How do you tell or what is the best rpm for your engine.? I want to run a 3-blade prop on an OS 1.60 FX and am wondering what numbers I should be looking for.? I was told by the prop manufacturer that if it where him he would run a 15x8 I don't know much when it comes to props so does this sound right.?

Hello; There's a lot to consider when making that decision. Plane type expected performance, altitude, air density, and lots more. I go by what I see and hear. I try to find the most pleasing performance rather then settling for "that'll do". I don't have a 160 OS, so I can't tell what works for me. I tend to rely on big props and torquey four strokes, and fly at one third throttle and below with quick acceleration and clean mid-range performance.

I hope you enjoy the seach for the kind of performance that suits the plane, I know I would.

Hi!
The OS 1.60 will gladly swing a 18x6 or 18x6 Prop (using the standard silencer and running 5-10%nitro.
Menz makes very good wood props...and Mejzlic makes very fine hollow carbon props two blades that is! 3 -blade props are always going to perform worse than a good 2-blade prop.
I fly at sea-level and a 3-blade 15x8 is compareable in load to a 16x8 2-blade prop...and this is definitely too small prop for an OS 1.60.
Why running a 3-blad prop? To small to look scale anyway and worse performance compared with a good 2-blade prop...so I can't see the point!

Regards!
Jan K
Sweden