While revisiting the whole sorry business of calculating trajectories with air resistance, considering the Burnswark thread, I ran into the following fairly recent paper
http://rspa.royalsocietypublishing.org/content/470/2161/20130497I didn't think articles from this site are usually freely available, but this one was available at least in U.K.
It deals with the trajectory of projectiles under quadratic drag and is fairly readable, though it does have equations in it
. There appear to be some results which are new (at least I wasn't aware of them) as far as calculating some of the optimal parameters.
I think there are at least two or three others here who might find it interesting. Apologies if it has been spotted and posted before - I havn't found any reference to it on this site, but I may have missed any such.