*David,*
**
*I wonder what the acoustic properties of syntactic foam or lead is? I
know some military subs have over a inch of rubber type coating on the
exterior of there hull for a number of reasons. Including I believe
absorbing active sonar. Perhaps for a channeling device you could use a
large capped at one end FRP, PVC or ABS plastic tube coated with a thick
layer of rubber, or Rhino type coating on the exterior of the tube,
would absorb noise on the outside of the tube, but allow in noise coming
from the direction the tube is pointed. My 2 pennies worth.*
**
*My grandpa always told me I could build just about any thing if I had
two pennies to rub together. I've just about rubbed those pennies to
half there original thickness. ;}*
*
Regards,*
*Szybowski*
------------------------------------------------------------------------
From: dbartsch2236@hotmail.com
To: personal_submersibles@psubs.org
Subject: RE: [PSUBS-MAILIST] DSV 3 Turtle, Styrofoam Shot Glass
Date: Wed, 8 Jul 2009 01:39:00 -0400
Brent,
The reason for my quest for finding or using foam is this:
I need a substance that has a drastic difference in medium than that
of water (salt or otherwise) the reason being I need this barrier to
reflect sound rather than absorb it. The piezo elements we use are
actually omni-dirrectional and I need this barrier to channel the sound
from a set direction into this element.
If this barrier is not seen by sound, (as cork was suggested) but is
simply passed thru it, this will be of little use to me. sound will be
heard by hydrophones on the opposite side of a circular array farthest
from the sound source.
From the earlier discussion, I have chosen plastic juice cups at
least for initial array testing. (Other channeling devices made from
differing materials could be used in later sessions.) This I will
further explain as this testing array becomes presentable and should
should also generate great discussions.
I should point out again that I am not all knowing about this field
of passive sonar or hydrophones and welcome any suggestions or things
discovered thru testing and experimentation. By combining the sum of all
of our know how, we can derive at better sound reception for our use
aboard these submarines. This is a road to learning that is best when
shared with all.
David Bartsch
------------------------------------------------------------------------
From: brenthartwig@hotmail.com
To: personal_submersibles@psubs.org
Subject: [PSUBS-MAILIST] DSV 3 Turtle, Styrofoam Shot Glass
Date: Tue, 7 Jul 2009 01:07:55 -0700
Hi **David and Vance,
It's interesting that just before you guys started to talk about the
styrofoam going deep, I was sizing and uploading pictures I very
recently took when I got to spend a fun day with a friend of mine by the
name of Joe Hurst. The pictures I took were of a signed styrofoam cup
for Joe that went down 10,000 fsw with the DSV 3 Turtle in 1987. Joe is
a composites expert, and worked extensively on the Turtle and Sea Cliff
DSV's. I've got a pile of interesting data from Joe for you guys.
http://cid-5085d10eb6afe47c.skydrive.live.com/browse.aspx/Turtle%20DSV%203%20%20Pictures
*
Regards,*
*Szybowski*
------------------------------------------------------------------------
To: personal_submersibles@psubs.org
Subject: [PSUBS-MAILIST] Re: [PSUBS-MAILIST
Date: Sat, 4 Jul 2009 10:34:45 -0400
From: vbra676539@aol.com
One other thing to do is have everyone involved sign a cup, write info
on the dive (location, depth, dive number, etc). The cup will squash,
and the writing will squash at exactly the same rate. It will still be
neat and legible after the dive and your passengers will have a neat
little souvenier of their dive. It only works partially in shallow
water, but after a couple of hundred feet, you get a shot glass for the
bookshelf that will not reexpand or change. I've still got a few from
memorable dives. The ABS certification dive on PC-8 in Norway for
instance, plus my first time over a thousand feet, over two thousand and
then at nearly five thousand (Pisces VI in Canada).
Vance
-----Original Message-----
From: Juergen Guerrero Kommritz <groplias2@yahoo.com>
To: personal_submersibles@psubs.org
Sent: Sat, Jul 4, 2009 8:11 am
Subject: Re: [PSUBS-MAILIST]
Hello David and Vance
the Styrofoam cups are allways a nice joke in deep sea expeditions, we
put then in a bag attached to the epibenthic sledge or Box corer or
Multicorer and let them go down to the bottom and when the device comes
again on board with the sample we also have tyni cups and are allways a
nice suvenir from the expedition. Other nice joke in holydays like
easter is to put some boiled eggs in a bag and send them down. If they
go to 400020m deept the presure push saltwater inside the egg so when
you get it on board again with the sample you have a salted egg. :-)).
Crazy things people do after some weeks on open ocean. Well part of the
scientific study of effect of pressure.
Best wishes
Jürgen
--- vbra676539@aol.com <mailto:vbra676539@aol.com> /<vbra676539@aol.com
<mailto:vbra676539@aol.com>>/ schrieb am *Sa, 4.7.2009:
*
*
Von: vbra676539@aol.com <mailto:vbra676539@aol.com>
<vbra676539@aol.com <mailto:vbra676539@aol.com>>
Betreff: Re: [PSUBS-MAILIST]
An: personal_submersibles@psubs.org
<mailto:personal_submersibles@psubs.org>
Datum: Samstag, 4. Juli 2009, 13:13
*
*David,
Styrofoam is a closed cell styrene foam and will compress almost
immediately. Cups will go from coffee size to shot glass size at
just a couple of hundred feet. Wig stands (the head you spoke of)
will be slower on the inside at shallow depths, but will distort
almost immediately, just like the cups. The issue is not really
about crushing the air out--it is the physical collapse of the foam
chambers (the bubbles). They do on come back, once crushed.
Vance
-----Original Message-----
From: David Bartsch <dbartsch2236@hotmail.com
<mailto:dbartsch2236@hotmail.com>>
To: personal_submersibles@psubs.org
<mailto:personal_submersibles@psubs.org>
Sent: Sat, Jul 4, 2009 5 :49 am
Subject: [PSUBS-MAILIST]
*
* I remember years ago seeing an article in a National Geographic
showing Alvin in which a styrofoam head was shown after the
submarine had come back up from very deep. This head was stored in
an external retrieval basket and was thus subjected to the pressure
of this deep dive. It was shown compared to what the head looked
like prior to the dive and was quite small having most of the air
within it crushed out.
How much pressure or rather how deep must styrofoam go down to
expel the air within it? If it were perhaps just cups and not
thicker, would it go down to say 500 feet without being crushed smaller?
Anyone have any idea? I was concidering using simple styrofoam
as an inexpensive sonar baffling for reletively shallow operations.
How far down should this be good for without changing shape upon
returning topside?
&n
bsp; David Bartsch
*
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