Home » Air » AF: F-22’s Extreme Performance May Be Behind Oxygen Problems

AF: F-22’s Extreme Performance May Be Behind Oxygen Problems

by John Reed on May 8, 2012

Well, the Air Force has figured out that its likely some combination of high operating altitudes and intense maneuvering at those altitudes that is causing either toxins to seep into the F-22 pilots’ oxygen supplies or allowing insufficient amounts of oxygen to reach the pilots’ lungs.

Lt. Gen. Janet Wolfenbarger, one of the service’s top weapons buyers, just told Senators that it has narrowed down possible causes for Raptor pilots to be experiencing hypoxia like symptoms in-flight to those factors.

Now, it’s almost a no-brainer that hypoxia-like symptoms are being triggered by either contaminants entering pilots’ oxygen supplies or by the fact that said pilots aren’t receiving enough oxygen since hypoxia happens when the brain isn’t receiving enough oxygen. However, that it’s the Raptor’s crazy performance may be behind what’s feeding its pilots limited or contaminated oxygen is pretty damned interesting; it hints that the jet is pushing the limits of aerospace science. Remember, the F-22 flies higher for longer than other jets and performs maneuvers that almost no other fighter in the world can match.

“We have some recent data that we are starting to believe, we are coming to closure on that root cause,” said Wolfenbarger during a May 8 Senate Armed Services Committee hearing. “We’re realizing that we operate this aircraft differently than we operate any of our other fighter aircraft, we fly at a higher altitude, we execute maneuvers that are high-G at that high altitude and we’re on that oxygen system at those high altitudes for periods of time.”

“I’m not ready to say yet that we’re ready to declare a root cause,” she added.

Keep in mind that the Air Force has been studying this problem for years and hasn’t been able to find a cause — despite enlisting the “best minds” from DoD, NASA, academia and industry to study the issue, as Wolfenbarger reminded the Senators today. The fact that the F-22 operates at such extreme (possibly record-setting) levels beyond what other fighters — including the Navy’s F/A-18E/F Super Hornet that uses a similar On-Board Oxygen Generating System  (OBOGS) as the Raptor — may explain why no one has been able to diagnose the problem.

Meanwhile, those Virginia Air National Guard F-22 pilots who went on 60 Minutes last weekend, they’re being protected by the service as whistleblowers, according to Wolfenbarger.

Click here to read more about the woes with the Raptor’s oxygen-system.

 

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{ 101 comments… read them below or add one }

guest May 8, 2012 at 5:20 pm

These conditions, i.e. thinner air and high Gs should be relatively trivial to replicate in controlled environment, in a centrifuge with a flight simulator. If there was any basis for "its too high performance for humans" claim, which i don't think there is, this could have been tested a long time ago.
Plus there are inaccurate claims here, SR-71 had much higher flight ceiling obviously ( but not the maneuverability ). SU-37 matches or exceeds Raptors maneuverability ..

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Cthel May 8, 2012 at 5:30 pm

But the SR-71 didn't bother trying to extract breathable oxygen from the air at that altitude, it used a stored-oxygen system; likewise the SU-37 uses a conventional stored-oxygen system.

As to replicating the conditions for testing, the problem is probably synergistic; thus to test it you'd need to put almost the entire aircraft (you could probably leave off the wings and tail, but that's about all) on the centrifuge and also find some way of getting the airflow to the engines to match those encountered at the altitude and speed involved.

A more practical proposition would probably be to take an airframe, jerry-rig a stored-oxygen system (possibly put it in one of the weapon bays) and then sample the OBOGS output whilst the pilot does the sort of manuevers under suspicion (using the bottle oxygen, obviously. That should uncover the mechanism involved, and if it doesn't then there's some other problem as yet unthought of.

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guest May 8, 2012 at 6:06 pm

OK, but this kind of testing should have been happening like what, 10-15 years ago ? plus, i understand the backup EOS bottle system is practically not usable in the craft. Mind boggling.

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passingby May 9, 2012 at 1:15 am

exactly. All these so-called "production copies" are in fact prototypes by Russian, European, and Chinese standards.

