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OT: What can be so problematic about fuel sensors?

C

ChairmanOfTheBored

Fuel sensors, and fuel sensor wires, and control boxes...
They have been having problems for many years.
http://www.spaceflightnow.com/shuttle/sts114/050716ecographic/
I just wonder what can be so difficult?
Click to expand...

Cryogenics has its own set of anomalous behavior for electronics
immersed in extremely cold baths. Then, there's that "gas tight" thing
to keep things like explosions from being caused by such sensors or the
wires that feed and or exit them.

Maybe they should just put a big sight glass down the side of the tank
and view it externally! :-]
 
J

Jan Panteltje

Fuel sensors, and fuel sensor wires, and control boxes...
They have been having problems for many years.
http://www.spaceflightnow.com/shuttle/sts114/050716ecographic/
I just wonder what can be so difficult?
Click to expand...

Cryogenics has its own set of anomalous behavior for electronics
immersed in extremely cold baths. Then, there's that "gas tight" thing
to keep things like explosions from being caused by such sensors or the
wires that feed and or exit them.

Maybe they should just put a big sight glass down the side of the tank
and view it externally! :-]
Click to expand...

Actually that is a cool idea.
I was sort of looking forward to watching it launch on NASA TV, always
impressive so much power.
I was thinking myself: 'air bubbles', not electronics.
Such a glass would make a check easy.
Else a small video camera next to the sensors with a white LED ?
 
C

ChairmanOfTheBored

Fuel sensors, and fuel sensor wires, and control boxes...
They have been having problems for many years.
http://www.spaceflightnow.com/shuttle/sts114/050716ecographic/
I just wonder what can be so difficult?
Click to expand...

Cryogenics has its own set of anomalous behavior for electronics
immersed in extremely cold baths. Then, there's that "gas tight" thing
to keep things like explosions from being caused by such sensors or the
wires that feed and or exit them.

Maybe they should just put a big sight glass down the side of the tank
and view it externally! :-]
Click to expand...

Actually that is a cool idea.
I was sort of looking forward to watching it launch on NASA TV, always
impressive so much power.
I was thinking myself: 'air bubbles', not electronics.
Such a glass would make a check easy.
Else a small video camera next to the sensors with a white LED ?
Click to expand...

There ya go. Make a series of holes down the tank side, and put pen
cameras in each hole. No more internal sensors.

There is a very interesting video of the redstone rocket days (1960s)
where they were very concerned about how efficiently a tank empties while
in use. They actually had cameras mounted inside the tanks for a long
time during those years. Some of the videos are pretty cool <sic>.
 
C

ChairmanOfTheBored

cold and vibration ?
Click to expand...


They failed on the launch pad. Where was the vibration?

They trip up to the pad at 1 MPH so don't even go there.
 
J

JosephKK

ChairmanOfTheBored [email protected] posted to
sci.electronics.design:
Fuel sensors, and fuel sensor wires, and control boxes...
They have been having problems for many years.
http://www.spaceflightnow.com/shuttle/sts114/050716ecographic/
I just wonder what can be so difficult?
Click to expand...

Cryogenics has its own set of anomalous behavior for electronics
immersed in extremely cold baths. Then, there's that "gas tight"
thing to keep things like explosions from being caused by such
sensors or the wires that feed and or exit them.

Maybe they should just put a big sight glass down the side of the
tank
and view it externally! :-]
Click to expand...

Cryogenic temperatures. Think about it some more.
 
J

JosephKK

Jamie [email protected] posted to
sci.electronics.design:
cold and vibration ?
Click to expand...

Actually i would go on a different tack. In some aircraft they use a
fiber optic "sword" and monitor the end reflectivity with a largish
linear sensor. With clean fuels it may never need cleaning and
dodges much of the cryogenic temperature induced issues.
 
J

Jan Panteltje

Jamie [email protected] posted to
sci.electronics.design:


Actually i would go on a different tack. In some aircraft they use a
fiber optic "sword" and monitor the end reflectivity with a largish
linear sensor. With clean fuels it may never need cleaning and
dodges much of the cryogenic temperature induced issues.
Click to expand...

Yes, fiber optics, and even using fiber optics with a camera to
monitor existing sensors, seems a cool idea that avoids thermal
and electrical problems.

It seems to me, that after they replaced everything several times, sensors,
wiring, and boxes, one SHOULD look for the obvious *it is somewhere else*.
But the days of Von Braun are long past, they fired all Apollo engineers,
so perhaps the shuttle was designed by politicians.
LOL
 
J

Jan Panteltje

One cryogenic level sensor I'm familiary with (I designed the rather
straightforward electronics to operate it) depends on
superconductivity to function. ;-)
Click to expand...

