Here is my basic RockSim file for this. I did end up putting an 18mm mount in the 2nd stage. I couldn't figure out how to create a funnel in RockSim but it will be right above the booster motor mounts. I'm using lexan fins and trying to figure out a way to make them removable for display. I'm also considering paper engine bells for the booster. Please take a look and give me your :2:
Looks pretty good... you can't do a funnel in rocksim... the only real way to 'account for it' is to do a "mass object" equal to it's weight and placement in the rocket, to get the weight distribution right.
What booster motors are you looking at for this??
I've made a rocket with lexan fins that basically just slides into the back of the rocket body, sorta like a removable motor mount. The fins are glued to it and the engine mount is inside it. Problem is, this sticks out the bottom of the rocket, which messes up the location of your 'motor mounts' and especially if you want to make them look like real engine bells (ALA Dr. Zooch) and have them mounted over the motor tubes.
One possibility is, you COULD make the 'bottom section' of the rocket removeable-- use a coupler and build TWO bottoms for the rocket of the proper length-- one just long enough to hold the two motor mounts and the Lexan fins, with the bottom end decorated up with the Titan II rocket nozzles and thrust structure tubes, and another bottom section strictly for display-- a coupler and piece of body tube with a simple cardboard disk in the bottom of it, with another set of nozzles and structure tubing glued to it, strictly for display-- no centering rings or motor tubes. Have the 'funnel' in the upper part of the lower stage, and friction fit the two together before launch. This is sort of what I'm thinking of doing with my Dr. Zooch Ares I since I don't want the "flame fins" stuck to the bottom of the rocket at all times... cut the tube above the fins/motor mount, use a coupler, and friction fit the main body tube to the coupler before launch, yet still be able to remove the motor mount and flame fin unit and display the model as it really would look.
It's a lot of work, but if you REALLY want a nice display model that flies, sans the lexan fins when she's sitting all pretty on the display shelf, it's about the only way I can think of on this rocket... At least your modelling skills would get a good workout!
PS... try to hide the 'seperation line' at the top edge of the roll pattern or something like that...