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Jeff May 9, 2012 at 6:14 am

As Cthel says the problems largely synergistic; the oxygen system was probably tested to work at altitude, tested at duration, and tested in maneuvering each with margins of error and safety that they expected to compensate for dealing with more than one of those at a time. On the ground you can't really test for all three simultaneously and the margin of safety appears to not have been enouh to deal with all three at the same time.

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DGR May 8, 2012 at 10:45 pm

SR-71 flew in strait lines with sweeping turns, the F-22 is pulling combat maneuvers at these altitudes. Yes the SR system might work for the F-22, but its still a vastly different situation between the 2 aircraft.

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Ron Burgundry May 9, 2012 at 4:53 am

Strong trolling with the SU-37 claim

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Pharsalus May 9, 2012 at 7:29 am

Wha…? Trolling? The SU37 is *by far* more maneuverable than a F22. That's what "you people" keep saying, isn't it? "Oh yes, it's a superb dogfighter but our OTH AMRAAMs will have them for lunch…"

OnTopic: Why the %#&* is it so hard to rig an O2 bottle?

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Domino May 9, 2012 at 6:09 pm

SU-37 isn't more maneuverable. The F22 has to have limitations installed into its brain just to keep the pilot from tearing himself out of his flight suit. The Human body can only handle so much.

The next step is to either make them unmanned or poke and prod DARPA until they give you artificial gravity to counter-balance the extreme G-levels.

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octopusmagnificens May 8, 2012 at 5:24 pm

Junk science.

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passingby May 9, 2012 at 1:17 am

an American invention.

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Nadnerbus May 9, 2012 at 3:57 am

Damn dude. You sure love racking up the negative feedback points.

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Noha307 May 9, 2012 at 11:02 am

I love the fact that DT's "profanity protection system" stops people from using the word that means "location in an aircraft where an the pilot sits" because it contains a slang word for a male anatomy part, but lets you use the word "damn" in your post.

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Domino May 9, 2012 at 6:12 pm

I think it's cute that there's a profanity system on a Mil website. Period.

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DGR May 9, 2012 at 8:24 am

And your years of scientific research by some of the most qualified scientists in the industry has shown this and can back it up?

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octopusmagnificens May 9, 2012 at 11:12 am

The Raptor is the best fighter in the world, but its speed and agility are similar to that of other aircraft in the world. I have to laugh when I read that "Raptor’s crazy performance may be behind what’s feeding its pilots limited or contaminated oxygen". This is junk science. We are not talking about an orbital hypersonic and intercontinental.aircraft.

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freds4hb May 8, 2012 at 5:27 pm

Bono doesn't know the answer, yet I think someone else with a U-2 might know.
Break out the spacesuits and O2 tanks!

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Nick May 8, 2012 at 5:31 pm

What a BS excuse "It's doesn't work because it's just so awesome"
I still read it as
"It's broken because we didn't design it well enough but we still have no idea where"

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jamFRIDGE May 8, 2012 at 6:03 pm

Agreed.

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HarveytheRabbit May 9, 2012 at 12:05 pm

Yup, there's nothling left to learn about life support in the aerospace business. It's all a matter of applying the totally complete library of info we have on the science, physiology and engineering. Then figure in the variabilities, and voila! Done. A child could do it with the cookbook we have. That's the problem. There are no children involved.

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Andy May 8, 2012 at 5:36 pm

why can Lockheed use the F35 Oxygen tank ?

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tiger May 8, 2012 at 6:19 pm

The f-35, nor any of the latest jets use tanks. That is the reason for the development of a OBOGS system. The onboard oxygen generating system(OBOGS) is an alternative to liquid oxygen(LOX). When compared to a LOX system, the OBOGS has several advantages. First, its availability may be as high as 99 percent. There is no requirement for depot-level maintenance.The OBOGS has no daily service requirements,and scheduled preventive maintenance occurs at 2,000 hours. Incorporation of the OBOGS eliminates the need to store and transport LOX. Additionally, it eliminates the need for LOX support equipment. The potential for accidents related to LOX and high-pressure gases is greatly reduced.

SYSTEM COMPONENTS
The basic components of the OBOGS are the concentrator, oxygen monitor, and oxygen breathing regulator. The concentrator produces an oxygen-rich gas by processing engine bleed airthrough two sieve beds. The oxygen monitor senses the partial pressure of the gas and, if necessary, provides a low-pressure warning to thepilot. The oxygen regulator is a positive pressure regulator.

