Fly in battery rotation help

I have this code and it works but I’d like it to move in 9 degree segments every 10% of battery drain. I can’t seem to figure out how to add that or if it’s even possible.
If it’s not possible I’d be ok with a string that rotates from 0 degrees to 90 degrees in 9 degree segments but I’m not sure how to do that either.

I managed to figure out the code without the interpAccel.
Still not sure the fly in motion is possible if I want it to tick down 9’ each 10% of battery drain but maybe someone smarter than me can figure it out. Until then I’ll just stick with this string.