Help on how to calibrate the red cube feel flow ( dynon D10 ems)

RicoB · #1 07-15-2018, 03:43 PM

Could anyone tell me the best and more accurate way to calibrate my red cube( using a dynon D10 ems, I have already entered the k- factor of 68k, what's the best thing todo next? thanks

Mark Dickens · #2 07-15-2018, 04:14 PM

I assume the D10 will tell you how much fuel it "thinks" you have left based on the output from the red cube. If so, fill your tanks to the same place, and compare the actual amount pumped to what the D10 says you should have left. Then adjust your K factor to match the actual amount pumped.

So, let's say you fill your tanks and have 42 gals available. When you land and taxi to the pumps, the fuel computer says you have 12 gallons left. This means you burned 30 gals. You fill the tanks to the same place you initially fueled your tanks, and the pump says you bought 32.5 gals, So the K factor has to be adjusted down to 62769 (30/32.5)*68000.

Do this for a few re-fuelings and you'll have it very close. It's worked for me.

RV7 To Go · #3 07-15-2018, 04:21 PM

Fill the tanks then go fly. Fill up when you return and compare the actual amount with the Dynon. Do this for a few flights. If they are the same you are done. If not, from the manual:

"Over time, you may notice that the instrument?s computation of gallons or liters remaining (based on fuel flow) is either high or low. This is a result of many factors, including individual installation. To correct for this, follow this procedure:
Over several fill-ups keep a running total of the amount of fuel added. Keep a running total of the GALS (or LTRS) USED parameter over this same time span.
Perform the following calculation: FuelUsed(computed)/FuelUsed (actual). You should obtain a number that is FuelFilled(actual) close to 1. We?ll call this number, KFactorRatio.
Now perform this calculation: CurrentKFactor*KFactorRatio. Enter this number as your new K- Factor.
Observe the results over your next tank for accuracy. Repeat the above if necessary.
The general rule of thumb: if your GALS (or LTRS) USED reads higher than you expect, increase the K-factor; if it reads lower than you expect, decrease the K-factor."

Al

RicoB · #4 07-15-2018, 05:01 PM

Oh ok, I thought there was a step to be done of actually disconnecting the fuel line and pumping into a container or something like that. But looks like its just a Math thing.

RV7 To Go · #5 07-16-2018, 10:35 AM

Quote:

Originally Posted by RicoB

Oh ok, I thought there was a step to be done of actually disconnecting the fuel line and pumping into a container or something like that. But looks like its just a Math thing.

That would be for doing the fuel flow check to ensure adequate supply to the carb and no restrictions.

Al

Jesse · #6 07-16-2018, 04:39 PM

In my experience the setting of 68,000 almost never needs to be changed if the cube is mounted correctly. Also, check and see if the flow changes noticeably when you turn on the boost pump. If so, then the amount the totalizer says you have will be below what you do have the more you run the boost pump.

RicoB · #7 07-17-2018, 12:17 AM

Thanks guys for the info.

bruceh · #8 07-17-2018, 01:44 PM

Check the Skyview documentation. There is a formula there for determining the K-factor.
I've kept track of my actual gallons used, and the gallons used determined by the flow meter. I think mine is set to 69350 now and it is pretty close. Always within a half-gallon or less on fill up.

titanhank · #9 07-17-2018, 04:00 PM

I have done several and i do it somewhat different. Fill up both tanks to the cap. Take off on the left tank and climb to 3000 ft, set 2500rpms, switch tanks and hack a stop watch. Fly for one hour then switch tanks and go land and fill up the tanks again. Note the gallons required to fill the right tank. Then take off and climb back to 3000ft, set 2500 rpms and see what the fuel flow indication shows. Go into the setup menu and change the k-factor until the displayed fuel flow indicates the same amount that was required to fill the tank. It usually takes 1000-2000 k factor to get it perfect. You now know exactly how much fuel the engine burns at 2500rpm and 3000ft and now have the displayed fuel flow reading to match. It will be within .1 gals/hr when done and does not take multple fuel loads and note taking to figure out the perfect k factor for you installation.

BobTurner · #10 07-17-2018, 04:29 PM

Quote:

Originally Posted by titanhank

I have done several and i do it somewhat different. Fill up both tanks to the cap. Take off on the left tank and climb to 3000 ft, set 2500rpms, switch tanks and hack a stop watch. Fly for one hour then switch tanks and go land and fill up the tanks again. Note the gallons required to fill the right tank. Then take off and climb back to 3000ft, set 2500 rpms and see what the fuel flow indication shows. Go into the setup menu and change the k-factor until the displayed fuel flow indicates the same amount that was required to fill the tank. It usually takes 1000-2000 k factor to get it perfect. You now know exactly how much fuel the engine burns at 2500rpm and 3000ft and now have the displayed fuel flow reading to match. It will be within .1 gals/hr when done and does not take multple fuel loads and note taking to figure out the perfect k factor for you installation.

For this to work, you will have to lean exactly the same for the two flights at 3,000?. Also the density altitude has to stay the same for both flights.