----- Original Message -----
Sent: Friday, June 10, 2005 3:31 PM
Subject: [PSUBS-MAILIST] When is ambient,
ambient and 1 atmosphere, 1 atmosphere?
Hi Ray and Ian.
I understand what you are both saying. I cannot
deny what you both say makes sense.
Part of the problem is the unusual way the
Hunley's ballast tanks are open to the hull interior and part of the problem
lies with terminology.
Just what is the meaning of the word "ambient"
when applied to submarines? I know most of us here
understand NORMALLY what we
mean when we say ambient verses 1 atmosphere subs
when the subs are very OBVIOUSLY either one or the other types. But the
Hunley's open to the hull ballast tanks
throws a monkey wrench into that "NORMAL" useage
of the term ambient that we normally use. Websters defines "ambient" as ..1.
completely surrounding: ambient air. 2. Circulating, going
around.
That doesn't tell us much in what relation
ambient means to submarines.
So I guess the question is....when is ambient,
ambient? and when is 1 atmosphere one atmosphere? (according to our
understanding of the terms)
To me, 1 atmosphere is 1 atmosphere. Not over.
Now I know we say a sub is 1 atmosphere for the purposes of knowing it is not
a normally pressurized sub's interior that always equals or (closely
equals) the outside water pressure.
We use these terms so we can all know what we
mean when we talk together but they are general and broad based so we can all understand each other.
They are not exact and specific all the
time.
Such as when you described small pressure
differentials within an otherwise normally 1 atmosphere sub making it
technically not 1 atmosphere. I have been unable to find a universally
recognized
to be correct source (such as websters
dictionary) that defines specifically and technically what the term "ambient"
means in relation to a submarine. I think there is a problem with our terms
when we call a
submarine 1 atmosphere and it is not at that
pressure. To my mind a 1 atmosphere submarine that deviates from 1 atmosphere
would be a variable pressure atmosphere sub. But then again as you decend
or
accend in what we NORMALLY describe as an ambient
sub, it is a variable pressure atmosphere sub too. The problem seems to be our
terms cannot be exactly specific for all occasions for either type.
I would like to find a specific universally
recognized source that defines these terms and accounts for any variables as
to pressure that would in any way not make the terms correct.
Do we need to call ALL submarines "variable
pressure vessels" and then we would be always correct since their interior
pressure will always vary somewhat no matter what type they are? And then
further define what kind of
variable pressure vessel they are by pressure
parameters that we find out specific to them that are found out by their sea
trials and then list those specific pressure variations for each boat so that
we can know what the
pressure variations are for any given situation
or depth for any given boat? That sounds much more specific and accurate than
what our terms are now. But complicated and unable to catagorize into a one of
two word term such as
ambient or 1 atmosphere.
Now my head hurts again. Lol.
Kindest regards,
Bill Akins.
----- Original Message -----
Sent: Friday, June 10, 2005 3:26
PM
Subject: Re: [PSUBS-MAILIST] Another
response from Hunley archaeologist.
Hi,
The Hunley is a 1 ATM. 1 ATM subs do not
maintain
absolute 1 ATM pressure. The pressure does change.
The
WWII USN fleet subs had air driven gear that
vented internally. Some of
there tanks did too. Also
they would bleed compressed air into the
interior to
freshen up the air after a really long submergence. As
a
result that after extended time submerged the first
guy to open the top
hatch had to be careful he wasn't
blown out from the higher pressure
rushing out.
In PSUBS with life support using tanked O2 and
CO2
scrubbing material. There is a slight depressurizstion
in cabin
presure as the CO2 is scrubbed before the
life support system senses the
change and bleeds more
O2 into the interior. In this case there is a
slight
depressurization.
At the surface the air temperature in the
interior
maybe 80F. As you go deeper and the cabin air chills
to 70F,
60F, 50F, .... the cabin air contracts a bit,
causing
depressurization.
Consider the pressure squeeze on the hull. As the
hull
contracts the interior air volume contracts, there by
compressing
the air a bit.
Think of a 1 ATM sub as a hard shell sub that
keeps
the occupants in a non-decompression environment. They
can come
back up and open the hatch without any worry
of nitrogen
buildup.
We can also get really picky with ambients. At
what
pressure is the cabin at. Water pressure at the top of
the cabin?
Or pressure at the water depth at the inlet
level. So is that truely
ambient since the pressure
thoughout the cabin is not equal to the each
water
depth.
An ambient is a design that adapts its
interior
pressure to some surrounding water depth
pressure.
Regards,
Ray
--- Ian Roxborough <irox@ix.netcom.com>
wrote:
>
> Hi Bill,
>
> I think technically
it's 1ATM submarine, not a
> hybrid, not ambient.
> It's a 1ATM
submarine with a slight higher than
> 14.7psi internal
pressure.
> I don't see any other way of looking at it, it's a
>
1ATM that works like
> a 1ATM. The slight increase in pressure
does not
> effect how the submarine
> works.
>
> If
it is a hybrid, how does it work?
>
> Some other
examples:
> - somebody farts in a submarine and increases
the
> internal pressure,
> does that
automatically stop being a 1ATM and
> become some sort
of
> hybrid?
>
> - A
new life support system that let's out a
> little too much
O2
> causing a slight pressurization of the
cabin.
> It's still 1ATM
> and still
worts like a 1ATM.
>
> - Some military subs vent
certain tanks into the
> pressure
vessel
> causing a higher internal pressure,
but this
> doesn't changes
> anything
about the sub that stops it from being
> 1ATM.
