How to ACCURATELY measure fuel/gas in a single-engine piston aircraft?

[NoSpam]

Is there a way to ACCURATELY measure the available fuel in the tanks of a
general single-engine piston aircraft??? I know there are fuel flow
computers available (such as JPI?). But these typically need to be "set"
with a starting fuel quantity, and then it accurately measures the fuel flow
rate (consumption rate) to calculate the remaining fuel. However, if you do
not start with full tanks, or a [accurate] known given amount of fuel in the
tanks, this method does not seem that reliable/accurate... Is there a way
to accurately measure the fuel in the tanks while the aircraft is on the
ground (using some "mechanical" measuring tool/gauge)? Is there a way to
accurately measure the amount of fuel in the tanks while in flight?

A friend of mine has bought some digital fuel gauges (a combination a
several digital engine instruments -- but I forgot the manufacturer's name).
Using these fuel gauges, you "calibrate" the instrument/gauges by leveling
the aircraft (both "wings level" and "pitch/flying attitude level") and
starting with 0 gals of fuel in the tank, then adding one gallon at a time,
wait a while for the fuel to settle, then take an electronic reading, add 1
gal of fuel and repeat the process until the tanks are full. How accurate
is this method? (personally I do not know how accurate this is, but would
like to know from someone with experience using these instruments...)

Thank you.

Cameron




----== Posted via Newsfeed.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeed.com The #1 Newsgroup Service in the World! >100,000 Newsgroups
---= 19 East/West-Coast Specialized Servers - Total Privacy via Encryption =---

[C J Campbell]

You could make a very accurate fuel stick by draining the tanks, filling
them a few gallons at a time, and marking the line on the stick each time.
Trouble is, a lot of these fuel sticks end up inside the fuel tank. :-)
Making a little cross bar at the handle end should prevent that.

[db]

You bet. It's called a sight guage. A transparent panel or tube in the root
end of the tank so that you can see the gas. You have to keep the plane in the
attitude you used to calibrate the guage, but it will never suffer an
electrical or mechanical failure. Fancy ones will have a stripe behind the
tube. The gas will act like a magnifying glass and make the stripe look real
wide. Helps with the nearly transparent gas. Add a little light on the subject
and you can see it in the dark, too.




In article >, "NoSpam" > wrote:
>Is there a way to ACCURATELY measure the available fuel in the tanks of a
>general single-engine piston aircraft??? I know there are fuel flow
>computers available (such as JPI?). But these typically need to be "set"
>with a starting fuel quantity, and then it accurately measures the fuel flow
>rate (consumption rate) to calculate the remaining fuel. However, if you do
>not start with full tanks, or a [accurate] known given amount of fuel in the
>tanks, this method does not seem that reliable/accurate... Is there a way
>to accurately measure the fuel in the tanks while the aircraft is on the
>ground (using some "mechanical" measuring tool/gauge)? Is there a way to
>accurately measure the amount of fuel in the tanks while in flight?
>
>A friend of mine has bought some digital fuel gauges (a combination a
>several digital engine instruments -- but I forgot the manufacturer's name).
>Using these fuel gauges, you "calibrate" the instrument/gauges by leveling
>the aircraft (both "wings level" and "pitch/flying attitude level") and
>starting with 0 gals of fuel in the tank, then adding one gallon at a time,
>wait a while for the fuel to settle, then take an electronic reading, add 1
>gal of fuel and repeat the process until the tanks are full. How accurate
>is this method? (personally I do not know how accurate this is, but would
>like to know from someone with experience using these instruments...)
>
>Thank you.
>
>Cameron
>
>
>
>
>----== Posted via Newsfeed.Com - Unlimited-Uncensored-Secure Usenet News==----
>http://www.newsfeed.com The #1 Newsgroup Service in the World! >100,000
> Newsgroups
>---= 19 East/West-Coast Specialized Servers - Total Privacy via Encryption =---

[Jim Weir]

Two questions:

What is "accurate"?

Why do you need "accuracy"?

