DIR- Generic Why use GUE nitrox only

[justinthedeeps]

You might be thinking of this article. Some U-2 pilots have experienced severe DCS including type-2 neurological symptoms. It's worth reading for divers to help recognize if they experience similar symptoms. The Air Force has modified some equipment and procedures to reduce the risk but I don't know whether those have been effective.

Killer at 70,000 Feet

The occupational hazards of flying the U-2

www.smithsonianmag.com

Is anyone enough of a wizard to estimate the GFs of flight takeoffs to 7000, 30000, and 70000 ft, with and without pre-breathing oxygen?

Maybe a "flight deco planner" in a future version of Subsurface?? Checkbox for "lost cabin pressure"?

EDIT: relevant

no fly time – The Theoretical Diver

thetheoreticaldiver.org

 

[inquis]

Is anyone enough of a wizard to estimate the GFs of flight takeoffs

The problem is identifying what GF value would be safe at such altitudes. Tons of people surface with GF=85% daily without issue. If you made a sea level dive (surfacing at GF=85%), then waited before takeoff such that your 8000-ft GF would also be 85%, you would almost certainly be bent. The study in 2002 by Duke University had DCS incidents occurring with a GF(8000 ft)=18%.

 

[justinthedeeps]

The study in 2002 by Duke University had DCS incidents occurring with a GF(8000 ft)=18%.

Today I learned why we might as well keep breathing that deco O₂ ALL the way down at the end of a deco diving trip

 

[ChrisMBC]

Is anyone enough of a wizard to estimate the GFs of flight takeoffs to 7000, 30000, and 70000 ft, with and without pre-breathing oxygen?

Maybe a "flight deco planner" in a future version of Subsurface?? Checkbox for "lost cabin pressure"?

EDIT: relevant

no fly time – The Theoretical Diver

thetheoreticaldiver.org

I think you could spoof this by setting the atmospheric pressure in Subsurface to the pressure at your target altitude, then planning a dive to a depth that equals sea level absolute pressure, for an absurdly long time

 

[inquis]

Today I learned why we might as well keep breathing that deco O₂ ALL the way down at the end of a deco diving trip

It's not uncommon after deco dives in NM to breath O2 on the drive out of town (which has a substantial elevation increase).

 

[inquis]

I think you could spoof this by setting the atmospheric pressure in Subsurface to the pressure at your target altitude, then planning a dive to a depth that equals sea level absolute pressure, for an absurdly long time

Or plan a 1 minute dive to 3 ft at 8000 ft elevation starting at your planned flight time (looking at the surfGF in the profile window).

 

[justinthedeeps]

How much dissolved nitrogen are we talking about, just from sea level saturation?

Seeing figures like ~15 mL N₂ / L (blood/'body?')
Higher for fats (~60mL/L)? But minor fraction of body tissue?
Sounds like quite a lot of gas.

Take the total volume as blood & fat only (~10 L?)
Or the whole body (~60-100L @ 1L/kg?)

Ranging from ~150 mL to ~1500 mL of total potentially gaseous nitrogen?

 

[justinthedeeps]

Now I'm tempted to make Subsurface estimate/output what actual volumes of gases are theoretically dissolved in each compartment (or the sum) at any point in a dive profile.

Relevant to the air vs. nitrox debate? What happens to these volumes on 21/35?

 

[KevinNM]

The price of oxygen is ridiculously variable. The first time I opened an account, I was charged $90 for a 300 cubic foot bottle. I immediately protested that I knew someone getting it for $60. The guy said, "OK, I can do that." As time went on and I became a regular customer, the same bottle would cost me about $20--from the same company.

I suspect it comes down to why they are running the air separator. If it’s for big customer that needs tons of argon every day, well, they have a lot of excess nitrogen and oxygen they they would like to make some money on.

 

[boulderjohn]

It's not uncommon after deco dives in NM to breath O2 on the drive out of town (which has a substantial elevation increase).

I can't begin to estimate how many times I've done this. I have breathed O2 all the way to the top of Raton Pass, which takes 2.5-3 hours.