SYSTEM OPERATION
The OBOGS, receives engine bleed air from the outlet of the air-conditioning heat exchanger. The partially cooled air passes through an air temperature sensor to a pressure reducer assembly. The air is then routed to the concentrator. The concentrator has a rotary valve that alternates the airflow over the molecularsieve beds. The sieve beds absorb the nitrogen and allow the oxygen and argon to pass through. TWO molecular sieve beds are used in the concentrator so that while one bed is absorbing, the other isdesorbing (releasing) nitrogen. This method allows a continuous flow of oxygen to the system. After the concentrator, the oxygen flows to a plenum assembly that acts as a surge tank and an accumulator. The plenum also functions as a heat exchanger to heat or cool the oxygen to approximately cockpit temperature. Before the oxygen reaches the oxygen regulator, the oxygen performance monitor senses the partial pressure of the gas and, if necessary, provides a signal to the pilot whenever the pressure exceeds prescribed limits. The oxygen then flows through the regulator to the pilot’s mask.
http://navyaviation.tpub.com/14020/css/14020_163….

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blight_ May 8, 2012 at 7:57 pm

One could resolve this by forcing ourselves to fly at much lower performance envelopes until a "high performance OBOGS" could be deployed? Hrm.

Not a pleasant selling point for 5th gen aircraft. It may even lead to a return of LOX.

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O_o May 9, 2012 at 9:26 am

THIS needs more +1's. Can I publish your statement?

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Pat May 8, 2012 at 5:40 pm

Wouldn't you think that with all the technology that we have in this world there would be at least one person out there that could figure out this problem?

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tiger May 8, 2012 at 7:22 pm

It takes time…
NASA has the smartest folks in the world and yet nobody thought foam insulation could take out a Space Shuttle. But it did……

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blight_ May 8, 2012 at 7:56 pm

More like there was no solid consensus on if it could be done. It took a string of events to bring down the Columbia. But then again, it took a string of events to nearly destroy Apollo 13, which alerts you to the probability of a series of improbable events causing a catastrophic, even-more-unlikely scenario.

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tiger May 8, 2012 at 7:58 pm

Shit happens….

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STemplar May 9, 2012 at 2:21 am

Actually a lot of very smart people thought it was a design problem and they were told to shut up by a lot of very not smart people.

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Andy May 8, 2012 at 5:42 pm

"""""Remember, the F-22 flies higher for longer than other jets and performs maneuvers that almost no other fighter in the world can match."""""

I was right….its the PILOT not the PLANE…..

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Nadnerbus May 9, 2012 at 4:04 am

Hu? The WEINER pilot you mean?

I don't think that was what the article said at all. The theory seems to be that the high altitudes and performance envelope of the Raptor is causing problems with the OBOGS system that other fighters haven't run into. At least that is what I got out of it. If that's the case, its still a hardware problem.

Seems pretty thin though. Thiner than the air at 60,000 feet.

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HarveytheRabbit May 9, 2012 at 12:09 pm

No, it is lack of knowledge about what the pilot needs to fly and fight that leads to an inadequate specification for the hardware.

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Ben May 8, 2012 at 6:11 pm

A totally ignorant layman question, but why do fighter pilots need to breathe out of that air-hose that connects to their helmet? Why can't the cockpit simply be filled with normal air, like the air inside a pressurized commercial airliner cabin?

Is the air-hose worn so that air can still be breathed in during high-G manuevers?

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Ben May 8, 2012 at 6:23 pm

It's probably easier to filter the exhaled CO2 from the inhaled oxygen if it's contained within a mask. Probably more difficult and inefficient if you're using the entire c0ckpit. Just my guess.

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Cthel May 8, 2012 at 6:23 pm

The mask is used so that air can actually be forced into the pilot's lungs, to help prevent blacking out from sustained G-Forces.

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Ralphie May 8, 2012 at 11:45 pm

You are close, but not quite there. During an ejection the mask operates as a shield for your face, and supplies O2 upon ejection. Plus, if a low pressure differential is maintained in the cockpit say 5 psi from the mid teens and higher, vice maintaining a lower level (under 10k') cabin pressure constantly, it's much less work load on the environmental control system.

