Hello all. I'm modelling several new aircraft as mods for a flight sim. These mods are all WW2 birds like the Kittyhawk and Ta152. The generic computer models have a series of terms I am unsure about. So far I've been using existing aircraft modelling as a guideline but as we are expanding our mods to include types which are distinctly different (a short tailed Kittyhawk and a long tailed one for example, which should have distinctive handling differences)... critical Cy Cy max Vy factor Cx curvature Cx straightness K max Spin Cx loss Spin Cy loss As aeronautical engineers were involved in development of the game-engine it naturally follows some or all of these terms might be generic engineering terms for the field. Any light which could be shed on them, or opinions as to what they might represent would be most welcomed. I'm more of an engines man myself (the engine models I had no problem figuring out). edit, got more questions now. What is moment arm?