Scorpene Stumbles Towards The Finish Line

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gf0012-aust 8/28/2010 8:02:50 AM

But it's the AIP boats that are the real killers.

seriously, do we have to see the capability definitions dumbed down like this? We've seen a number of events where well trained crews in conventional non AIP boats from various navies have outperformed the AIP wunderkinds. Its not an issue about AIP - its an issue about training and proficiency. The USN has seen this for themselves at RIMPAC. training and persistent sea time counts more than gucci kit.

The noise of the diesel engines can easily be picked up by other subs.

its not the diesel engines - its because they also have lousy props. the russians sold them subs with crap blade designs - in fact most modern merchies have better blade designs as well as better tech sets/material science issues

The Scorpenes are similar to the Agosta 90B subs

no they're not. the agostas were modified with post production signature management mods. they have well trained crews who also have more persistent sea time.

This enables the sub to stay under longer, thus making the sub harder to find. AIP allows the sub to travel under water for more than a week, at low speed (5-10 kilometers an hour).

which is meaningless without context. at 10kmh the sub will be a moving transducer anyway..

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earlm Question for gf 8/28/2010 11:05:09 AM

I know you don't like the hypothetical questions much, but:

How would an AIP boat perform compared to a non AIP boat if, and here's the zinger, all else were equal. We all know all else isn't equal but I do find this question interesting.

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Hamilcar 8/28/2010 12:56:04 PM

I know you don't like the hypothetical questions much, but:

How would an AIP boat perform compared to a non AIP boat if, and here's the zinger, all else were equal. We all know all else isn't equal but I do find this question interesting.

I would like to know myself, since I was always of the opinion that unless it was a fuel cell boat, that a Carnot cycle or Stirling was going to put noise into the water from some kind of sound short.

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gf0012-aust 8/28/2010 5:06:22 PM

How would an AIP boat perform compared to a non AIP boat if, and here's the zinger, all else were equal. We all know all else isn't equal but I do find this question interesting.

if all else is equal (and they NEVER are) - then AIP will change/improve the endurance and persistence parameters on select taskings.

its not that I object to hypotheticals, its more of an issue that I object to oversimplified and dumbed down throw away commentary such as AIP being a gamechanger.

to reiterate. some have done tests on AIP and shown that the bang for buck over capability was not warranted - it has been come the new buzzword which gets thrown around like some mystical techset which will change outcomes - just "because" its been fitted.

it doesn't - and it hasn't.

it's another tool which can be of benefit. a good crew in a crap boat will sink a less experienced crew in a gucci kitted boat every time.

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earlm 8/28/2010 11:25:41 PM

MESMA is a steam turbine so I can't imagine it's that quiet. I would also hypothesize that the hissing steam in the pipes provides a distinct signature although I doubt that anyone's going to post a confirmation of that.

Stirlings are quieter than Diesels because there is no deflagration-detonation in the cylinder itself, nor are there valves.

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Shawnc AIP Misconceptions 8/30/2010 6:04:15 AM

IMHO, a lot of people seem to think AIP systems are equivalent to having a nuclear reactor without the noise issues. Thus an AIP boat doesn't need to snorkel while still being as quiet as a regular diesel.

In most cases, AIP systems are used as a source of electrical power generation for battery recharge and to power the electric motors for propulsion. The current state-of-the-art, however, cannot provide a complete power solution for a submarine as the specific power generation is below demand, so it's considered a secondary or auxillary system.

For example, A Type 214 with hydrogen fuel cells has (taken from Wikipedia):

Diesel engines: 2x MTU 16V-396 - 3.96MW

Charging engines: 2X Pillar Ntb56.40-10 - 0.97MW

AIP system: 2X HDW PEM fuel cell BZM129 (.25MW)

Electric motor: 1X Simens Permasyn (2.85MW)

From these figures, it would still be far faster to recharge the batteries by snorkling than AIP, but where AIP comes in is in situations where snorkeling is too dangerous, such as if your sub is near a coastline doing something sneaky and you don't want to poke a snorkel out, but it's safe enough to sit on the bottom and take time to recharge.