Additionally, when a tactical aircraft is maneuvering from hi to low altitudes, it would create a great amount of stress on the canopy seals used to maintain cabin pressure.

Cthel had it right too, with the forced air bit being important, but it's not really to help keep a pilot from blacking out, but instead to maintain positive pressure air flowing into his lungs if he were to black out. When performing the hick, or even when just straining, your holding your breath (sort of) vice breathing heavily, so forced air is nice but it's only a small advantage for high G stuff.

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HarveytheRabbit May 9, 2012 at 12:22 pm

I think I understand your question. I'll oversimplify my inadequate understanding . The pressure in an airliner cabin is much higher, maybe equivalent to 8000 ft. In a fighter jet, it is equivalent to about 20-25000 ft. Although the propotions of oxygen, nitrogen etc. are the same in the outside air, the "partial pressure" of them all is much less. One way to get the partial pressure of oxygen up is to increase the proportion of oxygen in the breathing air, so the lungs get about the same number of oxygen molecules per breath, and the blood chemistry is maintained like it was 8000 ft. So that's why extra oxygen helps. Too much oxygen over too long a time gives other lung problems, like…say…"Raptor Cough" maybe?

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mpower6428 May 8, 2012 at 6:53 pm

we're in bigger trouble then i thought if anybody actually buys this crap.

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Hunter76 May 8, 2012 at 6:59 pm

Guest is right, this has taken much too long to diagnose. You think they'd have installed air and blood sensors on the pitlot long ago to determine what the f is going on.

Or tried drone pilots, so they could have installed gas and air flow detectors inside the fuselage. At least then they'd have someone to blame when it flew into a mountain.

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stephen russell May 8, 2012 at 8:01 pm

Change out whole 02 system for a newer one? adapt from F16?
Or merge F16 & F18 02 systems?

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blight_ May 8, 2012 at 9:21 pm

OBOGS is coming to an F-16 near you.
http://www.cobham.com/media/75388/SYSTEM%20F-16%2

Look at the list of aircraft it's already installed in (and no, I'm not counting the raptor or JSF).

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Lance May 8, 2012 at 9:10 pm

This is more cover up by USAF brass to save there own pet fighter. A redesign is needed for the oxygen system and they have to admit it. The F-22 is way better than a crappy F-18. Well the F-15 can fly faster and climb higher and carry more missiles than a Raptor. OOOps the Generals are embarrassed again.

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HarveytheRabbit May 9, 2012 at 12:34 pm

Redesign it to what? What is the change you want? Why? Will it cause any other problems?
The F-15 is still a magnificent performer, but it dies up against the F-22, whether BVR or in a close knife fight. Jet to jet, all around the envelope, the F-22 is a superior aero/propulsion package with all the gee whiz sensors. But, it is going to the bone yard in 5 years anyway because someone powerful wants it that way, so keep calm. The F-15 will out-live it. You win.

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NotME May 8, 2012 at 9:29 pm

Well the test would be to give bottled O2 to some pilots and give OBOGS to others. Take them over over 50,000 ft and let them go at each other hard. The F22 ceiling is 65,000 ft that we know of.

The famous Mig25 routinely flew over 100,000 ft. Did they have to use stored O2?

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Ralphie May 9, 2012 at 12:02 am

Better to fly the bird up high with the pilot on an aux O2 tank, and record what the OBOGS is producing, I think. 20 lbs. heads will figure that one out.

Foxbat's flew pretty high all right, but on a LOX (O2 bottles) type system. Also, as I mentioned below, the AF requires high altitude suits to be worn above 60k', though my hunch is the jet would fly much higher given the chance.

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Vaporhead May 9, 2012 at 7:21 am

I would think so. There's video of the F-15 going up to 100k feet. I think it was testing some sort of missile that could shoot down a satellite.

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HarveytheRabbit May 9, 2012 at 12:42 pm

It is a rare (less than 1% of sorties), intermittent phenomenon that does not seem to be repeatable, even with the same pilot. Maybe all the other fighter pilots in the world are on the edge of this without knowing it, no matter what oxygen system they use.
And maybe the famous Mig25 pilots were in space suits, like the legendary SR-71 pilots?

