Originally Posted by snaquin

Look at the fin thickness of the rocket image when you prepare for launch to load a motor or view the line diagram in the 2D base view of the design.

It's your fins. I'm assuming that you wanted 0.09380 instead of your 0.9380 for the thickness of the fin material since these fins are almost an inch thick? You also selected "custom" for the fin material and that has a "zero" mass for the fins. Instead choose balsa or one of the other materials.

I changed the design to balsa and 0.09380 for the fin thickness and it flys fine.

The 3D export did look kinda cool .....

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