Empty.
More empty tests.
One vessel.
Complete test for one vessel.
One vessel two steps.
Part removal.
Test part removal.
Comments.
Code cleanup.
Split common parts from acceleration.
No common parts.
Two vessels, first step.
Most of the 2nd step.
2nd step complete.
Factor out testing code.
Remove traces.
No traces.
More calculators.
Lint.
After egg's review.