I've removed the self-sustaining ammo since it was just using up too many resources to be worth it for a small design. There were times where if it got low on ammo mid-flight it couldn't keep the engines on long enough to make up for being pulled into a planet's gravity due to the iron consumption. So I had to supplement it with ammo deliveries anyways, and I decided to just rely entirely on that. I also swapped out one of the solar panels for an accumulator and it seems to be working well.
The other main improvement is to the chem plant logic. It no longer needs buffers for the fuel and oxidizer. I use the on recipe complete signal to run a counter, mod by 2, then use that to flip between fuel and oxidizer. There is still a water tank to trigger a low water override.
If the chem plant is filled with too many resources it tries to run the recipes twice causing a lot of problems with the counting logic. Now the inserter is only active if the chem plant is not actively working which keeps it happy.
I noticed that when idling at a planet it backs up on fuel or oxidizer, clogs the pipe, then uselessly thrashes recipes. This creates an imbalance in how much fuel is available and while not proven I'm assuming it could create a condition where it can't use enough fuel to clear out the pipe and everything stalls. To prevent this I detect when I'm in orbit around a planet and stop producing fuel at that time. However I also realized if it somehow gets into orbit with a very low to zero amount of fuel that could prevent it from firing up again. So the orbit kill switch is hooked up to a timer and only disables the fuel/oxidizer production after 8 seconds.
I believe I could get the design down to 74 tons if I can figure out a consistently safe way to run the logic without the water tank, but 75 is such a nice number. I could also remove the accumulator but that causes worrisome power dips. The blinky lights are a core part of the ship's functionality and cannot be removed.