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Dfens May 8, 2012 at 10:48 pm

So go to a LOX system and move on. Oh wait, not enough money has been spent on this yet. Sorry, carry on taking the stupid taxpayer's money.

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HarveytheRabbit May 9, 2012 at 12:43 pm

THX for the tip. What if it doen't work?

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Dfens May 9, 2012 at 1:19 pm

Which part, the LOX system? That always works. If you mean the part about taking the stupid taxpayer's money, well, that always works too. I guess there was just one answer.

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James Oberg May 8, 2012 at 11:22 pm

Is there any part of the OBOGS made in China? Just curious!

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Black Owl May 8, 2012 at 11:33 pm

I guess it would be a good idea to add multiple oxygen tanks that would increase the amount of oxygen given to the pilot if that's the case. They might cost more maintenance and need to be constantly refilled, but it's better than nothing.

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James Oberg May 8, 2012 at 11:44 pm

I'm a former system safety engineer for the Shuttle Program. NASA can miss stuff but I wonder if management is getting in the way of finding the problem. Were the design requirements met if not what is different, did the contractor or vendors who built the system cut corners without approval by the Air Force. Did cutting those corners cause the issue. Maybe it is bad engineering when it came to the design or the material used in the design not working properly. I have a Ford Expedition and it has had three throttle body replacements. Why you ask! Because the engineer who design the throttle body put a sensor that does not work properly and it will shutdown your engine forcing you off the road or putting you in a bad position like those F-22 pilots. Those pilots are in the right and should not fly. Because it is there job to defend and protect us even in peace time. Safety is preached all the time in the Air Force so lets see the managers MAN up to the challenge and ground the aircraft until further notice. Its been done before. Tired of the government being more concerned about saving face than doing the right thing.

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Black Owl May 9, 2012 at 1:15 am

"Tired of the government being more concerned about saving face than doing the right thing."

Too right.

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shawn1999 May 9, 2012 at 9:34 am

But if they aren't busy trying to save face, what exactly will they do to "earn" their oversized paychecks and undeserved pensions?

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Dfens May 9, 2012 at 1:27 pm

Most of the time mistakes are just mistakes. I question some things that happened in the F-22 program, such as the qualifications and capabilities of the people who designed the co ckpit, but certainly not their motives, which I am certain were only the best.

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Ralphie May 8, 2012 at 11:58 pm

Having flown on OBOGS and LOX, I think there are advantages and disadvantages of both. It is conceivable, however stupid, that nobody bothered to test OBOGS in the high altitude regime. The air force doesn't allow it's F-22 pilots to fly the birds above 60k' without high altitude suits (ok, ok space suits ;-) ), and most fighters operate tactically below 40k'. So the data just couldn't be there if the F-22's truly are aggressive above that (which is pretty damn impressive).

OBOGS receives air from one of the compressor stage bleed air lines, and because it was a tried and true system with relatively few (though not zero) complaints from hornet community, they most likely didn't evaluate it during the test phase properly. One would think, however, that O2 generation at varying altitudes and engine parameters should warrant a test point or two. Only one way to find out.

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Dfens May 9, 2012 at 1:32 pm

I personally think that they should stop relying on the engines to produce the compressed air for the environmental system and go to a stand alone system like the 787 did. It is easy enough to compress air using a 2 stage centrifugal compressor, or for a single place co ckpit they could use a positive displacement pump like a scroll compressor that wouldn't add any significant weight.

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Obsydean May 9, 2012 at 1:14 am

Sort of hinted at in the comments but, what or who exactly is the adversary at 60k ft we need hypoxia-inducing maneuvers to fight against? I also agree it is hard to believe the fundemental physiological issues are not long-since well-studied in the lab in humans and in animals.

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Cthel May 9, 2012 at 6:04 am

I'd guess missiles, mainly

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Ben May 9, 2012 at 11:06 am

High altitude means that you can extend the range of your missiles. A Raptor flying at 50,000 feet will be able to fire missiles that will fly further than if the Raptor were flying at only 20,000 feet.

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shawn1999 May 9, 2012 at 12:35 pm

Not to mention being able to out-fly any adversary with a lower ceiling limit- evasively or aggressively. Enemy on your 6? Go up, circle back, come down on top of him in his blind spot. End engagement. And, by perfecting 65k maneuvers, we gain the advantage by being "old hat" at it while others are new and still figuring it out.

