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Anyone know the best fuel measuring tool?

I'm looking for an accurate fuel measuring tool for pre-flight. Any suggestions on tank dip tools? I have a 7A.
Thanks!
Andy.
 
I made my own when I first filled the tanks.

Then I made a duplicate to keep as a spare.

You could drain a tank and make your own as you refill it----easy to do.

I used a bamboo paint stir stick, marked it with a permanent Sharpie every 5 gal. The Sharpie turns out not to very permanent so I made notches along one edge too. Redo the Sharpie marks as needed using the notches as a guide.
 
Wooden stick

This may seem low tech but a wooden stick that has been calibrated by marking increments as the tank is filled e.g. 5 gallons at a time is as accurate as anything.
 
I used a hollow plexi glass tube. Ground calibration marks on it. Put in the tank, put your finger over the end and pull the tube out of the tank. Can be read in any lighting conditions and doesn't dry out in hot winds.
 
I used a hollow plexi glass tube. Ground calibration marks on it. Put in the tank, put your finger over the end and pull the tube out of the tank. Can be read in any lighting conditions and doesn't dry out in hot winds.

We had these for our 172-----worked well.
 
I flew until I had an empty tank. Then calibrated a paint stick 2 gallons at a time. Works great! My sharpie seems to be holding up great!
 
gas gauge

I had to laugh.
I also have a bamboo stick. Same thing, sharpie marks to see the level if I need.
I have a tank in my truck to fill my plane with so usually fill to top.
Art
 
I use some clear fuel tubing zip-tied to a little sheet of aluminum so that I can put it in the tank, finger over the end, and pull it up leaving the tank depth in the column. I "calibrated" it with a magic marker and a little nipper when I calibrating the fuel gauges on a new EFIS. I had drained all the gas and got an empty weight for a new w/b, then refiilled both tanks two gallons at a time and entered those readings into the new EFIS. At the same time, I was careful to mark the new fuel "gauge" with the magic marker.
 
I have an ordinary dowel, marked at 2 gallon increments with notches. I used pencil to identify those. The only downside is that it does soak up a bit of fuel, so it needs to dry out befor I can put it back in the plane.

Hint - make the dipstick long enough that it can't possibly fall into the tank.

Dave
 
It depends on how accurate you want the device.

I wanted to be sure mine was precise and tested the tube, stick methods in a beaker. The wicking did not give an accurate reading. Somewhere I saw a strip of aluminum with holes so that was tested. It worked consistently. I

The alodined strip is .32" wide, .025 thickness and 1/16" holes drilled for each 1/2 gallon. Measured on the ramp, the fuel remaining is accurate to the 1/2 gallon if both sides are added together. Tilting is a variable but the total balances side to side. Having done the calibration several times - I think the good result was luck and have more confidence in it than a stick YMMV.

Over 20 gal the scale is very non linear i.e. worthless, and the bottom of the tank is about 6 gal. (bad memory).

Mine is a tail dragger, but you are welcome to my data. It had to be calibrated for ground and flight (3 deg).

View attachment Fuel Stick.pdf
 
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The only downside is that it does soak up a bit of fuel, so it needs to dry out befor I can put it back in the plane.
Dave

I used a wooden dowel as well and then finished it with 2 part epoxy. Once it dried, I cut a small groove down the length of it to expose the wood which becomes my "sight glass" when I dip the tank. I can clearly see the level of the tank where the fuel soaks into the groove but then it dries in about 10 seconds or so.
 
fuel level stick

Now this one gives me a good laugh
""Mine is a tail dragger, but you are welcome to my data. It had to be calibrated for ground and flight (3 deg).""
As I have never checked my fuel level IN flight. I usually do that on the ground.
Maybe I should Ha Ha Art
 
I've always used 1/2" hard wood dowel sticks, unvarnished. I use a soldering iron to mark it every 5 gallons (never fades). As far as accuracy, I always opt to error on the lesser value of the reading, as measurements are influenced by the levelness of the ground the plane is parked on & the angle & position of the stick in the tank (stick at rear/center/or forward edge of filler opening, stick perpendicular to the tank flange or perpendicular to the ground...) but generally I'd take a tank dipped reading over a float indicated reading anyday!
 
I just start every flight with a full tank - no thinking needed! :D

Seriously, my GRT with red cube is really accurate. I check it at each fill-up and I'm within about a liter every time.

On a taildragger, the visual inspection with the plexi tube is not that helpful.

