Italy, Russia to jointly develop SSKs.

[Betasys]

There can be in excess of 36 different metal types in a modern submarine. Its not the exoskeleton that counts - its the internal design that is critical.

There are far too many variabless involved to argue that a reduction of weight by using Ti is going to allow an increase in range or depth of operation.

eg, The Oyashios are the deepest diving conventional in the world - they rival some of the numbers thrown around for russian nukes. They don't use titanium.

You are referring to the ring stiffners and bulkheads? Then the greater depth of the Oyashios being a conseguence of having accepted a more performance driven internal layout in order to achieve failure pressure nearer to the hull material yield stress. Could their large size have favored a more efficient balance being struck in the efficient layout-habitability trade-off? I take the reference to different metals as an indication that different structural elements are optimized using different metals. Yes? The greater technical prowness of the Japanese could also indicate closer tolerances as further justification of the asserted greater op. depth. relative to the materials used.

The relationship between the specific strength of the structural materials and the performances still stands in principle, but now it's clearer that it's not a matter of simple substitution, but of complete redesign.

Which leads to a question. Do bigger subs offer more scope for improving hull structural efficiency than small subs?

 

[gf0012-aust]

Could their large size have favored a more efficient balance being struck in the efficient layout-habitability trade-off? I take the reference to different metals as an indication that different structural elements are optimized using different metals. Yes?

Yes - the comment about the number of different metal types was also in relationship to Collins. The point about titanium usage in general applies to both Collins and Oyashios.

The greater technical prowness of the Japanese could also indicate closer tolerances as further justification of the asserted greater op. depth. relative to the materials used.

The design of the sub is central to their own build philosophies - the build philosophy is closer to an australian similarity than a french or german.

The relationship between the specific strength of the structural materials and the performances still stands in principle, but now it's clearer that it's not a matter of simple substitution, but of complete redesign.

Its a whole of concept design issue. You just cannot substitute material "x" for material "y". There are implications on the whole design.

Which leads to a question. Do bigger subs offer more scope for improving hull structural efficiency than small subs?

Bigger subs (and I'm talking about anything over 3000 tonnes - in very very broad terms offer greater scope for signature management and control. A sub is a big underwater transducer. Mass has a singularly important effect on noise propogation.

Contrary to lots of popular assumptions, and again, on very very broad terms - smaller subs do not necessarily provide a smaller object of interrogation and/or for detection.

 

[Francois]

I am aware of the existance of technical difficulties with using titanium (or more appropriatly titanium alloys) for a submarine pressure hull.
Taking the discussion back to the S1000 Italian Russian co-operation project I believe that those difficulties have been overcome in Russia and that they possess the know-how for building them. Also the high alloy steels have building issues of their own, they are magnetic and Italy and Russia may not have the know-how. Also I doubt the high yield steel alloys currently employed are that close to titanium alloys in terms of specific strength.
And amagnetic steel doesn't have the required characteristics of strength-density.

Well, I think I said that even russians gave up the idea.
No, there are no solutions to the problem. The rest is blah-blah-blah.
Italians haven't designed a sub since WWII.

If the steel S1000 has submerged persistance of 10 days at 4 knots, a titanium hull S1000 will have 20 days at the same speed plus no (or smaller) magnetic signature. How much would one pay for this and how much would it cost? I don't know. But it certainly is extremely interesting.

Eh? What is the relation between submerge time and the composition of the hull. I am scared you are mixing things up a bit here.

See, gf, I was right.

 

[contedicavour]

Well, I think I said that even russians gave up the idea.
No, there are no solutions to the problem. The rest is blah-blah-blah.
Italians haven't designed a sub since WWII.

Eh? What is the relation between submerge time and the composition of the hull. I am scared you are mixing things up a bit here.

See, gf, I was right.

Ehm... we haven't exported a SSK since WW2. We have however designed 2 classes of subs, the coastal SSKs of the Toti class in the '60s and 4 separate batches of the Sauro SSK class. Fincantieri also designed a follow on class in the '90s, but given the small numbers that could be ordered, unitary costs were sky-high and it was obvious to all that participating to the German HDW U212A made much better sense.

Btw, in terms of design, Fincantieri and Ansaldo even conceived a SSN in the late '60s, that was to be called Marconi. Except that budget cuts and the notoriously anti-nuclear power Italian public opinion killed the project before it could be built.

cheers

 

[Francois]

Ehm... we haven't exported a SSK since WW2. We have however designed 2 classes of subs, the coastal SSKs of the Toti class in the '60s and 4 separate batches of the Sauro SSK class. Fincantieri also designed a follow on class in the '90s, but given the small numbers that could be ordered, unitary costs were sky-high and it was obvious to all that participating to the German HDW U212A made much better sense.

Btw, in terms of design, Fincantieri and Ansaldo even conceived a SSN in the late '60s, that was to be called Marconi. Except that budget cuts and the notoriously anti-nuclear power Italian public opinion killed the project before it could be built.

cheers

Wasn't Toti class a derivative of an aborted US design?

 

[contedicavour]

Wasn't Toti class a derivative of an aborted US design?

Not that I am aware of. The Toti class was a small coastal sub, I don't see why the USN would have been interested in it !
The Sauro (in its 4 batches) was a 100% Italian design, which btw almost got exported to Iraq together with the FFGs, corvettes and AOR which were in the final package.

cheers

 

[Francois]

Not that I am aware of. The Toti class was a small coastal sub, I don't see why the USN would have been interested in it !
The Sauro (in its 4 batches) was a 100% Italian design, which btw almost got exported to Iraq together with the FFGs, corvettes and AOR which were in the final package.

cheers

Well, actually, there was a program at the start of the cold war, initiated by the US Navy, for building like 2 or 300 small submarines to lay astraside of russian's subs routes.
That was mainly the answer to the Whiskey program.
I don't remember the name of the program, as I don't have my references by me right now.

The Italians got something in the program and ended with designing their own (Toti) by iteration of the former program.

Now, I think (but can't do much now, have to check my data again) that somewhere the Germans were involved in the design of the Sauro class.
But history kept that the design/built is Italian.

 

[contedicavour]

Could you also check your references on the design of the SSN Marconi ? I'm interested in the history of the design phase, especially if Fincantieri and Ansaldo did it all on their own or with foreign help.

thks

cheers