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Re: [PSUBS-MAILIST] Glass as a viewport material?

To: <personal_submersibles@psubs.org>
Subject: Re: [PSUBS-MAILIST] Glass as a viewport material?
From: MerlinSub@t-online.de
Date: 01 Oct 2010 15:05 GMT
Reply-to: personal_submersibles@psubs.org
Sender: owner-personal_submersibles@psubs.org
Funny, 
last week a water bottle from glas with mineralwater exploded without any reason in my basement.. 
.. I just close the room door and "bang". Really funny the head of the bottle
flows 2 meters away against a wall. 

VBR Carsten

"Greg Cottrell" <greg@precisionplastics.com> schrieb:
> I recently saw a post suggesting glass as a viewport material for Psubs.
> Although there are many reasons that glass was rejected early on for manned
> submersibles, one of those reasons is quite interesting. There is a form of
> failure that can occur in glass that has never been fully understood.
> Basically, a viewport can sometimes shatter after pressurization when the
> pressure is being released. It can sometimes occur at a relatively shallow
> depth. The failure appears to be from a build up of tensile force. Somehow,
> energy is stored in the material and released suddenly when most of the
> pressure has been removed. This can be seen to happen occasionally in glass
> buoyancy spheres. It can also happen to acrylic but, if I remember
> correctly, only during rapid decompression. In glass, it can happen during
> slow decompression and without warning. I think that Jerry Stachiw briefly
> mentioned this in his book but I don't remember exactly which page.
> George Kittredge once told me about some tests that he was aware of using
> glass spheres that went to great depth and then shattered near the surface.
> 
> At any rate, Acrylic remains the most thoroughly tested and best understood
> material for PVHO applications. 
> 
> 
> 
> Greg Cottrell
> Project Manager
>  
>  
> greg@precisionplastics.com
> http://www.precisionplastics.com
>  
> P please consider the environment before printing this email 
> -----Original Message-----
> From: owner-personal_submersibles@psubs.org
> [mailto:owner-personal_submersibles@psubs.org] On Behalf Of Marc de Piolenc
> Sent: Wednesday, September 29, 2010 11:19 PM
> To: personal_submersibles@psubs.org
> Subject: Re: [PSUBS-MAILIST] Electric Propulsion
> 
> Underwater the main component of drag is viscous, so drag is 
> proportional to the square of the speed, and power required is 
> proportional to the cube. So to triple your underwater speed from 10 to 
> 30 knots requires twenty-seven (three cubed) times the power. This is 
> not a feasible undertaking unless you provide a completely separate 
> power plant with a very concentrated power source - maybe a Walter 
> hydrogen-peroxide turbine. Just sizing your electrical installation for 
> this power range is impractical.
> 
> Marc de Piolenc
> 
> Archivale catalog: http://www.archivale.com/catalog
> Polymath weblog: http://www.archivale.com/weblog
> Translation services: http://www.proz.com/profile/639380
> Ducted fans: http://massflow.archivale.com/
> 
> On 9/30/2010 10:18 AM, Firebolt wrote:
> > Hello Again thanks everyone for the shaft seal info, I appreciate it. I
> > am down to only a few more things I need to know, the electric motor.
> > For me I will want to travel at a speed of 10 knots under water
> > _but_ I would like for there to be a possibility for me to go faster,
> > say, 25 to 30 knots. I know it depends on the dimensions of the sub, it
> > will most likely weigh 50 tons since it is 60 ft and 10 ft inside
> > diameter. this is not a cylinder shaped sub though
> > if you want a picture I will give it to you just tell me. I thought
> > about a 70 kw motor but I don't know if it will give me the speeds I
> > want. And if you can, I want to know what the best battery would be to
> > power the sub with lots of electronics and appliances (TV's, microwave,
> > water pumps etc.)
> > I await your assistance.
> > John
> 
> 
> 
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