What 912uls power/rpm setting gets the best range?

[jiott]

Yes its not a recommended engine speed range; that's one reason its not practical. Also max L/D speed only gives max range with no headwind. A 65 mph headwind gives zero groundspeed and you would go nowhere but could try for a long time. Prop pitch will also affect the results, especially a constant speed prop. A lot of interesting testing could be done here, with different setups of props.

[3kdscf]

LOL! Very true! There was a time on my USA tour when I had to use 5300rpm to get a groundspeed of 60mph. Had I throttled back to "best range", my groundspeed would have been less than a bicycle.