Abstract: An electromagnetic projectile launcher is provided with a cartridge-type switch for commutating current from a high current source to a pair of generally parallel conductive rails. A conductive cartridge switch in sliding electrical contact with the rails at the breech end includes a pressure chamber and aperture for receiving a projectile. An increase in pressure in the pressure chamber forces the projectile forward while forcing the cartridge rearward. Current is commutated from the cartridge to a conductive armature which subsequently propels a projectile along the conductive rails.

Abstract: The stress or strain in a magnetic workpiece is measured by a method in which the workpiece is locally magnetized by a constant magnetic field, an eddy current probe is placed adjacent to the workpiece, and an electrical characteristic of the probe, which is proportional to stress or strain in the workpiece is measured. The measured value is compared to calibration data to obtain the actual stress or strain. By continually subjecting the workpiece to a constant magnetic field, a maximum value of applied stress can be determined by making a first measurement before an external force is applied to the workpiece and making a second measurement after the force is removed. The difference between the two measurements is proportional to the maximum stress applied to the workpiece by the force between the two measurements. If stress or strain in a nonmagnetic workpiece is to be measured, a layer of magnetic material is bonded to the workpiece at the measurement point.

Abstract: A recoilless electromagnetic projectile launcher is provided with a pair of projectile launching conductors, a source of high current, a sliding armature for conducting current between the conductors and propelling a projectile, and a structure which creates a force which is equal but opposite to a recoil force created as the projectile is accelerated. This structure includes a second pair of conductors for accelerating a recoil mass in a direction opposite to the direction of travel of the projectile or, alternatively, an expansion chamber and nozzle for accelerating hot gases resulting from the creation of a plasma armature, in a direction opposite to the direction of travel of the projectile.