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Looking for A-14 (or similar) pressure breathing diluter demand regulator



 
 
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  #21  
Old November 3rd 18, 02:51 PM posted to rec.aviation.soaring
Tango Eight
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Default Looking for A-14 (or similar) pressure breathing diluter demand regulator

On Friday, November 2, 2018 at 6:55:07 PM UTC-4, Duster wrote:

The issue with the U2 pilots was that they were wearing uninflated suits in a cabin pressure way too low.


Okay... you're an insider then? Can you please amplify?

This isn't a great topic to speculate about.

Here are the facts as I know them:

The suit is backup for cabin pressure failure, only.

Nominal cabin pressure is 29K.

Pilot is on 100% ox (from two hours before takeoff).

This isn't a hypoxia problem.

The inference that can be drawn is that neurological DCS is more insidious than most realize. That was the point of linking the article.

T8

  #22  
Old November 3rd 18, 03:15 PM posted to rec.aviation.soaring
BobW
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Default Looking for A-14 (or similar) pressure breathing diluter demandregulator

On 11/3/2018 7:51 AM, Tango Eight wrote:
On Friday, November 2, 2018 at 6:55:07 PM UTC-4, Duster wrote:

The issue with the U2 pilots was that they were wearing uninflated suits
in a cabin pressure way too low.


Okay... you're an insider then? Can you please amplify?

This isn't a great topic to speculate about.

Here are the facts as I know them:

The suit is backup for cabin pressure failure, only.

Nominal cabin pressure is 29K.

Pilot is on 100% ox (from two hours before takeoff).

This isn't a hypoxia problem.

The inference that can be drawn is that neurological DCS is more insidious
than most realize. That was the point of linking the article.

T8


Some time in the past two months I happened to watch (on YouTube) a
(non-USAF, I seem to recall) nominally hour-long program on precisely this
issue. It named names, and included interview snippets of some of the key
principals - U2 pilots - involved. I *think* it was filmed ca. 2012-ish...as
in after confirmation of the info in TB's linked article, but wouldn't bet my
retirement on that being an accurate remembrance...but I seem to remember it
stating to the effect: "certain medically-detectable
brain-differences/potential-anomalies have been noted in former U2 pilots."

I would bet *some* of my retirement on the accuracy of remembering that ca.
2003 the USAF changed the cabin pressure of U2s from 29k to the 10k range.
Regrettably I don't remember the name of the program, and leave it to the
interested reader to ferret a link out for personal use...

Bob W.

P.S. By way of hoping to head-off RAS Thread Nazis (and I've occasionally been
one of 'em), I'll note I used - in pre EDS days - an A14-based system to soar
to ~31k feet...one time, without a backup system, and more than quite enough
for my then-somewhat-youthful risk tolerance.

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  #23  
Old November 4th 18, 02:27 AM posted to rec.aviation.soaring
[email protected]
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Default Looking for A-14 (or similar) pressure breathing diluter demand regulator

BobW: More recent than that, around 2012 or so.

T8: But you can be hypoxic even breathing pure oxygen. Yes, I was part (albeit in a small role) of the research team that lead to a series of articles on identifying white matter lesions in U2 pilots using MRI. These and other published studies convinced the Air Force to change the U2 cabin pressure from ~30K' to ~15K' (similar to Perlan II) fairly recently in a program called "C.A.R.E.". Although these brain lesions can arise via different mechanisms, they are reminiscent of damage resulting from emboli or clots. While the lower cockpit pressure had been used for many decades, one theory is that after 911, these pilots flew more frequently, for longer sorties and were tasked heavily both physically and mentally than previously. And, no, hypoxia is a problem in those conditions. Breathing 100% O2 at sea level is vastly different physiologically than at extreme altitudes since the absolute alveolar PO2 value needs to be at least ~14kPa. Even at less extreme heights breathing 100% oxygen is about as efficient as breathing air at around 12,000ft. Robert Harris for his 1986 49,009ft altitude record flew in an unpressurized Grob 102. He was forced to come down when his O2 system started to fail, apparently suffering from medical issues for some time thereafter.

Original article:
https://www.ncbi.nlm.nih.gov/pmc/art...ihms488856.pdf



  #24  
Old November 4th 18, 04:43 AM posted to rec.aviation.soaring
Tango Eight
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Default Looking for A-14 (or similar) pressure breathing diluter demand regulator

On Saturday, November 3, 2018 at 9:27:22 PM UTC-4, wrote:
BobW: More recent than that, around 2012 or so.

