Why are SSBNs so Quiet?

[Ghost Dog]

submarines are always some form of compromise. you balance what you need with what you'd like.

SSKs for example are better suited to defensive, coastal and shallow water operations. thier lack of range, small size and therefore limited weapon loadout means they need to stick closer to the homeland. Thier quietness makes them worthwhile.

SSNs are a bit on the flipside. Countries with more global foreign policy aspirations require submarines that can get to trouble spots fast, stay on station a long time during a developing crisis and carry more weapons for extended combat operations. nuc boats, maybe a bit 'louder', but its thier operational capabilities that attract the buyer countries like France, UK, USA and Russia.

[Kapitan]

india also has two new akula boats (one deliverd one under way)

before these two akula boats was the charlie class boats now india has always been on at pakistan about kasmir and vice versa whats stopping pakistan now is the fact india has nuke boats and pakistan old obsolete daphne boats.

india only wants to be dominant in the indian ocean which it is her forign policy only calls for defence rather than attack so the need for a SSBN is zero at the moment.

the SSK submarines india has do short close to home patrols the nukes are on extended patrol ie travel far and wide

this is the advantage of a nuke over diesel

[OKO]

Originally Posted by Orm

OKO, I could say that Kapitain is in some way right about French SSN and SSBN noise level. Amethyste/Rubis –class subs have had always a very bad reputation, as they are quite noisy and slow (25 knots, not very fast for SSN). But, as for the new Triomphant-class SSBN, it got a serious boost in underwater technology and indeed is very quiet. The same seems to be for the new Barracuda-class SSN that will be somewhat a “European Virginia�.
One thing more, as a French and as a former sailor, I have always think that French military ships were not up-to-date compared with other European and North American navies. For example, the lack of CIWS onboard makes them very vulnerable to SSM and the new Aster missile is still on development. Also, we know how expansive and inappropriate (too slow, too short, not very liable…) was the commission of the Charles de Gaulle carrier.
At least the new Mistral command and control ship was just commissioned and seems to look “modern� and very useful for this age of conflict.

As I mentionned, there is no lack of funds for submarines, but, for sure, our navy need a real update.
With professionalisme, the face of our army is changing.
But change takes time.
In 2012, we will have one of the most modern armee in the world (now, armee is not the first place where the gouvernment take money to pay off other items...).
Not in quantity, but in quality.
With a real force projection capability, far from the US one, but we are 67 millions french, not 260 millions, and our defense budget is 1/3 to the one of the united states per resident ...
this give you a budget of 1/12 of the US one in defense ...
You just can't compare.

french forces now center the interest on high quality equipment, to the detriment of the quantity.

we have the best tank ever made -the most recent also- (but also the most expensive), we have now a very good plane (rafale) able to do by himself all missions of the different older planes we had, with really greater efficiency.

For navy, the new BPCs, like the Mistral, will give us a real projection capability
With the Charles de Gaulle (and the next carrier build with english), the BPCs ( http://www.defense.gouv.fr/sites/mar...stral/mistral/ ... couldn't find something in english about it ...) and other vessels, we will have a real projection tool, comparable to the english one, and certainly (except if the russian budget for armee increase by X5 next 5 years, that is quite unlikely ...) best than the russian one.

Another strange thing of the french armee :
we sold fregate "horizon" to taiwan.
Fregate Horizon is the first warship (not transport ship) ever made with stealth design.
You can easily say it's the most modern fregate ever made.
But, as there was lots of budget problem for armee last years, the french ones are under equipped, when the taiwan ones are fully equipped .....
So we sold best hardware than we were able to make for us, here ...

But there was a real wake up on the armee problem, and now, this budget is not the first to cut into.
So we can hope in 2012, we will have a real good navy tool.

Concerning the Charles de Gaulle, this was our first nuclear surface vessel.
After lots of incidents, due to this new concept (we are the third natio to build this kind of vessel after United States and Russia), I can assure you the Charles de Gaulle is now 100% operationnal and fonctionnal
Some FA18 and US E2-C were landing on it recently during military exercice.
we still have to few modern planes on it (only some rafale at this time), but each years, the CVN receive some new, and will be completed full of rafale in the next 5 or 7 years.

I could say : not so bad for an average country like France.
Even if our navy was in really deep trouble last times, you will see a big change in the next years.

