I am a former student pilot (with about 15 hours) who is developing an autonomous UAV.
I've read contradicting reports that lateral acceleration is and isn't an accurate indication of slip. The inclinometer ("the ball") in a full scale/manned airplane measures lateral acceleration.
I've read that gliders use a string on the canopy instead of a turn and bank indicator.
Can you have that ball dead center, and still be slipping?