Remember the days this was so simple? Keep the ball in the middle and you were in a coordinated turn. No formulas required. I saw a skidding turn in a Bonanza out of Burbank, Ca. one day and it ended up in a fiery crash with 4 dead from 300 feet on take off with an engine malfunction. The pilot didn't keep the ball in the middle, simple as that. He rolled over when he stalled and went straight into the ground at the departure end.