If the German leadership in the early Nazi or late Weimar days decides that Surcoef or other ships like that French SSV are the future of warfare, could they pursue *very* large submarines as an alternative? 5000+ ton or maybe even larger ones to try and compensate? Granted they would be likely disasterous failures and resemble something out of a video game but might they go that direction?
It's possible, if they are prepared to give up something else. And why should a cruiser sub be a disastrous failure? Something like the I-400 or an American V-class with suitable dive controls would be a viable weapon system, with a credible mission niche as a special operations or strategic sub.
So McPherson, no way for a submarine under attack while submerged to defend itself?. I'll give you the floating primercord, tho, as I recall, it was suggested during WW2. Obviously, it would be deployed while the sub was underway, not as a position marker. Equally obvious would be that a sub preparing to blast a polyna thru arctic ice would withdraw to a safe distance.
I didn't expect that my description of a Buoyancy driven glider could apparently be confused with a towed paravane. As already demonstrated by Rutgers, it is entirely silent, capable of speed (I'll try for reference) and excellent L/D fluid equivalent, which could move it far from its launch location .
Such defenses as are practical, are
avoidance, masking, decoys, silence and maneuvering. Any active system or method that points back at the sub that announces "here' is where I am attached or where I came from" is a trackback and "kill me" invitation. This includes bubbling torpedoes, radio transmissions, towed objects that leave wake tracks or
anything identifiable that can be vectored or beared back to the sub as an origin point. Whenever someone proposes an active measure as a means of self protection, such automatic detection and enemy trackback is a certainty. And so far, every suggestion I've read proposed equals a loss of mission, a dead sub and ineffective tradeoff of investment to return in the scheme proposed. A submarine's defense and success, reiterated, lies in surprise, escape, maneuver, silence, misdirection, evasion after it strikes and them hiding and avoidance until the next attack opportunity.
Will try for clarity in the future.
Dynasoar
Clarity was not lacking. A fundamental understanding of what waking, signals transmission noise, and launch transients might be something that should be considered. Let me give an example. One of the reasons that wet heater torpedoes are a terrible idea, if the technology that produced them can find an alternative, solution is that a wet heater torpedo leaves a trail of bubbles in its wake. This is the reason why every nation that produced or adopted that type of technology had to develop a gyro based offset guidance to curve the torpedo into the target, because a straight runner left a trail of bubbles pointing back at the sub that pointed exactly where the sub was and where to drop the mortar bombs or depth charges to kill it. A curved path makes it harder to trackback as well as help with an aspect solution on a acute angle aspect target. This can be remedied with 100% combustion (oxygen or navol boosted) torpedoes with little bubble and wake exhaust, or by electrics which have no exhaust wake at all. Another problem with the wet header is that it is loud and noisy, giving an immediate sound bearing trackback to its launch point. A two speed electric torpedo does not. An electric torpedo is a defensive measure.
THESE are the kind of defensive measures that one must investigate with subs. Rubber tiles, radio absorbing plastics, jettisonable communications transmitters, low wake periscopes, fire and forget wake, sound or pattern running quiet no-wake torpedoes, fast cycle dive controls, mechanical quieting methods, no trackback passive detection gear, non-magnetic hulls, etc. Get the point? Noise (signal transmission of any kind)='s death. Quit trying to make noise.
We all have our own opinions, of course, and I for one find discussions of new and different ideas refreshing and fun.
I try to explain why I hold my opinions.I hope that it shows why I shoot down some proposals and I hope I offer reasonable alternatives. (See above.)
Interesting link and I thank you for it but I still think the Germans or the Americans could have made a lager solid fuel rocket than that used by the nebelwefer, I could be wrong, I'm not a rocket scientist (far from it

) but I think the main reason it wasn't done was because they saw more promise in liquid fuel rockets.
Von Braun, and Oberth started with Tsiolkovsky and Goddard. They were fixated on liquid fuels because that was the simplest practical path to a LARGE rocket. They knew about the problems with solid fuels and why large solid fuel rockets were problematic. They had not figured out how to make a large candle that would burn from the inside out without blowing apart. They were not fluid dynamicists
Van Kaman was. So was a devil worshipping lunatic associate of his named Jack Parsons who blew himself up perfecting a rubberized solid fuel rocket motor that eventually powered most of America's solid fuelled rockets of the 1950s and 1960s. To make it simple, the Americans had to find a way to make a large slow burning "candle" that would generate about 8x the pressure of gunpowder without blowing a lightweight motor casing apart. To do that, the Americans had to figure out how to make the burn itself operate as the pressure confiner and the plenum chamber, not the motor casing. There is no gun barrel made that can withstand the temperatures and pressures of a large solid fuel candle as big as a V-2. None exists and probably never will. And a gun barrel would be too heavy to lift.
Nobody, and I mean nobody, before JATO figured it out how to make the candle the confiner. It was a bit of geometry and a bit of fluid dynamics, and it was trial by error and a little alchemic chemistry that cost lives (Parsons was working on another scheme of his; an entirely new scheme lost to us. It was in his garage when it exploded and he died when something went horribly wrong.) The WW II Germans were stuck with gunpowder and nitro-cellulose bases and that limited them to either clumsy liquid fuelled rockets or the powder rockets of the type they made. Short ranged and size limited. So when I write, now, that Sidewinder, the later Polaris and its successors took ten years or more to develop after JATO, yeah I mean it. Could the Germans do it? Maybe; if they had the proper mix of maniacs and a single minded super-genius who went that solid fuel route. They chose liquid fuels. This will not work well at sea. Hypergolics go Boom.
Anyway; that's my two cents on the subject and I'm sure we could both go back and forth on the subject but this is a submarine thread not a rocket thread and I don't want to derail it.
Nice chatting with you.
Rockets are still a viable weapon; even black powder ones...
Like Jack Parsons, he died trying to perfect his weapon. The secret he took to his grave. The USN is just now devising a version as an anti-torpedo defense ===> a rocket shell that can be used as a last ditch bullet against a wake-homing torpedo. The Russian version, falsely advertised as an antisubmarine weapon, is a rocket shell that is called SHKVAL. It is poorly understood, but it appears to be a direct fire projectile that is designed to impact into a surface ship hull and sink it. The Russians consider it a suicide weapon that is to be used by a doomed sub as a kamikaze shot. It definitely violates every submarine rule about not announcing oneself to an enemy with a loud noisy weapon.
It makes a dandy oil tanker killer.