Abstract-In the real world application of railguns, the launch efficiency is one of the most important parameters. This efficiency directly relates to the capacity of the electrical energy storage that is needed for the launch. In this study, the rail/armature contact behavior for two different armature technologies was compared. To this end, experiments using aluminum c-shaped armature and copper brush armature type projectiles were performed under same initial conditions. The c-shaped armature type showed a superior behavior with respect to electrical contact to the rails and in acceleration. A 300 g projectile with a c-shaped armature reached a velocity of 3100 m/s and an overall launch efficiency including the power supply of 41%. This is to be compared to 2500 m/s and 23% for the launching of a projectile using a brush armature.

The Materials Science Laboratory is a unique tool designed to perform high temperature experiments from various fields of physics on board the International Space Station. During the first operating phase initiated in November 2009 the directional solidification of aluminum-silicon alloys is investigated. The experiments shall elucidate the influence of fluid flow within the melt on the microstucture of the casting. In contrast to terrestrial experiments fluid flow induced by convection is virtually absent under microgravity conditions. The Materials Science Laboratory allows for solidification under both diffusive and stimulated convective conditions. After processing on orbit samples are returned to earth for detailed analyses. A short description of the experimental setup is given to familiarize with the capability of the facility. One of the experiments is specified in detail including the preparations performed on ground and the execution on orbit. Corresponding telemetry data is analyzed and first results of the metallographic examination are presented.

Abstract-Railguns are capable to far exceed the muzzle energies of current naval deck guns. Therefore one of the most promising scenario for the future application of railguns in naval warfare is the long range artillery. Hypervelocity projectiles being propelled to velocities above 2 km/s reach targets at distances of 200 km or more. At the French-German Research Institute the PEGASUS launcher is used for investigations with respect to this scenario. The 6 m long barrel has a square caliber of 40 mm. The power supply unit is able to deliver 10 MJ to the gun. Within this investigation, a complete launch package is being developed and experiments are performed that aim at showing that this package can be accelerated to velocities ranging from 2000 m/s to 2500 m/s. A launch package consists out of an armature, a sabot and the projectile. The armature ensures the electrical contact during launch and pushes the sabot with its payload through the barrel. The sabot guides and protects the payload during the acceleration. At the same time the accelerating forces generated at the armature needs to be transferred to the projectile. After the launch package has left the barrel, the sabot should open and release its payload, the projectile into free-flight. Here the the current status of the launch package development and results from Experiments with the PEGASUS railgun are presented. I. IntroductionThe PEGASUS railgun installation at the French-German Research Institute (ISL) is being used for experiments in support of research for a long range artillery scenario. In future and current modern naval ships, the electric power requirements for a large muzzle energy railgun can be meet [1], [2]. Compared to existing naval deck guns the large muzzle velocities of 2 km/s to 3 km/s require the development of new guided hypervelocity projectiles. In response to this, activities for the design of such a projectile have started at ISL. The sub-caliber projectile is embedded in a sabot when launched with a railgun. This sabot ensures the mechanical contact to the armature, guidance through the railgun barrel and mechanical protection. Depending on the sensitivity of the on-board electronics of the projectile the sabot might also need to incorporate a shielding function against electromagnetic interference from the electromagnetic fields during railgun operation. The assembly of the armature, the sabot and the projectile is termed launch package. After the launch package has left the barrel, the projectile has to separate from the armature and sabot to embark on its free flight trajectory. Work at other research labs concerning the development and testing of electromagnetic gun launch packages is described in the recent literature [3]- [6]. The aim of the investigation described in this report is to demonstrate that close to realistic projectiles can be successfully launched with the existing railgun

Abstract-The French-German Research Institute (ISL) has several railguns installed, the largest of these is the PEGASUS accelerator. It is a 6 m long, 4 x 4 cm 2 caliber distributed energy supply (DES) railgun. It has a 10 MJ capacitor bank as energy supply attached to it. In the past, this installation was used to accelerate projectiles with a mass of about 300 g to velocities up to 2500 m/s. In the ongoing investigation, it is attempted to accelerate heavier projectiles to velocities above 2000 m/s. For this a new type of projectile including a payload section was developed. In this paper the results of the experiments with payload projectiles using a primary energy between 3.8 MJ and 4.8 MJ are discussed.

The French-German Research Institute (ISL) has several railguns installed, the largest of these is the PEGASUS accelerator. It is a 6 m long, 4 x 4 cm 2 caliber distributed energy supply (DES) railgun. It has a 10 MJ capacitor bank as energy supply attached to it. In the past, this installation was used to accelerate projectiles with a mass of about 300 g to velocities up to 2500 m/s. In the ongoing investigation, it is attempted to accelerate heavier projectiles to velocities above 2000 m/s. For this a new type of projectile including a payload section was developed. In this paper the results of the experiments with payload projectiles using a primary energy between 3.8 MJ and 4.8 MJ are discussed.