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[PSUBS-MAILIST] Re:

John,

You have several questions in your posting.  I can address only a few of them.

One layer of steel is much stronger then several layers laid up together.  Just look at a leaf spring in a auto.  It's made in layers to be flexible.  If it was one solid piece of metal it would be much stiffer.  If you fused the layers together, as they do when making plywood, your layer idea would be ok, but just laid together, there would be lateral movement between the plates when loaded.

It looks like your using a single tank ballast system.  Your description for achieving neutral buoyancy may be a little over simplified.  It's usually done with an additional smaller, "hard ballast tank."  If you were to use the area between your inner and outer hull as a open bottom "main ballast tank" and totally flood it to submerge, your outer hull can be built lighter allowing you to put extra steel on your inner hull.  Use the space between the hulls as a main ballast tank, to lift you high out of the water when surfaced only.  Full when diving or empty when surfaced.  No need for the bottom inlet valve.

 For controls, hydraulics is probably the way to go with a project this size .  Your control surfaces would probably be easier to operate with cylinders rather than motors though.  To determine if hydraulics should be used for your drive motors, you have to consider what your drive arrangement will be.  You loose power every time you switch from one form to another.  On a sub, power is at a premium, so if electric power straight from the batteries can be used for propulsion, it's probably better.

In order to dive a submarine it has to be the same weight as the water it displaces.  Think of trailering a volume of water the size and weight of the sub your designing.  Do you really think you could move it with anything less than a semi truck????  Also, if your hull is twelve feet in diameter, and that's with out dive planes or thrusters or whatever you might have sticking out on the sides, you will need wide load permits to move it through most places.  Your talking about a really BIG truck and trailer!

As you said, if you are going to build a sub, you want to build a good one.  Your taking on an expensive project.  Rather than look for a design program, you might do better looking for a navel engineer that you can hire to assist you with the highly technical parts instead of trying to learn the field yourself.  There are plenty of smaller part to keep you busy once you have the hull details ironed out.   The technical assistance investment will surely save you money in the long run, not to mention,  maybe your life.

Good luck with your project and welcome aboard PSUB.
Dan H.

John Haswell wrote:

> I am new to these message boards.  These message boards were the only place I found relating to PSUBs.  It's quite cool.  Anyways, I am working on a design, but of course I have no experience designing or building a sub. I figured if I am going to build one, it may as well be a good long lasting, never get tired of, type psub. I want to build a 1 atm sub. The inner hull will be 10' in diameter, the outer hull is 12' in diameter. I was would like a maximum operating depth of 500' (tis a good round number). I read somewhere on this board to design 2x over the limit and test 1.5x over the limit. So I need to design for 1000' depth. I think I will rib it using 12" I beam every 2'. Would 1/2" steel be sufficient for the inner hull? Supposedly the outer hull doesnt have to be as thick, but to be sure I probably will make it 1/2".
> As I said, I have never designed or built a PSUB, but I would very much like to.
> Is there a place to get a designing program?
> Also is there a place to get underwater maps on CD-ROM?
> Where would the best place to get scrubbers from? I would like to design it to support 3 ppl for 72-hours, even though I will probably be the only passenger most of the time. I need the dimensions of the scrubbers too, so I can design the ventilation system.
> I think hydraulic drive and control surfaces are best. A couple of hydraulic motors for the drive, one motor for rudder and another for the elevator. The hydraulic pump would be inside and piping the fluid to the out would be easy with steel piping.
>
> Also in regards to the hull, does layering steel nearly equivilate to a solid piece? For example, would tiling 1/8" to 1/2" thick be nearly as strong as a solid 1/2" piece? It seems it would be easier to aquire 1/8" steel and layer it (yeah it creates more welding) than it would be to find 1/2" steel. Also 1/8" steel would be much easier to roll than 1/2".
>
> This design I have is gonna be HEAVY !! lol
> Also getting it to water is gonna be a chore as well. I believe it would have to be hauled via big rig, I doubt it would be legal to haul using a small truck and fabricated trailer. Then having a big rig back into a huge ramp into water deeply enough to allow the sub to leave the trailer, wow it gets complex.
> In regaurds to weight, it seems it will need lots of air for bouyancy and little water to dive with.
>
> If someone could look at this page and tell me if I understand the ballast tank principle it would be greatly appreciated.
>
> http://www.angelfire.com/scifi/xsirsaw/pages/psubs/PSUBTOC.html
>
> Thanks for your reading this, and thanks for your help if you help... lol
> --
>
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