T8: But you can be hypoxic even breathing pure oxygen. Yes, I was part (albeit in a small role) of the research team that lead to a series of articles on identifying white matter lesions in U2 pilots using MRI. These and other published studies convinced the Air Force to change the U2 cabin pressure from ~30K' to ~15K' (similar to Perlan II) fairly recently in a program called "C.A.R.E.". Although these brain lesions can arise via different mechanisms, they are reminiscent of damage resulting from emboli or clots. While the lower cockpit pressure had been used for many decades, one theory is that after 911, these pilots flew more frequently, for longer sorties and were tasked heavily both physically and mentally than previously. And, no, hypoxia is a problem in those conditions. Breathing 100% O2 at sea level is vastly different physiologically than at extreme altitudes since the absolute alveolar PO2 value needs to be at least ~14kPa. Even at less extreme heights breathing 100% oxygen is about as efficient as breathing air at around 12,000ft. Robert Harris for his 1986 49,009ft altitude record flew in an unpressurized Grob 102. He was forced to come down when his O2 system started to fail, apparently suffering from medical issues for some time thereafter.

Original article:
https://www.ncbi.nlm.nih.gov/pmc/art...ihms488856.pdf


Thanks for that!

Following some links, I ran across this statement:
"The DCS risk per [high U2] flight was 0.076% from 1994-2005 but increased to 0.23% from 2006-2010."

That is to say, not terribly common, but not very darned rare.

T8
  #25  
Old November 4th 18, 03:54 PM posted to rec.aviation.soaring
BobW
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Posts: 504
Default Looking for A-14 (or similar) pressure breathing diluter demandregulator

On 11/3/2018 7:27 PM, wrote:

BobW: More recent than that, around 2012 or so.


Thanks for the time-correction...(and not taking me up on my possible bet;
good thing I might've bet only *part* of my retirement!).


T8: But you can be hypoxic even breathing pure oxygen. Yes, I was part (albeit in a small role) of the research team that lead to a series of articles on identifying white matter lesions in U2 pilots using MRI. These and other published studies convinced the Air Force to change the U2 cabin pressure from ~30K' to ~15K' (similar to Perlan II) fairly recently in a program called "C.A.R.E.". Although these brain lesions can arise via different mechanisms, they are reminiscent of damage resulting from emboli or clots. While the lower cockpit pressure had been used for many decades, one theory is that after 911, these pilots flew more frequently, for longer sorties and were tasked heavily both physically and mentally than previously. And, no, hypoxia is a problem in those conditions. Breathing 100% O2 at sea level is vastly different physiologically than at extreme altitudes since the absolute alveolar PO2 value needs to be at least ~14kPa. Even at less extreme heights breathing 100% oxygen is about as efficient as breathing air at around 12,000ft. Robert Harris for his 1986 49,009ft altitude record flew in an unpressurized Grob 102. He was forced to come down when his O2 system started to fail, apparently suffering from medical issues for some time thereafter.

Original article:
https://www.ncbi.nlm.nih.gov/pmc/art...ihms488856.pdf

And thanks for the link (not yet absorbed). More knowledge definitely more
better...

Bob W.


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  #26  
Old December 18th 18, 07:06 PM posted to rec.aviation.soaring
[email protected]
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Default Looking for A-14 (or similar) pressure breathing diluter demand regulator

On Tuesday, October 30, 2018 at 2:32:17 PM UTC-7, Keith Schwab wrote:
Hi Everyone!
I'm looking for an A-14 regulator, or something similar, to prepare for higher altitude wave flights in the Sierra. Curious if anyone has an one laying around they might be willing to part with or lend for a season.
Thanks!
Keith



Following up on Keith's post, I've done a lot of work investigating A14 regulators as I too am interested in getting equipped to fly high the Sierra wave. I'll spare you all the gory details of my research but here follow the key points to consider. I also found a line on several "NS", new surplus, A14s that meet all the the requirements for safe use and I will be glad to hook up interested pilots. Getting quantity and pricing info now.