I have essentially 4 levels:

  1. Full - easy to see, since I'm at the pump, 4 hours of flying
  2. Can pick up fuel with plex tube gauge - 3+ hours of flying
  3. Can see fuel, but can't pick it up with the plexi tube gauge - 2 hours of flying
  4. Can't see fuel - between 0 and 1 hour of flying - time to fill up

When I see less than 20 gallons on the fuel totalizer, I'm getting puckered and thinking about a fill-up.
 
Oops

Whatever tool you use, write your measurements down somewhere as soon as you take them. That when you leave your paint stick at the pump one day you can make a new one without measuring again. Dont ask why I know that.:D
 
Dihedral??

Reading all the posts on "accurately" measuring your fuel quantity makes me wonder how a stick is helpful when the fuel level is below the outside bottom corner of the tank?
When parked perfectly level in an RV-10, the remaining fuel is 12 gallons if the level of fuel rests at the intersection of the corner on the wingtip side of the tank. Obviously you can use a stick to accurately measure from there on up to full but not below.
On the lower side, your float sensor is more accurate if it was properly calibrated. However, having your tanks about 3/4 full will indicate full on your fuel level gauge, again due to dihedral.
Your most accurate sensor is probably your flow meter, again if properly calibrated. This instrument does not care about dihedral but it is prone to human error, ie forgetting to add fuel after a fill up.
I feel better knowing that my tanks are full rather than knowing that I have
14 and 5/8th of a gallon left in one tank and 8 and 3/16th of a gallon in the other.:rolleyes:
 
I don’t get what the need is. The tank floats and fuel totalizer provide independent redundancy. Also I know that right when the fuel is on the verge of not being visible anymore from the fill point, there is 10 gal left. What good is a stick? Nothing to measure using a stick when less than 10 gal and I’m fine with float gauges, totalizer and visual check when it’s more than 10 gal.
 
I don’t get what the need is. The tank floats and fuel totalizer provide independent redundancy. Also I know that right when the fuel is on the verge of not being visible anymore from the fill point, there is 10 gal left. What good is a stick? Nothing to measure using a stick when less than 10 gal and I’m fine with float gauges, totalizer and visual check when it’s more than 10 gal.

My -4 is measurable with a paint stick from 2 gallons all the way to full. Although I use my totalizer primarily, my gauges as a back up, the stick can also be useful. Sometimes I defuel if I plan an aerobatic flight or I’m going some place close with cheap fuel.. the stick allows me to readjust the totalizer to match what the plane contains after defueling.
 
I don’t get what the need is. The tank floats and fuel totalizer provide independent redundancy. Also I know that right when the fuel is on the verge of not being visible anymore from the fill point, there is 10 gal left. What good is a stick? Nothing to measure using a stick when less than 10 gal and I’m fine with float gauges, totalizer and visual check when it’s more than 10 gal.

What if someone removes fuel without your knowledge? That happened to two people I knew. Thieves siphoned the Lancair 235 tanks while they were tied down overnight and they crashed and died shortly after takeoff in the morning. If there was a fuel totalizer, it could not register the quantity that the thieves had pilfered.

Here's the link to the accident investigation report:
https://www.atsb.gov.au/publications/investigation_reports/1999/aair/aair199901340/

So for me, "the need" is to be confident of what is in the tanks before starting up. It costs nothing to do and takes only a minute during pre-flight.
 
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I guess that is what could happen if you fail to check your quantity of fuel in each tank during your walkaround.
And then ignore two fuel gauges that are reading empty...... This is pilot error, and nothing else.
 
I'm looking for an accurate fuel measuring tool for pre-flight. Any suggestions on tank dip tools? I have a 7A.
Thanks!
Andy.

I used an oak stick 1"X1/4"X9" A hole is drilled at the top and a loop made from a pull tie that my finger goes through to keep from dropping the stick into the tank. I marked the stick with a fine line Sharpie. The fuel will not wash the marks off, but your finger oil will. Do not mark where you hold the stick.

For an accurate stick, you must start with an empty tank and fill it at the pump one gallon at a time marking your stick as you go.

The RV6A (unlike the 7A mentioned a few posts above??) will show 3 gallons just in sight, and 5 gallons at the brace. The stick is started at 6 gallons and marked at each gallon to 18. 19 gallons is at the inside lip of the opening.

I know within 1/2 gallon extatically the amount of fuel I have in my tanks before I enter the aircraft. It doesn't get any safer than that.

The oak stick is hard enough that the fuel does not soak in, and evaporates just by waving it a few times. In use for over 16 years.
 
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Always a visual fuel check for me doing the pre-flight inspection. Open fuel tank cap, dip, compare to fuel gauge, and verify cap is secure. I don’t imagine you would pass your PP check ride if you failed this step, and for very good reason.
 
