On Wed, Jan 31, 2018 at 12:18:39AM -0500, Caleuche wrote:
> Could you explain that last part (" 50% margin for the harder to
> model variation of forces over the sphere") - do you mean with
> respect to the ability of the internal pressure of the sphere to
> keep the sphere rigid and spherical?

I mean that the drag comes from an average over the frontal surface,
and the pressure on the sphere near the stagnation point will
generally be greater than that further out.  The exact magnitude of
variation depends upon all sorts of surface detail factors that are
extremely annoying to model and may vary in reality anyway.  So I
allowed an extra 50% margin to cover these.

- Tim