There's nothing inherently wrong with being double-hulled. Just a different design philisophy and the Russians swear by it. Double hull makes anti-active sonar facetting easier as well.
New sailless SSN (provisional)
- Thread starter ACuriousPLAFan
- Start date
Double hull comes with some ugly acoustic issues like resonance between the hulls at speed. Russian swear by it due to needing large reserve buoyancy (and some rumored technical issues with single hull construction) and hence took some trade offs.
Anti-active sonar faceting is a pretty nebulous advantage given we have not seen any demonstrations of it and this sub does not appear to have any visible faceting. Active sonar is also of questionable use in actual combat right now, there's a reason USN has transitioned to a fully passive bow sonar and only keeping a small sail mounted active sonar.
Subs have their center of buoyancy above their center of gravity. Sail is a factor of instability. In side slip conditions -for example while sub is turning- it can generate enough lift force to roll the submarine. For this reason a truly maneuvrable sub would have to get rid of the sail. The Soviet Lira class (Alfa as it is named in the West) was very maneuverable and had a very streamlined sail too. Its sail was also towards the middle of the sub.
If the beam really is 12 meters, it is highly likely that this sub is of considerably higher displacement than the 09V and is essentially an elongated form of it. What the elongation would be for? We can only speculate at this point. The highest possibility would be an extended VLS farm.
Though if the submarine is double hulled, effective volume by still be considerably smaller than 09V which would limit the amount of VLS you could fit. Also, the flat portion of the hull on the back doesn't seem to be wide enough for rows with two large tubes like on the 09V and it doesn't seem to be long enough to fit more tubes than the 09V in a single file.
If 093B can fit 24 cell VLS, then this thing can fit in a lot more than that.
12m beam for double hull would be 10m inner hull beam, maybe a little more than that? An outer hull (especially if we consider the small sail) could potentially be designed to have lower radar reflection if elevated and probably lower return against active sonar ping (at least that's what I remembered the Brits said about follow on to Astute class). So it would allow them to test out some different concept in modern submarine. 10m inner hull would still be spacious enough for boat to be quiet like Virginia class.
If it's nuclear electric (as I would suspect), then propulsion unit would take up less space than traditional. Again, I would suspect a pretty large mission module or VLS farm or both. Part of this may be suspicion on my mind that due to the role it might be playing, it wouldn't need as many crew member and that you can have large mission module without it being 140m long.
The flat portion of the hull on the new submarine is significantly narrower than the 093B (Beam of 11m) and hence would likely not allow for 3 VLS being positioned in a single row. The extra couple of meter of hull and more compact propulsion could possibly compensate by adding a bit more columns of VLS but I doubt anything significantly more than the 09IIIB/09V. Also, assuming this submarine is fitted with VLS, IMO it'll likely be of the same multipack tube type on the 09V but in arrangement like the VPM for commonality and adaptability with future large VLS which will reduce packing density somewhat as a drawback.
Plausibly? I still somehow doubt the active sonar stealth part given that active sonar AFAIK isn't much of a threat in the open oceans as it has relatively short range and is tactically dubious to use, but anyhow normal submarines still have rubber tiles to help against active sonar. It may be more of a threat for coastal operations where you might face fixed installations etc which is why 039C and A26 are moving toward stealthy sails and even then, none of those have a faceted stealthy hull. Neither do there seem to be much public research on this, most that I could find are about optimising the control surfaces and sail design against active sonar, though it is possible that much of this type of research would not be public if it existed.
Main issue with double hulled submarines is difficulty of maintenance and rather tedious construction while if not designed or maintained properly the outer hull might get "loose" and resonate at high speeds which ruins acoustic performance and have a larger displacement for the same internal volume which drives up power demands and overall costs. There are certain advantages like having very high reserve buoyancy, likely having more survivability (Though is rather dubious given that if torpedo/mine detonated close enough to rupture your ballast tanks, you are probably facing much greater issues) and extra space to store external equipment like CMs and towed arrays. IMO, I personally don't think these advantages are important enough to outweigh the advantages gained by single/hybrid hull and even the biggest fan of double hulled submarines, the Russians are designing their new submarine to be hybrid hulled instead of being mostly/fully double hulled.
Given that the pressure hull segments seen in JN was measured to be ~11m in diameter (Credits to @Maikeru) and the pressure hull cap next to it seems to be slightly larger in diameter, IMO this submarine is more likely hybrid hulled instead of pure double hull like the older 09IIIBs which would allow most of the advantage of double hulls but combined with the relatively cheaper construction, ease of maintenance and larger internal volume for single hull.
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That's more a damping problem than a double hull problem because Resonance can be changed relatively easily.
you are being overly technical with name here. When I say VLS, I'm thinking anything from standard single tube to VPM, just a large section for attack missions.
If it is actually 11m in diameter, then I would agree it's more likely hybrid. Which then raise the question of what does this allow them to carry and what kind of special missions they intend.
It's probably wider than 11m, and also probably longer than 120m
But I am also curious about how it'll fit VLS on the non-flat portion.
But I am also curious about how it'll fit VLS on the non-flat portion.