I have been reading up on what I will need to do for setting up my APM. One of the confusing aspects was the PID settings. I have con across these before from using my 3D printer but really had very little idea as to what they really do and how they effect the machine.
I found this site: http://www.flitetest.com/articles/p-i-and-sometimes-d-gains-in-a-nutshell which has a great guide as to how the PID setting work on a rotary wing machine. Thought I would pop it up here for others who may not have seen it