[PSUBS-MAILIST] model testing

Tue Dec 30 14:11:00 EST 2014

It would be not so easy to make 1/10 T- frames or welds.. 

"hank pronk via Personal_Submersibles" <personal_submersibles at psubs.org>
schrieb:
> 
> 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
> 
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