Tank Inerting
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Bends seems to be related to physical state chemistry related to pressure. No matter where the sequestration or lack thereof of Nitrogen occurs, it’s the same fundamental chemistry mechanism as boiling point of a liquid being dependent on ambient pressure. I must disagree with the “nothing to do with” reply. Decompression sickness is a suitable example of the pressure-phase state relationship.
@Caper I can see it’s “over thinking it” but the same can be said for understanding how a car engine works is over thinking it when all you need to do is turn the key. You have hands on experience. All I have is some PDFs and my noodle so nothing is too obvious. The best understanding comes from being able to answer weird questions like what if X fails or will it still run if you hang the plane upside down from the hangar roof. I think some BMS pilots have the misconception that if you have full externals and somehow partial internals that you can’t rapidly transfer that fuel inboard. Say you forget the air source knob and you have 2,000# inside and full bags, can you fix it and expect to be able to combat drop bags and have full internal at any point?
One point I don’t understand is why combat pressure schedule is low pressure. What makes low pressure better than high if you’re being shot at?
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Bends seems to be related to physical state chemistry related to pressure. No matter where the sequestration or lack thereof of Nitrogen occurs, it’s the same fundamental chemistry mechanism as boiling point of a liquid being dependent on ambient pressure. I must disagree with the “nothing to do with” reply. Decompression sickness is a suitable example of the pressure-phase state relationship.?
A mayonnaise bottle exploded in my RV when I drove from Las Vegas to Flagstaff. Is that a good example??
@Frederf:I think some BMS pilots have the misconception that if you have full externals and somehow partial internals that you can’t rapidly transfer that fuel inboard. Say you forget the air source knob and you have 2,000# inside and full bags, can you fix it and expect to be able to combat drop bags and have full internal at any point?
I think some VFW understand the issues with the external tanks. They do the brevity that prevents or monitors issues with the external. I always thought that extra brevity was BS but now I understand why. And it would be kind of cool to be modeled. But then, “lateral fuel imbalance” only appears one time in the D1. Issues with externals is everywhere in the D1.
One point I don’t understand is why combat pressure schedule is low pressure. What makes low pressure better than high if you’re being shot at?
I could come up with a list. Maybe it also has something to do with ACM. “overthinking” to you maybe.
I want to know how the a/c know or what switch tells the a/c that it is in combat. -
and @ pumphead
I studied scuba a long time ago, back when it took 6weeks to get certify. Now days it takes a few hours and your diving. The ppl that start scuba now days, know nothing about the physics and medical stuff that I had to study.
iirc, Air bubbles in your arteries and veins is an Air Embolism. The Bends deals with the bones and joints.
Nitrogen normally is in a dissolved state the bloodstream. Depressurising causes the nitrogen to come out of solution causing many things including the bends. Getting certified to dive doesn’t necessarily mean one understands what happens with rapid accent.
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Nitrogen normally is in a dissolved state the bloodstream. Depressurising causes the nitrogen to come out of solution causing many things including the bends. Getting certified to dive doesn’t necessarily mean one understands what happens with rapid accent.
I should not used “rapid accent” . “Without decompressing” would be better.
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I want to know how the a/c know or what switch tells the a/c that it is in combat.
The lower pressure schedule is activated by the tank inerting switch or the AAR door being open.
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The lower pressure schedule is activated by the tank inerting switch or the AAR door being open.
I like my top two guesses now.
At higher pressure the vapor molecules proximity is closer. This can increase volatility and a more rapid reaction when ignited.
Improves BFM, airspeed, climb rate, range and shorter landing and t/o.
lol, I think Dawton’s Law of Partial Pressure is applicable on this one. I had to memorize it for a scuba test. lol -
You guys are digging too far into this….making it harder then it is. I worked on the F-16 for 12 years and mvsgas worked on it longer then that, he knows what he is talking about, you guys should listen to him.
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I was looking at the tank pressurization (blue with black dots) that come from the reservoirs and seem to terminate in the wing tanks. I guess that’s air ejectors? Legend shows check valves but it makes sense for those to be the ejectors (or at least directly after them), a sort of air loopback.
That’s system removes air from the reservoir tanks. I think there an air/fuel separator and air is expel from the tank and injected into tank pressure system.
That is not an air/fuel separator but how the system maintains fuel levels inside of the reservoir tanks. The fuel probes in those 2 tanks have thermistors on them at the top and the bottom. The top one is the one it uses to control the air ejector valves to maintain fuel levels in the reservoirs.
