To get enough airflow over the ailerons to stop torque roll, the prop must be bigger than 18". Mine is setup with a O.S. 160 and a mejzlik 18-8, enough power to hover but needs a bit more prop diameter to stop torkin'. BTW, you need to be quick on the sticks cause the good ol' O.S. doesnt have much power for pullout. Its a lot of fun down low.

I had a ZDZ50 on it at first but it flies MUCH better with the lighter setup.

Jamie