RE: [PSUBS-MAILIST] Submarines design.

[Alec Smyth <Asmyth@changepoint.com>]

Ken,

 

Its a bit funny for me to be giving advice... I don't consider myself any expert! But anyway, as a conceptual design this sounds feasible. Dual drop weights seem a bit unusual, I wonder what the rationale was for that? Also with ballast tanks fore and aft, its possible to control attitude with those and dispense with the travelling weight, although I've heard people say wonders about those -- one might consider this a nice-to-have feature. Anyway, the concept sounds OK but the devil is in the details. As Pat said, if you can send a scan that would take this to the next step. A CAD file would be even better, as you will save yourself a lot of work on re-drawing changes that inevitably come up.

 

One philosophical point... Maybe I'm reading between the lines, but it sounds like you envision the frame as the main structural component, with everything else hanging off that (including the pressure hull). That might lead to the frame being "heavy" in your mind, and the other things "light". Here's the problem; the frame does nothing for the sub's performance, it just holds things together. You want to maximize the weight of the pressure hull to get more depth or a better safety margin. You want to maximize the weight of the batteries to get more range. The frame should be minimized because it doesn't add any value. So, you might consider the pressure hull itself the "frame". Of course, this doesn't mean you won't need some sort of frame welded to that hull so you can hang things on it (lights, manipulators, whatever). But perhaps the frame should be more of a secondary component.

 

cheers,

 

- Alec

-----Original Message-----
From: ken and donna [mailto:kandd@softdisk.com]
Sent: Tuesday, August 07, 2001 10:19 AM
To: personal_submersibles@psubs.org
Subject: [PSUBS-MAILIST] Submarines design.

Your E-mail wasn't addressed to me but, I too am contemplating building a Sub.  I've been kicking arround designs in my head for about 2 months.  Let me run by you what I'm thinking currently and get you analysis and input.   I want to build a frame made of angle iron about 12 feet long.  The frame would cradle a crew tank in side.  The tank would be shapped like a butane tank (not a butane tank perhaps by cylindrical with hemi-spherical ends).  The frame would hold the crew tank, i.e. the tank would not be used for support, only strapped into the frame.  In front of the crew tank would be air tanks and maybe a drop weight. the frame would end infront of the air tanks.  A 75 gallon ballast tank would be secured to the front of the frame.  Behind the crew tank would be more air tanks and again a drop weight.  And  another 75 gallon ballast tank.  This ballast tank would be within the frame.  At the end of the frame would be an electric trolling motor.  The crew compartment would be approximately 36inches in diameter.  It would have twin conning towers (2 man sub)  The direction of the sub would be controlled with a stick (like an airplane) utilizing hydrolic pistons to vector the trust of the trolling motor.  Inside the sub would be a variable bouncy tank.  The frame would extend about a foot below the crew compartment.  It would be a truss  underneath the sub to support the weight out of the water.  Under the sub on each side would be 4 batteries.  In the middle would be a slide weight on a track moved back and forth via allthread and an electric motor.   This weight would be  used to change attitude.  I  also envision putting fiberglass pannels over the frame to decrease drag.  I can adjust the design, i.e. moving the crew tank forward or aft in order to adjust overall c.g and c.b conserns.  I await your analysis.  Thanks, Ken harris

----- Original Message -----

From: Alec Smyth

To: 'personal_submersibles@psubs.org'

Sent: Tuesday, August 07, 2001 8:41 AM

Subject: RE: [PSUBS-MAILIST] web sites

Matt,

 

I am building my first sub and am now a couple of years into the project. I came in with a little useful knowledge in areas like naval architecture and machining, and with over 10 years of picking up every submarine design book or article I could get my hands on. Yet there are many items I've spent months and months building only to have a better idea later on, realize I'd used the wrong material, etc., etc. In the worst case so far, I had to abandon parts with a full year of work in them and start over. This is the cost of developing a completely new design and having to locate all my sources from scratch. And I am nowhere near done. Even when the sub is eventually finished, I'm pretty certain the first hour of in the water will lead to mods requiring a year or two in the shop. That's just how it goes with prototypes built by an amateur in the wee hours of the night. 

 

Anyway, all that was just an intro for the hindsight lecture...

 

Unless you're hell-bent on an un-conventional type of sub, I'd strongly recommend building to proven plans. One of the Kittredge designs, for example. The cost (I think $500) is insignificant compared to the savings you'll get from this approach. Plans are the closest to a cook-book you'll get. Cook-books simply don't exist in this field. If they did, it wouldn't be half as interesting.

 

cheers,

 

- Alec

-----Original Message-----
From: Joanne Cadieux [mailto:compkid15@earthlink.net]
Sent: Tuesday, August 07, 2001 2:24 AM
To: personal_submersibles@psubs.org
Subject: [PSUBS-MAILIST] web sites

I am just starting out in the area of personal subs.  I was wondering of anyone has any website that can give me more information on how to build them.  I know how to build one but there are soe stupid thinkgs i am stuck with like what you use to control the air pressure inside the sub. And the best desighn for a hull i am only looking to dive to about 50 feet so only need a hull that will stand up to about 80feet.  If any body can help me it would be greatly apreciated.                                       

   

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