[PSUBS-MAILIST] Terminating a conical transition

Sun May 4 16:32:00 EDT 2014

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 

 From:

              via
 Personal_Submersibles <personal_submersibles at psubs.org>;

 To:

               <personal_submersibles at psubs.org>;

 Subject:

              Re:
 [PSUBS-MAILIST] Terminating
  a conical transition         

             Sent:

              Sat, May 3, 2014
 2:03:36 PM     

    Joe,

  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.

  Vance

  -----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

  Sean,

  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.

  Joe

    On Friday, May
  2, 2014 9:50 PM, Sean T. Stevenson via
 Personal_Submersibles
  <personal_submersibles at psubs.org>
  wrote:

  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 

 From:

              Sean T. Stevenson
 via
  Personal_Submersibles <personal_submersibles at psubs.org>; 

               To:

              Personal
 Submersibles General
  Discussion <personal_submersibles at psubs.org>; 

    Subject:

              Re:
 [PSUBS-MAILIST] Terminating
  a conical transition         

 Sent:

              Fri, May 2, 2014
 11:45:11 PM    

  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:

  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.

  Joe

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