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Hunter76 May 9, 2012 at 6:57 pm

60,000 may get you beyond a lot of weapons.

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Obsydean May 9, 2012 at 9:31 pm

I dunno. Its like this: patient comes into my office and says 'Doc, it hurts when I go like this (raises his arm or whatever)', I say, 'Stop doing that'. Problem solved.

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Mikeldy May 9, 2012 at 3:47 am

Some of the problems might be related to non-disclosure of physiological side-effects by the aircrews. Problems with a new aircraft have to be sorted out by the best test pilots and officers available and they won't risk revealing a medical issue, especially if they stand out from the crowd. They say single-crewed aircraft have no extra personnel to second-guess a pilot's judgement but that leaves only one person to keep the pilot honest…….would you admit to suffering hypoxia in the #1 ride of your career if nobody was the wiser? Not fair to leave that toilet unflushed for the next guy.

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HarveytheRabbit May 9, 2012 at 12:55 pm

Possible, but the jet has been flying since 1997 and operational since 2005. Only recently has this become a "60 minutes" issue. There have been so many flight test and operational test pilots doing so many things, a few of them should have mentioned a life support issue. What's the big deal? In keeping with the bathroom humor, I don't think you can hide who farted.

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Kool Guy May 9, 2012 at 5:16 am

Seriously, lockheed martin needs to be taught a lesson so that next time they take these defense contracts more serious. There has been so many issues with their latest designs of fighters, F22 and F35. Maybe award the 6th gen fighter or whatever to their arch rival Boeing, to let them know there is actually competition. And they will start wrapping up the F22 and F35 in order to save face and regain the public confidence for future contracts.

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Keep It Real May 9, 2012 at 9:35 am

remember that Boeings design sucked it's own exhaust when performing STOVL. Both companies will have flaws. LMT isn't the problem, High Altitude OBOGS is.

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Kool Guy May 9, 2012 at 2:07 pm

hahhaa yh high altitude OBOGS. how about the report that came in today? even land crew gets hypoxia like symptoms too.

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guest May 9, 2012 at 3:32 pm

Obviously you don't know squat about aircraft and the evaluations done during the flight test phase. Beloved Boeings aircraft the F-35's competitor (nicknamed Monica by the Pentagon ) landing gear hydraulic system failed on it's first flight. The F-35 did not have one failure during the flight test phase. I was there.

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HarveytheRabbit May 9, 2012 at 5:52 pm

I forgot to mention that the life support system design for the F-22 was part of the Boeing work share. Boeing did all the work. Lockheed installs it, and is ultimately responsible for foul-ups because thier logo is on the rudder pedals. So, then the lesson learned is never be the prime contractor, or what?

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passingnowhere May 10, 2012 at 2:50 pm

still after all lockheed is the main contractor of the jet, anything goes wrong they take the blame, cuss if the jet turn out to be a super success then they take all the credits, thats how life is. Just like Apple, majority of their iphone's hardware were produced by someone else, but the success of the iphone is solely Apple's credit. When the iphone's antenna fail, its also Apple who lost credits and take sole responsibility in compensating their customers, not those small contractors in China who produce the antennas or the phone case or any of the hardware.

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passingnowhere May 10, 2012 at 2:52 pm

Therefore, stop blaming on other guys when lockheed failed to recognize that theres a problem with the system as they are the one designing it and setting standards, testing, and etc. Cant play that child game, this is real world.

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dockem May 9, 2012 at 6:14 am

Since when are toxins of any kind allowed in the oxygen mix??

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Uranium238 May 9, 2012 at 9:50 am

One of my first thoughts was a tight maneuver where the Raptor would somehow fly through it's exhaust plume and the bleed air system sucks it in. I'm sure that would wreak hell on an OBOGS. Secondly, perhaps the OBOGS system is not built strong enough to handle the need required by the human body. It's not rocket science anymore to make an OBOGS for aircraft designers, but if they reduced the size for the F-22, that could be a huge red flag there.

