beeblebrox
8 C6-0, 12 D11-9, 20 D20-0, 20 E5-0, 3 Cinerocs
All that stuff...I have been pretty good at eyeballing a rocket and figuring out if it will fly....It isn't that complicated especially for a standard fins, one tube, and a nosecone. When you get into strange shapes and designs like multiple tube fins or uber cool looking spaceships...they can be difficult or impossible to model with openrocket. (Example, openrocket does not even accurately allow you to place fins on a boattail...)