On Tue, Jun 30, 2015 at 04:21:24PM +0000, Anthony Jackson wrote:
> Wrong threshold. Fluid penetration still cares about shape

Very little at these energies.  Not only do the impactor and target
behave like fluids, they behave like highly compressible fluids.  The
projectile and target matter collapse during the impact, reaching
densities far higher than normal.  This is only sustained for a very
short time.  By the time the matter of the projectile has slowed
significantly, it is already exploding outward regardless of whether
the original projectile was a ball or a rod.

> The time when orientation ceases to matter is when the crater depth
> (from explosive effects) exceeds the penetration depth.

That condition definitely holds at these speeds.

- Tim