.51D would limit the grav vehicle to .01D above the planet's surface, But grav vehicles have always been able to lift into at least LEO.
I do not think anything has been written on this, but I am not certain. That is why I suggested that a mechanism may need to be written for describing the game-mechanical differences between all of the different drives that use gravity manipulation.
This would work. Now it just needs to be written that way and put in the books.
All of those things are problems that will be solved by clarifying the different requirements, advantages / disadvantages, and trade-offs in each type of technology. There is already the problem that a Grav-belt ought to work differently on worlds of different gravity, near black holes, etc -- but they simply don't. This means that every referee who encounters this issue has to hand-wave & house-rule, because there is simply no guidance at all.
As I understand it, gravitic plumbing is integral to Fusion+.
Gravity Rifles (JTAS V04, p 31) are a high-tech weapon, a bit superior to Gauss weapons. Instead of using electromagnetism to accelerate rounds, they use
Well, valves with remote/automatic actuators would still be a thing to isolate areas for maintenance or to prevent backflow on a loss of power. But pumps would be relegated to niche maintenance roles at best.
For working on out-of-service piping, the plumber is not changing 'up' and 'down' in arbitrary directions over an entire dTon; just inside a pipe or two. Worst case, plug it into local power -- but I think a battery should handle the load just fine for a few hours. In-service piping would definitely be hard-wired to local power; which might rely on the battery-backup of the structure itself, or there might be a dedicated power backup specifically for the plumbing.
air density isn't a constant - unless you want to make it a constant variable. Atmosphere lower to sea level is denser than atmosphere higher. If you are de-orbiting and landing on a planet you can enter the upper atmosphere at very high speed (shuttle would de-orbit at about 17,500mph) at early re-entry, but it had to slow down because it would rip itself apart and/or melt if it tried to do that all the way down as air density increased, drag increased and heat/structural stress increased. It would enter over the Pacific and do a few corkscrews to bleed off speed and get down to lower mach as it descended towards Florida.
That's one of those version-dependent questions. I didn't buy the new SSOM book so I can't comment on how they explain their operation in there. In some versions the 1G would fail on a 2G world. In MT SSOM you had the drive that could be over-clocked to 400% output (terrible engineering explanation) to make up for how the field was projected.
