I think Abu has got it all worked out and anybody who would think he was overthinking the CG location has no mental grasp of the problem. The plans and one of the most successful model designers ever placed the CG in a location that contradicted the math. To do the math and ignore the contradiction without further investigation would have been foolish. In very short order he discovered where it should be and the math was correctly verified by what others had proven with identical models. That is not over thinking that is being very smart. If it is over thinking, I would do that every time given this situation. I do think he should thank the post that defined to all of us what CG is and what it does , and what a centerline is. I still wonder what the theoretical center line of the plane is since we are talking geometry and the center line is the center line. There must be a theoretical center line on the runway too. That line must run to the theoretical end of the runway.