Jim


"NoSpam" >
shared these priceless pearls of wisdom:

->Is there a way to ACCURATELY measure the available fuel in the tanks of a
->general single-engine piston aircraft???



Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com

[karl]

*****but it will never suffer an electrical or mechanical failure.*****

Never say never. I've personally seen the failure of just the type of gauge
you are talking about. In a Super Cub. Showed 3/4 actual zero.

Karl

[db]

Doesn't it have a float on a wire? Not the same. The sight guage I
described has nothing in it except gas. I suppose you could put
some chewing gum in the tube to plug it and it might stay full.
Can't really call that a mechanical failure.


In article >, "karl"
> wrote:
>*****but it will never suffer an electrical or mechanical failure.*****
>
>Never say never. I've personally seen the failure of just the type of gauge
>you are talking about. In a Super Cub. Showed 3/4 actual zero.
>
>Karl
>
>

[Peter R.]

NoSpam wrote:

> Is there a way to ACCURATELY measure the available fuel in the tanks of a
> general single-engine piston aircraft???

Just after receiving my private pilot certificate, I bought a FuelHawk
to accurately measure remaining fuel in my Skyhawk's tanks:

http://makeashorterlink.com/?O202128F6

Due to the type of missions I routinely fly, I often have to trade fuel
for passenger and luggage weight. This stick is indispensable in
assisting me with W/B planning and fuel/reserve estimates.

I would be very uncomfortable flying one of these missions without it.

--
Peter










----== Posted via Newsfeed.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeed.com The #1 Newsgroup Service in the World! >100,000 Newsgroups
---= 19 East/West-Coast Specialized Servers - Total Privacy via Encryption =---

[Newps]

Peter R. wrote:

> NoSpam wrote:
>
>
>>Is there a way to ACCURATELY measure the available fuel in the tanks of a
>>general single-engine piston aircraft???
>
>
> Just after receiving my private pilot certificate, I bought a FuelHawk
> to accurately measure remaining fuel in my Skyhawk's tanks:
>
> http://makeashorterlink.com/?O202128F6
>
> Due to the type of missions I routinely fly, I often have to trade fuel
> for passenger and luggage weight. This stick is indispensable in
> assisting me with W/B planning and fuel/reserve estimates.
>
> I would be very uncomfortable flying one of these missions without it.

I bought the fuel hawk for my 182. Total waste of money. My left tank
reads a different distance up the stick than the right tank for the same
amount of fuel. Also the stated quantity on the stick is not correct
for either tank. So I had to make my own. I used a 50 cent wooden
dowel and an ink pen to mark 5 gallon increments, left tank on one end
and right tank on the other.

[karl]

******Doesn't it have a float on a wire? Not the same******

Exactly the same.You really should go have a look. No wire. Just a sight
gauge with a red colored cork floating. I spent my pilot youth ferrying
these fine airplanes from Lock Haven to Washington. Oregon, Alaska.

The float on a wire is on a J3, Taylorcraft, Aeronca, usually on a forward
fuselage tank. Super Cub tanks are in the wings.

Karl

[C J Campbell]

"karl" > wrote in message
...
| *****but it will never suffer an electrical or mechanical failure.*****
|
| Never say never. I've personally seen the failure of just the type of
gauge
| you are talking about. In a Super Cub. Showed 3/4 actual zero.

John Denver's LongEZ also had a sight gauge. What he did not know was that
with the nose wheel retracted on the ground the gauge would always look more
full than it really was, even when the tank was almost empty.

The problem with sight gauges is that they are not linear, meaning that when
the gauge is 1/4 full it does not necessarily indicate that the tank is 1/4
full. This is true of fuel sticks, too. Fuel tanks tend to be rounded at the
top and bottom, so an inch of fuel in the bottom is less gas than an inch of
fuel in the middle. The gauge should be calibrated and marked with the fuel
quantity at several different levels, but no one had done this on Denver's
plane.

NTSB report here:
http://www.ntsb.gov/ntsb/brief.asp?ev_id=20001208X09045&key=1

[G.R. Patterson III]

NoSpam wrote:
>
> Is there a way to accurately measure the fuel in the tanks while the aircraft
> is on the ground (using some "mechanical" measuring tool/gauge)?

