Rumoured "mini-nuke/diesel" Submarine SSK-N(?) thread
- Thread starter ACuriousPLAFan
- Start date
You use the Stirling engine to charge the battery. There's no conflict between the 2. That's how AIP works in the first place. There's no mechanical transmission between engine and propeller. It's always engine charges battery, battery handles everything else. But you have to charge the battery somehow.
One point of using a Stirling is to avoid the use of a steam generator which is big, heavy and complex. The other is silence. If these don't exist then navies around the world are dumb for using it because its not the most powerful or efficient engine. Since they probably aren't idiots, it's used for a reason.
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It is much easier to build high power steam turbines. The technology also already exists in other kinds of power plants.
It is very hard to build a high efficiency Stirling engine. Let alone a high power one. And they are infamous for being much larger than internal combustion engines of similar power level as it is.
It is very hard to build a high efficiency Stirling engine. Let alone a high power one. And they are infamous for being much larger than internal combustion engines of similar power level as it is.
Again, Stirling makes a lot of noise compared to battery system & electric motor/drive, which normally makes very little noise. Drive an EV, you will know how quiet it gets.
So if you want to get Stirling engine to be as quiet as the battery system & eDrive, you need to raft it. The navies around the world, including China would mount their Stirling engine.
Stirling would need to be constantly running to provide enough power to move at a lower depth, which is what you want here. If you are going to do the extra hard work of fitting a nuclear reactor in a smaller submarine, then you need it to actually gain the advantages of a nuclear submarine. So, you will need to mount whatever number of Stirling engines to keep the noise down.
vs if you just a steam turbine, you just need to mount and isolate that 1 steam turbine
lol, 1.2MW isn't enough to go at 14 knots for any sustained length of time and you can't go too deep either
I think we may have a communication issue here? Stirling engine does not refer to a particular combustion engine. It refers to a heat engine that uses the Stirling thermodynamic cycle, just as a turbine is a Rankine engine that uses the Rankine cycle. The particular energy source of a Stirling engine does not matter, this is made very clear in my sources below.
In an earlier post, you had the wrong idea that a Stirling engine was a particular type of combustion engine, so I want to make very clear that it is not a particular combustion engine but a class of engine configurations (with engine broadly used here as a device that converts temperature gradients into mechanical work).
The steam turbine is also not integral to a reactor. The only things integral to the reactor is the reactor itself, any control devices, and the heat exchange loop. The steam generator and turbine are all external. All a reactor does is heat up. It doesn't do anything else by itself. The heat exchanger is integral because it must be hermetically sealed to prevent escape of any coolant that touches reactor parts but nothing else is.
Because all a reactor does by itself is heat up, to convert that heat to electricity, you need an engine. It does not matter what that engine is, only that it is an engine. For this particular application, it's best for that engine to be low noise, with acceptable efficiency. A turbine is 1 type of engine. A Stirling is another type of engine.
The Stirling engine does not replace the battery in any configuration, it replaces the diesel or the turbine. It is used to charge the batteries. It is irrelevant that it is not as quiet as battery, because neither is a turbine or diesel and the batteries have to be charged somehow. There is no alternative here. You can't pick 'battery', battery is not a energy source, it is a energy storage. You have to pick diesel, Stirling, fuel cell, or turbine.
Further proof that Stirling engines are not combustion engines:
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That is the thing. It does not need to do everything full sized sub can do to perform its role. For a sub stealth and endurance is the bread and butter, everything else is bonus. If it can perform like 70% of its role better, then full sized sub would be used for the rest 30% niche. That is most of its role replaced. Thus, the navy may dedicate 70% budget for this type, while leaving 30% to SSN. This is what I meant by replacing. Number here is for illustrating the point. How much it is actually replacing is dependent on final product of SSKN.
Rubis-class 7100kw 25 knots translate to 14 knots at 1280kw
Edit: I didn't mean to come across as so terse, but I'll leave the original text below for consistency's sake.
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No, you are incorrect, again.
Stop talking about the SSKN as if it can perform any part of a SSN's role "better," in fact stop comparing it to a SSN to begin with.
This entire framing of the SSKN is almost a waste of time because everyone is automatically comparing the "SSKN" upwards to SSNs with big hopes and dreams of somehow being able to use them to "master stroke" out a fleet of submarines that are "basically like SSNs" with only minor detriments yet at much lower cost and able to be fielded in larger numbers.
I am telling you, that is categorically the wrong way of framing the discussion -- it is not helpful to view the SSKN as if it is some sort of replacement or augmentation to a proper SSN capability, rather what it serves as (if it emerges at all) is to fit the SSK mission profile better.
If we were to roughly breakdown the various "traits" of usual nuclear attack submarines, and usual SSKs, and the proposed "SSKN," relative to one another, we would see this:
| Nuclear attack submarine | Diesel electric submarine | "Mini-nuke" submarine | |
| Cost | High | Low | Unknown |
| Submerged endurance | High | Low | High |
| Perishable endurance (food, crew) | High | Low | Low |
| Speed | High | Slow | Slow to moderate |
| Weapons load | High | Low | Low |
| Size | Large | Small/medium | Unknown, likely small/medium |
| Sensors and processing | High | Variable | Variable |
| Stealth | High | High | High |
Keeping in mind that we don't know the SSKN's true characteristics yet, and the few we do "know" are based off rumours right now, we still have enough basis to say that the SSKN is far closer to a SSK in characteristics rather than a genuine SSN -- the only domain in which it is similar to a SSN is its submerged endurance by virtue of being technically nuclear powered.
However in every other domain, including the perishable endurance of the ship (limited by food, crewing facilities), weapons load, hull diameter, sensors and processing capacity, and especially speed, the SSKN is far closer to that of a SSK.
Speed is vital and cannot be underestimated between that of a genuine SSN, because the ability to propel yourself at 30+ knots to ingress or egress out of a situation, with the powerplant to support it cannot be underestimated and it is arguably the most significant difference between that of a SSN and a regular SSK after submerged endurance.
Top speed, and ability to maintain top speed, is not something that can simply be handwaved away --- it is such a massive component of a nuclear submarine's capability profile, that by not having it, is the equivalent of comparing an aircraft limited to subsonic speeds versus an aircraft which is capable of sustained high mach supercruise.
That is why I keep banging on about how this "SSKN" shouldn't be compared with a SSN at all.
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