Okay I was thinking more about that coordinate system you introduced, ROTATION. In the 2nd picture i attached, with the definition of force and angles. I could probably use the ROTATION coordinate system, but to "simplify" it more, i could rotate one of the axis to the alpha angle so that i only need to calculate two force components from the sling force. A vertical force and horisontal force.. I dont know if you've done these kind of computations before but do you think its a important factor on where the lifting tool touches the hole ? Because depending on the sling angle phi the tool will be in contact with higher or lower part of the hole. ?
Regards Robin