The spacewalker II from Seagulls model is a really nice fier. I used it for my first low wing tail dragger about 3 months ago and never had a flight problem. I ran mine with a Magnum xl40 but it did fly sluggishly. I torque rolled it in twice after trying a Saito .72 on it and it just was way overpowerd. The model does say a .72 fourstroke can be used but I think it would be wise to go with a .46-52 two stroke for it. I did repair mine and now just stick with the Magnum engine for a sunday flier.