Just a normal heliblade spinner. For like, aircraft.

да. You could also just use plain hydrofoils on the outside like fins. That work too.

Here:

https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=1661280167

This is a sub I just recently finished. The only thing it doesn't have is programming in the LUA block to make it dive and submerge under AI power. But if you study how I set it up, you'll understand how a sub works. (And you won't need pesky rotor configs.)

Just be sure to pay attention to what I did for the game world configs. They're slightly off from default NETER settings.

heliblades are a good controllable way of diving, but hydrofoils also work well if your sub is in constant motion. use PID blocks to ensure ai can use the systems efficiently, or use acbs for a more rigid setup if you want a fixed float depth for your sub. additionally to make the sub more efficient, get it to an average buoyancy only slightly higher than 1 so it doesnt sink uncontrollably, but can be forced down by the above systems without needing absurd amounts of power to do so.