Regarding the use of diesel engines in aircraft; to my knowlidge there are non. The basic reasons are that diesel fuel freezes and goes to candle wax at about freezing point of water, and of course, power to weight ratio of diesel engines is poor compared to petrol engines. I support MAF in some ways, and would like to be of some assistance to them, but I am committed to staying in thr UK for a few years yet (wife, kids in school etc.) Best of luck in your studies, and if you come across a diesel engined aircraft, please let me know.
JFD