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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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