Yes, that is correct - they need the header tanks to make sure that fuel is immediately available, not sloshing around the main tanks as the ship flips. Rockets

Yes, that is correct - they need the header tanks to make sure that fuel is immediately available, not sloshing around the main tanks as the ship flips. Rockets really don't like sucking in vapour. I'm not sure if they're pressurized separately from the main tanks though - I would assume not, as that would be more complicated, but I could be completely wrong.