So far I have seen nothing to impress me in the diesel aero engine field, there are all sorts of things that all seem to be ready to fly in the "near future".
So far the three cylinder UK developed engine has flown in a few home builts but it is far from a production engine, my personal feeling is just a way of keeping employed on the back of govenment development grants.
The American Deltahawk looks to be the best of the bunch but this too is always promising certification next year!
I am off to do the manufactures maintenance course on one of the diesels that is flying in a few weeks, may be that will change my opinion?