Fuel Consumption Calibration

[DesertFox4]

Herman, my model 4 with the 912ULS, Ivo in-flight adjustable Patriot prop:

Wide open throttle on take off will show approx. 7.2g.p.h.
Right now my prop is "fixed" for cruise so take off rpm's are in the 5200 range but 5800 rpm's on take off yielded the same approx. fuel burn.

Cruise rpm's will range from 5200 to 5600 depending on need for speed.
Fuel burn will range from 5.5 gph to 6.1 gph at these rpm's.

[herman pahls]

Hi Desert Fox
Thanks for the fuel burn info.
Since you mentioned that you have the Patriot Ivo IFA prop, do you have any idea how it would perform in comparison to the 72" Warp drive taper tip that came on the model 4- 912S I recently acquired.
Is the Patriot the medium 3 blade?
I am considering this prop but like to know what to expect before I let go of $2700.
I have an Ivo IFA prop on my model 2 -582 and found that it allows me to have full RPM's for take off and then add more pitch to reduce fuel burn but it did not increase the cruise speed over the fixed pitch Ivo.
Herman

[DesertFox4]

The Patriot would be considered one of the "lite" 3- blade props from Ivo. The Medium is a heavier prop and much more money. I've never flown a Warp prop so can't compare for you. On my 912ULS the inflight increased cruise about 15 mph. over fixed.

[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.