This could bring in many opinions. it all depends on the type of plane and flying you want to do. many different combinations. Say you have a 40 size trainer and a 46fx. 10/6 propon the average. take thatsame engine and install it in a Shrike or Q500 plane or similar with a 9/7 prop and you now go from a 50mph plane to over 100mph.

Or 40 size engine, 10/6 or 7. .60 size engine, 11/6 or 7 .90 12-137/ or 8 but this can be wrong also if your into 3d where as you wil reduce the pitch to lets say 11/4. If you have a prop jet. Pitch is important for speed. You'l find that the pitch number gets close to the dia sort of.

Many variables. A very common question on the RCU is "what's the best prop for this plane or whats the best prop for this engine?" How are we suppose to know when you didn't tell us what type of engine or plane ? They say there is no such thing as a stupid question. Yes there is and this is it.

So since your new, ask away but give us details so we can give you better answers. LIke your original question of wanting to know how props work. Sounds to me like your leading up to something. Tell us what it is and we can better help you.