Don't know about the He-111 torpedoes but i can have a root around my library and see what i can come up with...probably won't be much though .

The reason for the Japanese torps being faster and longer ranged is that the Japanese used pure oxygen rather than compressed air in the torps. With oxygen all of the contents of the pressurised bottle used to store it are used in propulsion (the heavy steel pressurised bottle used to store the compressed air/oxygen was very heavy...over 1000 lbs).Compressed air is only about 28% oxygen with 70% being Nitrogen which not only does not contribute to propulsion,but gives you that nice visable trail of bubbles behind the torp. With pure oxygen 100% of the contents are available for propulsion and the exhaust gases are mostly soluable in sea-water...so no bubble trail. So using oxygen you had a torp which could go faster and be longer ranged (more oxygen for combustion in the torpedoe's engine) but which also did not leave any visable trail behind it. As for the Germans copying the design i'm not sure...i'll have to check it out is i think i did see somewhere a reference to an experimental German torpedeo with and oxygen power plant.

The germans concentrated on Electric power and towards the end of the war tried to introduce a series of Walter H2O2 powered torpedoes. The attractiveness of the Walter H2O2 process over pure oxygen is that H2O2 was a liquid which could be stored at atmospheric pressure.....thus it did not need a heavy pressurised container and could be stored in a light,rubber-lined compartment in the torpedeo. More weight could be dedicated to propellent and/or warhead in a Walter torpedeo than in a compressed air/oxygen or electric torpedeo. The engineering and safety
problems with H2O2 meant that none of the German designs became operational.

The allies all introduced H2O2 torpedeos after the war...the British withdrew their H2O2 torps after HMS Sidon blew-up and sank while loading H2O2 torpedeos.The Americans modifired their main compressed air torp, the Mk14 to run on H2O2 (they called it Navol,i think) as the Mk16 and it was in srevice up to the early 70's.The Russians also adopted H2O2 as a torp fuel and the recent sinking of the Kursk has been blamed on an explosion of a H2O2 powered torpedeo.

The problem with high concentration H2O2 is that it is VERY reactive...it will react with allmost ANY substance and decompose explosively into Oxygen and high temperature Steam. That said the Japanese did not have an easy time developing the 'Long Lance' oxygen torpedeos...it took nearly 15 years to get the torpedoes right. The main problem was that the torpedoes kept on blowing up prematurely on their runs.Eventually it was found that the line carrying the oxygen from the storage bottle to the engine was the cause. This line twisted and curved to reach the engine and in the curves the oxygen tended to build-up and any 'rough-spots' in the line encouraged this.The line would then rupture and pure oxygen would flood tha after body of the torpedeo causing the torpedeo to blow up. The solution was to straighten out the oxygen lines and to clean them regularly with a potassium based cleaner.


I hope this has been of some interst/use.

Rgrds

Sniper.