I haven't looked at the blueprint yet, but if you're going for a constant altitude spaceship, use a PID set to control altitude. These usually do best with the "6 axis" movement type.

That's not helpful.

How is the AI’s altitude keeping programmed? If it’s been told to keep to a certain altitude above the terrain, it may follow that terrain down to the water over deep areas. If it’s set to measure altitude off of sea level, that might solve the problem.

I am sorry but that's an absolutely awful propulsion design.

1) Putting propulsion on spin blocks require to have a good understanding of what you are doing

2) Putting a secondary propulsion on spinblock on top of another spinblock with propulsion is commentless

3) Why the ♥♥♥♥ are the spinblocks set to continuous rotation ? What are you trying to do ???

4) Why is rotation speed controlled by ACB depending if there is an enemy or not ??? The rotation speed is set to 0 if there is an enemy, absolutely *not* brilliant move.

5) The control PIDs in the control room are getting in conflict with the AI PIDs (no, you can't have a control PID and an AI PID control the same listening axis at the same time, it's a terrible idea).

6) Six axis is the worst maneuver AI. Hover is clearly not adapted here. Your best chance is Airplane AI with what the spaceship is trying to be.

7) I still haven't found why the propulsion is switching on and off for some reason.

The ion engine clusters are on spinblocks to allow me to put them inside in many different places without their being obstructed. Their rotation is meaningless as they are locked. They are on a few other ships that work fine.

The main engines are on spinblocks to allow for thrust vectoring. They all work perfectly under manual control. I was fairly certain I didn't set the ACBs as you were suggesting. It was a few versions ago, so who knows how things got mangled. They were originally set to go to zero at a certain altitude where vectoring turns off and the ship goes purely to ion drives, acting more like a spacecraft.

I did try airplane AI. It had limited success, but would still land itself in the drink.

As I said, under manual control, it runs beautifully. It's fast and even somewhat agile for its size. It's just that the AI can't fly it. I always start one of these by making sure it flies as intended under manual control first.

I'll double-check the PiDs. I usually turn them all off under manual.

I stand by the propulsion design, though a few other design choices that led it to shoot parts of itself...not so much. I'll need to go back into FtD to load it up and have another look at it. I haven't played FtD in 2+ months and I've forgotten more than a couple of things about the mk 7. It's propulsion design is a steady refinement going back to the mk 2 or 3, all of which worked quite well under manual, but were uncontrollable by the AI.

Yup, the uploaded one was seriously out-of-date. The current ship has upgraded main laser cannons and uses a script-based AI from Discord that can fly it sufficiently well.

I'm gonna sort of call this case closed as the problem was solved. I'd close the comments, but I lack the admin rights to lock a thread.