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Jungmann
08-21-2007, 12:34 PM
When 8th AF Libs and Fortresses neared their targets, and the fighters started boring in and the flak started coming up, did the aircrew turn the knobs on their oxygen regulators from Auto to Full Oxygen, to calm their beating hearts?

Anybody ever hear anything about this?

Jungmann
08-21-2007, 12:34 PM
When 8th AF Libs and Fortresses neared their targets, and the fighters started boring in and the flak started coming up, did the aircrew turn the knobs on their oxygen regulators from Auto to Full Oxygen, to calm their beating hearts?

Anybody ever hear anything about this?

LEBillfish
08-21-2007, 12:48 PM
I'd find that hard to believe....most of all for the reason that pure oxygen for too long is a sure way to kill you.

FPSOLKOR
08-21-2007, 01:12 PM
No... If they would look for a switch of the oxygen, they would not press a trigger, what could lead to being killed...

Jungmann
08-21-2007, 01:59 PM
Thanks for the reply, LEB, but I'm not sure I agree with you.

My source is a copy of a Pilot's Information File, revisions to May 1, 1945, from the library at Castle Jungman. This was issued to all AAF pilots from around 1943 on. It has a section on oxygen use, and that section was added to the specific information files issued to all other bomber crewman.

On the opening page of section 4, Man Goes Aloft, there's a chart showing the percentage of oxygen in the free atmosphere with increasing altitude. At sea level, it's 20.9%. At 25,000 feet, a good average for 8AF bombing runs, it's 7.8 percent.

On page 4-2-1, the file discusses oxygen regulators, type A-9 and A11. These were placed at all stations for aircrew. They were basically aneroid barometers connected to a valve--as the airplane climbed, the valve opened and let more oxygen flow to the user's mask. They were set to deliver a combination of oxygen from the stored tanks and ambient air that would be the equivalent to free breathing at 10,000 feet.

The regulators had a valve that could be switched between normal oxygen and 100% oxygen. Obviously, normal was for normal use and the normal mix of oxygen and ambient air depending on the altitude. But the valve could be turned to 100% oxygen, which would bypass the barometer and flow 100% oxygen to the mask. And with both regulators, above 30,000 feet, page 4-2-2 says the "air intake port is entirely closed and the oxygen port is wide open and delivers pure oxygen to the mask." The same regulators were used in USAAF fighters, by the way.

The PIF isn't clear on what physiological effects there may be from breathing pure oxygen, but clearly it sees no reason it can't be done--and must be done--over 30,000 feet

But the PIF does say when 100% oxygen must be used, and that's in emergency cases where carbon monoxide, gas vapors, hydraulic vapors, or smoke. In the case of carbon monoxide, for example, the manual says on page 4-4-1: "The only safe rule for protecting yourself against carbon monoxide in flight is to wear your oxygen mask with the Auto-Mix in the "OFF" or "100%" position whenever you smell exhaust gases. In this way, you get pure oxygen to breath and are completely protected from any gases in the cockpit. As soon as you safely can, land your plane and report the trouble to the Engineering Officer."

So the PIF doesn't mention side effects from breathing 100% oxygen, but in this passage, it seems clear a pilot was advised to keep his regulator delivering 100% oxygen until the emergency was over, or until he landed, which might be a matter of hours.

I flunked biology, Billfish, so I have no idea what the affect of breathing pure oxygen might be, but at least in this official manual, aircrew are instructed to breathe pure oxygen during emergencies until they're back on the ground.

And this returns me to my little question. I know from books that aircrew often suffered from anoxia on high altitude missions, either by misuse of their equipment or battle damage, and the first thing anybody did was clamp a mask on their face and feed them full oxygen, undiluted. I just wondered if aircrew ever used full oxygen during the most tense parts of their missions, in order to reduce the strain on their hearts, to calm them down as their heartbeats increased.

LEBillfish
08-21-2007, 02:48 PM
The human body can only endure "pure" ovygen so long, as the repiratory system then decides it doesn't need to work to get it...Hence, trapped on it........Least how it was explained to me in FF training. Though clearly no physician by any means.

FPSOLKOR
08-21-2007, 03:06 PM
From medical point of view 2 effects cam be obtained from pure oxygen inhalin - your lungs will dry out and "Burn"? not by flames of course, but by somewhat similar chemical reaction (thats why oxygen is usualy given through spirit) and second - yes, human breathing is based on the CO2 level. If it's too low brain decides there is no need for further breathing.

Scen
08-21-2007, 03:14 PM
Okay here is how it works. If you start to breath pure oxygen it washes your blood of CO2 which will make you pass out. Your body actually needs a certain amount of CO2.

It's the same thing as Hyperventilating and why they want you to breath into a paper bag. If you don't you will continue to over Oxygenate your blood and you pass out. What makes you want to breath is CO2. Hold your breath and you will quickly learn why.

Sorry I simplified that's pretty much what happens.

