I agree with the smurf. OS engines are very user friendly. If you have a standard .40 size trainer, a 40 LA will be perfect. For example, last Saturday I helped a glider guy with his first powered plane. It was an H9 Solo Sport with 40 LA. He ran one tankful on the ground the night beflore we flew. We flew for 2 hours whithout one hicup. No of deadstick landings - 0. I've flown one on my club instruction plane for 4 years and its in great shape. The only time I have deadstick landings is when my gas tank gets filled up with air. Hehehe