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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 UK EM Gun Facility located at Kirkcudbright, Scotland at 7-MJ muzzle energy.

The physical and chemical phenomena involved in the ballistic process, both in conventional guns and in electrothermal-chemical (ETC) guns, are very complex, so that optimization of gun performance requires a detailed understanding of the influence of different parameters. The initial stage of propellant ignition is critical to the rest of the process, in terms of both performance (muzzle velocity, repeatability) and safety. A better understanding of the ignition stage is thus very important in achieving improved performance. In this paper, we propose a new method and ignition sensor aimed at providing direct experimental information about the propellant ignition process. We further report on measurements of the ignition delays, and the propagation of the "ignition wave", performed using these sensors in experimental devices such as closed bombs and gun simulators.

The use of telemetry in gun-launched projectiles is not as common as in missile and aircraft systems. A primary reason is the launch environment of guns. Conventional solid propellant guns often produce launch accelerations approaching 100,000 g's. Additionally, if the bore is rifled, large lateral accelerations are also produced. Recently, the Hardened Subminiature Telemetry and Sensor System (HSTSS) program has developed and demonstrated a series of telemetry products and technologies specifically designed to make gun-launched in-bore and flight measurements more routine and affordable. This paper reviews the products and flight experiences from the HSTSS program and addresses the potential use of the HSTSS products and techniques for use on projectiles launched from electromagnetic rail guns.

The ability of electromagnetic (EM) guns to launch payloads at very high velocities has been shown to enable some new potential for long range bombardment from both ship and shore. This paper examines long-range ballistics in detail to highlight the launch parameters of importance to EM gun designers. The use of kinetic energy at long range for target defeat is introduced in the atmospheric effects section of this paper and later examined through specific case studies. High kinetic energy, on target, is a key capability enabled by the higher launch velocities associated with EM guns. This paper also shows the sensitivity of range, impact energy, and time of flight on the launch velocity in the regime of high altitude trajectories (enabled by EM launch).

The most important research results and the prospect directions for the electromagnetic (EM), electrothermal (TT) and electrothermochemical (ETC) launch in Russia are presented in this paper. The development of pulse power supplies, materials, projectile ballistics and simulation is also considered.

A detailed experimental investigation of the launch and flight performance of a kinetic energy fin-stabilized penetrator has been performed. The integrated launch package (ILP) consists of the subprojectile and mid-riding armature. The armature front contact is electrically insulated from the rails. This configuration has shown potential for effectively managing the launch disturbances. To evaluate the transitional ballistics, aeroballistics, and jump characteristics, single-shot firings with an exit velocity of 1350 m/s were conducted at the ARL Transonic Experimental Facility, APG, MD. The impact data show larger variability in the vertical direction than in the horizontal direction. Results from the jump survey indicate that effects of the deviation from the launcher centerline (i.e., straightness) contribute significantly to the target impact dispersion. Substantial contributions from the linear and angular rates at the muzzle are evident in the vertical direction. The contribution attributable to sabot discard in either plane is minimal. When possible, comparisons are made to our earlier investigation which examined the ballistic behavior of a similar ILP with a conducting front contact.

Today the electrodischarge light-gas launcher (EDL) is not only the subject of investigation, but may be a suitable tool for different kinds of explorations. Such a hypervelocity accelerator gives the possibility to carry out experiments on impact interaction over a wide range of velocities (up to several kilometers per second) with substantial accelerated body masses. This experiment demands the creation of special impactor which in turn requires the launch package design. This paper considers the development of launch package for multiple rod hypervelocity impact investigation. Distinctive features of multiple rod impact investigation are the requirements to the simultaneity and desired impact geometry of interaction (mutual position of penetrators and approach angle). To meet all mentioned demands penetrators were placed in inseparable holding cartridge. The exact approach angle was ensured by means of aerodynamic stabilization. The holding cartridge has to be made from materials with least possible density to decrease its Influence on interaction process. At the same time the holding cartridge has to be strong enough to withstand the overloads during the in-bore acceleration. In this paper the design and test results of the launch package for the multiple rod hypervelocity impact studying are presented. All experiments were carried out with the (EDL) of 30-mm caliber. Hydrogen under the initial pressure of 40 MPa was used as a working gas. It permits us to use the projectiles with masses up to 150 g and explore the velocity range from 1500 up to 3000 m/s.

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

In recent years, great strides have been made regarding the identification of the dominant loads that cause beam type vibrations of cannons during ballistic operation. These motions infringe upon shot accuracy because at projectile disengagement, the muzzle's kinematic state may compromise the projectile's intended flight path. This is particularly relevant to coil gun loading, which, unlike gas launch, applies the recoil load to the muzzle end of the barrel instead of the breech. This effectively places the barrel in a state of columnar compression during the launch cycle that may exacerbate structural vibrations known as gun "whip".