Yes. Make or buy some sort of dipstick. Mine is a clear plastic tube. I bought it
and drained one of my fuel tanks. We then pumped in 5 gallons and marked where the
level was when I stuck the tube in. Put in another 5 gallons and marked that. And
so forth. Now I can stick the tube in the tank, pull it out, and know within a
gallon or two how much is in that tank.

> Is there a way to
> accurately measure the amount of fuel in the tanks while in flight?

No. As others have stated, use your watch and the gauges. Whichever indicates the
least amount of fuel is what you "believe". Land if you even think you *might* be
getting low.

George Patterson
Great discoveries are not announced with "Eureka!". What's usually said is
"Hummmmm... That's interesting...."

[Dennis O'Connor]

John, who had more ratings than I ever will, approached a homebuilt with the
mindset that he was dealing with a certified aircraft - that don't have
such 'gotchas'...
Denny
"C J Campbell" > wrote The gauge
should be calibrated and marked with the fuel
> quantity at several different levels, but no one had done this on Denver's
> plane.

[Peter R.]

Newps ) wrote:

> I bought the fuel hawk for my 182. Total waste of money.

LOL! Hence the value of Usenet.

Just out of curiosity, was the FuelHawk you bought *specifically* for your
model 182? The one I bought only listed late model 172SPs.

In my case, I did confirm the stick's readings on a few occasions by
reading the remaining, then refilling the tanks. The amount of gallons
going in equaled total capacity minus my stick's reading. This was done
for varying amounts of remaining fuel over a few flights.

--
Peter












----== Posted via Newsfeed.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeed.com The #1 Newsgroup Service in the World! >100,000 Newsgroups
---= 19 East/West-Coast Specialized Servers - Total Privacy via Encryption =---

[Snowbird]

Peter R. > wrote in message >...
> NoSpam wrote:
>
> > Is there a way to ACCURATELY measure the available fuel in the tanks of a
> > general single-engine piston aircraft???

> Just after receiving my private pilot certificate, I bought a FuelHawk
> to accurately measure remaining fuel in my Skyhawk's tanks:

> http://makeashorterlink.com/?O202128F6
<...>
> I would be very uncomfortable flying one of these missions without it.

Peter,

I would be very uncomfortable relying on that FuelHawk unless you
have personally calibrated it in your plane and know it to be accurate.
We used to rent C172s, we had a FuelHawk, and the reading would be
different in different tanks which had the same amount of fuel left
as judged by how much fuel was added to 'top off', even different tanks
in the same plane.

I think Greg Travis posted a similar observation regarding his 180 HP
C172.

When we bought our Grumman, we calibrated the FuelHawk by noting the
reading before each top-off then doing a polynomial fit once we got
enough readings across the range. The other method of course is to
fly one tank dry then pour in fuel 1 gallon at a time, taking due
precautions against static. The latter method is quicker, both methods
are quite accurate if carefully done.

Once the stick (any stick -- fuel hawk, paint stirrer, etc) is
calibrated, it is quite accurate and I recommend it even to people
who always take off with full tanks, to determine whether they
actually landed with the amount of time in the tanks that they
thought they had. This has been a revelation to us a couple of
times (though, when the tank under the stick is dry, I still have
between 0 and 14 gallons, just our tank design).

Cheers,
Sydney

[Peter R.]

Snowbird ) wrote:

> I would be very uncomfortable relying on that FuelHawk unless you
> have personally calibrated it in your plane and know it to be accurate.

Thanks, Sydney. See my reply to NewPS.

--
Peter












----== Posted via Newsfeed.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeed.com The #1 Newsgroup Service in the World! >100,000 Newsgroups
---= 19 East/West-Coast Specialized Servers - Total Privacy via Encryption =---

[Snowbird]

"NoSpam" > wrote in message >...
> Is there a way
> to accurately measure the fuel in the tanks while the aircraft is on the
> ground (using some "mechanical" measuring tool/gauge)?

