ORIGINAL: Campy
ORIGINAL: 747
What kind of a Prop is ideal for my rascal 40 's OSFX40 engine? Some say 11x7, is it right?
thanks
For an OS 40 you need to run a 10" prop (unless you are racing, then a 9" prop).
A 46 would use an 11" prop (except for racing or 3D).
These prop sizes are suggested to keep the engine from over revving (prop to small ) or bogging down from too much of a prop load (prop to large ).
The Rascal 40 is a "floater". Even with a low idle plan on having A LOT of runway to land.
Because the Rascal is such a floater, I recommend a Master Airscrew (the black one) 10x5 prop.
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.