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

[3kdscf]

OK, my first data! 20.75mpg

I know best glide is 65mph so that is the most effeciently aerodynamically but the engine is more effecient at higher power settings than that so my first guess was that the best range would be at 80mph indicated.

I had a 3-6mph headwind during this test:

Altitude: 2500 feet
Indicated airspeed: 80mph
Groundspeed: 84mph
RPM: 4600
Distance: 166 miles
Fuel: 8.0 gallons

Note that during this 166 miles I landed twice. Had I flown the 166 miles nonstop without the headwind, I probably could have gotten 22mpg or so. My next attempt will be at 75mph.

[Delta Whisky]

Not exactly the answer to your question but very appropriate to the issue: https://www.aopa.org/news-and-media/...ue-cheap-speed

There's more to the Carson speed then covered in the article; recommend you download a copy of his paper for all the details.

[3kdscf]

Not exactly the answer to your question but very appropriate to the issue: https://www.aopa.org/news-and-media/...ue-cheap-speed

There's more to the Carson speed then covered in the article; recommend you download a copy of his paper for all the details.

THAT is the article I was looking for, THANK YOU!!!!


In summary:
"A typical piston airplane’s maximum-range speed is about 10 percent above L/D max"

"Simply multiply your airplane’s best-glide speed by 1.316—or add 32 percent—and that’s the Carson number. "


This means for the Kitfox with its best glide speed of 65mph :
best range: 72mph ( 65*1.1)
Carson speed (best value): 85mph (65*1.316)


I now have the next two airspeeds to measure fuel economy!