Yes, using a dipstick calibrated *for that aircraft*. This is quite
accurate w/in the range it can measure (for example, when my dipstick
reads 0 on each tank, I have between 0 and 14 gallons of fuel left.

> Is there a way to
> accurately measure the amount of fuel in the tanks while in flight?

Not of which I'm aware. As you note, fuel computers measure fuel
flow, but don't account for fuel loss due to, say, leakage around
an improperly sealed gas cap or sump valve.

> A friend of mine has bought some digital fuel gauges (a combination a
> several digital engine instruments -- but I forgot the manufacturer's name).
> Using these fuel gauges, you "calibrate" the instrument/gauges by leveling
> the aircraft (both "wings level" and "pitch/flying attitude level") and
> starting with 0 gals of fuel in the tank, then adding one gallon at a time,
> wait a while for the fuel to settle, then take an electronic reading, add 1
> gal of fuel and repeat the process until the tanks are full. How accurate
> is this method? (personally I do not know how accurate this is, but would
> like to know from someone with experience using these instruments...)

The method of adding 1 gallon and taking a reading on the ground is
accurate enough -- it's one way of calibrating a fuel dipstick.

I'm not sure how accurately it would translate to monitoring fuel in
flight -- the pitch attitude for level flight will vary so much
depending upon the atmosphere, the W&B, airspeed, and so forth.
It seems to me the design of the fuel tanks and the placement of
the gauge would be critical to accuracy, but I'm unfamiliar with the
technology used to make what you call an "electronic reading". That's
the point I'd want to investigate, though -- how much do the readings
I get with this wonder differ if I change the plane's pitch?

Cheers,
Sydney

[Robert M. Gary]

I use a fuel stick to measure the fuel and put that information in my
fuel flow computer. I'm usually within a tenth of a gallon on landing.
Its pretty easy to make your own fuel stick, the best ones are wood.
I've made some out of the paint stir sticks you get at the home
improvement stores (they look like rulers). The best part about wood
is once you measure the fuel you just shake it and the fuel stain is
gone and ready for the next tank. The glass ones that you have to
stick your thumb in kinda suck.

-Robert

[Jaap Berkhout]

Newps ) wrote:

> I bought the fuel hawk for my 182. Total waste of money.

I use a fuelhawk with general markings. I have a calibration table for a
specific Cessna 172 with long range tanks. I use it for any Cessna with
long range tanks, and use it for others with standard tanks by multiplying
the amount by 0.8. Is it accurate? Certainly not. Is it better than the
fuel gauges or my unaided eye? Sure is. So, by being conservative about
fuel burn and possible inaccuracy this tells me wether I have enough fuel
for the trip. Works thus far ;-)

[db]

Ok. I give up. How did it fail? The cork stick to the tube or what kept the
gas from draining through the bottom of the guage?

In article >, "karl"
> wrote:
>******Doesn't it have a float on a wire? Not the same******
>
>Exactly the same.You really should go have a look. No wire. Just a sight
>gauge with a red colored cork floating. I spent my pilot youth ferrying
>these fine airplanes from Lock Haven to Washington. Oregon, Alaska.
>
>The float on a wire is on a J3, Taylorcraft, Aeronca, usually on a forward
>fuselage tank. Super Cub tanks are in the wings.
>
>Karl
>
>

[NoSpam]

By acurate I mean within one galon of actual fuel quantity.

I am only asking for interest sake. Whenever I fly our club's Archer, I
calculated the amount of fuel remaining by starting with a full tank and
then estimating the fuel burn per hour, etc. etc. But this has always left
me feeling nervous -- the aircraft did not have an accurate fuel flow
instrument (e.g. JPI) on board, and as a result a was always
"guestimating" -- although I was on the conservative side...