Out of gas

My airplane is in MY locked hangar. I never fire up the motor EVER without first visually checking the tanks for fuel and it lives in my locked hangar.
Maybe I'm over cautious, But I've ran other ground equipment, cars, trucks, etc. out of fuel.
But never an airplane.
Those who do so are being a bit careless or have on heck of a leak.
Ya I know, a bit opinionated
I'm one of the bamboo stick guys Art
 
To each his own, but if you’re not visually checking your fuel before flight, you are adding an unnecessary level of risk to your flying. I have personally seen fuel gauges fail or become uncalibrated. I have seen fuel totalizers not function because of fuel theft. I have seen fuel stolen, leaking, you name it. Why would you not visually check your fuel? And I use a clear tube with markings on it. And I also, as a previous poster noted, wrote my measurements down for each plane I fly and noted them in the aircraft paperwork so I can easily recreate the tools.

You cannot pass a PPL check ride in my neck of the woods if you fail in this step.
 
very useful tool

That tool could double up to measure how many ounces of beer are left in your bottle?? :cool:
 
I just recently got a 11" Fuelhawk and emailed Bobby Hester (above in thread). He graciously and within hours emailed me his readings - thank you, Bobby! He noted that these are the numbers that he got but that that his numbers should be very close to any plans built RV-7A, but that you should still verify yours.

Fuelhawk: https://www.aircraftspruce.com/catal...clickkey=75835 (also on Amazon at higher price but free Prime shipping).

Bobby's Numbers (forwarded with permission):

Fuel Level Check Tube
1 = 6 gallons
2 = 8 gallons
3 = 10 gallons
4 = 12 gallons
5.5 = 14 gallons
6.5 = 16 gallons
7.5 = 18 gallons
9.5 = 20 gallons

I plotted these and there was a little 'noise' evident, and I also wanted a finer scale on the dip stick so I don't have to interpolate 'by eye'. So I wrote a little Python script to fit a 3rd order polynomial (gallons vs reading) and then evaluated at the integer and half-integer readings. It's a little hinky I admit but gets things within a gallon and is sufficient for my purposes.

Reading Fuel
1.0 6.0
1.5 7.0
2.0 8.0
2.5 9.0
3.0 10.0
3.5 11.0
4.0 11.8
4.5 12.7
5.0 13.6
5.5 14.5
6.0 15.3
6.5 16.1
7.0 16.9
7.5 17.6
8.0 18.3
8.5 18.9
9.0 19.5
9.5 20.1
 
I plotted these and there was a little 'noise' evident, and I also wanted a finer scale on the dip stick so I don't have to interpolate 'by eye'. So I wrote a little Python script to fit a 3rd order polynomial (gallons vs reading) and then evaluated at the integer and half-integer readings.

No offense, but...somebody has waaaaay too much time on their hands :).
 
The builder of my plane chose to make a stick that you just touch the top of the fuel surface (you see a little ripple) then read the tick mark that lines up with the wing skin around the fuel cap hole. It is one of those solutions to a problem that doesn't exist, but it works well.
 
Does anybody have these measurements for a RV9A?

This is the device I use and I've found it to be very accurate measured against my display and the fuel computer. I don't have the actual measurements handy, but if it would be helpful, I'd be happy to measure the marks in the next day or two so you could duplicate this device. This is for my RV-9A with two standard 18 gallon tanks.

..
 

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9A Measurements

Measuring from the furthest outboard edge of the filler.

4 gallon - .3"
5 - .7"
6 - 1"
7 - 1.3"
8 - 1.6"
9 - 2.0"
10 - 2.4"
12 - 3.1"
14 - 3.9"
16 - 4.9"
17 - 5.4"
18.3 - touches the bottom of the neck

Like many, simple 1/2" flat bar of AL. Marked with die set the measurements above and drilled holes to capture a bit of fuel to make it easier to read. Found that a rough buff with sandpaper lets the fuel bite on the side of the stick as well making it easier to read.
 
Thank you

Measuring from the furthest outboard edge of the filler.

4 gallon - .3"
5 - .7"
6 - 1"
7 - 1.3"
8 - 1.6"
9 - 2.0"
10 - 2.4"
12 - 3.1"
14 - 3.9"
16 - 4.9"
17 - 5.4"
18.3 - touches the bottom of the neck

Like many, simple 1/2" flat bar of AL. Marked with die set the measurements above and drilled holes to capture a bit of fuel to make it easier to read. Found that a rough buff with sandpaper lets the fuel bite on the side of the stick as well making it easier to read.
Thank you
I plan to do my fuel cal this weekend. Hopefully this is close, but will let me know if I am screwed in the head if I am pretty far off.
 
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