[Member-Forum] Moment of Inertia

[Alan James]

Hi Paul,
can you tell us a bit more about the thermo forming of the 165mm sphere.
Was it pressed in to a female mold? Was it from a cell cast acrylic sheet especially made?
I am wanting to thermo form a 700mm dome for 500ft, so gleaning all I can about the process.
Guy Richards from Blanson spoke on some of their failures, at the recent U.I. convention;
in particular about gluing a 4" thick sphere which he told me later was for Triton. They
overcame the problem of the glue bubbling by adding more pre polymerized MMA & going
to a German glue.
Saw your video that showed the piece of wood embedded in the dome Stanley made for you. 
What a tragedy.
Regards Alan 


________________________________
 From: Paul Moorhouse <paul at steel-fish.com>
To: brian at ojaivalleybeefarm.com; 'PSUBS Member Discussion Group' <member-forum at psubs.org> 
Sent: Wednesday, March 26, 2014 4:19 AM
Subject: Re: [Member-Forum] Moment of Inertia
 


Hi Brian
My Triton friends are hugely relieved that the first of their German made spheres arrived last week and  has gone through pressure test already. They have three vehicles that are almost complete apart from the spheres. These 165mm thick spheres proved a step too far for conventional techniques and from three attempts only one serviceable sphere emerged from Stanley’s. It is a task beset with risks from start to finish and it was brave of them to attempt it. One finished sphere was lost on final anneal due to a power failure to the auto-clave over the week-end. 
 
The new spheres are made in a very different way employing thermo forming rather than traditional slush casting techniques. This results in excellent clarity. Keep glued to their web-site for progress. 
 
Paul
 
Paul Moorhouse
Design Engineer
paul at steel-fish.com
www.steel-fish.com
#44 7837 542878
 
From:Member-Forum [mailto:member-forum-bounces at psubs.org] On Behalf Of Brian Cox
Sent: 25 March 2014 14:56
To: PSUBS Member Discussion Group
Subject: Re: [Member-Forum] Moment of Inertia
 
Hi Paul,
                 On your web site it says  "The 3300/3 program has been dogged by acrylic manufacturing problems"  , do you mind if I ask what problems you encountered" ?
 
Brian

--- paul at steel-fish.com wrote:

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
Date: Tue, 25 Mar 2014 09:10:06 -0000
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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