Seconded. Principia is amazing; first thing I did after installing it was set up a Kerbin-Mun L4 orbit.
Another thing I found, due to the full n-body integration Principia adds, is that I was able to correctly guess which side of Kerbin the Mun was on due to tiny perturbations in my craft's equatorial orbit.
Another thing I found, due to the full n-body integration Principia adds, is that I was able to correctly guess which side of Kerbin the Mun was on due to tiny perturbations in my craft's equatorial orbit.