SmilingJack

SmilingJack

Well Known Member
Hi All,

I've read the threads on this, but haven't seen the consensus on what you all placard.

I have done the "fly until your empty trick" and when I refueled it took 21 gallons a side.

Right now I have them placarded as "21 Gallons Usable Fuel".

Anyone else out there doing something else? 20.5, 20.0...etc...

Thanks,
 
HA! I think I got my answer in one post!!! looks like you have built many airplanes...I like that experience. Thanks!
 
Useable Fuel

My RV-7 took 20.9 on the left and 20.8 on the right after running the tanks dry, but I post my useable as 39 gallons. Why? Because I'm willing to drain a tank to empty when I know I've got fuel in the other, but I'm not going to drain that last tank below what I need to ensure fuel to the engine regardless of bank angle or turbulence that might cause fuel to un-port at the tank fuel pickup point. So I use every bit of that 20.9 in the left tank for planning purposes, but I only allow myself another 18.1 gallons in the right.
My 2 cents worth.



jthocker said:
Consensus?
Yeah right!
21 gal. Sounds good to me!
Click to expand...
 
I have built two RV8's and I am not sure what good the placard is for knowing how much fuel you have. One trick I have done in the past is on fuel indication calibration. If I remember correctly I calibrated the tanks at 5 gal increments. The first calibration was done with six gallons in the tank however calibrated to five. That meant when the indication hit empty there was still one gallon in each tank. The remaining calibration was done on five gallon increments.

Pat
 
Interesting timing as I just re-calibrated my right tank this afternoon because the float indicator got stuck the first time I calibrated it (it was sitting empty for a year and a half). What I found was in a level attitude using 2 gal increments, the fuel sender hits the top of the tank at exactly 17 gals. The rest of the fuel up to 21.0 gals (4 gal) is filling the void left over due to the dihedral. This is fine with me as my fuel totalizer works to within .25 gals for a full tank of gas and I although I cannot tell how much fuel I have in each tank when they are above 17 gallons I'm confident that below 17 I've got good information down to zero.
 
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