Interesting idea, goes zero Ohm when it sees cold fluid?
Some current and a 4 wire system?
 
J

John Larkin

One cryogenic level sensor I'm familiary with (I designed the rather
straightforward electronics to operate it) depends on
superconductivity to function. ;-)

Best regards,
Spehro Pefhany
Click to expand...


Point sensor or the vertical-wire level sensing thing?

John
 
J

John Larkin

One cryogenic level sensor I'm familiary with (I designed the rather
straightforward electronics to operate it) depends on
superconductivity to function. ;-)

Best regards,
Spehro Pefhany
Click to expand...


Hey, here's one:

http://www.highlandtechnology.com/DSS/M520DS.html

I designed this for Jefferson Labs in Newport News, a
superconductive-cavity electron accelerator.

I didn't realize that this antique was still up on our web site.


John
 
S

Spehro Pefhany

Point sensor or the vertical-wire level sensing thing?

John
Click to expand...

The latter- Nb wire. N2 point sensors can use ordinary Si diodes,
IIRC, but they make assumptions about the vapor temperature.

Best regards,
Spehro Pefhany
 
C

ChairmanOfTheBored

Yes, fiber optics, and even using fiber optics with a camera to
monitor existing sensors, seems a cool idea that avoids thermal
and electrical problems.
Click to expand...

Well... a series of fibers with polished ends, spaced a couple inches
apart, all the way up a rod in the tank center would be a nice idea, but
I wonder if the refractivity of the LO2 or LH would be able to be sensed
accurately enough to please them.
It seems to me, that after they replaced everything several times, sensors,
wiring, and boxes, one SHOULD look for the obvious *it is somewhere else*.
But the days of Von Braun are long past, they fired all Apollo engineers,
so perhaps the shuttle was designed by politicians.
LOL
Click to expand...

Nope. Their would have been many more catastrophic mission failures if
the boobs we have had in office for the last three decades had anything
to do with any of the systems.

Hell, look at the catastrophic national economic mission failure that
their tenure in office has caused.
 
C

ChairmanOfTheBored

ChairmanOfTheBored [email protected] posted to
sci.electronics.design:
Fuel sensors, and fuel sensor wires, and control boxes...
They have been having problems for many years.
http://www.spaceflightnow.com/shuttle/sts114/050716ecographic/
I just wonder what can be so difficult?
Click to expand...

Cryogenics has its own set of anomalous behavior for electronics
immersed in extremely cold baths. Then, there's that "gas tight"
thing to keep things like explosions from being caused by such
sensors or the wires that feed and or exit them.

Maybe they should just put a big sight glass down the side of the
tank
and view it externally! :-]
Click to expand...

Cryogenic temperatures. Think about it some more.
Click to expand...

Two inches of glass by two inches wide by however many feet long,
expansion mounted with Conap polyurethane epoxy.

YOU think about it some more. Hell, we grow quarts now that is very
pure. Wouldn't be that hard to grow a bar of that long enough.

Or even a large, round glass rod where the exposed line of sight is
only about 5 degrees or so of the rod circumference, and the rest is in
the tank. You could even grind notches in the inner side of it to cause
notable refractions between the liquid and rod as it passed over the
notches. "Notches... we need stinking notches!" :-]

The "exposed "part would "see" very little "thermal attack" or expansion
issues in such a case.
 
C

ChairmanOfTheBored

The latter- Nb wire. N2 point sensors can use ordinary Si diodes,
IIRC, but they make assumptions about the vapor temperature.
Click to expand...


In a big stationary tank setting, this might cause a problem, but in
the shuttle, which gets topped off just before launch, and empties at a
very fast rate, I doubt it would be an issue at all.
 
J

Jan Panteltje

On a sunny day (Mon, 10 Dec 2007 18:39:44 -0800) it happened
Nope. Their would have been many more catastrophic mission failures if
the boobs we have had in office for the last three decades had anything
to do with any of the systems.
LOL


Hell, look at the catastrophic national economic mission failure that
their tenure in office has caused.
Click to expand...

Na, one of them could have tech as a hobby perhaps.
:)
 
J

JosephKK

Jan Panteltje [email protected] posted to
sci.electronics.design:
Yes, fiber optics, and even using fiber optics with a camera to
monitor existing sensors, seems a cool idea that avoids thermal
and electrical problems.

It seems to me, that after they replaced everything several times,
sensors, wiring, and boxes, one SHOULD look for the obvious *it is
somewhere else*. But the days of Von Braun are long past, they fired
all Apollo engineers, so perhaps the shuttle was designed by
politicians. LOL
Click to expand...

Way too many important decisions were made by bean counters instead of
engineers. They had to reverse some when Challenger was destroyed,
just not all of them.
 
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