Re: [PSUBS-MAILIST] Fiberglass Hull

Having a composite hull that you don't have the worry, or as much cost to deal with protecting from rust and electralysis is an advantage. I would hoelectrolysismuch safer cutting a big hole in a steel hull and then re-welding it, then cutting a big hole in a composite material with all it's interlinking fabric and then try to replace that section and it be just as strong or stronger. Not that it can't be done but you better know what your doing.

That was a very good point that was brought up about having more freeboard stability in a composite sub since you have allot less weight up top. The RV Needlefish has trouble in this area with all the thick steel in the conning tower. Also since as you guys say you'll need allot more lead weights to submerge, I think that is a good thing since you could add more batteries to your design and/or have much heavier drop weights that could give you a extra factor of safety. Of course you will not usually want to come up to fast for fear of hitting a boat or swimmer. Also if you come up fast and you don't have good control surfaces you'll get a phenomenon known as "vortex shedding" that causes a relatively bulbous sub to oscillate uncontrollably during surfacing, similar to the way a leaf falls. The Dennoch PSUB was designed to deal with vortex shedding. You'll still want to make sure that if you need to release all your drop weights you won't float belly up. : )'

It's one thing to have a properly calculated composite pressure hull with no through hulls in it, and another thing to trying to design safe through hulls like view ports, conning towers and the like. That's where I get into trouble trying to blend those elements into the main hull. It of course can and has been done but it would have to be researched. The private space plane that won the Ansari X prize SpaceShipOne in Mojave, California is a composite craft as well as the plane that takes it part way up. These planes take some very serious stresses and have through hull view ports, hatches, etc., etc.. SpaceShipOne was built by famed aerospace designer Burt Rutan of Mojave-based Scaled Composites who was a very big part of the canard style aircraft development using allot of composite materials in them.

http://www.msnbc.msn.com/id/6167761/

Regards,

Brent

"The person who says it cannot be done should not interrupt the person doing it."
Chinese Proverb.

From: "Joseph Perkel" <joeperkel@hotmail.com>
Reply-To: personal_submersibles@psubs.org
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Fiberglass Hull
Date: Sun, 28 Jan 2007 22:19:45 +0000

Mark,

Brainstorming is indeed...."a good thing".

'However.... if you wanted a lightweight sub, i.e. trailer able, there
>might be a great advantage in moving the sub, and attaching weight
>on site."

.....Deja vu for me here. This was a thought that I had with my original "Octopus"ambient...

http://www.frappr.com/?a=viewphoto&id=269116&pid=1489776&myphotos=1

....which with her rounded shape, would have required composite construction and, as Dan pointed out, significant lead compensation. The detachable weight idea did occur to me as well as the fact that it would also require transport.....just too much to deal with.

Anyone who has ever owned a trailer able sailboat, will tell you that stepping the mast gets old real fast.

