What engine are you running....??

For most .46 size engines on the market, they are well within usable rpm range with a 9x7 or 9x8 2 blade prop bolted on.

For something like the TT46 or OS46FX or AX on the stock muffler, you will want to prop it to run around 15,000-16,500 ground peak rpm for best power.

3 blade will slow you down and reduce performance. But sometimes they look cool [8D]