It's probable that some did play with the mixture and it would make breathing easier but you have to be very careful. What is scary is at those very high Alts like 30k and above it's very dangerous. If you are starved of O2 you have only a few seconds of useful concisenesses. Hypoxia is bad news for anyone but especially Pilots. All your higher level thinking goes down the tubes and fast

Doolittle81
08-21-2007, 03:23 PM
The cited side effects of breathing pure o2 are in cases of extended continuous breathing of same...such as under certain medical procedures. A few hours at 100% is going to do no permanent damage. As noted in the earlier post, and as practiced today, near 100% o2 is normal above 30,000 feet or so...in an unpressurized situation. The gunners on WWII bombers (unpressurized as they were, with exception of B29) would already be at 80-90% oxygen during their "high-altitude' mission profiles...kicking it up to 100% could give a bit of psychological boost, perhaps. In my military flying days, the first thing I'd do settling in before takeoff would be to suck in a few minutes of 100% Oxygen to clear my head/hangover.

WhtBoy
08-21-2007, 03:32 PM
Keep in mind that at 30000 feet the pressure is only 25% of sea level pressure with an equivalent reduction in the volume of each breath. So 80% oxygen at 30000 feet would generate the same partial pressure of oxygen as you get at sea level.

Conversely, when scuba diving, at about 130 feet, each breath delivers the same amount of oxygen as you would get if you were breathing 100% oxygen at the surface. That's why the recreational limit is set at 130 feet b/c beyond that, oxygen toxicity can become a problem. Of course it all depends on the person and some people have done 250'+ dives on air. Then again, some of those people died doing it.

While I am no doctor either, I would think that your metabolic process would be quick enough to use up a high concentration of O2 fairly quickly.

--Outlaw.

ImMoreBetter
08-21-2007, 03:32 PM
Just so we know what we are talking about here...

Oxygen was stored in 18 type G-1 Cylinders. Each cylinder was approximately 5 hours for one man at 30,000ft.

100% oxygen was used to prevent illness (The bends) or for medical treatment (shock, blood loss), or protection from poisonous gases.

Oxygen use started at 10,000 feet. Except at night, where it was used all the way up (Not 100% oxygen).


The flight manual cautions the use of oxygen. It is strongly advised not to use pure oxygen unless absolutely necessary, there was little extra oxygen onboard.

If a crew did use pure oxygen for some parts of the mission, it may have been a deadly gamble.

Nevertheless, I'm sure some crews DID use the oxygen inappropriately.

I'd have some charts on man-hours of oxygen. But they are not complete. I don't have the difference between 100% and mixed oxygen.

Doolittle81
08-21-2007, 03:41 PM
I think there is some confusion in the thread between CO2 and nitrogen.

Another note...During spacesuit opeations, astronauts breathe pure 100% oxygen...side efects, I assume, are very acceptable.

Copperhead310th
08-21-2007, 05:51 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by LEBillfish:
The human body can only endure "pure" ovygen so long, as the repiratory system then decides it doesn't need to work to get it...Hence, trapped on it........Least how it was explained to me in FF training. Though clearly no physician by any means. </div></BLOCKQUOTE>

Billfish they would not have been breathing pure Oxygen. They would have been breathing Aviator Oxygen Wich is a speacilty gas mixture. & yes such a thing exists. I deliver it to the airport persoanly about twice a week. To the 187th Fighter Wing Ala. Air National Guard & to ASE Airlines.

This artical should explain everything in fine deatail regarding oxygen use in US military Avaiation, Jungmann.
A Brief History of US Military Aviation Oxygen Breathing Systems (http://webs.lanset.com/aeolusaero/Articles/Oxygen%20Systems%20history--Pt1.htm)
Artical by:Christopher T. Carey

Ares_336sqn
08-21-2007, 06:42 PM
The important factor is not the concentration of oxygen but its partial pressure.

Breathing 100% oxygen at sea level can cause pulmonary edema, blindness, atelectasia (parts of the lung will collapse) etc. after 12 to 24 hours. That does not mean it is ok to do that for a shorter period of time at sea level

Astronauts breath high concentrations of oxygen for many hours at really low atmospheric pressure.

Breathing high concentrations of oxygen for a few hours to treat CO poisoning is standard practise. But the patient's life is at stake in this case anyway, so it has to be done.

Copperhead310th
08-21-2007, 07:00 PM
iT IS ALSO IMPORTANT TO NOTE THAT THE ONLY DIFFERANCE between Medical Oxygen & Welding Oxgen is the purity content ppm (part per million) And you can breath the wellding gas Just as well as you can the Medical or Aviator.
So if you ever find your self traped uner a bridge that colapsed in a river (hey it's happend recantly) try and remember if you were behind a welding gas supply truck. Cause if my truck ever crashes and i find my self underwater....i'm going for the 1st oxygen tank i can find. lol
(would be my luck i'd grab a tank of Nitrous Oxcide)

WhtBoy
08-21-2007, 08:36 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Copperhead310th:
(would be my luck i'd grab a tank of Nitrous Oxcide) </div></BLOCKQUOTE>

At least you'd die happy!!! NOx is good stuff.


--Outlaw.