Another thing... match the prop to the airframe.

A .46 on a Sig Kougar needs a 10X7, as the Kougar is meant to fly fast. That same .46 on a 4*40, you want a 11X4 or 12.25X3.75, as the 4* is a relatively slow flying design. (too many try to fly it too fast... not good for it.)

Most .40 size trainers... 11X4 (using a .40 or .46) Again... you are not after the high top speed from the shorter, higher pitch prop.

Low pitch and long blades means more pull at low arspeed at high throttle. Prop blades can stall just like your wing. (they are rotary wings...)