Two-Stage Light Gas Guns

    Most modern rifles are limited to velocities below 2 km/s (4,500 mi/h). WSTF HVI two-stage light gas gun launchers use highly compressed hydrogen to accelerate projectiles at velocities in excess of 7.5 km/s (16,800 mi/h). These velocities simulate impacts of particles on spacecraft and satellite materials and components.

    LGG Schematic
    Light Gas Gun Schematic

    The two-stage light gas gun uses conventional smokeless gunpowder as its first stage. The second-stage propellant is a highly compressible light gas such as hydrogen. The gunpowder is set off by an electronic igniter, and provides rapidly expanding gas that drives the plastic piston forward. The pump tube contains the hydrogen gas which is compressed rapidly by the piston. The hydrogen gas provides the second-stage firing power. In the high pressure section, rapid internal pressurization is followed by a high level of impact caused by the halted piston. The hydrogen gas and launch package are separated by a burst disc. The launch package, which consists of a sabot, and projectile, is located at the beginning of the barrel, just downrange of the burst disc. When the pressure in the pump tube becomes sufficiently high, the burst disc fails, releasing the hydrogen gas at very high pressure into the back of the launch package. The launch package is propelled down the barrel into the expansion tank. The expansion tank allows collection and dissipation of high pressure hydrogen gas and permits the controlled separation of the sabot/projectile assembly.

    The projectile is photographed with high-speed cameras and flash x-rays just before impact. At times, the impacts are photographed to characterize the debris cloud. 35-mm infrared cameras are capable of 2 million frames per second, and the digital cameras are capable of 200 million.

    Infrared Camera


    Digital Camera


    Projectile into glass
    .44 mm Projectile into Glass

    Laser intervalometers measure projectile velocity. The time difference between interruption of laser beams by the projectile yield an extremely accurate calculation of its velocity. In addition, high-speed data acquisition systems using light detectors, strain gauges, pressure transducers, accelerometers, and thermocouples provide reliable diagnostics.

    For additional information, contact Karen Rodriguez at (575) 524-5279 or karen.m.rodriguez@nasa.gov.