Hmm, I am not sure I follow Dave’s point. My 25kg (55lbs) 1:4 Mig-15, flies very well with a JetsMunt 140 (14kg/30lbs thrust) turbine. Scale like takeoffs with «long» takeoff run, and shallow climb. Once airspeed is up and running, it is all about managing mass and throttle. Yes, speed will drop in vertical maneuvers, but so will the full size as well. The full size did not have power in reserve to maintain airspeed during verticals. I tend to plan ahead more with half power to weight ratio, which also contributes to a more scale fashioned flying style.