[masklinn]

> Attack submarines are much smaller than missile subs. I don't understand exactly why this is

SLBM are big, a Trident II is 13.6m long and 2.11m wide[0] and Ohios need to fit them straight up plus the hull, so we're talking 14m moulded depth or so (excluding the sail), and a pretty similar beam, at which point… you just have a big sub, because it can't exactly be a ball: you need to fit 12 Tridents in a row, plus the reactor, engine, crew compartments, passages for the crew to move around, torpedo tubes, and enough stores to last for literally months.

Attack subs can have vertically mounted cruise missiles but those are puny compared to an SLBM, a Tomahawk is 6.25m long with booster[1]: an Ohio-class carries 24 Tridents in SSBN configuration, if converted to SSGN it carries 154 tomahawks.

Los Angeles carries 37, Seawolf carries 50 (and on both this competes with torpedoes and anti-ship missiles, on an Ohio you get 24 tridents or 154 tomahawks plus a dozen torpedoes or anti-ship missiles).

[0] and Typhoon's SLBMs were even larger at 16.1m by 2.4

[1] and 0.5m wide

[goatinaboat]

SLBM are big, a Trident II is 13.6m long and 2.11m wide[0] and Ohios need to fit them straight up plus the hull, so we're talking 14m moulded depth or so (excluding the sail),

There are designs that use the sail, the North Koreans are using that configuration. They took old Romeo class and extended the sail back along the hull to fit 3 launch tubes. But the tubes extend so far down into the hull that they have had to remove batteries in order to do it. Which is a pretty severe compromise as what you absolutely want in such a sub is endurance.

Interestingly they have designated those missiles Pukkuksong, which translates as... Polaris!

[jbc1]

The Typhoon was also built to operate in the Arctic. The bigger it is the more ice it can punch through to fire missiles.

[dmurray]

I didn't consider that the missiles need to be stored vertically, but that makes a lot of sense, thanks.

[masklinn]

Technically they don't need to, but storing them vertically means you don't have to surface to launch: if you can make the missiles buoyant (at will, usually by pumping gas or vaporising a bunch of water when you want to launch them) they'll pop out the water like corks at which point the rocket engines fire and off it goes. This means your sub can stay safe and secure below the waves while launching.

[dmurray]

Why do you need them vertically stored for that scenario? Couldn't you make the front of the missile more buoyant than the rest, so once you pop it out of the sub it self-rights and likewise pops out of the water?

I imagine flipping from horizontal to vertical would put stresses on the rocket body, so there are engineering problems to solve, but still it's surprising that the only way to solve that problem has to been to build a launch platform 5 or 10 times bigger than is otherwise desirable.

[masklinn]

> Why do you need them vertically stored for that scenario? Couldn't you make the front of the missile more buoyant than the rest, so once you pop it out of the sub it self-rights and likewise pops out of the water?

That would make the entire thing more complicated with more chances of failure because now the SLBM wobbles around when it tries to right itself up (on a non-aerodynamic axis so more chance it'll move wrong), you need much bigger openings for the missiles, and your gain will be limited: remember, they're 2m wide so if you stack them by 4 you still need 9m for the missiles alone except now you also need to have 3 rows of missiles meaning you need a lot of extra horizontal space (in the current configuration the missile compartment of an Ohio is about 40m, it'd need to be 60+). It also makes the launch procedure take longer, as the missile can't accelerate as fast out of its casing: it doesn't just pop straight up like a cork anymore.

[jabl]

Also, reportedly Soviet ballistic missiles were/are less accurate than US ones, so they compensated by having a bigger bang, in turn needing a bigger missile to launch it.

Another solution would be to do what the North Korean missile subs, putting the missile tubes in the (lengthened) sail.

[masklinn]

> Another solution would be to do what the North Korean missile subs, putting the missile tubes in the (lengthened) sail.

The US used to have something like this in the Regulus, their intended launcher (the Grayback-class) essentially had hangars.

The great advantage of SLBMs is that the vertical mounting and a good enough launch sequence means you don't have to surface to launch: https://youtu.be/sUlXty69-Y8