[hevansrv7a]

I'm just trying to get ready for flight. I noticed that with the dihedral that the float type sender may not be able to read the top .25 or .33 of the tank. I'm using GRT EIS to read the fuel level and it can be calibrated to show one-gallon increments. However, does it show full at only, about 2/3 full?
Anyone with experience, please comment. Thanks.

 

[Mel]

Yep. Not much way around that, unless you put the float in the outboard section, then you couldn't read the lower third. Better the way it is.

 

[Jamie]

Yep, Mel's right. This is why Van's analog guages do not show the full 21 gallons per tank.

 

[fodrv7]

Good Heavens

GRT suggest that you calibrate the fuel system so that when the tank is full it only read the number of gallons in the tank that are required to cause the float to touch the top of the tank.
As you have discovered this will be less than the full capacity. It will however, make the display linear for volumes less than this and thus more accurate at lower levels when you need the most accurate indications.

I have sent you a copy of an Excel spreadsheet (by email), that I wrote for the calibration procedure.
I shall post the GRT procedure later today when I retrieve it from my RV.

The procedure works as follows in principle (from memory)
1/. Set AUX SF to 100. This will effectively cause the millivolt readings to be factord by 100% and displayed as gallons. (The procedure will calculate what acutal % you will need.)
Set AUX OFF TO 0 (ZERO). This is the Offset to adjust the millivolts from your senders to read zero gallons when the tank is empty.
2/. Drain the tanks.
3/. Note the tank reading. Call this reading #A
4/. Begin filling the tank and note the number of gallons when the tank reading begins to increase. This will be the gallons remaining when the system indicates empty when the float reaches the bottom of the tank.
5/. Continue to fill the tank and note the reading when it stops reading as the float reaches the top of the tanks. Call this reading #B. Also note at this point how many gallons you have added to the tank. Call this #C
6/. Subtract #A from B#. Call this #D. This is difference in indicated volume from empty to full with a scale factor of 100.
7/. Calculate the AUX SF for you system by dividing #D by #C by the number of gallons. Call this #E
8/. This will now cause your system to reading a correct decrease in gallons as fuel is burnt but the empty value will not be zero until the AUX OFF is inserted.
9/. To calculate AUX OFF you need to factor #A by #E (AUX SF) and then multiply the answer by 2 (Two)[Don't ask me why] and subtract 1 (One) AUX OFF must be Odd.

Will send GRTs procedure later.
Pete.

 

[fodrv7]

Fuel Level Calibraion

Here's GRTs procedure.
Pete.