for a 40 LA,, use a 10x6 master airscrew glass filled prop.. i've found it to be best for basic flying.

for a 46 FX, you have more choices based on what kind of flying you want to do
use an 11x5 master airscrew for most flying.. a 12x4 can be used for hovering..
i use a APC 12.25x3.75 on an OS 46 FX, and with a mouse can pipe, it hovers very well