There is a high-quality mod which adds n-body gravity: https://github.com/mockingbirdnest/Principia https://github.com/mockingbirdnest/Principia It will also a

There is a high-quality mod which adds n-body gravity: https://github.com/mockingbirdnest/Principia https://github.com/mockingbirdnest/Principia It will also add orbital perturbations/frozen orbits if you use Real Solar System: https://github.com/mockingbirdnest/Principia/blob/master/astronomy/sol_gravity_model.cfg https://github.com/mockingbirdnest/Principia/blob/master/ast... That said, to my knowledge there isn't yet a mod that adds high-altitude drag.