I read the articles. Three of those were acts of desperation by a submarine commander could not use his vessel's PRIMARY defensive tactic of submerging and sneaking away. Two of those three cases resulted in the loss of the U-boat and enemy victory.Which, like the teeth of a cornered rabbit, is not their intended use, nor is it even their typical use, and as per the examples you cited, turned out to be a highly ineffective use after all.
Your definition of highly ineffective is either off or you just didn't bother to read the articles. Stern tubes were of use to discourage and potentially sink pursuing ships.
Funny math.
U-85 missed with her stern torpedo and was eventually sunk. That is case 1 where defense didn't work.
The O-21 used her stern torpedoes against the following, then pursuing U-95. That is case 1 where defense did work.
The Tang successfully used her stern tubes against ships that attempted to ram her and also against a destroyer firing on her as she was making her escape. That is case 2 where defense did work.
The Spadefish missed with her stern torpedoes but forced a destroyer to zig and attempt to depth charge her but she escaped. That is case 3 where defense did work.
One of them wasn't a case of "discourage pursuers" but was a preemptive attack by a Norwegian submarine to sink what it suddenly realized was an enemy vessel.
So what was the Norwegian sub going to do to defend themselves? Use harsh words to discourage them?
Yes, OFFENSIVELY, at ships you have specifically targeted and are maneuvering to get a position on. "Discourage pursuers" is not what the designers had in mind when they installed them; you can use mines and fishing nets for that too, but those devices were also developed with a different purpose in mind.
Now you're just being silly. That torpedo tube is there for offense and defense. A pursuing ship on the stern of a sub would qualify for a down the throat shot.
It's really no different than the Romulans tossing an old-style demolition nuke out of their garbage chute. The nuke is designed for self-destruction, but a sufficiently desperate commander might rig one as a mine if he thought it was his only chance to survive.
Or no different than the E-D firing her aft torpedoes to slow down or blind a pursuing enemy ship to affect an escape.
That's the main scenario: a submarine running on the surface has a top speed of not more than 20 knots (usually much less), while in WW-II submarines mainly attacked while submerged where their top speed was not much more than 10 knots.Obviously stern tubes could also be used for attack as the sub turns to leave and open distance after attacking with her bow tubes.
You're oversimplifying it. For daytime and nighttime periscope attacks that would be true but not for daytime and nighttime surface attacks. Depending on visibility conditions the WW2 submarine could choose to fight on the surface and utilize her faster surface speed.
A vessel at that speed doesn't "open the distance" as such;
I was speaking in reference to the sub conducting combat on the surface. This occurred during mostly nighttime when conditions in WW2 allowed for surface attacks.
Wake homing torpedoes, IIRC, were used in this capacity in 1944 and 45 and were pretty effective. Significant to note that wake-homing torpedoes cannot be used in a "down the throat" attack and have to be fired from a rear aspect on an enemy ship or else they'll have nothing to guide on. The acoustic torpedoes you mention in your link were mainly experimental and from what I've read were only used a handful of times before Germany surrendered.Also interestingly, the Germans thought of using torpedoes to take out escorts. They had some kinks to work out but apparently got it to work near the end of the war.
According to "Naval Weapons of WW2", p264 by John Campbell the T5 torpedo was in use in Sept 1943 and used 640 times with 58 hits (9% hit rate) against typically "difficult" targets. This is compared to the aggregate hit rate of over 20% for other German torpedoes. That doesn't sound experimental or used only a handful of times.
You should read "US Submarine Operations in WW2" by Theodore Roscoe. It's a fascinating account of combat operations in WW2 and it's not all "daytime periscope" combat as you'd like to make it out as.