Chances are Lockmart is, or will be doing the following to address it:

- Temporary install LOx systems until the OBOGS is diagnosed
- Reconstructing the OBOGS
- Identifying a solution on how to reduce OBOGS contamination in the event of extreme maneuvering

I can completely see how it's possible to suck your own exhaust in during a J-turn or a Pugachev Cobra. It wasn't long ago that the Navy realized lining up Hornets for cat launches with the engines on contaminated the aircraft's OBOGS.

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todd007 May 9, 2012 at 10:28 am

Now you've got me wondering if hypoxia could have started, even remotely, after a refueling maneuver….i.e. did the Raptor drive through the KC-135 exhaust air before/during/after refueling? Or maybe it's even simpler………intake air has to be clean air……even on the ground…..is it possible the OBOGS system is so sensitive it can sniff (parts per million) bad air and "shut itself off"? Is it sniffing PPM of pollution in the jet-stream and shutting down? You may be onto something.

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Uranium238 May 9, 2012 at 10:52 am

This is a very strong possibilty. It's almost along the lines of leaving your car running with the garage door closed while fiddling with the stereo.

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HarveytheRabbit May 9, 2012 at 1:02 pm

"a tight maneuver where the Raptor would somehow fly through it's exhaust plume and the bleed air system sucks it in."

not flying, but on the ground, there are many exhaust plumes…Hmmmm…Ahhh…I'll get back to you..

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Guest May 9, 2012 at 10:45 am

Ralphie may be on to something. Is the cockpit of F-22 fully pressurized? Working harder in a lower pressure environment all by itself is problematic. Note the Mount Everest "death zone".

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Uranium238 May 9, 2012 at 10:51 am

I don't believe it's pressurized at all if the USAF requires a Zero-G suit for ops above 60k feet.

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Ralphie May 9, 2012 at 11:50 am

No, it's going to have some pressurization, basically to keep the pilots from getting the bends and blowing out their ear drums. And the hi-altitude suits are not for 0-G's, as the aircraft probably has a 0-G and negative G limit due to engine fuel and oil starvation. Instead, the suits would be necessary in case of rapid cockpit depressurization, where serious outgassing within your blood due to the pressure differential between the outside air and the cabin pressure could cause severe decompression sickness. It happens sometimes anyways, but above 60k' there is an unacceptable risk factor for pilots without hi-altitude suits.

Think space suit, only not quite as bulky. Also, I imagine there is a requirement for an onboard supply of O2, though that is strictly a guess.

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Jon May 9, 2012 at 11:36 am

I'm not an expert but there are many air forces around the world that have Russian made fighter aircraft with thrust vectoring enhanced maneuverability. Could we possibly consult with Vietnam or Ukraine and see of their pilots have experienced similar issues? Although I think this is BS. They need to redesign the entire oxygen system, maybe other systems as well…That could mean grounding the plan for years…

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Jon May 9, 2012 at 11:37 am

I'm not an expert but there are many air forces around the world that have Russian made fighter aircraft with thrust vectoring enhanced maneuverability. Could we possibly consult with Vietnam or Ukraine and see of their pilots have experienced similar issues? Although I think this is BS. They need to redesign the entire oxygen system, maybe other systems as well…That could mean grounding the plan for years…

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Infidel4LIFE May 9, 2012 at 12:14 pm

They are replacing the filters, so maybe that will end the problem. The pilots say this plane can't be beat. They sounded ultra confident, on 60 Minutes, so damn fix the problem. The aircraft is super, so they say..

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Infidel4LIFE May 9, 2012 at 12:17 pm

You guys see the piece on 60 Minutes Sunday? Im sure many have, I saw the black gunk they scraped from the 02 line, they say it may be the filters, and these 2 pilots stood up for a reason. I hope it works. They said the plane is incredible.

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ski May 9, 2012 at 5:00 pm

Even though I’m not privy to alot of the information the air force has I’ve always felt it had to with the performance of the plane. The fact that it could perform the way it does at high speeds and has thrust vectoring not only shifting your brains, breathing and heart in ways that were not done previously. Its probably a combination of the three that causes the brain to go sleep or shut down. New limits and maneuvers are being done. It could be a phenomenon that we are not aware of that’s why we are unable to figure it out. It may have nothing to do with the oxygen since they can’t find the problem.

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Hunter76 May 9, 2012 at 7:16 pm

Ridiculous. There are other possibilities. There could be a crack in the ductwork, and air is bleeding in from a hot, oily engine compartment.

