RE: DD - what engine
If you are going to use a Jett engine, consider the Jett FIRE 60LX, it is the same weight as the Jett 50 and will turn the prop faster. Mine turns an APC 8.8X9 at 19,600 rpm and the APC 8.8X8.5 over 20,000. After flying my DD with this engine all of my other planes seem to be flying in slow motion. Call Jett and talk to Dubb he will give you some good information on engine choices.