I'm building a clone of the Semroc Ranger using a Big Bertha as a starting point. I created the rocket in open rocket but I'm having an issue with doing the flight simulations. I created an inner tube, marked it as a motor tube then set the cluster to 3. The tube sizes are all correct and it looks good, shows three motor tubes. When I go to run the simulation it puts only 1 motor in the center of the cluster. Does anyone know of a way around this or by chance have a sim file for the Ranger?