Design limitations on ultra-high velocity projectile launchers

The maximum velocity attainable in a gasdynamic gun is limited by the maximum sound speed in the driver gas. For a conventional 2-stage light gas gun, the limit is 10 km/s. Higher velocities are possible, but probably not without the destruction of the gun barrel. As long as this occurs on a time scale longer than the residence time of the projectile, a useful system may still result. Using a newly developed computer code called IGUN, we have evaluated the performance of several multistage designs capable of achieving ultra-high projectile velocities. The main problem is in maintaining the integrity of the projectile. Our calculations indicate that 20 km/s should be achievable without fracturing the projectile. If it is only required to retain near original areal density, velocities in excess of 30 km/s appear feasible.