On 12/19/2018 8:34 AM, wrote:
The diluter-demand function of the A14, from what I have read, occurs below
a certain altitude, 30,000' if I recall correctly. In this mode the mixing
chamber mixes cabin air with O2 and the amount of O2 increases with
altitude. Above this altitude it supplies 100% O2. The pressure breathing
function is a separate function that has different dial settings for
increasing altitudes. Here the pressure of the O2 supplied not the mixture
to the mask increases. The markings on the A14 dial suggest 5 different
pressures for settings of Safety, 41,000', 43,000', 45,000', & above
45,000'. Not sure why the 1st dial setting is marked Safety but it is the
1st position when the dial is turned off normal.

FWIW...
Everything I've read (inhaled, unavoidable pun) since the early 1970s -
primary source: "Soaring" mags" (multiple/excellent "near-first-hand"
articles/columns throughout '70s/'80s) - said the same thing(s). Nothing on
RAS to which I lend credibility (i.e. "hearsay" seriously discounted) has
contradicted any of the above, since my RAS-introduction/continuing-exposure
ca. '96.


I've read the same about blood boiling. I think, as you have pointed out,
they are referring to an uncontained and uncirculating liquid and meant to
make a point about how low the pressure is. Articles I've read also use
statements like "seems to boil" instead of boils. I guess the body can
contain the vapor pressure sufficiently so it doesn't reach atmospheric
pressure and really boil. Apparently the skin will expand and early
experiments with dogs in space or a vacuum chamber discovered this. Saliva
boiling on the tongue makes sense.

I do plan to get experience in a hypobaric chamber and am hoping they will
let me use my own mask, regulator, and bottle however, I suspect this might
be considered a liability for them to allow. I still plan to ask. What
better way to test the performance of the system I intend to use at
FL350-400!

That's "exactly" what the late Bill Ivans (ca. '92) told me he did in the
years after WW-II before setting the world-altitude soaring-record (42,100',
as I seem to recall; '52?) that Paul Bikle broke (1961); memory sez both were
set in Schweizer 1-23s. Excerpts of my tape-recorded interview with Ivans
about those years of his soaring can be found in the book "Exploring the Monster".

Kinda-sorta related, I also interviewed (several times) Dr. J. Kuettner
(credited with the "scientific discovery" of standing lee waves, & Lead
Investigator of the subsequent Sierra Wave Projects), about: wave; his
experiences in same; his involvement(s) in illuminating waves' atmospheric
physics; his perception of "existing knowledge" of high-altitude physiology in
the timeframe ~'35-'55; etc.

My takeaways from my brain-picking - and a "chamber ride" ca. early-'80s) -
were/remain several...

- humans are physiologically complex critters, and one size definitely does
NOT fit all; almost certainly YMWV
- any "cast in concrete" safety claims regarding "high-altitude (say 35k'),
unpressurized-cockpit, supplementally-O2-assisted" flight beyond "It's
definitely life-threateningly risky," are likely misleading/inaccurate. "Back
then," high-altitude human physiology was FAR from being "pigeon-holed by
science" in "absolute safety" terms, and in a related vein,
"personally-derived high-altitude limits" seemed to be the accepted norm, at
least among the Sierra Wave Project participants. (Anecdotes below...)

Bill Ivans couldn't remember exactly how high he'd been taken in his chamber
ride, but "definitely" above 40k' (possibly 46k'). Without digging into
ancient notes, I can't remember how-high he set his personal limits prior to
his record-setting altitude flight, but I DO remember him chuckling that the
flight completely satisfied his "altitude curiosity!" I took that to mean he
felt he'd no continuing need to soar "near the physiological edge" going
forward. His job prevented him from piloting during the Sierra Wave Projects,
and I don't know if he was sounded out about doing so or not, but had he been
able, my long-after-the-fact guess was he might've declined.

The long-standing 2-seater world-soaring-altitude/gain flight of ~42k' set in
a Pratt-Read by Larry Edgar and Hal Klieforth (broken by Einar Enevoldsen and
the late Steve Fossett, I believe), had been intended to go no higher than
40k', the nominal limit the Sierra Wave Project soaring participants
pre-selected as their safety-limit for physiological reasons. The extra height
was due solely to the search time required to find descending air, once the
crew had decided "enough for today."

None of the Sierra Wave Project pilots could remember, or admitted to, any
"serious physiologic issues" on/after any of their high-altitude forays
(intestinal gas and cold temperatures notwithstanding). They all practiced
"best practices" before/during each flight, e.g. dietary choices, sleep
practices (not always hewed to, per Dr. K., commonly becuzza the need to
change-out batteries post-flight during a spell of more-or-less-daily standing
waves good for research), pre-breathing 100% O2, etc.

My sense is much of the "high-altitude-physiological-related" institutional
knowledge within the general sport-soaring world (U.S. anyway) has been
gradually lessened/lost due to the passage of time/aging/decreasing
availability of high-altitude chamber access for civilians/etc., to be
"commonly replaced" by a generation of pilots having distinctly different
norms for acceptable risk than the WW-II and immediately-following generations.

Insofar as deciding to take up a voluntary sporting activity (soaring, in this
case), some level of general ignorance is normally the beginning state.
Sometimes (often?) this natural ignorance is expressed in
needlessly/misguidingly stated maxims that quite simply are incorrect. This -
IMHO - is fairly common regarding high-altitude soaring flight...which is
definitely increasingly-seriously risky with increasing altitude, but those
risks are "adequately comprehensible and systematically-addressable," as
(thinks I) the history of post-WW-II high altitude soaring in the U.S. well
documents.

Personally, have at it and may good fortune accompany your preparations!

Bob W.

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