I had an OS 70II 4-stroke on mine swinging a 13 x 8 APC prop and it was a blast. Sounded and looked good doing slow passes just over the runway. That big prop let me do outside loops at 1/3 throttle. Not blindingly fast but it would accelerate straight up and then keep going as far as I dared to take it. Moved quickly but not what I would consider fast. Maybe 80mph? Mine was a tail-dragger also. I had to add an ounce of lead in the tail. Lost *sob* to a mid-air. Fuselage hit a rock after a 400 ft drop with the remains of the wing (less the panel the other plane sawed through, snapping my wingbolts) fluttering cross country. Smashed the OS 70II and that ounce weight was IN the fuel tank after shredding it's way through the servo tray.

It was a darned fun plane.