Fuel flow test

[danerazz]

Just curious, what angle of pitch is everyone using as their "estimated maximum climb pitch angle" when they check their fuel flow? My best guess is about 20 degrees based on a SWAG.

[helmetfire]

I would think that would be too much. Think about how many degrees nose up your attitude indicator shows in a climb. I would imagine no more than ten degrees for a normal climb. Haven't really paid attention to that gauge for awhile though

[danerazz]

Just thinking of the initial climb after a last minute go-around/clearing trees on a short field takeoff. Looking for the maximum angle.

[helmetfire]

Sorry, I missed the "maximum" part. 20degrees might be right then. Although im a little confused why you would do a test in this configuration

Is there a required fuel flow check in different attitudes?? A test needed for "certification"?? New to the experimental side of things.

[danerazz]

Not much is "required," but it is recommended that a fuel flow test is completed at the assumed maximum climb pitch attitude +5 degrees to ensure 150% max power fuel flow for gravity systems and (I think) 125% for "boosted" non-gravity systems.

There is an AC that discusses these recommendations, and they are just recommendations but a DAR may ask you about this.

The idea is if you do a full-rich full-power sea level go around, you will have full power available.

[danerazz]

It is ac 90-89a titled "AMATEUR-BUILT AIRCRAFT AND ULTRALIGHT FLIGHT TESTING HANDBOOK"

http://www.faa.gov/library/manuals/airc ... 90-89a.pdf

Lots of really good info in it.

[helmetfire]

It is ac 90-89a titled "AMATEUR-BUILT AIRCRAFT AND ULTRALIGHT FLIGHT TESTING HANDBOOK"

http://www.faa.gov/library/manuals/airc ... 90-89a.pdf

Lots of really good info in it.

Great, I'll check it out, thanks!!

[danerazz]

Just to bring this back to the top, all the guys flying with EFIS, what pitch angle are you seeing at maximum climb?

[FredHoffman]

Steady state over 20 degrees pitch is obtainable.

[danerazz]

Damn, that is higher than expected. That makes it a recommended 25 deg angle to test flow. Need to find a hill.

Thanks for the pic! And 24 MPH!

[danerazz]

Fuel flow test today.

18.75 GPH with electric pump measured at the carb (disconnected inlet) and pumping through the mechanical pump.

Had the tail down a hill, in a hole, and mains on ramps. 25 degrees nose up.

[EchoWhiskey]

Dane what was is calculated 125 or 150% fuel requirement?

[danerazz]

Sorry, didn’t see your question.

I have an electric and engine driven pumps, so I am going with the 125% figure, there really isn’t a good way to test gravity only anyway, unless I physically eliminated the engine driven pump.

Using the FAA .55lbs per horsepower and a rated 110hp, I come up with an estimated 10gph WOT. So 12.5gph with pumps, or 15gph gravity for the minimum test flow at 125% and 150% respectively.

The .55 figure sounds a bit conservative, but I guess better more fuel flow available than too little.

[BucF16]

Dane, that "Back Yard" is beautiful! Maine sure is nice in the summer.....


Cheer
Bruce

[danerazz]

Both weeks of it!

You can’t see it, but our property ends about 350’ down hill behind the plane and at the bank of the Penobscot River.