[PSUBS-MAILIST] Terminating a conical transition
Joe Perkel via Personal_Submersibles
personal_submersibles at psubs.org
Mon May 5 07:22:56 EDT 2014
Jim,
I had not seen that particular spreadsheet, thank you!
I do have the advantage of software that will accurately calculate weights and balances based on materials and position within the model. But, I have to get the broad strokes done first to do some fine tweaking later. In the past, all this was done on paper and then trial and error in practice.
Joe
On Sunday, May 4, 2014 9:09 PM, via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
Joe,
Per ABS, the CB must be at least 2" above the CG when
submerged. It must still be at least 1" above in the event the drop weight
is released.
When I was considering auxiliary saddle tanks I planned to
position them so the tops were even with the water line when all tanks were
blown. My thinking was to gain the maximum freeboard available since any
portion of the tanks above the water line contributes nothing to buoyancy.
However Alec very correctly pointed out that the portion above the water line
functions as reserve buoyancy to counteract roll when that side of the boat is
depressed such as when someone steps on that tank.
The CG/CB spreadsheet that Cliff developed is on the Psubs
website. It's an excellent design tool. If you aren't already using
it: Psubs/org>Resources & Reference>Design
Tools. "Ballast & Buoyancy Control" is on the menu at
the left side. Once you open the spreadsheet, choose the tab at the bottom
labeled "Instructions."
Best regards,
Jim
In a message dated 5/4/2014 4:54:05 P.M. Central Daylight Time,
personal_submersibles at psubs.org writes:
Hank,
>
>
>Most boats see about 100 hours use a year. I expect this to be no different. I want a neat little toy to play with in the garage on the occasions when my wife turns me loose! :)
>
>
>This is why I want to section the hull,...and I just convinced myself to shorten the thing a bit!
>
>
>Joe
>
>
>
>
>On Sunday, May 4, 2014 5:45 PM, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>Joe,
>Sounds like you need to have the longest
cones possible at each end to reduce the size of the free flooded areas.
Another option is to change the design, decide what your priorities are.
What is most important? if long transits are the plan then you may need to
change things. If fuel cost is a consideration, another change.
Looking very cool dock side, you nailed it. It just wouldn't be fun if it was
easy.
>Hank
>--------------------------------------------
>On Sun,
5/4/14, Joe Perkel via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>Subject: Re: [PSUBS-MAILIST] Terminating a conical
transition
>To: "Personal Submersibles General Discussion" <personal_submersibles at psubs.org>
>Received:
Sunday, May 4, 2014, 5:30 PM
>
>Sean,
>Have
>you ever notice how the
Civil War design of the USS
>Alligator stabilized the boat submerged? A
couple of crazy
>little tethered floats, but the rationale
has
>never escaped me.
>I
>will reduce free flood space wherever I
can. Trapped
>inertia being on my mind, but I needed someone to remind
me
>of the waste in efficiency / power requirements,
>thanks! Also,
your comments bring home some compelling
>reasons to shorten the
design with a "Just
>enough but no more"
design
>mindset.
>I've
>given thought to the conical section in the
front, I can
>reduce this down to a 30" head with forward viewing
ala
>Kraka, but quite the tight fit! Not sure, I have to give it
>some
more thought.
>If
>I reduce the aft end with a cone, then I would bring
the
>motor inside and do a standard marine hybrid
>installation.
Expensive, but certainly a more reliable
>answer. If I do that, I would
dispense with the notion of
>propulsion units in the aft end of
the pods, truly no
> need then. This boat
requires a massive
>ventilation / climate control scheme for
surface operations,
>that's why I've been overly generous with
the
>machinery space in these early drafts.
>I'm
>still concerned about
stability because I have to contend
>with what to do with all of that
centerline space. The VBT
>would take up some, but I would have to flood
the
>rest.
>Thanks
>again Sean!
>Joe
> On Sunday, May
4,
>2014 4:56 PM, Joe Perkel via Personal_Submersibles
><personal_submersibles at psubs.org> wrote:
> Hank,
>What
>you see there is the
>
original Seehund arrangement, my intention is as you say,
>up higher. The
aft cone on mine essentially now an MBT.
>Those lower volumes will be
flooded in practice, but I am
>wondering if they could be blown down dry to
help with
>trailer launching and recovery??
