Sigrun I respectfully disagree. Most 46 size 2 strokes recomend an 11-6 as the starting prop or as one of the alternative props. An old rule of thumb on engine loading is go up 1 in diameter and down 1 in pitch, or vise-versa. When propping a trainer one is looking for pulling power,not speed. The larger the prop diameter the more power, more disc area. You want to accelerate out of a potential bad situation. You cannot do that with a small diameter prop. It would take too long to build up enough speed and thrust to get out of trouble.

The TT 46 pro is a strong engine it will be able to pull the bigger prop. BTW the 12.5x3.75 is a funfly prop. They are all about pulling power. They need thrust to hover and do the things they do. So this would be a great trainer prop. And that prop was designed specificly for the 40-46 size 2 strokes.

I will stand by my original statement. If someone else would like to chime in. I may have forgotten or missed something.

Respectfully- Mark Shuman

BTW I suggested a 12-5 not a 12-6. I agree a tt 46 Pro would struggle a bit with a 12-6