Hi
I just finished my PT-40 about a week ago and it really flies nice with minimal "tinkering", although I had to play with the CG a little. I first flew it with an OS LA .40 which performed pretty well, I then switched to a K&B 40 which really increased the performance. I am running a 10.5 X 7.5 Zinger wood prop. I am currently thinking about a 46, just haven,t decided which brand. I think that a .60 would be too heavy and over power the airplane, as I have one I thought about using until I weighed it, I am not sure of the weight of a .50 although,perhaps someone here has tried it. Good Luck on your first flight.
-Tom