A Potential Approach to Launch Hypervelocity Projectiles up to 10 km/s Based on Two-stage Gas Gun Facilities

On the basis of Sandia's third-stage launcher, a new scheme of hypervelocity launchers is brought forward for purpose of propelling a one-gram-weight projectile in the shape of sphere or cylinder upwards of 10 km/s. It includes an assembly of a sabot, a projectile and a steel impactor, and a hypervelocity launcher (HVL) that is attached to the muzzle end of two-stage light gas gun (LGG). With a specially designed sabot for LGG, the projectile together with the ring-shaped impactor being fixed on the sabot is first driven by LGG to a speed of 6-7 km/s. The projectile will gain the secondary acceleration in the HVL synchronously controlled by the high-speed impactor.Three kinds of designs are put forth for a HVL with propelling media of explosive, epoxy resin, or hydrogen respectively. To accomplish the sabot/projectile separation and secondary driven of the projectile, enormous computations have been performed to attain an optimized configuration of the sabot and the HVL. For the launcher using explosive, the projectile is driven by gas productions resulted from strong detonation. It is illustrated by simulations that a 1.03 g spherical projectile of 2024 alloy can be accelerated from an injection velocity of 6 km/s (LGG launching speed) to 9.6 km/s without extremely large deformation and spall damage. To launch a cylindrical projectile with constrained deformation, an improved design for HVL is achieved with adoption of a secondary impactor and an epoxy resin ring in place of explosive. It is capable of propelling a cylindrical projectile from 6 km/s towards 8 km/s by converging gas production of decomposition of epoxy. In the third design for a HVL, a pressure container with hydrogen is embedded in the tube of a HVL in an attempt to drive a projectile with hydrogen. Preliminary simulations reveal that a projectile (chunk plate) is possible to be accelerated towards 10.6 km/s at initial hydrogen pressure of 7 MPa, and towards 12 km/s at an increased pressure of 20 MPa. Enormous efforts are still required, however, to put this scheme into practice.