Jim, a problem? Waiting on that.
I've been doing this staging stuff for a few years now, so you might think I have some clue as to what I am doing. The design always starts with a simulation, and then the simulation is a critical part of the construction and then the flight itself. Imagine my surprise when I realized that I missed the proper simulation result on this flight by a paltry 100K. How did I manage this feat? Well, in RasAero, there is more than one way to produce the shape of the rocket (with the 6" by 4" transition). One way is to build the sustainer, add a transition and then add a booster. The second is to build the sustainer, add a booster, and then specify the shape of the transition for the booster. Only the second way is correct. When you do it the first way, all of the simulations are with the transition still attached to the sustainer. As Rick Perry put it so well..., oops.
I finally figured it out when I tried to model the rocket as a three-stager, with the stabilization spool as the second stage. I'm not quite sure on the first attempt at this if the transition was associated correctly with the first stage, or if it was part of the stabilization spool, but the important thing was that it was no longer part of the sustainer. All of the sudden, things stopped making sense, and after looking at CDs, drag, frontal areas, etc., I figured it out.
I was thinking that this flight would go to something like 180K (the simulated result, with an actual altitude of 160K or so). Nice flight! The new simulation, however, is 290K. That would be good, except that I'm not sure such an altitude can get Class 3 approval, the speed is much higher (Mach 3.6, albeit at 50K), the rocket would likely be doing cartwheels for the last 100K, and it may not be physically possible this year to get to the location where we would have to go to launch to this altitude. Details.
So, we need a Plan B. Turns out I have another motor in hand that would get things back in the range of the original simulation. The problem is that the stabilities of the various configurations is kind of a fine balance, and changing the motor affects everything. I'm still looking at this, but I think one thing that will be necessary is to add some wing tips to the booster fin can. I did this on the three-stager booster last year. Adding 1" to the span takes the initial stability from 1.4 to 2.4 calibers, which I think is about right. That will force a change in the pad design, and so it goes. At least I figured it out before the Class 3 guys "brought the issue to my attention", and perhaps too late to fix.
One other minor issue is that the smaller motor is the one that I was planning to use for one final test of the stabilization spool. That's a flight that I tried a few months ago. That flight uncovered a software bug (a good thing) but fell short on other objectives. With Plan B, I don't have a motor to try it again.
I will now retreat to my cave, hoping that it will be at least another few years before I do something like this again.
Jim