i found an old fs 40 surpass, i bought about 1990. pulled it apart, to put in new bearings and ring and cylinder, ect. i have a lanier .40 trainer (4.5-5 lb) for a niece that wants to learn to fly. is this enough engine? (i would have chosen the .52) what prop to start with? i like to use a low pitch, around 5" for good acceleration and climb. i was thinking either 11x5 or 12x5. keep it just @ 10k, like my os 70 fs? i figure if it will turn a 11x5 @ 10k+, then it should have plenty of power for this trainer w/13 ounce engine.
jon b

The O.S. FS-40 Surpass would turn an 11 x 6 APC prop above 10K RPM. You should be OK for most 40-size trainers.

I run an 11x6 APC on my OS FS-40 (non surpass) At 6,100ft it'll turn about 9k..
Your surpass should swing it just fine.

Works great on an Eagle II