how to choose prop size and type of prop for a new plane

[KyleStamm]

I am learning to fly on an Avistar by great planes it is an awesome trainer to learn to fly on. I want to know how to choose a 3 bladed prop that will meet or exceed the 12X5 2 bladed prop that came with the plane. I am not looking for complex math to do. Just an answer to my question. Oh and by the way the plane has an OS .46 glow engine on it right now. Thanks

[F22trainer]

You will have better speed with the 2 blade, and your reduced power / idle glide will be reduced dramatically. You can look forward to a good climb, but get ready for the extra torque effect which will require right rudder. I don’t think you will like it but you could safely try a 9 x 6, maybe a 10. They are more for Scale appearance.

[fhhuber]

More blades is less efficient.

Basic rule of thumb for changing from 2 blade to 3 blade is to reduce pitch or diameter by 1 when adding the 3rd blade, so you would change from 12X5 2 blade to 11X5 3 blade or 12X4 3 blade.
Expect reduced thrust with the lower diameter or reduced speed with the lower pitch.

Because of the rule of thumb being an estimate, results will vary due to changing blade shape and what rpm you have been running.

12X5 2 blade is a heavy prop load for a .46. You should see improvement by changing to a 11X5 2 blade.

[KyleStamm]

Thank you very much I have some thinking to do.