Joe

From:  "Mark Roberts - Harbortronics" <Mark@Harbortronics.com>
Reply-To:  personal_submersibles@psubs.org
To:  <personal_submersibles@psubs.org>
Subject:  Re: [PSUBS-MAILIST] Fiberglass Hull
Date:  Sun, 28 Jan 2007 12:55:36 -0800
>I don't think anyone is saying there is an advantage.... this is
>simply a discussion of possibilities :)  Brainstorming is a good
>thing.
>
>However.... if you wanted a lightweight sub, i.e. trailerable, there
>might be a great advantage in moving the sub, and attaching weight
>on site.  If you need periodic access to the innards, it 'might' be
>easier to cut through a fiber composite, and repair it, than to cut
>steel, re-weld and protect it...   I dunno, I've never welded nor
>glassed.
>
>Mark Roberts
>
>From: " Dan. H." <jumachine@comcast.net>
>To: <personal_submersibles@psubs.org>
>Sent: Sunday, January 28, 2007 11:58 AM
>Subject: Re: [PSUBS-MAILIST] Fiberglass Hull
>
>
>>But where is the real advantage of the design?   You still need to
>>have a rather elaborate framework of steel.
>>
>>If it's the outward appearance your trying to customize, you can do
>>that with fiberglass fairings.
>>
>>Remember, a sub has to replace it's weight in water so the weight
>>savings with fiberglass will have to be offset with lead or steel
>>or something making your sub as heavy as an all steel design.
>>
>>All I see is, your trading some of the smell of welding for the
>>smell of fiberglass resin.  And also trading a long proven material
>>for one not quite as proven in the sub world.
>>
>>Dan H.
>>
>>----- Original Message ----- From: "Mark Roberts - Harbortronics"
>><Mark@Harbortronics.com>
>>To: <personal_submersibles@psubs.org>
>>Sent: Saturday, January 27, 2007 9:59 PM
>>Subject: Re: [PSUBS-MAILIST] Fiberglass Hull
>>
>>
>>>I was just thinking something long those lines too, as I arrived
>>>home tonite....  of course the framework will have to be sized to
>>>hold all of the stresses, but it could be done.  The construction
>>>process could be simplified quite nicely, and retro-fits would be
>>>so much easier.
>>>
>>>----- Original Message ----- From: "Charles Perkins"
>>><chuck@memetech.com>
>>>To: <personal_submersibles@psubs.org>
>>>Sent: Saturday, January 27, 2007 12:19 PM
>>>Subject: Re: [PSUBS-MAILIST] Fiberglass Hull
>>>
>>>
>>>>
>>>>On Jan 27, 2007, at 10:37 AM, Mark Roberts - Harbortronics wrote:
>>>>
>>>>>One guy per the link points out a very important thing with
>>>>>regards  to fibers....  they can be very strong in tension, but
>>>>>have  effectively no compressive strength. To my mind, that's a
>>>>>show  stopper right there.
>>>>>
>>>>
>>>>
>>>>A show changer, true... but not necessarily a show stopper. All
>>>>one  has to do is put the casing of the pressure vessel under
>>>>tension,  rather than compression.
>>>>
>>>>How?
>>>>
>>>>As a thought experiment, imagine a soccer ball. Let's replace the
>>>>  seams with steal beams, and the skin with fiberglass... but
>>>>allow the fiberglass to bow inwards. The fiberglass under tension
>>>>will transmit the compressive force to the steel framework which
>>>>can resist it  under compression and bending forces.
>>>>
>>>>One could make a cylinder similarly... take a hexagonal lattice,
>>>>roll it up, etc.
>>>>
>>>>Chuck
>>>>
>>>>
>>>>
>>>>
>>>>>
>>>>>----- Original Message -----
>>>>>From: Brent Hartwig
>>>>>To: personal_submersibles@psubs.org
>>>>>Sent: Saturday, January 27, 2007 4:34 AM
>>>>>Subject: RE: [PSUBS-MAILIST] Fiberglass Hull
>>>>>
>>>>>Doug,
>>>>>
>>>>>I'm not qualified to answere your questions about fiberglass
>>>>>composite sub hulls under external pressure, but here is a
>>>>>interesting thred about just that sort of thing. Here is the
>>>>>link  and a small quote from the discussion that has the most
>>>>>meat in it.
>>>>>
>>>>>http://www.eng-tips.com/viewthread.cfm?qid=174497&page=1
>>>>>
>>>>>"Spend some time looking through ASME III (Unfired Pressure
>>>>>Vessels) for vessels under external pressure.  And keep in mind
>>>>>that if you intend to operate at 100 ft (~45 psi) that you'll
>>>>>want  a hefty margin against any kind of pressure boundary
>>>>>buckling  failure.  Think in terms of emergency recovery time
>>>>>from a depth  overshoot if you experience horizontal control
>>>>>plane malfunction  while descending at some speed and down angle
>>>>>when nearly at your  maximum operating depth.
>>>>>
>>>>>I may be able to find a more specific ASME reference for you,
>>>>>but  for a number of reasons I don't think I can provide any
>>>>>hints as  regards a design collapse depth, so you're on your own
>>>>>there.
>>>>>
>>>>>
>>>>>Norm
>>>>>arto (Mechanical)
>>>>>12 Jan 07 9:46
>>>>>also look under ASME PVHO (Human occupancy)  & Sec. X {fiber
>>>>>reinforced plastic) pressure vessel codes"
>>>>>
>>>>>end quote
>>>>>
>>>>>In the past I saw a web site for a deep diving live aboard
>>>>>submarine project called the Neptune. They were working on a
>>>>>design  for a carbon fiber pressure hull that they claimed could
>>>>>be used  down to 6000 meters. The web site
>>>>>waswww.neptunesubmarines.com but  it's a dead link now. I was
>>>>>put onto this site originally by a web  site for the Perendev
>>>>>magnetic motor. At one time I thought it  might be a great motor
>>>>>for subs in general but there is some  serious greed problems
>>>>>with the owner of the company. Neptune  Submarines were wanting
>>>>>to put the Perendev magnetic motor in there  live aboard
>>>>>submarine to replace a nuclear type power source. Maybe  someone
>>>>>here knows what happened to this Neptune Submarines group  out
>>>>>of Switzerland? Here is a pic of there submarine design.
>>>>>
>>>>>http://img224.imageshack.us/img224/7608/24243158bk0.jpg
>>>>>
>>>>>Regards
>>>>>
>>>>>Brent
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>From: djackson99@aol.com
>>>>>Reply-To: personal_submersibles@psubs.org
>>>>>To: personal_submersibles@psubs.org
>>>>>Subject: [PSUBS-MAILIST] Fiberglass Hull
>>>>>Date: Fri, 26 Jan 2007 00:35:40 -0500
>>>>>
>>>>>I know  it's an old  topic but I have mostly ignored the
>>>>>previous  post regarding fiberglass because I never thought I
>>>>>was going to  give it a second thought.  ...wrong again.
>>>>>
>>>>>1) Did anyone ever come up with a way to calculate even a
>>>>>ball-park working depth given all, or at lease some of the
>>>>>variables for fiberglass construction?  If so can you point me
>>>>>in that direction?
>>>>>
>>>>>2) I know that the externally loaded working psi for a non-
>>>>>reinforced cylinder is lower than  it's internal working psi.
>>>>>That  makes even more scene to me when thinking about the
>>>>>alignment and  tensile strength of glass or carbon fibers
>>>>>compared to their  compression strength. However it seems that
>>>>>there would be a ratio  that could be used to estimate the
>>>>>reduction in loading ability.   Would that be true?  For example
>>>>>if pipe section is rated for  1000psi, could it's external load
>>>>>psi rating be stated as x% lower,  say 20% lower, based on the
>>>>>type of material?
>>>>>
>>>>>Thanks --Doug J
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>Check out the new AOL. Most comprehensive set of free safety and
>>>>>security tools, free access to millions of high-quality videos
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>>>>>
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