[TLAM Strike]

Originally Posted by OKO

Fregate Horizon is the first warship (not transport ship) ever made with stealth design.

I thought our USS Holland was first true stealth warship. :rotfl:

JK

[OKO]

Originally Posted by TLAM Strike

I thought our USS Holland was first true stealth warship. :rotfl:

JK

oopss and the first french stealth fregate was the La Fayette and not Horizon ..........

the next one, the FREMM is really the next century fregate =>

http://www.dcn.fr/us/produits/fregate.html

isn't it a beautifull ship also ?

we will have 17 of them from 2008.

From 2012, french navy will be much more modern than today.
You can say it's not that difficult ...
but next generation ship coming in the near future will greatly change the face of our navy.

for the USS Holland, I think you joke at me, but as I don't know this boat, I can't laught with you
can you show me something about it please ?

[PeriscopeDepth]

USS Holland was the first US submarine, OKO.

http://www.history.navy.mil/photos/s...snsh-h/ss1.htm

[TLAM Strike]

Originally Posted by OKO

for the USS Holland, I think you joke at me, but as I don't know this boat, I can't laught with you
can you show me something about it please ?

The USS Holland was the US Navy’s first modern submarine bult around 1900. There was an ad by General Dynamics that was run in USNI's Proceedings (A magazine about Naval Warfare) that said "The original Stealth Fighter" and it had a picture of a submarine.

There was also "There is no (line drawing of a sub)-stitute" (Substitute, get it?) and "Every commander should bring a concealed weapon... A submarine".

[Orm]

To OKO,

I am not saying that our navy is obsolete but until now, most of the ships are commonly looked as under armed – even the La Fayette – like you said sold to Taiwan but with American weaponry.

[Deathblow]

Originally Posted by Neutrino 123

SSBN are reportedly very quiet, but why is this so? It seems to me in a basic analysis that they really shouldn’t be much quieter then SSNs of similar technology (though all sources say they are, so I would of course expect this to be true).

SSBNs have similar propulsion to SSNs, but they have a lower maximum speed. Approximately speaking, this implies similar machinery to the SSNs (this seems to be the case on cutaways I’ve seen, too…), but since the SSBNs are larger, they need more power to get the same speed, and thus, the machinery would generate more noise for the same effect. Presumably, this would be somewhat mitigated by additional quieting equipment. However, the storage space for the large missiles should limit the amount of space available for other things such as this, especially since the SSBNs usually have a larger crew and a fairly good torpedo armament, too.

In addition, the water noise flow that accounts for a portion of the BB noise (I am not sure how much, but this is something I would like to know…) would be significantly greater in the SSBNs.

…so, when considering the above, why are the SSBNs much quieter? Can they really fit enough quieting equipment to do this? If this is efficient, why not add similar equipment to the SSNs?

This is a long dead topic, and rightfully so because it basically degraded into a flame war... but I found some interesting comments that address the original questoin and wanted to share. Why are SSBN's quiet?

http://en.wikipedia.org/wiki/Natural_circulation

Apparently the Ohio is quieter than the LA because its reactor, the S8G, maintains a natural circulation mode (reactor cooling without pumps) for a good fraction of the ships power. It does so by the geometrical arrangement of the reactor, steamflows, and turbines as well as coolant ducts that minimize flow resistance, and remove the pumps from the waterflow when not in use. This might also mean that when the pumps *are* turned on, they are not optimally arranged and peak cooling power (and thus reactor power) is not optimal.

On the other hand the LAs S6G reactor, according to the article, cannot operate in natural circulation mode (NCM) for very long if at all, needing its pumps at all times, probably because less geometrical freedom for the neccesary flow arrangements and the decision to use space for optimal pump placement for sprinting.

:hmm: If we were to carry this idea forward a bit more.... we might even surmise that the reason the SW has such a larger hull diameter than the LA was to allow the geometrical freedom needed for a significant natural circulating mode, without sacrificing peak cooling power; its hull is even wider than the hull of the Ohio... enough room for both a good NCM for quiet and optimal coolant pumps for sprints.

We might also surmise that the VA's smaller size maintains its NCM ability of the SW, but looses some of the peak cooling power, so its peak reactor ouput (and thus peak speed) is slower than the SW though its "silence level" is maintained.

Or course there are the other quiet methods incorporated into the various systems as well and this is all spectculation of course but seems to fit reasonably well :hmm: