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With more than 1 trillion artificial objects smaller than 1 μm in low and geostationary Earth orbit, space assets are subject to the constant threat of space debris impact. These collisions occur at hypervelocity or speeds greater than 3 km/s. In order to characterize material behavior under this extreme event as well as study next-generation materials for space exploration, this paper presents a unique two-stage light-gas gun capable of replicating hypervelocity impacts. While a limited number of these types of facilities exist, they typically are extremely large and can be costly and dangerous to operate. The design presented in this paper is novel in two distinct ways. First, it does not use a form of combustion in the first stage. The projectile is accelerated from a pressure differential using air and inert gases (or purely inert gases), firing a projectile in a nominal range of 1–4 km/s. Second, the design is modular in that the first stage sits on a track sled and can be pulled back and used in itself to study lower speed impacts without any further modifications, with the first stage piston as the impactor. The modularity of the instrument allows the ability to investigate three orders of magnitude of impact velocities or between 101 and 103 m/s in a single, relatively small, cost effective instrument.

There has long been a need to understand the impact response of explosive materials, and continual improvements result from the design of careful, well-instrumented experiments. This article summarizes details of the design and construction of a laboratory facility capable of launching projectiles at explosive targets at velocities up to 1500 m s−1. There are two types of experiment that are required. In the first, a gun launches a plate of great planarity at an equally flat target. This geometry is known as plate impact and a target loaded in this manner experiences a state of one-dimensional strain. This loading is accomplished by launching plane impactors onto targets aligned to micron tolerances, normal to the impact axis to less than 0.5 mrad of tilt. In the second, it is required to attain the ability to recover impacted explosive targets that have been loaded in one-dimensional strain for subsequent microstructural assessment. The development of this capability will be described in a subsequent pub...

We developed a compact two-stage light-gas gun and optimized several operating parameters for aiming at velocities higher than 9 km/s. A firing test achieved a velocity of 6.2 km/s using helium as driver gas with a projectile weighing 0.6 g and a piston weighing 430 g. In the case of firing tests using hydrogen, a velocity of 8.1 km/s was obtained under the same condition. Moreover, it was found that higher velocities could be achieved by using a lighter piston to increase piston velocities, and that the efficiency of acceleration strongly depended on the initial gas pressure for each piston. Finally, a projectile velocity of 8.9 km/s was achieved using a piston weighing 290 g.

A VISAR (velocity interferometer system for any reflector) with a new type delay leg is described, which uses multireflection in the etalon for increasing the delay time τ. When the incident angle is changed, the sensitivity of the VISAR can be changed. A few step values of the sensitivities can be selected for different applications. Experimental results for measuring the bullet’s motion in the 7.62‐mm gun are presented.

A new microvelocity sensor unit was developed to measure the instantaneous velocity of a high velocity impactor during the penetration process. The concept of this device is based on the induced current generated in a coil due to the passage of a magnet. A special digital circuit was designed to yield a spatial resolution of better than 0.05 in. by eliminating the problem of signal overlap. The precise time delays obtained from these signals can be used to determine the slowing down or energy loss of a high‐velocity projectile. The details of this sensor unit will be described and its resolution will be demonstrated. A light gas gun was used to propel aluminum projectiles to velocities up to 320 m/s. Energy loss of these high‐velocity projectiles in composites reinforced with polyethylene, polyester, and graphite fabrics as well as pure Kevlar fabric was measured using this system. Results show that this microvelocity sensor is capable of identifying various energy‐loss processes during the impact of high‐velocity projectiles.

A photoelectronic apparatus has been developed which makes possible the continuous simultaneous measurement of the depth of penetration, the speed, and the deceleration of a nondeforming small‐caliber projectile dring armor penetration. The basic operating principle of the apparatus is to have the flight path of the projectile pass perpendicularly through a thin parallel light beam of uniform intensity which activates a vacuum‐type phototube. The output of the phototube is proportional to position or the depth of penetration under appropriate geometry. A voltage signal derived from the phototube circuit is preamplified and differentiated to give voltage signals proportional to speed and deceleration. Permanent records of the signals are made by photography of cathode‐ray tube traces and analyzed. The apparatus is capable of measuring real transient accelerations or decelerations as great as 108 ft/sec2 (3×109 cm/sec2) with average error of 2 percent. Possible applications of the system to mechanical problems as an accelerometer, speed, and displacement measuring device are indicated.