>Plenty,
>and I mean plenty
of room along the centerline for keel
>ballast.
>I
>keep thinking about
what you've told me regarding Gammas
>attachment, always in the back of
my
> mind!
>Thanks
>Hank!
>Joe
> On Sunday, May
4,
>2014 4:34 PM, hank pronk via Personal_Submersibles
><personal_submersibles at psubs.org> wrote:
> Joe,
>Your dive tanks are to low, they should be
at
>the top of the sub. The way you have it will be
less
>stable.
>The motor pod should be okay, just
>like the K subs. You
do not want your torpedo's to be
>buoyant, they should be as heavy as
possible
for
>stability.
>Hank
>--------------------------------------------
>On
>
Sun, 5/4/14, Joe Perkel via Personal_Submersibles <personal_submersibles at psubs.org>
>wrote:
>
>
Subject: Re:
>[PSUBS-MAILIST] Terminating a conical transition
> To:
"Personal Submersibles General
>Discussion" <personal_submersibles at psubs.org>
>
Received: Sunday, May 4, 2014, 3:07 PM
>
> I've
incorporated
> some of the suggestions in the attached
>drawing.
Still,
> I've got a lot to think
>about here but I am also
excited
> about the
>possibilities and the potential outcome.
This
> image should give some idea of
> what's on my
mind.
> What you see is the
>water ballast arrangement
> on
the original
>Seehund, and how my proposed pressure
>
>boundary fits
into this scaled down version. The
>following
> is a list of
concerns and or
>design
> considerations.
>
>1)
>
Clearly, I have no need to compensate
>for the loss of
>
>
torpedoes
> 2)
> New pressure
>boundary provides for massive
MBT volumes
>
>(Low pressure compressor to blow
down
>
>volumes)
> 3)
> Torpedo
>battery pods may need
to incorporate some free
> flooding spaces to reduce weight, or
perhaps
>reduce battery capacity to a single pod in
>
>lieu of the
former forward water ballast tank, then
> completely free
flood both torpedoes
>completely??.
> (Boat will incorporate
a
>gen-set)
> 4) Questionable
>
>reliability of external motor
pod assembly.
>
>5)
> Stability considerations
> Thanks
for the input
> gents,
>It really helps me to take a step back
on
>
>occasion!
> Joe
>
>
>
On
>Sunday,
> May 4,
> 2014 10:19 AM, hank pronk
via
>Personal_Submersibles
> <personal_submersibles at psubs.org>
>wrote:
>
Joe,
>
>When I mounted the tanks back on
> Gamma, I
changed the
> mounting location to
>give a greater angle also I did
what
> Vance
>is saying on a small scale. I then
poured
> a gallon of paint in
> each tank and rolled the
sub slowly to
>ensure there was
> complete paint
>coverage.
If I was operating in salt
>
>water I would mount some nipples to the
tanks with
> plugs. After a dive in salt water,
>remove the
plug and
> you have access to
>spray fresh water inside and rinse
the
> salt
>water out. A large panel is a good idea also
because
> you
> can open it up after each
>dive and let it
dry out.
> If I
>had a K350, I would not copy the
Nekton tanks
> exactly. I would change the shape so
>they have
more
> volume at the top reducing
>the
> rolling effect.
Also I would
> consider
>making them from SS. Also SS heads solves
the
> problems entirely. Start watching ebay for ss
>heads.
I
> once saw a ss tank exactly
>the
> same as a 500gal
propane tank
> for 1,500
>dollars on ebay.
>
Hank
>
>--------------------------------------------
> On Sun,
5/4/14, via Personal_Submersibles
><personal_submersibles at psubs.org>
>wrote:
>
>
>Subject: Re: [PSUBS-MAILIST] Terminating a conical
>
transition
> To: personal_submersibles at psubs.org
>
Received: Sunday, May 4, 2014, 8:32
>AM
>
> Joe,
>
>
>
>
> Consider using an elliptical head
back
>there, for
> starters. You aren't
>building for much depth
here, so
> the
>K-350 size will be fine (.375" ish). The
ellipses
> are cheaper, do the same job, and give
>you a touch
more
> inside
>room. Then I would have
> a cone
rolled
> with a short flange on
>the major diameter, maybe a
couple
> of
> inches, to match the hull OD.
