The last plane I flew with the 18x6W was a H9 120 size Ultra stick. It had plenty of airspeed for me. Biggest advantages of the 18x6W is the vertical pulling power and down line breaking. This is a wide blade prop (Fun Fly). ON my ST 2300 at 8700 rpm it would hover my Ultra Stick ( 14.5 lbs wet). And pulling the throttle back to idle is like putting on the air brakes.