[Spaceships] Reactionless Drives, Pseudovelocity, and NOT breaking a setting (much)

[RogerBW]

My mental model of pseudo-velocity drive is something like 2300AD's stutterwarp, or the drive used in Poul Anderson's Polesotechnic League stories.

In that case, the energy cost of moving from point A to point B needs to vary with gravitational potential difference. If you move your 100-ton ship "up" by 100 metres from Earth's surface, that costs you the same 100MJ or so that you would have needed to feed into an electric motor (though the inefficiency level will be different).

So the standard perpetual motion setup, where you jump something upwards and let it fall down, is circumvented.

In game terms what this will mean is that outward acceleration drops off sharply when you're in any sort of gravity well. It may even be that ships can't use this drive near planets at all, and need rockets or something else for surface-to-orbit.

Is this a useful starting point?