Well I just got the Cox Tailwind trainer 40. Workmanship to my eyes(Beginner's) looks pretty good. I got this ARF cause there is a good chance I will have a few mishaps and the cost of the plane will soften these mishaps. The box states 5.5 lbs flying weight and indicates a engine from .40 to .51. But the plane looks pretty large and I think a .40 engine may not be the engine of choice.
So I am thinking of a .61 engine rather than the .51 engine. I need comments on my choice of engine and suggestions of some engines to consider.....one that will have the least noise as possible.

Thank You, Lakeviewjim

Jim, the plane might be big, but it's light. Trainers are designed to have a lot of lift (the wing probably looks very big to you). With all of that lift, it takes less power for the plane to fly. A good, ball-bearing .46-.52 should be more than enough power for the plane. A .61 will be considerably heavier, which might give you some balancing issues, and raise the overall weight of the plane, which is something you want to try to avoid in a trainer. Sometimes over-powering a plane is definitely a good idea, but I have yet to see a .40-sized trainer that needed to be overpowered.

Agree with glowplug. A plainbearing .40/46 will be acceptable, a good BB 40 will be more than acceptable, & a good BB .46 or 51 will be much more than necessary for training. A .61 will be too much -- 60 size engines are notably larger & heavier than 46's.

Another vote for a BB46

The wingloading of your trainer is on 19 oz./sq. ft. That is light. It will do nicely with a BB46. I would recommend a Thunder Tiger Pro46. It is an excellent engine and a great value.

Thanks a million, I will go with the TT pro 46, All of you have a great day making lots of money...

Jim