Problems associated with launching hypervelocity projectiles from the fast shock tube

Modeling and experiments are being done with the goal of understanding the physics of projectile acceleration at high driving pressures (megabar range) and short acceleration times (a few microseconds) well enough to design and test successful hypervelocity launch systems. The Fast Shock Tube, a cylindrically convergent high-explosive driver, has been used to accelerate projectiles. Detailed modeling of the experiments, including high-pressure gas flow, projectile instability, and projectile fracture, has been done with the MESA/2D code. Modeling results show quantitative agreement with the average behavior of the system. However, details of projectile behavior are not predicted well. Observed velocity distributions across the diameter of a projectile or projectile shapes are only in qualitative agreement with calculations. This, then, presents the major constraint on the successful design of a launch system: that the processes that limit projectile integrity depend on the details of the drive conditions, and these details are not quantitatively modeled at this time.