said. You talk about nuclear submarines like they're based on WW2 era conventional hulls that slow down underwater due to their hull design being optimized for the upper hull being above the water whereas the modern teardrop shape is optimized for high speeds entirely under the water without accounting for air friction, and yes to a submarine air has more drag than water does as weird as it sounds.>>1330>>1335
Stealth is not nearly as much as a factor as you think it is, its mostly propigated by the US because that's literally the only thing their subs did better than their Soviet counterparts… until the Soviets built the Akula and Victor IIIs which had rafter machinery basically making US subs redundant. Anyways, it's mostly useless because stealth only matters when your enemy is using passive sonar, AKA hiding and masking your sound signature, and the assumption is always to make it masked by masking it with environmental sounds however it can only ever get so quiet. The Soviets once again figured out the answer and masked it by simply changing the resonance and harmonics of their subs' engines on the fly, so if they're detected American subs check their database of Soviet sub sounds and realize it's actually a local trawler. Yes that thing from Red October sounding like a whale is a real thing and wasn't some experimental device but really just the engineer of any given sub hitting the engine slightly to change its pitch. As to why it only matters with passive sonar, that's cause you physically cannot hide from active sonar. Passive sonar is when you hear a ship's propellers whereas active is the pinging and works kinda like underwater radar. Anyways, you cannot hide from it since it WILL bounce off your hull since it physically exists. You can dampen it with rubber padding, you can misdirect it with thermal layers, or even try hiding on the bottom of the ocean but in general once your enemy turns on the pings, it's a game of cat and mouse.
And that's why stealth is trumped by speed. See speed is fucking life, since according to soviet simulations in the 1980s, all sub combat falls into 2 catagories: launching an attack from out of range or the game of cat and mouse. So positioning in both is key, both to get into an attack position and to dodge sweeps and attacks. Now you might say well speed doesn't mean you can dodge torpedoes but yes it fucking does. The Papa and Alfa class scared NATO so much because they could literally outrun and go deeper than any of their deeprunning torpedoes and in the UK at least caused a crash programme to develop the Tigerfish torpedo. And even if a torpedo catches up to you, a weird quirck of how water physics work is that the faster you go, the better you turn since you get more water moving over the control surfaces, meaning more drag meaning your drift better, so you want to go fast in order to turn fast to get under or over a torpedo since that's how submarine tactics work when dodging torpedoes(Launch a decoy, torp goes for decoy does a 90 degree turn to come back around and catch you but you've move above its search circle in a 3D plane). Also check >>1223
as to why they don't do supercavitating submarines, it's not because the reactors can't handle it(The Soviets literally design liquid metal reactors to work on deep running subs because of the reason OP stated), but because of the human factor. The Papa and Alfa only went 47 and 45 knots respectively because their crews were too afraid to go any faster lest they DO actually supercavitate which is a very very slippery slope since once you start supercavitating it's hard to not go even faster and they didn't want to be fucking squished since that did almost happen on the Papa class's speed trial.