The main point is to get the best performance that you can while watching engine RPM and your good old ground clearance. If you can get something to work for you at a lower RPM, then you are better off using that prop. You will increase the life of your engine and keep the noise down at the same time.

I would call that a good trade-off. Good performance with lower RPM and low noise.

I have the OS .75 AX on a Goldberg Skylark 70 and I am using a 14-6 prop and getting outstanding performance with reasonable noise levels. In fact, our club has been doing a noise check on our models and my Skylark 70 - OS 75 AX - 14-5 prop are below the maximum noise limits that are recommended by the AMA.

CGr.