Thanks for the info. I read of some amateurs that tried to reach the Karman line with staging using smaller motors, commercial or homemade, and it seems that the problem was with the staging. So if a team can iron out those problems with staging perhaps an all commercial motor flight to the Karman line is possible. Note also universities have more financial resources than the independent amateur so can essentially make another attempt every year.
I tried doing some tweaks on the design of the OpenRocket sim to see what altitude I could wring out of it. First, I used a slimmer sustainer motor at 75 mm, 3 inches, diameter to reduce drag. I used the M2245 motor.
Next, I gave it more realistic shapes for the booster fins. Note though the reason in the OpenRocket sim I used those exaggerated fins was I was trying to pull back the CP for stability. With the new fins, the CP is disturbingly close to the CG. I didn't get any stability warnings so I let them stay. I also increased the fin thickness to 0.1 cm. For strength of the fins at this slim thickness I chose the fin material as carbon fiber. I also chose carbon fiber for the nose cone and transition.
About the body tube, most rockets meant to get to space, orbital or suborbital, use the rocket tanks themselves as the body of the rocket. So to reduce weight further I chose "Custom" in the selection for the body material and set the density to 0.0.
The nice thing about OpenRocket is that it'll display its estimated altitude as you are making these changes. I was surprised then how much the altitude changed by changing the nose cone shape and length, and how much it was changed by the transition length. The result below:
The link to the new OpenRocket sim is here:
https://drive.google.com/file/d/1ybAB9So4x2ngVJzI72h6-CrPC4oLOc-O/view?usp=sharing
Bob Clark