DROP_BLEND_SHARE

The share of the drop over which the orbit camera's roll is blended into the surface camera's.

The orbit arm keeps the pole up and the surface arm keeps the local vertical up, and at a mid-latitude the two differ by tens of degrees. A cut between them at release would be a horizon that snaps; a slerp over the first fifth is a horizon that settles.

entryArc.ts:235