On 29 Jun 2015 at 10:54, Craig Berry wrote:

> Spin stabilization doesn't work the same way in vacuum. The
> in-atmosphere version is designed to combat drag torque effects to
> keep the streamlined profile nose-on to the direction of travel. Drag
> torque doesn't happen in a vacuum. For a dumb projectile, orientation
> won't matter at all on impact. A smart projectile will need active
> attitude control (gyros, jets, or a combination.

Unless the projectile is spherical, orientation matters. Even at
multi-km/sec velocities. It affects the sectional density, which
effects the pentration characteristics.

The classic "long rod" penetrator doesn't do nearly as well if it
hits sideways instead on point first.

--
Leonard Erickson (aka shadow)
shadow at shadowgard dot com