Electrothermal-chemical (ETC) guns offer the prospect of significantly increased muzzle kinetic energy over conventional solid propellant gun systems as evidenced by experimental data collected over the past several years. To support the various experimental programs, codes developed specifically for ETC interior ballistic processes have matured including 0D, 1D, and 2D/3D models. Although these models in general have been successfully applied to simulate experimental data, prediction of gun interior ballistic performance at high gun energies has been more difficult. In this paper we examine comparisons of 0D and 1D model results with experimental data in order to gain a clearer understanding of the way that electrothermal energy input modifies the interior ballistics in ETC guns. These comparisons suggest that both axial and radial effects must be considered, necessitating development of first-principles 2D/3D models. Results from one such model, CRAFT, are presented in the paper. >

A multidimensional, transient, fluid dynamic model, BISON, has been developed to study the interior ballistic processes in an electrothermal-chemical (ETC) gun. The model solves the full Navier-Stokes equations and uses a high-order numerical scheme to integrate the governing equations. Most of the important physical processes pertinent to ETC gun interior ballistics, including multiphase flow, chemical reaction, and plasma dynamics, are incorporated in the model. Examples of model applications to study basic ETC gun phenomena, such as plasma jet penetration and real gun design component analyses, are presented and discussed. The modeling results not only compare well with experimental data but also provide a better understanding of the interior ballistics physics. The multidimensional model BISON proves to a very useful tool for ETC gun interior ballistics simulations. >

Experimental gun firings and computer simulations of hybrid solid propellant-electrothermal gun propulsion concepts are reported. The test firings were conducted using loose and compacted ball propellant in a 30-mm test fixture. A plasma capillary located at the breech of the gun was used both to ignite the propellant charge and to augment the ballistic process. Computer simulations of selected tests were conducted using modified lumped parameter interior ballistic models, which were originally developed for conventional charge simulations. More general optimization studies of the solid propellant electrothermal-chemical interior ballistic process are also discussed. >

A dual-density Rodman cone, with 1/d=7, has been found to be attractive for electromagnetic launch and may have adequate terminal ballistic performance. Stable flight is achieved from the correct distribution of mass within the projectile body. The design provides some flexibility for the armature in that all the armature mass is used for aerodynamic stability. Furthermore, the acceleration can be supported by a simple one-piece armature. A bore rider, which is less than 10% of the total mass, is needed for in-bore stability and structural support at the tungsten/aluminum interface. Work to date has focused on small-caliber applications, but substantial gains can be achieved when the bore size is increased to cannon caliber. General design principles for a mass stabilized projectile are presented. Nearly all aspects of launch, flight, and terminal effects as a function of bore size are addressed. Flight and terminal effects are computed from curve fits to existing experimental data. >

A railgun for the study of the interaction of meteorites with planetary surfaces and the interaction of space debris was developed. The authors have attained a velocity constantly higher than 5 km/s, with a maximum of 6 km/s. The importance of plasma confinement behind the projectile to prevent a leakage is shown to realize a high velocity. An effective acceleration using an aluminum rail is also shown. >

The impact of launch acceleration on the design of electromagnetic launcher barrels and on the design of associated launch packages is discussed. This is of particular interest because launch package size and mass directly affect the overall armament system size and mass. A common design approach is to use as the peak launch acceleration the maximum acceleration which the projectile can be designed to withstand. While this approach will minimize barrel length, it may also yield an excessively large overall system size and mass, especially for the long, slender projectile configurations which are desired for high aero-thermal and terminal ballistics performance. An alternate design approach which balances the goals of reducing barrel length ad reducing launch package mass is described. Results illustrate the benefits of this balanced design approach on overall armament system size and mass. >

LTV Aerospace and Defense Company (LTVAD) using the company's highly reliable, reusable electromagnetic (EM) railguns have conducted over 200 projectile launchings since the second Electromagnetic Launch Technology Symposium and have established a projectile/launcher data base covering interior as well as exterior ballistic considerations. Projectiles weighing 2 to 43 grams have been launched with the LTVAD EM launcher lab's 12.7 and 20 mm railguns over the velocity range of 1.5 to 8.5 km/sec. This paper describes the interface and compatibility relationship between an EM launcher and the launch package during the interior ballistics of launch and the influence on the subsequent exterior ballistics. Some terminal effects and test descriptions conducted at LTVAD are presented along with associated projectile monitoring instrumentation utilized in determining projectile motion, integrity, orientation, flight characteristics, and impact phenomenology. This work was sponsored by the Army Ballistic Missile Advanced Technology Center.

A program was initiated to design, build and evaluate the performance of a two-stage light gas gun, utilizing hydrogen gas, for use as an injector to an electromagnetic railgun. This effort is part of a project to develop a hypervelocity electromagnetic launcher for equation-of-state studies (HELEOS). The specific design features that enhance compatibility of the injector with the railgun, including a slip-joint between the injector launch tube and the coupling to the railgun, are described. The operational capabilites for using all major projectile velocity measuring techniques, such as in-bore pressure gauges, laser and CW (continuous wave) X-ray interrupt techniques, flash X-ray, and continuous in-bore velocity measurements using VISAR interferometry, are discussed. An internal ballistics code for optimizing gun performance has been utilized to interpret performance data of the gun. >