Hei Ferram, Thanks a lot for this mod. I have a question concerning the drag calculation for a rocket. I try to make a numerical model for the ascent trajectory and would need some info for that. There was once a post in this thread where the formulas were described but that post is gone since the backup. If I'm not mistaken the Drag force is calculated as follows: D = 0.5*rho*S*C_d*v^2. The drag coefficient I will try to estimate from a test launch and the info given by the FERRAM flight info window. My question is about S. Where do you get the cross-section area from? Any help on that would be highly appreciated