Wouldn't a 10x5 be a bit underpropped for this engine? I run this size on my Webra .32.

I've always found that if you want to slow down a plane it's better to go with a larger diameter and smaller pitch. This would indicate that an 11x5 might be a better choice, although that's still a bit below the smallest recommended by OS for this engine. if the plane has enough ground clearance, a 12x5 or 12x4 could even be worth trying. The larger diameter seems to create a bit better flywheel effect, which can help reduce the idle RPMs.

< Message edited by piper_chuck -- 4/19/2006 2:19:22 PM >

I agree with you on the flywheel effect. It can allow you to get a lower idle. However, an 11" prop (for general flying) on a 40 has a high probability of bogging the engine down. Remember, you are talking about a SIG Rascal, not a 3D plane.