READ THE TLDR FIRST

Okay, this will be hard to explain as I’m not a very good math guy. For my most recent post, I have made a jet with a sorta realistic startup. This next part *MAY* not be necessary but will be helpful. The dumbed down version of my code to make the APU and battery voltage meter is kinda like this:

APU variable:
“Switch2 & Battery <1100 ? clamp(80,0,1100) : 0”

It’s switch2 (APU switch) and battery is less than its max (1100) = true? Then: keep between 1100 and 0 at 80 per second.

Battery level variable:
“clamp(sum(( apu )+( engine )-( system *1.15)),0,1100”

its the sum of “ APU ” plus the power from the engines minus the aircraft systems power requirements times 1.15.
All this clamped between 0 and 1100 which is converted later inside the plane to be from 0v to 39v.

Engine charge variable:
“ Battery >150 & Switch3 * Switch4 * Switch5 * Switch6 * Switch1 & Battery < 1100 ? clamp(Throttle * 160,0,1100) : 0”

Its battery is greater than 150 (the minimum requirement for the engine start AS OF NOW. THIS MAY CHANGE OR BE DELETED IF SOMEONE HAS AN ANSWER ) and all the switches are flicked that need be (fuel pump L and R, Starter L and R), and battery is less than 1100 ? Then: throttle times 160 is the amount of charge rate

Of course there is more, but it’s probably not necessary.

THE REAL QUESTION:
I want the engines to actually take power as they start, like a starter. But once they rev up, they create power and it stops (or maybe to make it simpler to code, it just overpowers the starters power draining).
THE ONLY IDEA I HAVE IS LIKE AN IMAGINARY GRAPH LINE that starts negative and increases smoothly at a certain rate all of the way to the positive number rate of change (the engines charge)

Please ask me more questions in the comments if you have them, this took me too long to type out 💀
TLDR; I want to be able to flip some switches and have to wait for my starter to start my engines before I can just spool up super fast.