Submarine Autistry, on August 4, 2023, providedinteresting insights on conventional submarine evolution:
“Right now, I think there are two major trends in
conventional submarine design.
The first is size. For many years, there weren't really any
modern diesel submarines of large size (around 3,000 tons or more) and range
(>15,000 nm). The Soviet Union did have conventional submarines with an
enormous radius of action [eg. Foxtrots up to 20,000nm] and eg. Tango-class. But these had to rely on the aged
principles of the Type XXI submarine (with inferior submerged performance in that German wartime design) in as late as the 1970s. (The succeeding and far more
modern Kilo-class was smaller with a much-reduced range [of up to 8,600nm].) But in recent years, Defense Companies have increasingly come up with
designs of large, AIP-equipped subs that can cover a lot of distance (examples
include Type 216, Type 212CD (E), Saab Blekinge Oceanic, Shortfin Barracuda, Navantia S-80
Plus, Japanese Soryu/Taigei and South Korean KSS-III).
The second trend is VLS cells for SLBM capability, which is most
certainly the purpose of [INS Drakon’s] extended sail. I can imagine Drakon [a
Dolphin 2] to be used primarily as a one-off test platform for the newly
developed missiles so that the technology will be ready by the time the Dakar-class
["Dolphin 3"] boats arrive. Since Israel/TKMS will follow suit after KSS-III kicked off
this VLS trend, I can also imagine cooperation with South Korea for missile
development, although Israel's missiles will likely be quite a bit larger than South
Korea's Hyunmoo 4-4. Certainly very interesting to see such
a large sail [on INS Drakon] a modern submarine when people think they will
disappear entirely within this century, a charming callback to the early Soviet
SSB(N)s! [particularly the Soviet Golf-class SSB that had up to 3 SLBMs in its sail.]
Overall, these two trends clearly point toward an expansion of conventional submarine capabilities into areas that were thus far reserved for nuclear propelled submarines. While I can understand this striving, I'd doubt that the enlarging of conventional submarines can give them the same strategic perks that the nuclear submarine possesses by its very nature (unlimited power!!!; i.e. infinite (submerged) range, blistering speeds). I suppose the biggest benefit of conventional subs, quietness, has already come quite close to its optimum, meaning that constructors are now reorienting toward special features (e.g. “diamond” shape). Also conventional subs have broader capabilities and strategic value (range, armament), while not making the submarine much less quiet than its predecessors - but certainly much more expensive to acquire for potential contractors due to its size.”