Hello gents!

I've got a few questions that I hope you might be able to answer, specifically about a few details of some of the torpedoes produced and used during the war that I'm unclear about.

First, about the detonators used in the torpedoes, were magnetic detonators used with the G7a torpedoes, or only contact detonators?

Second, I understand that the T-II G7e was very similar to the T-III G7e. What were the primary differences between these two variants? There seems to be some confusion about this. For example, I heard first that the T-II ran a distance of only 3000m at a speed of 28kts, while the T-III ran 5000m at a speed of 30kts. Later I heard that the difference in range and speed reflects a non pre-heated vs. pre-heated battery, and the torpedoes were different only in detonator mechanism.

Third, with regards to the T-III torpedoes, I've read that the pattern running variant had a longer range of 7,500m at the same speed of 30kts. How was such an improvement in range possible, and was this something applied only to the pattern runners or the straight running type as well? If anything, I would expect additional mechanisms in the torpedo used to allow it to run a pattern would reduce the maximum range...

And finally, is there any knowlidge on how common the various pattern running and acoustic homing torpedoes were in service? Was there an effort to replace the older straight running torpedoes completely with the newer types, or were they only available as an addition to the standard versions?

Thanks for your time!