[Spaceships] Is This Legal?

[Anthony]

Originally Posted by Ulzgoroth

Not totally, no.

Empty fuel tanks are weightless for delta-V purposes, but acceleration treats them as if they're full.

Only because it's less math that way.

Originally Posted by Ulzgoroth

Drop tanks are less efficient for pure delta-V than just cramming your actual ship into a tiny clump of sub-sized systems and building toward that 1.0 fuel-to-mass ratio, but if you're picky about the performance of the vessel that you deliver at the other end they have some points in their favor.

The proper way to do drop tanks is via stages (and since the OP was talking about jets, what you'd probably do is just design the bottom stage with jets).