>
>
>
>
>
> The
Nekton
>cone-to-dome caused a
> pinch point
>that was always a
hassle to clean and paint,
> and
> ultimately left
>some
pitting in the pressure hull that had
> to
>
be
>weld-repaired. A short cylinder on the sheet metal
> would give
you a little more room under
>there to sandblast
> and paint
during
>assembly and later for overhauls. I would
> say for
maintenance a couple of
>flush-mount, gasketed
> panels
> in
the tank would serve you well.
>Don't make them
> too
>
ornery to remove or you
>won't do it as often as you
>
will
> wish you had.
>
>
>
>
>
> I'm wondering now about my own
> boat and using
tanks like that. Is there
> anyone in the
>
group
>
>who can plug and chug a metacentric height on
Nekton
>tanks
> installed on a K-350? Assembly
>would be so simple
that
> way.
> And it would tow better, which is always
>a
good thing. The
> Nektons roll a bit,
>but are reasonably stable. A
K with
> the
> pods should have plenty of weight down
>low.
Hmm. Would it
> work? I'm
>thinking yes. Anybody else have an
opinion
>
>on
> that?
>
>
>
>
>
> Vance
>
>
>
>
>
>
>
> -----Original
>
Message-----
>
> From: Joe Perkel
via
>Personal_Submersibles
> <personal_submersibles at psubs.org>
>
> To:
>personal_submersibles
> <personal_submersibles at psubs.org>
>
> Sent: Sun, May
>4, 2014 12:28 am
>
> Subject:
Re: [PSUBS-MAILIST] Terminating
>a conical
> transition
>
>
>
>
>
>
>
>
>
> Vance,
>
>
>
>
Rethinking that aft assembly to make it
>all soft tanks aft
> of a
hemi head ala
>Nekton.
>
> If I
>go weld-on to the head
ala Nekton, how best to attach
> to the head to allow for periodic
access
>and maintenance?
>
>
>
>
Joe
>
>
>
> Sent from Yahoo Mail for iPad
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> From:
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via
> Personal_Submersibles <personal_submersibles at psubs.org>;
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> To:
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<personal_submersibles at psubs.org>;
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Subject:
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> Re:
> [PSUBS-MAILIST]
Terminating
> a conical transition
>
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>Sent:
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Sat, May 3,
>2014
> 2:03:36 PM
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> Joe,
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> It
> seems like
an expensive and complex
>assembly for what you
> get. Why
not
>close the aft segment in a simpler way and
> fair
> the
stern to the
>shape you prefer? A hemisphere with an
> extended
shaft housing to put the prop
>where you want it,
> for
instance.
>
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>
Vance
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-----Original
>
>Message-----
>
>
>
>
From: Joe Perkel via
>Personal_Submersibles <personal_submersibles at psubs.org>
>
>
> To: Personal Submersibles General
>Discussion <personal_submersibles at psubs.org>
>
>
> Sent: Sat, May 3, 2014 8:17 am
>
>
> Subject: Re: [PSUBS-MAILIST] Terminating
>a conical
>
transition
>
>
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Sean,
>
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>
>
>
> Yes,
> a
bolted
>flange with O ring.
>
>
>
>
>
>
>
>
>
>
>
I've
> attached an image of what's on my
>mind. This hull
is
> 36" OD,
>cylinder length is 120". Anything bigger
> in
diameter, simply gets way to big and
>bulky for
>
handling.
>
>
>
>
>
>
>
>
>
>
>
>
I'm
> thinking at this size, I must bolt at
>least two
hull
> sections together for
>outfitting and maintenance, and
the
>
>cones can be un-stiffened or perhaps only at the
>
joints.
>
>
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> Joe
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On
>Friday, May
> 2, 2014 9:50 PM, Sean T.
>Stevenson
via
> Personal_Submersibles
> <personal_submersibles at psubs.org>
>
wrote:
>
>
>
>
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> Each cone
>section in that case is
considered
>
>alone, so if you were using stiffeners, you would need
a
> heavy stiffener at every joint.
>Depending on the size,
it
> may be
>simpler to use unstiffened geometry for such
an
>
> assembly.
