The Abbot Lift and Drive is an Anti-gravity machine. Energy goes in and lift occurs, pushing against the nearest center of gravity.
The smallest ones are solid machines About 1 cubic meter. The Big ones are... well... Bigger.
Between Abbots and Reaction thrusters, there's space drive.
To hover, one turns the drive on-and-off rapidly to avhieve neutral bouancy. leave it on a fraction longer and you drift up. Leave it off a fraction longer and you drift down.
For motion using only the Abbot, use them on the corners and activaste them differentially. the vehicle's center of gravity slides forward and so does the machine.
These grow weaker the greater the distance from the gravity being pushed against - inverse Square law.
These can be fed a trickle of energy for very little force - useful for exchanging time and distance of thrust for lots of energy.
Normally these are fed from very large Super Batteries. Losing power to your Abbots can ruin your whole day. Even the biggest of ships can fly with these - but if circumstances get weird or extreme, big ships can tear themselves apart.