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Re: [PSUBS-MAILIST] spec qustions

Well, I'll give you my half-cent worth on part of this.  Streamlining is streamlining regardless of size.  a "fish" shaped hull will give you (a) greater speed for the propulsive force applied, and (b) greater range of travel for the availble power/fuel supply.

How important these features are depends upon the intended purpose for the machine.  Navy subs are streamlined for both of the above reasons... as well as stealth, I believe, to some degree.  Their intended purpose is to go on long patrols where they may have to maintain speed with some very fast surface vessels, not to mention escaping from enemy vessels, so streamlining makes sense for them.

It might make sense for yours as well, though if speed is not a major concern and you don't intend to travel very far, other shapes might work just fine.  The sphere, I gather, makes the most sense as far as maximum crush depth is concerned, i.e.: the Trieste's passenger compartment and the old bathysphere design.  Spheres do not lend themselves well to streamlining, however. 

Hull design is always a compromise between streamlining, and other factors.  WWII military subs had a veritable forest of antennae on their conning towers by the end of the war, which was very bad for streamlining, but they needed such things for command and control, so the forest was not harvested until after the war.  I belive that the Polaris class were the first really streamlined designs widely adapted, though the Hunley and the Holland designs were remarkably streamlined, considering that the concepts were not well understood at the time.  Bushnell's Turtle was not especially streamlined, but it didn't have to be, it only needed to travel a short distance to a ship at anchor in a harbor, attach a bomb and make an escape.  That it failed in its mission was not due to it's hull design, but rather the inability of the attachment screw to penetrate the copper sheathed hull of the enemy vessel.  In the case of the Hunley, with a spar torpedo that had to penetrate the hull and pull away detaching the spar, and given only human muscle power for propulsion, streamlining was quite important to attain the speed so that the spar would stay stuck in the hull of the target.

I've always thought that a teardrop shape might be the way to go as it is more or less a streamlined sphere.  The aft section would not even have to be pressurized, though it probably would need some kind of trim tank.


On Thu, 2003-01-09 at 06:20, Coalbunny wrote: 
In a sub that is designed for a working dpeth of no greater than 120
feet, I presume the designed crush depth would be no less than 240 feet,
correct?

What would the proper alloy and diminsions of the ribs be?  I presume a
ring with the annulus of 6", 1/4" thick.  The external diameter of the
rib would be 5' and the internal diameter would be 4'.  Is this correct
or am I designing this wrong?

Also, on a small sub, would it be beneficial to have a streamlined hull
like that on the USN SSBNs or because of the size, does it not matter? 
My preference is using this in rivers, with some use in lakes and
possibly in salt water. 
Carl






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