[PSUBS-MAILIST] model testing

Tue Dec 30 11:56:49 EST 2014

Hi Cliff
Thank you, that is perfect.  
Hank--------------------------------------------
On Tue, 12/30/14, Cliff Redus via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

 Subject: Re: [PSUBS-MAILIST] model testing
 To: "Personal Submersibles General Discussion" <personal_submersibles at psubs.org>
 Received: Tuesday, December 30, 2014, 9:44 AM

 Hank,
 just to bring closure to this thread.  Stress on the boat
 due to depth scales geometrically between motel and
 prototype.  Drag scales based on Reynolds
 number.
 As an example
 for stress, go to Psubs.org flat acrylic viewport calculator
 that Jon coded based on PVHO http://www.psubs.org/design/viewports/1ATMFD/
 Put in a 500 ft depth and a 10"
 viewable diameter Di and record all results for the acrylic
 viewport.  Repeat with same depth but 1/10" the
 viewable diameter, i.e., 1" and record results.  Note
 that all dimension scale geometrically.  This is based on
 the assumption that the material is isotropic. These
  results would not be true for anisotropic materials like a
 carbon fiber layup were material properties are 
 directional dependent.  Additionally for carbon fiber, you
 would not be able to scale the scale the size of the
 fibers.
 So if you are
 using an isotropic material such as steel, and can fabricate
 a dimensionally corrected scaled model of a component like
 a pressure hull including details like weld filler size,
 then crush depth observed in the motel test cell would match
 the full scale prototype.  Like any experiment, you would
 need multiple test to average the results.
 Cliff

 Cliff Redus
 Redus Engineering
 USA
 mobile:  830-931-1280
 cliffordredus at sbcglobal.com 
         From: hank pronk via
 Personal_Submersibles
 <personal_submersibles at psubs.org>

 To: Personal
 Submersibles General Discussion
 <personal_submersibles at psubs.org> 

 Sent: Monday,
 December 29, 2014 2:41 PM
  Subject: Re:
 [PSUBS-MAILIST] model testing

 I am not
 looking for drag comparisons, I am looking for failure due
 to pressure comparisons.  I though I read that the Nekton
 subs
  were built as a model first to establish crush depth.
 Hank
 --------------------------------------------
 On Mon, 12/29/14, Cliff Redus via
 Personal_Submersibles <personal_submersibles at psubs.org>
 wrote:

  Subject: Re:
 [PSUBS-MAILIST] model testing
  To:
 "Personal Submersibles General Discussion" <personal_submersibles at psubs.org>
  Received: Monday, December 29, 2014, 3:06
 PM

  Drag

 results between a model and full scale does not scale
  geometrically.  You have to scale model and
 full scale off
  the dimensionless  Reynolds
  number.   Reynolds number
  scaling
 enables you to scale results between model and full
  scale using either a water tunnel or air
  tunnel.
  Cliff

          From: Alan James via
  Personal_Submersibles
  <personal_submersibles at psubs.org>

  To: Personal
  Submersibles General Discussion
  <personal_submersibles at psubs.org>

  Sent: Monday,
  December 29, 2014 1:55 PM

 Subject: Re:
  [PSUBS-MAILIST] model
 testing

  Hank,I just ran
  a test on my
 pressure program & you get the same crush
  depthon a
  sphere of A516-70
 steel that is 1000mm diameter & 10mm

 thick as youdo on a
  sphere 100mm diameter
 & 1mm thick.What I am
  not sure of is if
 you can scale up the drag results on a

 model.If you
  have a scale model that is
 1/50th & it takes X amount of
  force to
 push
   it at 3
  knots, can
 you multiply X by 50 to get the required

 thrust?Alan

     From: Brian Cox
 via
  Personal_Submersibles

 <personal_submersibles at psubs.org>

  To: Personal
  Submersibles General Discussion
  <personal_submersibles at psubs.org>

  Sent: Tuesday,
  December 30, 2014 8:43 AM

 Subject: Re:
  [PSUBS-MAILIST] model
 testing

  Hank,
        I would say
  no.  It would have to be so exact that it
 would be
  virtually impossible to
 extrapolate from the small model,
  and
   aside from that I think there are other
 engineering
  principles involved that would
 come into play , Sean would
  be the person
 to ask !   I know that it is done in wave

 tanks and wind tunnels, but in those you are looking at
  laminar flow and such things, not structural
 strength so
  much.  You might be able to
 get a rough idea of how it
  would start to
 collapse maybe.  The larger the model the

 better I would think.

 Brian

  --- personal_submersibles at psubs.org
  wrote:

 From: hank pronk via
  Personal_Submersibles
 <personal_submersibles at psubs.org>
  To: personal_submersibles at psubs.org
  Subject: [PSUBS-MAILIST] model testing
  Date: Mon, 29 Dec 2014 10:52:46 -0800

  Hi all
  If
 you
  make a scale model of a submarine in
 complete detail. 
  Scale the size and metal
 thickness, is it a reasonable

 representation of depth capabilities when pressure
  tested?
  Hank

 _______________________________________________
  Personal_Submersibles mailing list
  Personal_Submersibles at psubs.org
  http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles

 _______________________________________________
  Personal_Submersibles mailing list
  Personal_Submersibles at psubs.org
  http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles

 _______________________________________________
  Personal_Submersibles
  mailing list
  Personal_Submersibles at psubs.org
  http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles

  -----Inline Attachment
 Follows-----

 _______________________________________________
  Personal_Submersibles mailing list
  Personal_Submersibles at psubs.org
  http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles

 _______________________________________________
 Personal_Submersibles mailing list
 Personal_Submersibles at psubs.org
 http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles

 -----Inline Attachment Follows-----

 _______________________________________________
 Personal_Submersibles mailing list
 Personal_Submersibles at psubs.org
 http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles