Q for Jim Weir or others: solid state fuel level probes?

Jim or anyone else who has 'been there',

Are circuit boards available for the capacitive fuel guages featured in
the year2000 Kitplanes articles?

Or (more desirable to me) is there an easily fabricated optical sensor
available for fuel level measurement?

Other options???

Thanks,

Charlie

Charlie England
shared these priceless pearls of wisdom:

-Jim or anyone else who has 'been there',
-
-Are circuit boards available for the capacitive fuel guages featured in
-the year2000 Kitplanes articles?

Unfortunately, no. For a couple of good reasons. One that I know you
understand is liability. While I have no good reason to believe that the design
is anything but triple-redundant safe, the Denver case outlines that anybody
whose name is anywhere on the airplane will get to explain to a particularly
picky black robe why their part of the airplane could not have possibly been
involved in the accident.

Two is that I get about one request every six months for a circuit board. That
makes it economically unfeasable to even do the layout, much less make a hundred
boards and have a 50 year supply sitting on the shelf.


-
-Or (more desirable to me) is there an easily fabricated optical sensor
-available for fuel level measurement?

Optical? Hmmm...with green fuel, blue fuel, red fuel, and clear fuel around
(and we all know there's no fuel like an old fuel) I'm not sure what sort of
optical system would be stable and sensitive enough to cover this range of
optical barriers.


-
-Other options???


I've been particularly intrigued with the possiblity of using the Polaroid
autofocus sonar setup but have never investigated it. THAT is damn near totally
failsafe.

Jim

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

Jim Weir wrote:
Charlie England
shared these priceless pearls of wisdom:

-Jim or anyone else who has 'been there',
-
-Are circuit boards available for the capacitive fuel guages featured in
-the year2000 Kitplanes articles?

Unfortunately, no. For a couple of good reasons. One that I know you
understand is liability. While I have no good reason to believe that the design
is anything but triple-redundant safe, the Denver case outlines that anybody
whose name is anywhere on the airplane will get to explain to a particularly
picky black robe why their part of the airplane could not have possibly been
involved in the accident.

Two is that I get about one request every six months for a circuit board. That
makes it economically unfeasable to even do the layout, much less make a hundred
boards and have a 50 year supply sitting on the shelf.


-
-Or (more desirable to me) is there an easily fabricated optical sensor
-available for fuel level measurement?

Optical? Hmmm...with green fuel, blue fuel, red fuel, and clear fuel around
(and we all know there's no fuel like an old fuel) I'm not sure what sort of
optical system would be stable and sensitive enough to cover this range of
optical barriers.


-
-Other options???


I've been particularly intrigued with the possiblity of using the Polaroid
autofocus sonar setup but have never investigated it. THAT is damn near totally
failsafe.

Jim

Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com
There are currently available liquid level sensors that use a light
source feeding a plexiglas rod with the sensor (IIRC) adjacent to the
light source. Change in refraction between covered/uncovered end of the
rod causes a 0/1 change in output state of the sensor. These are
typically promoted as low-level sensors. I am hoping for a variation on
this sensing technique. I've seen proposals for multiple rods/sensors,
but no 'cookbook' & parts source to build one 'cheap'.

Charlie

"Jim Weir" wrote in message
...

Optical? Hmmm...with green fuel, blue fuel, red fuel, and clear fuel
around
(and we all know there's no fuel like an old fuel) I'm not sure what sort
of
optical system would be stable and sensitive enough to cover this range of
optical barriers.


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

Well, there's brute force. Just install a closed circuit TV camera that
looks in through a window in the tank. Nothing like directly eyeballing how
much fuel there is in the tank. Make sure there is a "dipstick" in the
camera view. Hey, everybody's going "glass cockpit" anyway.

The fiber optic trick.... Just use a bundle of plastic fibers, each cut to
a different length on the tank end. In the cockpit, just break out the
bundle into a vertical array of fiber ends. Illuminate the interior of the
tank with "ultrabright" LED's. A fiber end in the cockpit will either
illuminate if the other end is submerged in fuel or go dark if it isn't.
Want a brighter display? Just install more LED's.

Bill Daniels

I believe I saw a posting a year or more ago that that will work with out
the light. If I remember correctly the light from the cockpit will be
reflected when there is no fuel and will be dark when there is..I thought
about using this on an ultralight gas tank. Buy a standard 5 gallon gas can.
install a fuel pick up in the lid and the fuel gauge sensor in the vent.
When I need gas I can unsnap the the bungee cords, pull the cap and vent and
take the whole thing down to the gas station and fill it up, and the FAA
want be able to claim my tank is too big.

Cheers
Jeff
"Bill Daniels" wrote in message
...

"Jim Weir" wrote in message
...

Optical? Hmmm...with green fuel, blue fuel, red fuel, and clear fuel
around
(and we all know there's no fuel like an old fuel) I'm not sure what
sort
of
optical system would be stable and sensitive enough to cover this range
of
optical barriers.


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

Well, there's brute force. Just install a closed circuit TV camera that
looks in through a window in the tank. Nothing like directly eyeballing
how
much fuel there is in the tank. Make sure there is a "dipstick" in the
camera view. Hey, everybody's going "glass cockpit" anyway.

The fiber optic trick.... Just use a bundle of plastic fibers, each cut
to
a different length on the tank end. In the cockpit, just break out the
bundle into a vertical array of fiber ends. Illuminate the interior of
the
tank with "ultrabright" LED's. A fiber end in the cockpit will either
illuminate if the other end is submerged in fuel or go dark if it isn't.
Want a brighter display? Just install more LED's.

Bill Daniels

"Jim Weir" wrote in message
...
Charlie England
shared these priceless pearls of wisdom:

-
-Or (more desirable to me) is there an easily fabricated optical sensor
-available for fuel level measurement?

Optical? Hmmm...with green fuel, blue fuel, red fuel, and clear fuel
around
(and we all know there's no fuel like an old fuel) I'm not sure what sort
of
optical system would be stable and sensitive enough to cover this range of
optical barriers.


-
-Other options???


I've been particularly intrigued with the possiblity of using the Polaroid
autofocus sonar setup but have never investigated it. THAT is damn near
totally
failsafe.

Jim

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

If you want to do some tinkering of your own (legal disclaimer here..) you
may want to look at sensor chips from QProx (www.qprox.com). They have a
couple of capacitive level monitor chips like the QT300/301 or QT117L that
may provide real-time non-contact level information. If you have a non-metal
tank you may be able to just attach two strips on the side of the tank and
be done.

Jim, what do you think?

Rob

I think the chips themselves are worth investigating. I do have a prejudice
against UK semiconductor manufacturers, having had a major one and a minor one
simply stop producing parts that rendered several tens of thousands of dollars
of hardware and engineering time down the drain.

I realize that they are not ALL like that, but the only two that have screwed me
thus far in 40 years have been UK based.

Jim


-If you want to do some tinkering of your own (legal disclaimer here..) you
-may want to look at sensor chips from QProx (www.qprox.com). They have a
-couple of capacitive level monitor chips like the QT300/301 or QT117L that
-may provide real-time non-contact level information. If you have a non-metal
-tank you may be able to just attach two strips on the side of the tank and
-be done.
-
-Jim, what do you think?
-
-Rob
-

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

I've run into the same niche product kind of issue myself. I could
make a cool like PCB that does some function but how many people would
be interested? Not enough to pay for my time. I could do it for "fun"
but I do that kind of work 40+hrs week 5/6 days week.

Colored Fuel- Well I assume its all translucent, regardless of the
color. I designed a color sensor that shined different color LEDs on
the subject material and measured the amount of light that came back.
From that the uC could make a pretty good guess on what color it was
looking at. I suppose you could tell if someone put the wrong color
gas in your tanks.

Regards

Jim Weir wrote in message . ..
Charlie England
shared these priceless pearls of wisdom:

-Jim or anyone else who has 'been there',
-
-Are circuit boards available for the capacitive fuel guages featured in
-the year2000 Kitplanes articles?

Unfortunately, no. For a couple of good reasons. One that I know you
understand is liability. While I have no good reason to believe that the design
is anything but triple-redundant safe, the Denver case outlines that anybody
whose name is anywhere on the airplane will get to explain to a particularly
picky black robe why their part of the airplane could not have possibly been
involved in the accident.

Two is that I get about one request every six months for a circuit board. That
makes it economically unfeasable to even do the layout, much less make a hundred
boards and have a 50 year supply sitting on the shelf.


-
-Or (more desirable to me) is there an easily fabricated optical sensor
-available for fuel level measurement?

Optical? Hmmm...with green fuel, blue fuel, red fuel, and clear fuel around
(and we all know there's no fuel like an old fuel) I'm not sure what sort of
optical system would be stable and sensitive enough to cover this range of
optical barriers.


-
-Other options???


I've been particularly intrigued with the possiblity of using the Polaroid
autofocus sonar setup but have never investigated it. THAT is damn near totally
failsafe.

Jim

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

Jim Weir wrote:

I've been particularly intrigued with the possiblity of using the Polaroid
autofocus sonar setup but have never investigated it. THAT is damn near totally
failsafe.

I vaguely recall that one of the high-end German car makers (Mercedes-Benz, BMW, or
Porsche) had such a system. Dunno if they still have it. Might want to check that
out; it seems likely that it could be adapted.

Russell Kent

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Isn't this just a capacitance meter on a chip?

Evan
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.0.6 (GNU/Linux)
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org

iD8DBQFAT5Vzoo/Prlj9GScRAgHOAJ9CZ+o/w7vHV8QSMFPFyExCPZO6KACff+t0
nq7pFYnQTBlwl0ZWzTVc6Wk=
=F0/B
-----END PGP SIGNATURE-----