[Member-Forum] Moment of Inertia

[Dan Still]

Anything with chips in them hate humans.



On Wednesday, March 26, 2014 7:29 AM, Joe Perkel <josephperkel at yahoo.com> wrote:
 
Wow, 24+ hours for email delivery and doubled to boot. 

Can iPads go insane?

Joe

Sent from Yahoo Mail for iPad 



________________________________
 From:  Joe Perkel <josephperkel at yahoo.com>; 
To:  member-forum at psubs.org <member-forum at psubs.org>; 
Subject:  Re: [Member-Forum] Moment of Inertia 
Sent:  Tue, Mar 25, 2014 4:00:01 PM 


Hi Paul,

The question is anecdotal based on an off the cuff thought of upsizing the shell O.D. to 42" from 36". I am very hesitant to do this do to weight and handling issues however, several members have made a compelling rationale r/t simple comfort. At 53 I'm 6' 190 lbs and should expect that L to W ratio to change by build time! 

I have to think a bit about the shell thickness r/t welding and corrosion issues, but Depth no more than 350'. I seem to remember a cross section drawing of a T section somewhere with a simple L/W/H relationship to shell T, but can't find it again. 

I'll take that pdf if you don't mind. I'm not at home and won't be until later this week
 to do some number crunching.

Thanks Paul!


Joe

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Sent from Yahoo Mail for
 iPad 



________________________________
 From:  Paul Moorhouse <paul at steel-fish.com>; 
To:  'PSUBS Member Discussion Group' <member-forum at psubs.org>; 
Subject:  Re: [Member-Forum] Moment of Inertia 
Sent:  Tue, Mar 25, 2014 9:10:06 AM 


Joe
As it happens, this is my day job. I have been designing submarine pressure vessels for the last 28 years. I am sure there are others on the forum who do this but I am happy to help if you would like, and others at PSUBS should the need arise. 
Frame size and spacing is inter-related and there is no one answer. I have developed some models based on the European pressure vessel code PD5500 so running a new configuration is easy and surprisingly quick. PD5500 produces much lighter vessels than ASME VIII which is really aimed at chemical plant. In this way it is more similar to military codes but it does rely on quality assurance levels that do not generally come with home construction. So to cater for this, you put a factor in. I apologise in advance for all of the calculations being in metric but give me info in either. 
I would need to know
·        Outside diameter
·        Shell thickness
·        Shell material 
·        Frame material
·        Diving depth
·        Length of parallel body
·        Ends, hemi or 2:1 dished.
·        Preferred frame spacing 
·        Inside or outside frames
I can send you the PDF of the work sheet as the PD5500 sums do look very pretty. 
The next step is to design the hatch penetration and I can help you here also. 
 
This guy can thermo form your acrylic
http://www.airesearch.nl/
 
 
Regards
Paul
 
Paul Moorhouse
www.steel-fish.com
 
 
 
From:Member-Forum [mailto:member-forum-bounces at psubs.org] On Behalf Of Joe Perkel
Sent: 25 March 2014 03:55
To: PSUBS Member Discussion Group
Subject: [Member-Forum] Moment of Inertia
 
Where did I see the rule of thumb for T-section rib sizing relative to shell thickness? I can't seem to find it now.

Joe

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