I have been messing with my GP ultimate. I have moved the CG back to improve its snapping / tumbling characteristics. It is back far enough that the model is unstable in pitch, not a lot but others that have flown it have noticed it. This makes it tumble really well but.. I have tried knife edge and it has horrible coupling. I was going to mix it out but would have required 3/4 of the available up travel of elevator on high rate to stop it. I did not want to mix this much in.
This got me thinking what effect the CG had on knife edge. So whats the answer?