IIRC, I was once discussing flank sonar arrays with GF on diesel boats, and he mentioned that one of the reasons the Colllins class isn't AIP is that they didn't need to. I figured from his comment that as the Australians were seeking a bigger than usual diesel boat for extended open ocean service, their requirements included increased battery capacity - thus there was no need for AIP in a sense, as the Collins wouldn't need to snorkel as frequently as other diesels.

Oh, and imagine snorkeling in a crowded litorrial conditions - like say, the Straits of Malacca, where your diesel engine could be one of hundred marine diesels operating within a 20km radius...

So let me ask... instead of implementing a USD$60 million, 300 ton MESMA AIP module into a Scorpene, why not add an an equivlent weight module with batteries and another charging engine? It's be more cost effective, you would extend battery range and duration, and snorkelling recharge would be quick.

On the Indian submarine front - as usual, their purchasing decisions are screwy - they're currently operating 2 diesel sub classes from very different manufacturers (Russian Kilos & German Type 209s), and they're adding French Scorpenes into the mix, as well as Akulas and their own ATV design.

As for the Scorpenes... one wonders why the Spanish cancelled their order and chose to develop the S80 instead.. anything to do with French sensor and combat management systems perhaps?

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earlm 8/30/2010 4:35:41 PM

Why do they have separate main diesels and charging engines?

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gf0012-aust 8/30/2010 5:30:50 PM

The Stirling AIP engine originally procured for Collins is an orphan sitting on a pallet in a warehouse. Tests showed that the cost benefit and capability analysis didn't support its integration into the sub. valuable space was then used for other duties.

As I stated before, there are any number of RIMPAC events as well as training events in the Indian Ocean where skimmers made some very bad assumptions about endurance, based on commonly acquired data and perceptions about what long range diesels could do. Irrespective of the fact that these are partial prosecution successes, it doesn't alter the fact that commonly held beliefs even by professionals can be fundamentally flawed and drive incorrect tactical decisions.

Although in the current generation of smaller subs I can see benefit in having AIP double duty as a companion generation asset, I think its utility is a narrow set of opportunities.

That doesn't alter the fact that any sub that can increase underwater endurance will keep its crew happy, we need to remember as you say that it does not make them mini nukes at an endurance level. If thats the belief then its false comfort and excellent marketing spin from the box floggers of AIP systems.

Is AIP useful? - sure - in tight parameters

Is it a gamechanger? - potentially - in tight parameters

Is it necessary? - no, but see the first point.

all this spin about the magic of AIP is just unadulterated tosh. Its all about context, utility and the end state is ultimately about crew competency.

as a counter point, there are nuke subs out there with better endurance but they sound like the overflow of the Hoover dam during full flight - acoustic transmission = death

rhetorically speaking - what would you rather be in? :)

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gf0012-aust frelling SP software 8/30/2010 6:04:15 PM

my prev was quoting parts of Shawns post.

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Shawnc 8/31/2010 1:38:57 AM

as a counter point, there are nuke subs out there with better endurance but they sound like the overflow of the Hoover dam during full flight - acoustic transmission = death

rhetorically speaking - what would you rather be in? :)

Strangely enough, I recently started playing that old subsim game Red Storm Rising (it's abandonware and available in DOSBox for Mac) and even though it's a game (and an old one at that), it's smegging hard to sneak up onto a Soviet Tango or Kilo in a Seawolf... best tactic is to get an approximate range bearing and fire Sealances at them.. too bad the US Navy cancelled that in real life. An alternative method is to fire a guided torp in the general direction from a distance where they can't pick up your noise, then ping them to fix their location just before the torp reaches attack range...

In this case, the game's assumption is that the diesels have less sonar capabilities than American nukes, which should be the case in reality, as the nukes are able to generate more 'hotel' power for more powerful flank and towed sonar.. unless you happen to be a nuke that runs into a hunter-killer diesel like the Collins...

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