Multiple interesting facts:
A. Several folks chimed in with smooth-running Legacy IO-550s with stock 3-blade. I think we have solid indications that it's not just the 550; and that it's not just the 550 plus the Hartzell scimitar. To Clark Baker: Yes, I'm very clear that there's no interference between cowl and prop on my airplane -- but thanks for checking.
B. Dennis Johnson found a Hartzell page, and Bob Rickard found a Lancair page, that both characterize their propellers as different diameters than Hartzell's blade model number indicates. According to Hartzell's application guide: -- An F7693DF blade (Rickard) is 76 inches (F76; and no dash number). -- An F7391D-3 (stock Legacy) is 70 inches (F73; minus 3 inches for the -3) Not sure how much difference that makes; but it's good to start with consistent data.
On Jul 25, 2013, at 7:46 PM, Dennis Johnson wrote: I have a smooth running Legacy RG IO-550 with a three blade Hartzell scimitar prop, HC-J3YF-1RF/F7391D-3/SM7. According to Hartzell's website, this is the recommended three blade scimitar prop for the Legacy RG with IO-550 engine. It is a 72" diameter prop, not the 78" prop mentioned in Bob R's posting. I thought all the scimitar props on Legacys were the same as mine. I consider mine to be "smooth," but that is a terribly subjective concept. However, I can say for sure that I do not feel vibration in the stick and don't see any aileron vibration or wing tip vibration. Another Legacy builder and pilot commented on how smooth mine is, but maybe he was just being polite. Unless there is a way to quantify "vibration" and "smoothness," I don't see how we can accurately communicate about this. One person's rough could be another person's smooth. Maybe if someone had a video of stick shake or aileron shake? A glass of water sitting on the glare shield? Dennis Legacy 625 hours
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