally that an automatic loading system allows increasing the fire rate of a medium calibre railgun from 50 Hz to 75 Hz.

Modelling of a Parallel Augmented Railgun with Pspice Validation of the Model and Optimization of the Augmenting Circuit

Experiments with LARA, a 15 mm caliber parallel augmented railgun at the French-German Research Institute ISL, have shown that the augmenting circuit of this railgun was not efficient. In order to minimize the energy losses in the augmenting circuit of this railgun, a PSSpice model was developed. This model combines an electrical model of the pulse forming network and the rails with a model of the kinematics of the projectile.

Design Considerations for an Electromagnetic Railgun to be Used Against Antiship Missiles

Railguns can reach higher muzzle velocities and fire rates than conventional guns. Muzzle velocities up to 2400 m/s and fire rates of > 50 Hz have already been demonstrated with projectiles having a mass of 140 g and a square caliber of 25 mm2. We investigated if a Close-In Weapon System (CIWS) based on a railgun performs better against incoming anti-ship missiles than a conventional CIWS such as the Goalkeeper. CIWS are operational systems that defend a ship against incoming subsonic antiship missiles. Future antiship missiles will be, however, supersonic and more difficult to defeat with conventional gun systems. Railguns are expected to perform better against these future threats thanks to their higher muzzle velocity and fire rate. We developed a simulation model calculating the hit probability of a burst of projectiles fired with muzzle velocities ranging from 1200 to 2400 m/s and fire rates ranging from 75 to 300 rounds/s. The target velocity ranges from subsonic (300 m/s) to supersonic (600 m/s). The performance requirements for a corresponding railgun are used to discuss possible system layouts. The kinetic energy to be delivered by the launcher translates into requirements for the pulsed power supply. However, thermal management has to be considered for repetitive launching. Therefore, we carried out numerical simulations on the electrical and thermal behavior of various solutions and compare their advantages and drawbacks.

Design of a New Setup for the Dynamic Analysis of the Recoil-Shoulder Interaction

We addressed the measurement and modeling of contact forces during intense, short impact loading of the shoulder. Experimental recoil force measurements show significant intra- and inter subject dispersion, advocating a an approach without real shooters but based on a biomechanical model for the dynamic analysis of the recoil-shoulder interaction. This mechanical prototype would replace actual shooters and is being developed and optimized for the standard, military, standing shooting position, but the framework could easily be extended to other positions and applications like clay shooting and hunting. The obtained recoil parameters are more realistic than current measures. The latter are not registered in realistic conditions as they are not based on direct measurements of the recoil forces on the shoulder but evaluated in a free-to-move or blocked setup. We illustrate the effects of these conditions on the recorded recoil force.

Smart Clothing Design Issues in Military Applications

Smart clothes development history started in the military field and this still remains a main application field. A soldier is like a high-performance athlete, where monitoring of physical and physiological capabilities of primary importance. Wearable systems and smart clothes can answer this need appropriately. Smart cloth represents a “second skin” that has a close, “intimate” relation with the human body. The relation is physiological, psychological, biomechanical and ergonomical. Effectiveness of functional wear is based on the integration of all these considerations into the design of a smart clothing system. The design of smart cloth is crucial to obtain the best results. Identifying all the steps involved in the co-design workflow can prevent a decrease in wearer’s performance ensuring a more successful design. This paper presents all the steps involved in the workflow for the design of a proposed solution of a smart garment for monitoring soldier’s performance.

Assessment of Human Balance Due to Recoil Destabilization Using Smart Clothing

Several studies focused on the importance of postural balance as a key for success of shooting performance and training. The most destabilizing factor is recoil that is the reaction effect produced on humans by a shooting task. To assess the postural control during a shooting task, stabilometry (posturography) is the golden standard technique. Force and pressure plate are the main traditional instruments. Today, smart clothing provides a method to monitor in real time mechanical, environmental, and physiological parameters in an ecological and in non-intrusive approach. Smart clothing (t-shirt) based on body-worn accelerometers (trunk accelerometers) was compared with posturographical by a pressure plate obtained during each shooting trial. The smart t-shirt revealed to be an innovative tool to assess human balance due to recoil destabilization.

Experimental and Numerical Study of a Combined Blast and Ballistic Protection

The work presented in this paper concerns a project on the optimization of protections subjected to explosions (IED’s threat). Explosions generate two types of threats for a protective structure: blast and impact of fragments. Perforating and non-perforating impact tests were performed in our laboratory with steel spherical projectiles impacting a target based on Kevlar® textile layers and a crushable material, Crushmat®. These tests required to develop a specific experimental test setup in order to contain the composite protective structure and to be able to measure the relevant parameters. The experiments allow us to determine the ballistic performance and basic parameters of the protection, and to validate finite element numerical models (LS-DYNA) resulting in a performant prediction tool. The approach used for the simulation consists in the representation of the full textile architecture with solid elements. Therefore, the textile material is explicitly represented in the model in order to have a good representation of the physical phenomena occurring during impact. For the crushable material, a representation using SPH was chosen in order to take the granular behaviour of this material into account. Good results are obtained with such models. However, these models are very complicated and computing time consuming. The geometry has to be well adapted and symmetry has to be exploited. On the other hand, representation of a granular material with SPH does not take into account some characteristics of this material during impact, such as the pulverisation process of the granular material. Solutions to take these phenomena into account in the model are proposed.