A14 Issues
* vintage units use Radium-226 paint and are no longer legal. No one will work on these even if brand new.
* vintage units were only rated for 500 psi maximum inlet pressure and had a brass inlet housing. Need stainless steel inlet housing or an insert modification for anyone to overhaul.
* only FPI out of Ohio will overhaul A14s. Demand was too low for other shops to continue so most, if not all, discontinued service. If anyone knows of another shop let me know. Monopoly shops tend to charge more!
* FPI will only service FPI units build in 1990 with part #1550. They will return all other units to you. Liability issues? New A14s from FPI are $1,700.
* for the purpose of this listing, vintage = 1989 and older. I bought a "NS" unit from 1954. Beautiful but only good as a boat anchor.

A MH system will only get you to single Lennie territory (FL250). To get to double and triple Lennie altitudes, up to FL400+, you will need a diluter demand pressure breathing unit like the A14.

Masks, hoses, flow meters, pressure gauges, bailout bottles, and microphone amplifiers, jacks and plugs, to convert from military to civilian impedance radio systems, are also readily available in new condition. Contact me for details on suppliers and part numbers.

Jim
VVII
  #27  
Old December 19th 18, 06:39 AM posted to rec.aviation.soaring
Tango Whisky
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Default Looking for A-14 (or similar) pressure breathing diluter demand regulator

At FL300+, you will need a pressure suit.
  #28  
Old December 19th 18, 07:20 AM posted to rec.aviation.soaring
[email protected]
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Default Looking for A-14 (or similar) pressure breathing diluter demand regulator

TW,

Not so. FL500 is the generally accepted altitude where pressurized suits are required and by FL620 your blood at body temperature boils.

I think you are mixing up pressurized breathing with pressurized suits which is needed above FL400. I've flown to FL280 with an Alps mask on a MH system and had no difficulties. I know pilots who pushed this limit to FL320 with a MH system and an unpressurized system but this is certainly not recommended. The A14 will allow you to pressure breath at FL400 and above and apparently even a short duration trip to FL500 is possible. I personally would not go above FL450.

If you recall the recent passing of Bob Harris you will note that he flew to FL490 with a redundant A14 system. Probably the best lesson learned from his flight was the importance of having a well secured mask. Apparently he had to limit his climb because he couldn't keep his mask on as the pressure increased! He did not have a pressure suit.

Jim
VVII
  #29  
Old December 19th 18, 12:07 PM posted to rec.aviation.soaring
Duster[_2_]
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Posts: 198
Default Looking for A-14 (or similar) pressure breathing diluter demand regulator

The A-14 system, so I thought, is not a true pressure-demand type required at greater altitudes, but is a diluter-demand pressure regulated system with manual pressure valving available(?) Not to be confused with "pulse-demand" EDS. If needed I have a diluter-demand mask with microphone that can be loaned to Keith for his adventure.

While a cup of blood (or water for that matter) will boil at that altitude, circulating blood in a semi-sealed body will likely not (look up "Myth, boiling blood"). Mouth saliva would freeze first. Amazingly, experts say the astronaut in "2001 a Space Odyssey" caught in open space could theoretically have survived his short exposure.

If there's one locally, take a "flight" in an altitude chamber to discover how you function under hypoxic conditions (or you can try breathing a mixture of N2 with air/O2 to get your blood sat to 90% and less).

  #30  
Old December 19th 18, 12:11 PM posted to rec.aviation.soaring
Duster[_2_]
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Posts: 198
Default Looking for A-14 (or similar) pressure breathing diluter demand regulator

The A-14 system, so I thought, is not a true pressure-demand type required at greater altitudes, but is a diluter-demand pressure regulated system with manual pressure valving available(?) Not to be confused with "pulse-demand" EDS. If needed I have a diluter-demand mask with microphone that can be loaned to Keith for his adventure.

While a cup of blood (or water for that matter) will boil at that altitude, circulating blood in a semi-sealed body will likely not (look up "Myth, boiling blood"). Mouth saliva would freeze first. Amazingly, experts say the astronaut in "2001 a Space Odyssey" caught in open space could theoretically have survived his short exposure.

If there's one locally, take a "flight" in an altitude chamber to discover how you function under hypoxic conditions (or you can try breathing a mixture of N2 with air/O2 to get your blood sat to 90% and less). "drunk" pilot: https://www.reddit.com/r/videos/comm...are_emergency/
 




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