No worries, I am new also. Only a week in :P Yeah I was thinking integrated forces but ignored it because it controlled it at least :P.
Yes, $' . ' denotes the scripts parent or "self". The $ is an easy way to get nodes inside the scripts parent, so just the . basically means parent :).
BUT..>BUT> I will experiment with using "self" instead also to test just in case! TY for the help Ill try these out now and let you all know if that helps :) TY MUCH!
UPDATE: So, since I cant use integrated physics in the _input section, I assigned a variable for mouse detection and said if that variable is true, then in the integrated_forces section I added add_force for the variable's relative movement. It makes it smooth :) I just need to figure out how to convert it to correct movements and 3D, since its mouse coordinates :) Thank you for the help so far :)
UPDATE FINAL: Fixed :) I created variables for both relative mouseX and mouseY coordinates based on the last position so it resets everytime I stop moving the mouse. Then, I applied variables in the integrated_forces states to get the local origin of the main body and then when the mouse moves, the torque is added as a differential of each axis to the proper body rotation and BOOM :) Flies like a smooth charm now. I flew great before but now its not choppy so SOLVED! Here is a video of the new physics of the heli :)
HELICOPTER PHYSICS IN GODOT!