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One point I don’t understand is why combat pressure schedule is low pressure. What makes low pressure better than high if you’re being shot at?
Here’s a another one:
engine that run on Hydrocarbon fuels meter the fuel at ~15:1 air to fuel ratio.
So maybe Normal tank pressure schedule is closer to that 15:1 than the Combat schedule. The richer the ratio (more fuel, less air) the safer.@Stubbie
I’ve never heard of using a thermistor for fluid level sensor. Do you know what is used for the fuel gauge sensor and res low level mastercaution? -
Yeah maybe extra air is more combustible than lower pressure which is more vapor but less air (O2).
I’m pretty sure normal fuel level sensors are capacitance type. Like http://www.ametekaerodefense.com/products/sku.cfm?ProductCAtegory_Id=4180&Product_Id=780&SKU_Id=885 Or http://www.gillsensors.com/content/fuel_level_sensors.htm
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just happy that you agreed on something here - otherwise I would have to throw in my 600 pages thermodynamics textbook from physical chemistry class - and that does hurt :rolleyes:
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I’m pretty sure normal fuel level sensors are capacitance type. Like http://www.ametekaerodefense.com/products/sku.cfm?ProductCAtegory_Id=4180&Product_Id=780&SKU_Id=885 Or http://www.gillsensors.com/content/fuel_level_sensors.htm
I flew RC a/c with an old Lockheed RF engineer. He was tasked to develop an oil level sensor for the C-130 engines. At the time they used float sensor that balance up and down. Too much probe build up for electric. He used ultrasound and his paten was for putting the transducer in the bottom of the tank, shooting the ultrasound upwards and tuning it to bounce off the surface tension. After he was done with it, he said Lockheed was trying to use it for fuel tanks.
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Does anyone know if it’s possible to inert this thread?
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Does anyone know if it’s possible to inert this thread?
Lol, some people ignore experience because what they read on the net. Sometimes the people with experience are wrong and sometimes the sources on the net are wrong. I wouldn’t argue to much with someone that worked on the jet for 10+ years and I looked on the net….just my .02 about it.
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I’m pretty sure normal fuel level sensors are capacitance type. Like http://www.ametekaerodefense.com/products/sku.cfm?ProductCAtegory_Id=4180&Product_Id=780&SKU_Id=885 Or http://www.gillsensors.com/content/fuel_level_sensors.htm
You are confusing fuel QUANTITY with fuel level sensing. Yes the quantity system is capacitance based. No the fuel level sensing system in the F-16 is not. The fuel level sensing system in the F-16 is only in the two reservoirs and it is only for maintaining the fuel level in those two tanks. It is a thermistor that changes resistance based on temperature. That temperature is dependent on whether or not the thermistors are covered in fuel or not.
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Yes, yes I am. So there’s a fuel quantity sensor and a fuel presence sensor?
Cali, is the inerting done with any regularity (with and without Halon)?
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Does anyone know if it’s possible to inert this thread?
Yes, but you need to capture the fart of a Unicorn, which is Negative Energy…also needed for warp drives! :uham:
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LOL. Dear God guys. I think we stop talking about Tank inerting 3 pages ago. So funny.
Cali, did you guys worked on the inerting system or was it electricians? I can’t remember any more. I know we change the halon bottle, but I don’t remember ever having any problems with the system, so I can remember who worked on it.Additionally, are there differences with tanks inerting pressure and air refueling pressure of the tanks?
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LOL. Dear God guys. I think we stop talking about Tank inerting 3 pages ago. So funny.
Cali, did you guys worked on the inerting system or was it electricians? I can’t remember any more. I know we change the halon bottle, but I don’t remember ever having any problems with the system, so I can remember who worked on it.Additionally, are there differences with tanks inerting pressure and air refueling pressure of the tanks?
I never worked on it, the only thnig we ever did was cap the line on top of the right wing as part of one of our checks. I don’t ever recall hearing about any problems with the system either, can’t say that about other systems.
@Frederf, not sure how regularly it was used.
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Yes, yes I am. So there’s a fuel quantity sensor and a fuel presence sensor?
There are many fuel quantity sensors in the aircraft to tell the pilot how much fuel he has. The totalizer shows the balance of all that electronic wizardry. The fuel level sensing system doesn’t do anything with the quantity. There are only two fuel level sensors (one per reservoir) so it is very much a binary system. On or off. It just manages the fuel levels in the two reservoir tanks.
Matter of fact the fuel level sensors (as well as the fuel level low warning thermistors) are mounted to the fuel quantity sensors in the reservoirs. Just to add back to the confusion.