Fuel Consumption Calibration

[kitfox2009]

My IVO ultralight IFA prop also increased cruise by about 15 mph over the GSC. I have a 912UL on a Vixen.
The big advantage though is being able to get full RPM on take off!
I have found that the very small planetary pinion on the Ultralight model has a limited lifetime though. Keep a spare.
Cheers
Don

[HighWing]

One more thought on fuel burn. The prop discussion is very informative, but there is one more factor to consider.

When we were doing our annual flight of six to the Idaho back country we always flew at the speed of the slowest airplane. On our first trip, we stopped at Winnemucca, Nevada after the first three hour leg for fuel. Everyone stood around each fueling airplane watching the pump tick away. I don't recall all of the numbers, but the largest fuel burn was 12.6 gallons. The lowest load was 7.2 gallons a Model IV with every fairing option who had actually flown an additional 30 minutes to hook up with the flight. The burn rates were at almost exactly the same airspeeds.

Granted, the fuel burn as it relates to RPM should be pretty much the same . In our flight, the least aerodynamically clean airplane was at maximum cruise throttle to maximize speed, whereas the cleanest airplane (7.2 gallons per three hours) averaged about 4700 RPM in cruise.