"So mainly there's that one unpleasant reality of submerging a volume of air"
The word nightmare seems appropriate here. Reality does indeed 'bite", I am rethinking the entire project, it's that Boyle and Archimedes thing!
Smaller is better, (way smaller), semi-dry (from torso up) a centerline bubble (narrow and up high) weighted keel, two or three crew!
I am looking real hard at what is commercially being done in the ambient sport sub market.
Thank you
Paul, Rick and Bill
From: Paul Kreemer <paulkreemer@gmail.com>
Reply-To: personal_submersibles@psubs.org
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Re: Some issues
Date: Mon, 7 Nov 2005 10:01:54 -0800
Joe,
So mainly there's that one unpleasant reality of submerging a volume of air: it has a lot of buoyancy! 63 lbs/cf of seawater adds up pretty quickly into a too-heavy-to-trailer submarine. And the fact that you're considering an ambient sub doesn't really help your displacement, right? The construction is easier in that you don't need a 1 inch thick pressure hull but unfortunately the boat needs to weigh just as much as if you did.
I've liked the DeepFlight two person sub (model 502) which has a separate pressure compartment for each occupant. It really helps to reduce the cabin air volume but it also locks you into a small space which is very different from your original dream. And does anyone know why it's been decommisioned now? I think they built that one for their pilot training program. Maybe they didn't get many people buying the training? http://deepflight.com/subs/dfa.htm
What we need is a clever trick like that used in water ballasted sailboats - just fill the tanks before sailing to increase your displacement. But of course that doesn't help a sub, unless you look at flooding most of your crew compartment while diving. Maybe you need a sand ballast keel system. :-) Run along in shallow water scooping up sand until you've got the two tons or so that you need...
take care-
Paul
On 11/7/05, Joseph Perkel <joeperkel@hotmail.com> wrote:
Rick,Thank you for the info and support. With further research my initial
exuberance has now been tempered a bit by reality. Something I am quite sure all of the newbie's must experience at the beginning.My main issue at the moment is material density and it's effects on
buoyancy and ballast requirements, in this case of course, ply composites for this ambient design. Lead is my friend in this case but still there are some hurdles to overcome.Pat Regans boat has a "proper" pressure hull underneath but it is
tiny. I want a compromise between size and the necessity of having to be launched by crane, so my belief is that an ambient design could be light enough to be trailer able and still give some reasonable interior volume but therein lies the technical hurdles.I am looking at aluminum again as I did last year for a surface
yacht (see the attachment for the quote)...outrageous! This could quite possibly be riveted as in the old 'R" boats but that of course presents it's own problems. One would use lighter gauge alloy than what you see in the quote so welding would not really be an option.I must admit though all these technical hurdles are quite fun to try to figure out.
Joe
From: "Rick and Marcia" <empiricus@telus.net >
Reply-To: personal_submersibles@psubs.org
To: < personal_submersibles@psubs.org>
Subject: Re: [PSUBS-MAILIST] Some issues
Date: Mon, 7 Nov 2005 02:47:37 -0800
Hi, Joe - 560 cu.ft. is about 35,800 lb. of buoyancy. That's quite a bit. :-)Onceneutral buoyancy was achieved, dynamic control (i.e.: planes) maintained depth. The HP air was more than enough to get the boats back up in case of planes failure or even partial flooding.Asfar as limiting your posts to a time when "flatter curves" would be appropriate, keep in mind that, as far as I know, our archives are listed by date and by thread, not by key word search. As long as we, the "pro's", neglect to label our subject headings appropriately, please feel free to ask all the ridiculous questions you want.Asfar as archival searches are concerned, I'm sure Ray would love to spend thousands of hours (!?) labeling each and every post from the past six or seven years according to design ethic, systems analysis, materials science, commercial suppliers, fluid dynamics, parts availability, hydrodynamics, conceptual rationale, human engineering, etc.Ihope everyone realises that, besides being impossible, the only thing almost as hard as codifiying the archives is finding the proverbial needle in the haystack.Again, as above, please feel free to ask all the ridiculous questions you want.RickVancouver----- Original Message ----- From: Joseph Perkel To: personal_submersibles@psubs.org Sent: Friday, November 04, 2005 8:02 AM Subject: [PSUBS-MAILIST] Some issuesGroup
I am discovering material density issues along with the air supply, buoyancy and control issues inherent to a dry ambient design. In that regard the following excerpt is from the NAVPERS manual for air systems aboard WWII fleet boats, specifically the 3000 lb system.
2A3. Air banks. Each of the five air banks consists of seven flasks, with the exception of the No. 1 air bank, which has eight. Each flask is provided with a drain valve. The total capacity of the air banks is 560 cubic feet. The No 1 air bank is located inside the pressure hull, with four flasks in each battery compartment. The other four air banks are located in the main ballast tanks
The 560 total cubic feet caught my eye and I wondered if this could possibly be correct? Since this is equivalent of seven 80 SCUBA tanks on such a large vessel to blow tons of seawater. I understand the concept of the low-pressure blowers on the surface and would employ that feature. But I am still trying to make sense of buoyancy tankage and air supply issues for a dry ambient design.
Incidentally, I have been dealing with post Hurricane issues (somewhat "irritating") but was distressed to see the recent posts, as the animosity was palpable. If as a "new guy" some of my previous posts were somewhat "irritating" to some, I did so in ignorance of the culture within this community however, I cannot offer any apologies for this reason. Although I am a neophyte in this field, I am an expert in others where the basics were once complex issues to me.
That having been said, I will respect the house "rules" and limit my posts to those times when the learning curve has flattened a bit as above.
Thank You
Joe
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