SWATHKSDU, For a trainer we did answer your question(s). Two planes from quality mfg's were recomended. If you read my post #11 you will see that I said I have an ASP .61 in my LT 40 ARF. Is a .61 overkill yes. Does it balance, yes with quite a bit of tail weight. I use mine for banners towing. A .40 to .50 is just fine for the LT 40. Watch overpowering the Telemaster, had a friend fold the wings doing tight loops (his own fault for recking it). He likes the Tele so much he bought another. A .50 to .70 size 4 stroke would work nice on these planes as well.