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Fuel Quantity Display With A Skyview

T

todehnal

Well Known Member
Wow! A Buddy, who is also an RV-12 builder ask me a couple of questions about our fuel gauge display on the EMS page, and I realized just how little I know about it. Hopefully I know enough to ask a couple of intelligent questions. If not.....

First, Am I correct in stating that the number at the top of the "FUEL GAL" indicator on our EMS screen is a measured number, and depending on how good of a job that we did when we calibrated the gauge while adding each 2 gal. increment, this should be pretty accurate. I have always wondered why that number doesn't fluctuate in bumpy air, but my guess is that the Skyview dampens that for us.

2nd, After adding fuel, the fuel computer menu comes up with an alert that you have a "Fuel Mismatch", and asks for some input, such as: Accept, Full, Add, or Cancel. My guess is that this is a computed value, with accuracy based on the "K" factor that we loaded during setup. Now, can you access that screen without adding fuel, and if so, how?? I thought that this might be a good way of fine tuning the "K" factor.

The book makes mention that there is "fuel Remaining, Fuel Used, fuel Efficiency, Fuel at Waypoint, and Range Values" information available, but I have never seen it. Anybody know how to get to it during a flight?

Thanks for your thoughts...........Tom
 
The number above the gauge is the measured quantity in the tank. I'm not sure about the construction of the tank in the RV-12, but it probably doesn't fluctuate in bumpy air because of some dampening in the Skyview and the construction of the tank and location of the sender.

The fuel mismatch has nothing to do with the k-factor. It means that the measured quantity and the totalizer remaining fuel numbers are off by a certain amount. It's mainly a reminder to update the fuel remaining in the totalizer. I don't think there's a way to get to that without adding fuel unless the totalizer or level sender is way off on its own.

To get to the fuel computer info on screen, I hunk you just have to make the engine monitor more than it's standard 1/4th of the screen. In half screen or full screen mode it should show all the fuel computer numbers.
 
It's the sensor location

I think the float sensor in the RV-12, being somewhere near the front of the tank, doesn't have the "reach" to detect roughly four or five gallons that sit higher up in the back part of the tank.

The prompt when you refuel is the Dynon saying "Something has changed, but I can only see some of it. Did you put more in than I can sense?"
 
Dgamble said:
The prompt when you refuel is the Dynon saying "Something has changed, but I can only see some of it. Did you put more in than I can sense?"
Click to expand...

I don't think that's accurate. Once the float hits the top of the tank, it will read "##+", which means that is is near full or at least above where it can read. This will not prompt the mismatch unless the totalizer shows lower than the max read amount. It is basically saying "your two fuel systems are saying different amounts, so please update the totalizer if you care." If the max amount read is 24 gallons (in the case of an. RV-10), and you have 28 gallons in the tank and the totalizer shows 25, you won't get the mismatch. Just if the totalizer shows less than the 24 will you get it.
 
This is RV12. You calibrate it by putting the plane on blocks per the manual, and then adding in a gallon at a time (might be 2, I forget.) Shortly after you add the 14th gallon the float sender feeding the Skyview hits the top of the tank. Remember, it is a cylindrical FLOAT. When it hits the top of the tank there is still an air gap between the TOP of the float and the TOP SURFACE of the gasoline.

SO my Skyview gauge never reads more than "14+" - the plus sign appears. You can continue to add more gallons. (My Moller gauge "tops out" at a higher point than the float gauge connected to the Skyview.)

You can keep filling until you hear the gurgle in the filler tube (or stopping before that), submerging the float though it can move no further. That is 19.8 gallons or "FULL" and you can tell the Skyview that is where you are. Or some other PRESET amount more than 14. It will then use that value to keep its internal running total of fuel remaining, which will decrement based on the fuel flow integration (K-FACTOR calibration needed over time!!!) even though the Skyview gauge has not yet moved below "14+" That gauge starts reading 14, 13, 12 etc. when the float comes off hitting the top of the tank.
 
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Exactly. Two completely separate systems and it prompts you to reset the one that doesn't see the tank so you can verify the one that does as you drain the tank.
 
Thanks guys. Good explanations. Can't wait to try the EMS at half screen, and see the fuel computer info.

Tom
 
Jesse said:
The number above the gauge is the measured quantity in the tank. I'm not sure about the construction of the tank in the RV-12, but it probably doesn't fluctuate in bumpy air because of some dampening in the Skyview...
Click to expand...

...unless your SkyView has water in it, I am sure the correct term is 'damping'. I hate to be a wet blanket about this ( pun intended). :). Yes the SkyView filters the fluctuations in fuel level caused by turbulence.

Cheers,
 
My float reaches it's limit stop at 17 Gal, but it is within a few tenths of a gallon in its indicating range. I cruise at about 5100 RPM and 21 inches which consistently gives me 4.5 GPH, so I set my K-factor to read 4.5 GPH in cruise. The result is that after a 3 hour flight my totalizer is with 1 or 2 tenths of what the gas bill says to top off.
 
RFSchaller said:
My float reaches it's limit stop at 17 Gal, but it is within a few tenths of a gallon in its indicating range. I cruise at about 5100 RPM and 21 inches which consistently gives me 4.5 GPH, so I set my K-factor to read 4.5 GPH in cruise. The result is that after a 3 hour flight my totalizer is with 1 or 2 tenths of what the gas bill says to top off.
Click to expand...

Hey Rich!! Sound good, but you could save us some trial and error efforts by offering your "K" factor

Tom
 
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