RE: ducted fan engines
Hi,
You havent mentioned what size of DF-engine you wanna use? My rossi 105 turns a APC 10x10 about 17000rpm. The tuned length must be longer than on the fan pipe. I am using it on a 11LBS airplane 80" wingspan and geting about 120mph. On a smaller airplane it should give you at least 160mph.
Good luck, Amir