My spacewalker rolled to the left real bad with the Saito 72 too much torque and not enough airspeed. I did re-install the magnum 40 engine and it flew real steady but just not enough power. I am in the proccess of installing a Super tigre 51 and hope this will cure the power needs. Also with the 40 it did mush a lot and flew a little sideways like your model. I havent quite figured why yet but as soon as the weather clears it will be airborn again.