I was fairly certain it did not. So I made a small ship last night and tested the time it took to get up to top speed with varying amounts of thrust over the 2.5 ratio. It did take less time when the thrust was increased beyond the 2.5 ratio.
You're correct. The thrust to mass 2.5 cap only applies for top speed. Your acceleration is currently uncapped.
Could we get a value for advanced build mode that tells us our acceleration? I have a few ships that both have 2.5 thrust mass ratio, but one is quite a bit better than the other at accelerating.
Thrust output I suppose doesn't have a limit. And you were correct stating the 2.5 limit is solely to control top speed but thrust and mass do affect acceleration (I'm not saying you didn't know this already) which is why I would like it to be more realistic in that acceleration is controlled by the t:m ratio and not top speed.
Build mode already tells you your thrust and your mass. Only the display is capped at 2.5, but nothing stops you from calculating the actual T/M yourself.
