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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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