Fuel flow test

[Scott Todd]

The most important thing to do is a proper fuel flow test. I'm surprised how many home builders don't.

[Bryan Cotton]

Here is the post from my Cotton Waiex 191 thread.

Good day today. We completed our fuel flow test.


Our 3 point attitude was about 8.4 degrees. On the hill we were about 16.5 degrees.

From 4 to 3 gallons 24.3 GPH average
From 3 to 2 gallons 18.7 GPH average
From 2 to 1 gallon 14.2 GPH average
From 1 to empty 11.4 GPH average

[builderflyer]

Bryan, others, since in our case a nearby hillside wasn't available, it was necessary to dig a hole to drop the tail into in order to achieve the desired climb attitude for the fuel flow test (yes, I know that we could have raised the front of the airplane rather than lower the rear of the airplane.........actually we did both to achieve the desired climb attitude). Because of this "inconvenience", we also ran the fuel flow tests in the 3 point attitude to establish a comparison with the "climb attitude" tests. These secondary test results have proved to be beneficial to have on hand when future alterations to the fuel system were accomplished.........a new fuel flow test could then be done with the airplane sitting on level ground and the results could be compared with the original values for the 3 point attitude very quickly.

Art,,,,,,,,,,,,,,,,,,Sonex taildragger #95,,,,,,,,,,,,,,,,,,,,Jabiru 3300 #261

[tps8903]

The most important thing to do is a proper fuel flow test. I'm surprised how many home builders don't.

I agree, I conducted an initial fuel flow test on my Turbo powered legacy Sonex. It had a Usher Gascolator and a red cube installed at the time. Below 2 Gallons it just failed the test. So I removed the gascolator for a large inline filter exiting the tank and ditched the Red Cube. I went from 11gph to 21gph for the test. The Red Cube definitely restricts flow.

After searching, I found other builders had similar results. I realize folks are having success with the Red Cube, however I would exercise caution.

viewtopic.php?f=21&t=1559&p=11123&hilit=Fuel+consumption+turbo+gph#p11123

[Jerry09w]

If you look at the manufacturers specifications, the Red cube is only for engines with a fuel pump. The gold cube is for gravity feed systems. As I recall it has about 1/10th of the pressure drop.