Setting Red Cube K-Factor

[74-07]

I just installed a new to me Dynon EMS D-10 and have started flying with it. On first flight, the fuel flow was wildly inaccurate so, I checked the K-factor at it had somehow gotten set to 30,000. I set it to 68,000 and it was in the ballpark. I really don't do any cross country with our 8 so I wanted some way to set the flow as accurately as possible without flying hours and hours to compare actual burn to recorded burn. I found an app called Aircraft Power which allows you to select the engine, altitude, manifold pressure and temperature. Once the parameters are set, it will tell you the exact horsepower being produced (leaned to best power or 50 degrees rich of peak). Once you have that number, you can go to the Lycoming Operators Manual and using the chart shown below, you can determine the fuel flow in pounds per hour which is easily converted to gallons per hour. So, I just selected 3,500 feet, 20 inches of MP, 2400 RPM and 41 degrees OAT and the app said I would be producing 116 horsepower on my IO-360 A series engine (angle valve). The Lycoming chart said I should be burning 10 gal/hr when producing that horsepower. I then flew the airplane, set those exact parameters and while the Dynon was close, I was able to dial it in exactly in a matter of minutes by adjusting the K-factor while in-flight. Time will tell just how close I was able to get it but it seems like an easy, quick way to set the K-Factor. I would appreciate other eyes looking over my calculations and making any suggestions.

[Bgill]

I don't have the Dynon manual but assume it is very similar to the Advanced Flight Systems that I have - clip below. I set mine using just the fuel truck fill gallons and the fuel used readings off the scree. I did it three times getting closer each time. Hope you get it worked out.



Version 15.1 AF-5000 Series Install Manual 161

Fuel Flow Calibration

The accuracy of the fuel computer is affected by the value of Counts per .01 gals (K Factor). The Counts per .01 gals (K Factor) sets the calibration of the instrument to match the flow transducer and the variations in the installation. After running a tank of fuel use the following formula to adjust the accuracy.

The Counts per .01 gals (K Factor) is adjusted from the Fuel Flow/Computer page in Instrument Calibration.

New Counts per .01 gals = (Old Counts per .01 gals) x (Disp GAL USED/PUMP GALS)

[smithflys23]

Originally Posted by 74-07

I just installed a new to me Dynon EMS D-10 and have started flying with it. On first flight, the fuel flow was wildly inaccurate so, I checked the K-factor at it had somehow gotten set to 30,000. I set it to 60,000 and it was in the ballpark. I really don't do any cross country with our 8 so I wanted some way to set the flow as accurately as possible without flying hours and hours to compare actual burn to recorded burn. I found an app called Aircraft Power which allows you to select the engine, altitude, manifold pressure and temperature. Once the parameters are set, it will tell you the exact horsepower being produced (leaned to best power or 50 degrees rich of peak). Once you have that number, you can go to the Lycoming Operators Manual and using the chart shown below, you can determine the fuel flow in pounds per hour which is easily converted to gallons per hour. So, I just selected 3,500 feet, 20 inches of MP, 2400 RPM and 41 degrees OAT and the app said I would be producing 116 horsepower on my IO-360 A series engine (angle valve). The Lycoming chart said I should be burning 10 gal/hr when producing that horsepower. I then flew the airplane, set those exact parameters and while the Dynon was close, I was able to dial it in exactly in a matter of minutes by adjusting the K-factor while in-flight. Time will tell just how close I was able to get it but it seems like an easy, quick way to set the K-Factor. I would appreciate other eyes looking over my calculations and making any suggestions.

68,000 is the general ball park setting for the EMS 220/221. Maybe that’s a good starting point?

[74-07]

Yep, that is where I started but this method looks like it can nail it with one flight. We'll see. I went back and read my first post and I had mistakenly put 60,000 when, in actuality, it was 68,000.

Thanks

[Taltruda]

Bgill has the formula.. fill the tanks, fly the plane on a regular flight, then write down what the totalizer said you burned, and what the fuel pump said you pumped in. Use the formula Byron posted and you can accurately adjust your K factor. I noticed on my plane that using the electric boost pump shows the fuel flow higher than actually using, so maybe for purposes of this calibration, minimize the time you use the fuel pump or don’t use it while doing this calibration, unless your setup is uneffected by the electric pump. The longer the flight, the better sample and accuracy, but you can even do several small flights without refueling, but there may be some inaccuracies compared to one long flight.