>
>
>
>
>
> The rules do not address bolting
>pressure
> hull
sections together, but
>I don't see why you
> couldn't,
>provided
you meet the requirements in terms
>
>of
> the stress analysis
under the
>maximum combined loading
> conditions,
>which are
prescribed in the ABS rules.
> Might
> require
>some FEA to
be sure. You're thinking an O-ring
> groove seal? Or other
arrangement?
>I think an ASME
> code compliant flange
>would
be a good place to start, but
> I
> would make sure that the
cross-sectional
>area of each half
> of the flange
>considered
individually met the requirements
> of
> a heavy stiffener per
ABS, at a minimum material
> location
> (bolt hole).
I
>would also be inclined to use SuperBolts
>
>for
> the
connection.
>
>
>
>
> http://www.nord-lock.com/superbolt/multi-jackbolt-tensioners/
>
>
>
>
> Sean
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> On May 2,
2014
>6:03:21
> PM MDT, Joe Perkel via
>Personal_Submersibles
<personal_submersibles at psubs.org>
>
> wrote:
> Sean,
>
>
>
>
>
> Would the heavy stiffener rule apply
>equally to
several
> cone
> segments stepping down at
different
>angles?
>
>
>
>
>
> Also, do ASME
>pipe flange specifications translate
equally
> to bolted
> pressure hull sections? Have I missed a
section
> somewhere on bolted cylindrical
>sections?
>
>
>
>
>
> Very helpful
>Sean
thank you!
>
>
>
>
>
>
Joe
>
>
>
>
>
> Sent from
Yahoo Mail for iPad
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> From:
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Sean T. Stevenson
> via
>
>Personal_Submersibles <personal_submersibles at psubs.org>;
>
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To:
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> Personal
>
Submersibles General
>
>Discussion <personal_submersibles at psubs.org>;
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>Subject:
>
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>
Re:
> [PSUBS-MAILIST] Terminating
> a conical transition
>
>
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>
>
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> Sent:
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> Fri, May 2, 2014
>
11:45:11 PM
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> 2:1
>semi-elliptical heads are
usually
>
>fabricated with some
> length of straight flange
(tangential
> cylindrical section) beyond the axis of
>the
ellipse.
> Hemispherical heads may
>or may not have a straight
flange
>
>section, but in either case are
> permissible to
use
> adjacent
> to conical sections, provided all
other
>requirements are
> met. For stiffened
>cones, you must have
stiffeners meeting
> the "heavy stiffener" criteria
>at both ends,
as
> close as practicable
>to the cone-to-cylinder
and
>
>cone-to-head transitions. For unstiffened cones,
the
> length
> L_c used in
>overall buckling calculations
must be the
>
>total
> length between the next heavy
>stiffener
to either side of
> the
>entire compartment length, or between the
40% of head
> depth points if otherwise
> unbounded.
Cone to head
> welds are done in the same manner as
>cone to
cylinder
> welds,
> and if your
>
> head is
supplied w!
> ith a
> flange, it is the
same
>
> thing.
>
>
>
>
>
> Sean
>
>
>
>
>
>
>
>
>
>
>
> On
May 2, 2014 2:48:52
> PM MDT, Joe Perkel via
>Personal_Submersibles
<personal_submersibles at psubs.org>
>
wrote:
>
>
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> I have
>
spotted the ABS diagrams and
>specifications for
> re-enforcement
and
>butt welds at conical to cylinder
>
>transitions. I am
somewhat unclear however as to
> terminating
>
> at
the head.
>
>
>
>
>
>
>
>
>
> For
> example, the
>diagrams in the
2014 ABS underwater vehicles
> and hyperbaric chamber publication
shows
>conical
> transitions
>
>either bordered by
a
> cylinder at
>either end, or simply
> open
> at
the small end???
>
>
>
>
>
>
>
>
> I want to terminate the
small end of a
>conical
> transition
>
>directly to a
small diameter hemi-head without another
> straight section, but I
am unclear
>as to whether or
> not
>
>that is
acceptable
> in practice.
>
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>
Joe
>
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> Personal_Submersibles mailing
list
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> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
>
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>Personal_Submersibles mailing
list
>
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>
> Personal_Submersibles at psubs.org
>
>
> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
>
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>_______________________________________________
>
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>_______________________________________________
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