Here's the output from a 'what-if' RockSim model of the Denny's rocket cup. I added a 'phantom cone' on the base to account for the base drag (per Bruce Levison's article in Apogee Newsletter #158). The CP moved from the bottom of the 'nose cone' to the indicated position at the front of the fins. Now that's a big difference. I added nose mass as noted by a TRF user. However, the indicated CG is an override approximating where I thought it would be given that nose weight (hence the 'what-if' qualifier). It will be interesting to see how that one flies. Update: I need to point out that even if the CG is as indicated, the CP may be over optimistic! I have a hard time believing the CP is that far back. Only the phantom knows.