Thanks

Cameron


"Jim Weir" > wrote in message
...
> Two questions:
>
> What is "accurate"?
>
> Why do you need "accuracy"?
>
> Jim
>
>
> "NoSpam" >
> shared these priceless pearls of wisdom:
>
> ->Is there a way to ACCURATELY measure the available fuel in the tanks of
a
> ->general single-engine piston aircraft???
>
>
>
> Jim Weir (A&P/IA, CFI, & other good alphabet soup)
> VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
> http://www.rst-engr.com




----== Posted via Newsfeed.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeed.com The #1 Newsgroup Service in the World! >100,000 Newsgroups
---= 19 East/West-Coast Specialized Servers - Total Privacy via Encryption =---

[NoSpam]

B.t.w. the fuel gauge that I was referring to (that a friend of mine had
installed) was the FL-100 by AerospaceLogic

See: http://www.aerospacelogic.com

Regards,

Cameron




----== Posted via Newsfeed.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeed.com The #1 Newsgroup Service in the World! >100,000 Newsgroups
---= 19 East/West-Coast Specialized Servers - Total Privacy via Encryption =---

[John Galban]

Newps > wrote in message news:<aeqKb.745729$HS4.5807961@attbi_s01>...
> I bought the fuel hawk for my 182. Total waste of money. My left tank
> reads a different distance up the stick than the right tank for the same
> amount of fuel.

<snip>

That's strange. Is there something about the 182's construction
that puts the tanks at different attitudes? I would think that they
should be just about the same if you were measuring on level ground.

John Galban=====>N4BQ (PA28-180)

[Mike O'Malley]

"G.R. Patterson III" > wrote in message
...
>
>
> NoSpam wrote:
> >
> > Is there a way to accurately measure the fuel in the tanks while the
aircraft
> > is on the ground (using some "mechanical" measuring tool/gauge)?
>
> Yes. Make or buy some sort of dipstick. Mine is a clear plastic tube. I bought
it
> and drained one of my fuel tanks. We then pumped in 5 gallons and marked where
the
> level was when I stuck the tube in. Put in another 5 gallons and marked that.
And
> so forth. Now I can stick the tube in the tank, pull it out, and know within a
> gallon or two how much is in that tank.
>

Of course, that would be "total" fuel, right? Not usable. Unless you managed
to get all the gas out when you drained it, and those drains for some reason
don't always get all the gas out. Found out when trying to remove a Cub's wing
tank (PA-11). Drained till it stopped. Went to disconnect the fuel line, and
fuel comes running out. Caught about 1/4 gal.

That would tell me there was another 1/4 gallon available to the engine below
the strainer- and that raised all kinds of other questions too... When we took
the tank out of the wing, we were STILL able to drain another 1/4 gallon of
fuel, too.

--
Mike

[Peter Duniho]

"Mike O'Malley" > wrote in message
...
> Of course, that would be "total" fuel, right? Not usable. Unless you
managed
> to get all the gas out when you drained it, and those drains for some
reason
> don't always get all the gas out.

Actually, you have it backwards. If he got all the gas out when draining
the tanks, then the calibrations would indicate total fuel, rather than
usable. On the other hand, there's no guarantee that even a partial drain
would result in an amount equal to usable fuel being left in the tank (as
you found out, it could be more, and of course it could also be less).

A correct procedure, IMHO, would be to ensure that the tanks are
*completely* empty. Then add an amount of fuel equal to the known unusable
amount. At that point, mark the zero point on the dipstick and start with
the remainder of the fuel intervals.

I use a dipstick calibrated in that manner with my airplane. The only
gotcha is, of course, unless the plane is parked on perfectly level ground,
there's a bit of error due to the slope. But it does a pretty good job.
Certainly it is better than eyeballing it, or trying to decide whether the
fuel is "at the tabs", completely full, somewhere in between, or not even
visible. :)

Pete

[mqd_117.3]

