Les,

I think you might want to hollow the nose cone. It would allow gases to get passed the end of the motor tube and “wrap back around” to get to the ducts you have to cut, assuming you are committed to ducting the ejection gases.

The other option is to not use motor ejection. This means no complicated cuts for ducting, greater strength in the structure, and more reliable timing of ejection by using electronics to blow the chute out. You are going to need a very robust joint at each junction of ducting tube to the upper and lower body tubes.

__________________
Lee Reep
NAR 55948

Projects: Semroc Saturn 1B, Ken Foss Designs Mini Satellite Interceptor
In the Paint Shop: Nothing! Too cold!
Launch-Ready: Farside-X, Maxi Honest John, Super Scamp