I had a chance to run my ringed SF .61 with the SK .70 muffler. I always forget to bring something to the field and this time it was the stock muffler for comparisons.

Since the bearings and the ring are brand new - less than two tanks having been run - I didn't lean it out to the absolute peak.

Power Master 10% with 3% extra castor added.

APC 12x6 - 11960

APC 12x8 - 11010

I think when the ring is fully seated it will improve some more, but I'm not really disappointed. These numbers are actually a couple hundred better than my Tower .61.

I still plan to tach the stock muffler and also run these same tests on my ABC version. I also want to test some "pattern" props an APC 11x10 and 11x11.

More to come.

David

I'm adding a screenshot of Pe's spreadsheet. Either prop is producing plenty of thrust for a 7 1/2lb UFO (this isn't a 3D plane). The calculated speeds are very different, though.