ORIGINAL: cap_232_2000
Hey there !!! Just wondered if a APC 14x4W loads the Saito .82 enough ??? Also, I'm considering the Graupner 12.5x7, Any opinions out there ??? Thanks; (Robert)
I think a 12.5 anything is too small for that engine; it has enough torque to turn a 16 inch prop without overloading it, although you wouldn't get max rpm. A 14 or 15 would be optimum, maybe a 13-8 if you used a 3 blade. This is based on what I see guys at the field use, and my experience with my Saitos. I use a 14-6 on my .65 (Master Airscrew K-series) and it will turn just under 10K rpm. I think the smaller prop you mentioned will let the engine over-rev--remember, you'll get as much as another 500-600 rpm in the air as you will on the ground. The 4-strokes will handle loading up better than a 2-stroke, so err on the larger side. Buy a 13-8, a 14-6 and a 15-4 or 5 and see which one comes closest to what you want, performance wise. The larger diameter will provide more thrust.
Whether or not Saito recommends blended or all synthetic, it will run cleaner on all synthetic, and as for lifespan, there's a guy at the field running a 1.50 he's had for at least ten years, runs it on all synthetic, looks and runs like new, and it gets run a lot--he goes to a lot of regional fly-ins and warbird meets (it's in a BUSA DR-I)