Newps wrote:
> *Peter R. wrote:
>
> > NoSpam wrote:
> >
> >
> >>Is there a way to ACCURATELY measure the available fuel in the
> tanks of a
> >>general single-engine piston aircraft???
> >
> >
> > Just after receiving my private pilot certificate, I bought a
> FuelHawk
> > to accurately measure remaining fuel in my Skyhawk's tanks:
> >
> > http://makeashorterlink.com/?O202128F6
> >
> > Due to the type of missions I routinely fly, I often have to trade
> fuel
> > for passenger and luggage weight. This stick is indispensable in
> > assisting me with W/B planning and fuel/reserve estimates.
> >
> > I would be very uncomfortable flying one of these missions without
> it.
>
> I bought the fuel hawk for my 182. Total waste of money. My left
> tank
> reads a different distance up the stick than the right tank for the
> same
> amount of fuel. Also the stated quantity on the stick is not
> correct
> for either tank. So I had to make my own. I used a 50 cent wooden
> dowel and an ink pen to mark 5 gallon increments, left tank on one
> end
> and right tank on the other. *

Yep! I did the same although not for a Cessna except I used saw cuts in
the stick just in case the pen wore off. Surprisingly, it hasn't yet!
It may only be only a difference of 3 or 4 litres between the tanks,
but you never know when you might need 'em.


MQD_117.3


--
mqd_117.3
------------------------------------------------------------------------
Posted via OziPilots Online [ http://www.OziPilotsOnline.com.au ]
- A website for Australian Pilots regardless of when, why, or what they fly -

[G.R. Patterson III]

Mike O'Malley wrote:
>
> Of course, that would be "total" fuel, right? Not usable.

Nope. Usable fuel. The Maule has two fuel lines (doh!) that run down the left side
of the fuselage and come together at the selector switch. Each line has a drain at
the bottom of the fuselage. These drains can be locked open. When no more fuel
comes out when the drain is open, you've run out of useable fuel. There's probably
still some in the tank.

George Patterson
Great discoveries are not announced with "Eureka!". What's usually said is
"Hummmmm... That's interesting...."

[Newps]

John Galban wrote:

> Newps > wrote in message news:<aeqKb.745729$HS4.5807961@attbi_s01>...
>
>>I bought the fuel hawk for my 182. Total waste of money. My left tank
>>reads a different distance up the stick than the right tank for the same
>>amount of fuel.
>
>
> <snip>
>
> That's strange. Is there something about the 182's construction
> that puts the tanks at different attitudes? I would think that they
> should be just about the same if you were measuring on level ground.
>
It's not much difference, maybe 1/8 to a 1/4 inch. But that's quite a
few gallons in a long range tank. Plus I calibrated in my hangar. It
is of no use to get the plane level, you must calibrate where you will
normally be dipping the tanks. The plane looks level but if I took a
level to the seat rails it may be off a little.

[Newps]

mqd_117.3 wrote:


> Yep! I did the same although not for a Cessna except I used saw cuts in
> the stick just in case the pen wore off. Surprisingly, it hasn't yet!
> It may only be only a difference of 3 or 4 litres between the tanks,
> but you never know when you might need 'em.

I wondered about the ink too when I did it, but it has been 4 years now
and it looks like the day I did it.

[G.R. Patterson III]

Newps wrote:
>
> I bought the fuel hawk for my 182. Total waste of money. My left tank
> reads a different distance up the stick than the right tank for the same
> amount of fuel.

Doesn't the 182 have fuel bladders? That might have something to do with it.
Not that that's a good excuse for that degree of inaccuracy.

George Patterson
Great discoveries are not announced with "Eureka!". What's usually said is
"Hummmmm... That's interesting...."

[Newps]

Most 182's have bladders like mine.

G.R. Patterson III wrote:

>
> Newps wrote:
>
>>I bought the fuel hawk for my 182. Total waste of money. My left tank
>>reads a different distance up the stick than the right tank for the same
>>amount of fuel.
>
>
> Doesn't the 182 have fuel bladders? That might have something to do with it.
> Not that that's a good excuse for that degree of inaccuracy.
>
> George Patterson
> Great discoveries are not announced with "Eureka!". What's usually said is
> "Hummmmm... That's interesting...."

[Jim Weir]

Would you care to elaborate {;-)

Jim



Newps >
shared these priceless pearls of wisdom:

->Most 182's have bladders like mine.



Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com

[Newps]

Jim Weir wrote:

> Would you care to elaborate {;-)

Yep, too small and they tend to leak.