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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 U.K. EM Gun Facility, Kirkcudbright, Scotland, at 7-MJ muzzle energy. Index Terms--Electromagnetic railgun, integrated launch packages, muzzle energies, subscale projectile packages, 32-MJ U.K. EM gun facility.

The U.S. Navy is considering the development of electromagnetic railguns for future ships for naval surface-fire support (NSFS) and other missions. To reach long ranges, muzzle velocities in excess of 2000 m/s with projectile flight mass of 16 kg and above are needed. Relatively high firing rates are desired; typically 6-12 rounds per minute, so substantial power demands will be made on the ship. For an electrically driven ship, as in the DD(X) concepts presently being explored by the Navy, an existing electrical infrastructure would be in place that could be modified to recharge the pulsed power supplies for the railgun. This study focused on the railgun, the pulsed power system needed to drive the gun, the power system needed to restore the energy required to match the firing rate, and special ship interfaces. Railgun concepts and sizing for the NSFS mission were undertaken, and research and development issues of importance for the success of a future system were identified. Recommendations for analytical and experimental studies that should be undertaken to further address these issues are provided. Index Terms--Electromagnetic railgun, fire support, kinetic energy, projectile, pulsed power.

This paper describes a preliminary experimental investigation to convey acceleration measurements, made on-board an electromagnetic (EM) launched projectile, using microwave telemetry techniques. The focus of the investigation is to extend the Hardened Subminiature Telemetry and Sensor Systems (HSTSS) technology for use in EM launch environments. Many aspects of the HSTSS technology have already been successfully demonstrated in high-G, high-pressure launch environments in conventional gun systems. In addition, microwave transmission in stationary experiments, where the telemetry package was exposed to relatively high magnetic fields and EM transients in a railgun launcher, has been demonstrated. However, microwave telemetry during an EM launch has not been demonstrated until now. In this work, setback acceleration measurements obtained with an on-board accelerometer were processed by HSTSS electronics and transmitted simultaneously during launch via an antenna located in front of the EM launch package. While only the test conducted at 9-kG peak acceleration provided the most useful data, detailed analyses suggest that mechanical problems--rather than the microwave telemetry process itself--were probably responsible for difficulties experienced at higher accelerations. This paper reviews the experimental methodology and discusses the results of the investigation. Index Terms--Accelerometer, FM, hardened, RF, S-band.