(Can't
> remember which tanks or which subs,
but I
> remember hearing older
>
submariners complaining of ear poping when they
> vented
certain
> tanks.)
>
> I've sure
there are others as well (so I could be
> wrong with
> some of
the above), but a minor increase in pressure
> in 1ATM
> doesn't
stop the boat from being a 1ATM, nor does it
> add any
>
features of an ambient.
>
> Cheers,
>
Ian.
>
> On Fri, 10 Jun 2005 00:41:57 -0400
> "Akins"
<lakins1@tampabay.rr.com>
wrote:
>
> > You raise valid points Ian. But if the
Hunley was
> not ambient, she could not technically be 1
>
atmosphere either, since any compression of her
> atmosphere over 1
atmosphere of pressure would
> technically make her not 1
atmosphere.
> >
> > I am starting to wonder if the Hunley
is actually
> neither, but a hybrid of both, not falling
>
technically into either catagory but having
> attributes of both.
Something I have never seen
> before.
> >
> > I
received another e mail from the Hunley
> archaeologist Michael P.
Scafuri as a follow up to
> his first e mail. In it he said that they
are not
> really sure how the Hunley worked yet, and that
>
further investigation may prove that she was
> >
> >
slightly buoyant and did have to use her forward
> motion and dive
planes to submerge like the later
> Holland did. This somewhat
contradicted his first e
> mail and further confuses the
issue.
> >
> > I wrote him back again asking for a
definite
> answer as to whether the Hunley was ambient, not
>
ambient, or some kind of hybrid. I also mentioned we
> would love to
know if she was always slightly
> positive buoyant as soon as
he
> >
> > and the conservatory can determine that. So
bottom
> line here is the best information we have coming
> from
the archaeology experts is that they are not
> sure of a lot of things
yet. I'm trying to find out
> for us all, but we may have to
wait
> >
> > for more investigation by them, or we may
actually
> not ever know. Here's our latest correspondence
>
below. The first below one is my response to his
> original e
mail, the second one his lastest and
> second e mail to me, and the
third one my latest e
> mail
> >
> > to him that I
am waiting for a reply from him on.
> I'll post his reply here as soon
as I receive it.
> The mystery of the Hunley goes on.
> >
> > Kindest regards,
> >
> > Bill
Akins.
> >
> >
> > ----- Original Message -----
> > From: Akins
> > To: Michael Scafuri
> >
Sent: Thursday, June 09, 2005 3:05 PM
> > Subject: Re: H.L.
Hunley
> >
> >
> > Thank you very much Mr.
Scafuri.
> >
> > I posted your reply to the PSUBS.ORG
forum where
> we have been discussing the Hunley a lot. I know
>
they will be glad to hear from you.
> >
> > I had thought
that the Hunley was always slightly
> positively buoyant like the
later Holland submarine
> was and that she had to use her dive planes
to
> >
> > force her under like the Holland did. From
your
> reply it seems the Hunley was technically ambient
> but
not always slightly positive buoyant.
> >
> > Thanks
again for your reply clearing these
> questions for me.
> >
> > Kindest regards,
> >
> > Bill
Akins.
> >
> > ----- Original Message -----
> >
From: Michael Scafuri
> > To: Akins
> > Sent: Thursday,
June 09, 2005 3:55 PM
> > Subject: Re: H.L. Hunley
> >
> >
> > I am glad to help. Please keep in mind
though
> that, at this point, we don't really know how
the
> Hunley performed, how seaworthy she was, exactly
> where
her waterline was, etc. It is still
> speculation for the most
part - educated speculation
> but speculation nonetheless.
We might find out one
> day that yes, she did in fact need her dive
planes
> to submerge; I don't think so, but with such a
> unique
vessel almost anything could ultimately be
> true. The Hunley
has surprised us before.
> > Take care,
> >
> >
Mike Scafuri
> >
> >
> >
> >
>
> Hi Mr. Scafuri.
> >
> > Thanks again for your help
and explainations.
> >
> > I take from your most recent
e mail that it is
> actually unclear if the Hunley was always
slightly
> positive buoyant like the Holland submarine was. As
>
you said you may find that the Hunley was only able
> to submerge by
using her forward motion and dive
> >
> > planes to keep
her under just like the Holland
> submarine. I understand it will take
a lot of time
> and research to acertain exactly how she
really
> worked.
> >
> > One thing I hope you could
clear up for me is
> whether the Hunley was technically ambient or
not.
> Was she ambient because her atmosphere was slightly
>
compressed due to the ballast tanks
> >
> > being open to
the hull interior? Or was she NOT
> ambient because of what my fellow
Psub.org member
> says here....."I still don't see any reason that
the
> Hunley is ambient. If it was ambient it couldn't
>
>
> > dive without pressure compensation, this does not
>
appear to the the case. Unless some piece of
> information is missing,
the Hunley is 1ATM. The
> crew were always subjected to surface
pressure (give
> or take the very small amount of
> >
> > pressure increase from the ballast tanks venting
> into
the cabin). Once submerged, it doesn't matter
> what depth the
Hunley is at, the crew will be under
> the same pressure, if it was
ambient, the pressure
> the crew would be experiencing would
>
>
> > be the same as the external water pressure. If
>
somebody can supply me the internal volume of the
> Hunley and the
volume of water used to dive, I will
> calculate the internal pressure
after diving."
> >
> > So Mike, could you please clear up
for us whether
> the Hunley was technically ambient or not? Was
she
> some
=== message truncated
===
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