The CG changes with engine size, the book CG would be okay with an OS 40FX or OS 46AX engine. I recommend Flaparons if you have a computer radio. I built two of these and they are super flyers. Leave the struts off as they are for show only. You will find the Decathelon very aerobatic with a strong engine, real big only creates the CG problem. Nothing bigger than a OS 40FX is really needed as it should fly vertical up out of sight with that engine. Happy Landings,

Sea Bird