I'd suggest hiring Boeing to diagnose and bill LM. But that would just drive Boeing to take as long as possible.

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HarveytheRabbit May 10, 2012 at 11:06 am

As I said, Boeing was responsible for the design of the F-22 life support system in the first place, so this suggestion is ill-informed, except for the billing of LM part. You can be sure they are doing that for every question they are asked to answer.

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ross May 9, 2012 at 10:35 pm

any chance the biochemical products in the radar-reflecting paint are getting into the air mixture and messing with hemoglobin saturation? if they're using a newer chemical make up for the paint it could possibly explain why it hasn't affected pilots in the early years of the aircraft or in other similar aircraft that instead have closed-oxygen systems.

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John May 10, 2012 at 12:59 am

More lame crap from our Air Force "Leaders". If it's a performance problem than how come maintainers on the ground doing engine runs are experiencing the same problems. http://defensetech.org/2012/05/09/f-22-ground-cre

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HarveytheRabbit May 10, 2012 at 11:13 am

John, how do you know it is the same problem? You may be making the wrong diagnosis. There may be multiple possibilities for causing the same symptoms. Everything negative to your expectations is not a cover-up. Based on one non-technical sensational story by an un-qualified reporter, you impune the entire USAF.Wow. It is not true. It's probably only a few of them :)

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David Franz May 11, 2012 at 12:21 am

OBOGS is actually very efficient in filtering out contaminates, even nasty things like nerve gas. That is because 100% of the air comes off the compressor stages of the engine and is then absorbed by the zeolite. Traditional LOX systems dilute the oxygen with cabin air and that will give the pilot contaminates. So, contaminates aren't likely the problem. But, since water is also removed, this means that the pilot breaths very dry air. That accounts for the cronic cough some pilotst complain about. It may also cause some individuals to take shallow breaths and not expell all the CO2 from their lungs. And that, just like hyperventilation, will cause hypoxia. I tested a prototype OBOGS on my F-16 from 1981 to 1985 and loved it.

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Peter Park May 14, 2012 at 2:23 pm

Has anyone thought this may lead faster evolution towards completely pilot-less fighter jets? Yes, we are already heading there, but I mean, at an accelerated rate.

Sadness, this. But if it saves lives and gives us better leap in technology…

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Ed F May 20, 2012 at 9:43 am

They need to redesign the expansion valve which iced up at higher altitude with a much lower ambient temp. This was considered when the sub orbital Mach 2 version of the Avro CF-105 Arrow were variat before it was undermined and thrashed in 1959!!!.

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Winston May 24, 2012 at 11:00 am

The long lasting symptoms they describe cannot be due to temporary hypoxia. They must be due to some volatile organic compound (VOC) somewhere in the path of their O2 supply causing hypoxia and other long lasting effects. But those problematic carbon filters should have captured at least some of that and allowed its discovery through mass spectrometry analysis. Unless it's some sort of VOC that is itself modified into something harmless by the carbon filters before it can be analyzed. Very weird.

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johnysmith June 1, 2012 at 12:50 am

so goodbye f-22 :))
The final F-22 Raptor rolled off the production line last December 13th. http://airsoc.com/articles/view/id/4fac5770c6f8fa

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sapereaude June 25, 2012 at 6:35 pm

What a lot of completely ignorant and naive comments. Such is OK, but are just stupid when made with even a touch of arrogance. Easy to replicate in a centrifuge? No! Simple? No, MiG25 had the answer? No. Get REAL!

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Dfens May 9, 2012 at 1:24 pm

You can hyperventilate, which stems from a lack of CO2 in the lungs. Even when you breathe pure O2, though, the CO2 naturally builds up in the lungs and keeps that from happening. Plus, when you bring the cabin altitude up the mix tends to go toward pure O2 anyway, so except for the remote possibility of a fire hazard I can't think of a down side to too much oxygen.

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HarveytheRabbit May 10, 2012 at 11:29 am

It was a rhetorical question. I was referring to this: http://findarticles.com/p/articles/mi_m0IBT/is_3_
There is a saying in medicine: "The dose makes the poison", meaning a tiny amout of a toxic substance can be benign, and a massive amount of a benign substance can be toxic. It is something to think about, isn't it?

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