RE: understanding prop size on my saito powered rambler 45----help
You may want to use an APC prop as they weigh a bit more than wood. This will give more flywheel effect giving a lower, smoother idle. I used an APC13x7 for break in on my 82. Made two flights with a 12x9 yesterday, woo hoo! Mine has about a gallon through it now. Mounted sideways, the idle is incredibly smooth and low.
Get some time on it!