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Fuel level markings inside the tank?

claycookiemonster

claycookiemonster

Well Known Member
I know the EFIS fuel monitoring systems and float/capacitative systems do a great job of keeping track of fuel usage, but for a stone simple system, I was wondering about simply putting marks on the ribs within the fuel tanks.

First question: are the ribs really easily visible from the tank opening with the cap off? Visible enough so that if there were marks on them, you could easily confirm the fuel level there? To be easily seen, should the marks be directly (vertically) below the opening or aft a bit?

Second question: does anyone have a calibrated broom handle or yardstick with measurements up from the bottom of the tank (or down from the cap) that equate to gallons of fuel in the tank?

If I'm going to do this, and I'm thinking of lines made of proseal, I might's well have gallon quantities to aim for.
 
Probably could be done and would certainly give you a good visual indication but I've found that once you get accustomed to fueling the RV tanks that simply eyeballing the fuel level against the rib, you can get a good enough idea about how far from the bottom or top equals how many gallons are in there.
 
stairstep fuel gage...

Electric fuel gages are nice, but for something as mission critical as fuel quantity, a direct read backup is nice. There are many ways to confuse elecrtonic gages. With my -7A parked on level apron, six gallons is at the bottom of the outer rib. This I typically check before fueling, since it is most important to know that the gage is accurate at the lower end. Less than four gallons in the tank won't show in the outer bay. I did contemplate putting a stair-stepped plate near the outboard rib as a visual gage. A little tab is folded over 90 degrees on each step, with a number stamped into it. Easy to see which tabs are above and below the fuel level. Nothing messy to make the cockpit smell like fuel. Be careful that the fuel nozzle cannot damage the stairstep gage... If I were to do it again, I'd probably work something up. Maybe next project.
-Roger
 
I have a paint mixing stick that is notched at some levels I calibrated to use as a dip stick. I stamped the gallon markings into the wood next to the notches and painted it black so the fuel shows up better. Cheap, light and won't dent if I drop it. Works great.
 
old school wooden fuel stick is nearly foolproof ;)

I have a wooden fuel stick with left tank lines on one end and right side marks on the other. Just use permanent marker or ink to mark the lines.. you don't need proseal marked on the stick and wouldn't want to risk anything coming loose in the tank. It's quick, easy and part of every preflight (unless the fuel is nearly topped off.)
 
Proseal as rib marker

I plan on just masking off the the ribs inboard from the filler cap so that horizontal lines of unmasked rib will be visible from the outside, then applying proseal to those areas, removing the mask, and presto: Proseal marks on the ribs. Unless there are some reliable levels others can provide, I'll just put lines at 1/4, 1/2, 5/8, 3/4 and 7/8 of the total depth of the tank at the cap. Nothing to come loose and eventually I'll learn what those lines mean. Obviously the aft baffle hasn't been installed on the tanks yet.
 
I attached an aluminum strip to the gas cap. Marked with drilled holes for 6 gallons on up. Works good, Got the idea from this forum a few years ago.
 
I made a tab...

Like Bill R. suggested, ala a Cherokee fuel tank. I made the tab about 3 1/2" long with the last 1/4" bent 90*. I then drilled a small hole in the middle. I now have four levels of known fuel quantity in each tank; base of the tank, bottom of the tab, the hole in the tab, and full. In addition, my Dynon fuel totalizer works very well.

Here's are a few links to my build log with photos: http://mykitlog.com/users/display_log.php?user=ggbaker&project=427&category=2487&log=113828&row=278 and http://mykitlog.com/users/display_log.php?user=ggbaker&project=427&category=2487&log=113830&row=276
 
rib, or spar?

Is it just me...or are tanks of the -8 different...but I can see much more of the back of the tank ( spar side) than putting my nose right on the wing to see the first rib....perhaps you mean the outboard end of the tank.
in any case, I agree that a strip of metal rivetted in there would be my choice, and save carrying my dipstick around in my back pocket during walkaround.
I find equally important, writing down the quantity immediately after viewing or dipping.
I can't count how many times I've gone back to the cockpit, and paused just before entering it in my fuel timer...."hmmm, was that 13 on the right, and 17 on the left??"...wait, MY left, or......starboard...dangit!!!!
 
Fuel Hawk diptube...

I find a lot of these about 50 feet down the runway. Guys will preflight, set the tube someplace to dry off, forget about it, and then take off.
IMHO, a superior solution doesn't require use of a loose piece like a dipstick or diptube.
- Roger
 
Tank rib markings

When I built my tanks I marked the outside rib with one inch spacing . Still building. Will calibrate later
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William
RV8A for sale
RV7 finishing
 
I also use the Fuel Hawk dipstick and it works fine. But, then again, I also use a checklist on pre-flight that includes accounting for any tool I use during it.
 
YES!

Kitfoxbill, you've got it! That's exactly what I'm thinking of.

Seriously, all you guys who use some sort of dip stick to check your quantity: could you send in your "inches from bottom" to gallons conversion? I know you've got it written on that broomstick handle. I also know it varies between types and kits, so maybe you really can't do better than generic markings which get calibrated later.
 
RV-6A on level surface:
gal: in (from bottom)
5 : 0.89
8 : 1.98
10: 2.71
13: 3.79
16: 4.88

For reference only! Your tanks may be different! Don't run out of fuel! Not to be used for navigation! etc.,etc.,etc.!
 
flyboy1963 said:
Is it just me...or are tanks of the -8 different...
Click to expand...

The -7 and -8 use the same tanks. All of the rest are different capacities...

I simply used a 'dot' of proseal inside of the tank through the neck at specific fuel levels. (i.e. 5 gal, 10 gal, etc) Simple and easy to do. Of course you will need to read that fuel level with the aircraft parked on level ground which may not always be possible...
 
dougmattson said:
I attached an aluminum strip to the gas cap. Marked with drilled holes for 6 gallons on up. Works good, Got the idea from this forum a few years ago.
Click to expand...

Same thing for me, works great, always right there at the fuel tank when I need it.
 
Here's what I did. My plane isn't flying yet, so I don't have any feedback on this approach.

gallery_11575_1360_326634.jpg
 
Fuel tank step ladder / fuel level indicator

I've posted this before but couldn't find the original thread... I made a stair-step-ladder out of aluminum and attached it to the fuel filler (rivets) and bottom of the tank (proseal). It's labeled at the top starting with A to G. The step prosealed so the bottom of the tank is labeled "Need Gas" :) No special sizing when I made it (other than symetrical steps), and it turned out to be about 2 gallons/step. At a glance, I know about how much fuel I have to within 2 gallons. The is no-issue (splashing) when filling the tanks. Rosie

fuel_tank_step_ladder.jpg


Here's the left tank filler neck, leading edge of the wing is towards the bottom of the picture;

fuel_tank_step_ladder_01.jpg
 
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