the 3blade I use with my OS91's is a 14/7 it works well with the engine size,I tried a 14/9 3bl and it bogged a bit, a little too much pitch I think.

the engine was fairly new when I tried it, so when I get a few more gal.of fuel through it I might see how well it works again.

the prop I am using for my OS120 is a 15/7 3bl but I will switch to a 15/6 2bl for the maiden, I am still dialing the engine it was newly rebuilt and is a bit on the rich running side,I would give the 14/7 3bl prop a try it is a good match.

good news looks like we may have found another field, our club is doing sound readings so we don't bother the neighbors but it looks promising.
there is also another club I am looking at near by but I would rather stick with the one I belong to now.