3 blade props

[cody42001]

How can I know what size 3 blade prop will replace my
12x8 2 blade prop? [Electric is my choice!]
Don Jeune

[steve lewin]

Simple answer - try 11 x 8 or maybe 11 x7 if you can find them.

For the details read http://www.mh-aerotools.de/airfoils/propuls2.htm

HTH - Steve

[JMP_blackfoot]

With similar blade shape :
- Do not change the pitch
- If changing from 2 blade to 1 blade, increase diameter 15%
- If changing from 2 blade to 3 blade, reduce diameter 8%

The diameter should change as the 1/5th power of the blade number.

Your example : 12 - 8% = 11