Fuel Calibration question

[Spcialeffects]

Hey guy's, sorry for the very, very later reply but the results are in. Now my aircraft is a mono so the first thing i did was to raise the tail to put the aircraft in the flying attitude. Next i filled the aircraft up until i could see the fuel in the cobra through the filler cap. I then drained all the fuel in the MAIN tank and got out 60 litres. I then drain the RESERVE and got 11 litres. (71 Litres total)
   Now when i was building my aircraft i left fuel in the tank before bonding it into the cockpit module (for about 6 months) and it bulged/expanded quite a bit. I then made a seat for it to sit on and bonded that to the cockpit module so that when the tank shrunk back to its normal size it was actually loose in position. Anyway this is why over time you can get more fuel in then when you originally built it.
   Back to the calibration - I have 2 sensors but have decided to just use the one like everyone else. First i poured in the 11 litres to fill the RESERVE side of the tank. Next i divided the 60 litres by 12 and got 5. So filled up the aircraft with 5 litres at a time and then pressed the ADD button and FULL TANK on the 12th fill up. When i looked at the fuel widget on the dynon it read 54+. I then drained out 20 litres, as i didn't want to leave it with all that fuel in it and the dynon read 40 litres.......SPOT ON!!
   Also the only values, while filling up, which were the same were the first and last which makes sense as the sender doesn't go all the way to the bottom of the tank and the float was all the way at the top while still pouring in the last 10 litres.

Frank

 

[BobD]

Hi Frank,
Glad to hear you have had better results with the 18 point probe than I did with the 11 point probe, maybe is't time I bought one.
Having done lots of flying this last summer, and diligently recording the actual fuel usage against the Skyview calculated usage, I have established an accurate setting for K-Value on the Red Cube, which gives me an accurate reading on the Fuel Remaining read-out from the Fuel Computer part of Skyview. To do this, you have to change the K-Value from the following Menu. SETUP MENU >HARDWARE CALIBRATION > EMS CALIBRATION > FUEL FLOW CALIBRATION > PUL/GAL(C37 P14) > (value). The default value is 68000, and I was surprised that I had to change it by such a large margin up to 120000. However, it is giving me the most reliable value for the fuel flow, and especially the fuel remaining figure. The Fuel Tank Quantity is still way off and unusable.
I have attached the spreadsheet I created to come up with the figure used. The actual figure I use is 120000 (not the 134448 average calculated), so it gives me a good safety margin, and I use 15 Ltrs/Hr usage for my pre-flight calculations, even though I am usually getting better economy than this.

 

[Spcialeffects]

Thanks very much for the spread sheet Bob. I hope to do a lot of flying this year and will start off with your value and see what results I get. I have a 914 in my aircraft and so will be interesting to see the results.

Frank