I am running a 3 bladed prop on a magnum 70 FS and was thinking that if I went to a 2 bladed prop I would get a little bit better performance. I have that engine on my Daco Red. Any suggestions as to what size prop would be best?
Thanks

Gene

Go down one in pitch and go up one is diameter......at least that is the general rule.

My 70s work well with 13x6.

on a racer he may want to drop to 12x8

I run 13 x 7 on my OS 70 FSII.

Thanks for the help. One more question. If it says break in an .52fs with a 12x5 would it hurt anything by using a 12x6?
Thanks.

Gene

Noope....just don't break it in too long - they break in much better in the air after a couple tanks of fuel.

I prefer to use a light prop load for break-in as apparently your manufacturer has. This regardless of the way you choose to beak-in whether it be on a stand, the airplane or perhaps a combination of the two. While no you may not "hurt" anything using the heavier prop load you just may find yourself with a better engine by using the recommended break-in prop.

You never said what airplane but now is the time to start building your "propwall" Every flyer of fixed wing aircraft needs a prop selection and besides whatever that ship is you may just find out the 12x5 could work better, only you will be able to ultimately answer that by actual trial.

John